Development and Validation of the ElectroSacroGram (ESG): A Digital Point-of-Care Tool for Real- time Neuro-Sacral Assessment After Spinal Cord Injury

Development and Validation of the ElectroSacroGram (ESG): A Digital Point-of-Care Tool for Real- time Neuro-Sacral Assessment After Spinal Cord Injury | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Development and Validation of the ElectroSacroGram (ESG): A Digital Point-of-Care Tool for Real- time Neuro-Sacral Assessment After Spinal Cord Injury Maude Duguay, Jean-Marc Mac-Thiong, Juan-David Cifuentes-Hernandez, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7135084/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 11 Dec, 2025 Read the published version in Journal of NeuroEngineering and Rehabilitation → Version 1 posted 9 You are reading this latest preprint version Abstract Background Accurate assessment of neuro-sacral function after spinal cord injury or lesion (SCI/L) is critical for diagnosis, prognosis, and early management. However, current bedside methods such as the digital rectal examination (DRE) remain subjective, invasive, and examiner-dependent. Surface electromyography (s-EMG) offers a quantitative alternative but lacks point-of-care integration. We developed and validated the ElectroSacroGram (ESG), a digital, surface-EMG-based tool for real-time sacral neurophysiological assessment. Methods This study aimed to 1) develop the ESG protocol based on clinical consensus; and 2) evaluate its diagnostic performance compared to radiological findings and expert-performed DRE. In this prospective diagnostic accuracy study at a specialized Level 1 trauma center, 52 adult patients with suspected SCI/L and 21 healthy participants underwent ESG and DRE assessments. ESG captured sacral motor (resting anal tone, maximal voluntary anal contraction (maxVAC), reflex (bulbospongious or bulbocavernosus reflex [BSR]), and sensory (electrical perceptual threshold [EPT]) function using s-EMG and electrical stimulation. Clinically relevant DRE parameters were selected by a nine-member expert panel. Content validity was quantified using item and scale content validity indices (I/S-CVI). Although DRE is inherently subjective, it is the current bedside reference standard; therefore, agreement with ESG was evaluated using Cohen’s kappa (k) to assess concurrent validity. Diagnostic accuracy was assessed using contingency tables with imaging-confirmed spinal lesions as reference. Results Normative ESG values were defined in healthy participants. Neurologically impaired patients had lower maxVAC and BSR amplitudes and higher EPT. ESG showed excellent content validity (S-CVI = 1) versus DRE (S-CVI = 0.43). Agreement with DRE was almost perfect for VAC (κ = 0.876) and EPT (κ = 0.881), moderate for BSR (κ = 0.671), and slight for resting anal tone (κ = 0.205). ESG showed 83.3% sensitivity, 100% specificity, and 86.5% overall accuracy for detecting radiological abnormalities. Conclusions ESG is a novel digital diagnostic tool that enables objective, real-time neuro-sacral assessment at bedside. By overcoming the limitations of DRE, ESG may improve diagnostic precision and early decision-making in SCI/L. Its point-of-care digital format supports future integration with clinical decision support systems, remote monitoring platforms, and machine learning models for predictive neurodiagnostic. Multicenter validation and longitudinal modeling are warranted. digital diagnostics digital neurophysiology spinal cord injury surface electromyography point-of-care technology neuro-sacral assessment Figures Figure 1 Figure 2 INTRODUCTION The digital rectal examination (DRE) is a cornerstone of neuro-sacral function assessment and spinal cord integrity evaluation following spinal cord injury/lesion (SCI/L). While essential, DRE is inherently subjective, invasive, and highly dependent on examiner expertise, limiting its ability to provide quantitative and reproducible assessments. (1) As a result, subtle neurogenic dysfunction may go undetected, and inter-examiner variability can impact clinical decision-making. Neurophysiological testing offers a more objective approach by measuring the electrical activity of sacral-nerve-innervated muscles. (2) However, conventional electromyography (EMG) has not been widely adopted in clinical practice due to several limitations, including offline analysis, incomplete assessment of neuro-sacral parameters (e.g., resting anal tone, voluntary motor and reflex activity, and sensory function), and reliance on needle electrodes, which reduces patient acceptability. Surface electromyography (s-EMG) has recently emerged as a non-invasive, quantitative alternative for neuro-sacral function. (3) Notably, s-EMG has demonstrated the ability to detect voluntary anal contractions (VAC) that are undetected by expert-performed DRE, suggesting its potential to enhance early detection of neurological improvement. (3) However, existing s-EMG methods are not optimized for real-time, point-of-care use, limiting their integration into acute care settings. To address this gap, we developed the ElectroSacroGram (ESG): a digital neurophysiological tool designed for bedside use, which combines real-time surface EMG recording with automated sacral function assessment. ESG captures motor, reflex, and sensory data relevant to the sacral spinal cord and generates interpretable digital outputs suitable for rapid clinical decision-making. By transforming a subjective exam into an objective digital signal, ESG has the potential to improve the standardization and scalability of neuro-sacral assessment in SCI. Although DRE is limited in reliability, it remains the current clinical reference standard; therefore, evaluating the ESG’s agreement with DRE is necessary to establish concurrent validity within the existing diagnostic framework. In parallel, we assessed the ESG’s diagnostic performance against imaging-confirmed spinal pathology, to examine its potential as digital screening tool for early neurogenic dysfunction. This study aimed to 1) define and validate the ESG protocol based on expert consensus; 2) evaluate its content and concurrent validity in comparison with DRE; and 3) assess its diagnostic accuracy in identifying radiological abnormalities following SCI/L using normative data derived from healthy participants. METHODS Design and population This prospective diagnostic accuracy study represents the first validation of the ElectroSacroGram (ESG), a digital neurophysiological assessment tool, conducted at a Level 1 trauma center specializing in spinal cord injury (SCI) care. A total of 73 participants were enrolled, including 21 healthy controls and 52 adult patients (³18 years) with acute spinal vertebral injuries or lesions– with or without neurological involvement- recruited between March 1 st , 2023, and January 31 st , 2024. To be eligible, patients had to undergo a physiatry consultation, provide written informed consent, and demonstrate full cooperation for neuro-sacral assessments using both ESG and the digital rectal examination (DRE). Patients who refused either test were excluded. Participants were divided into three groups: 1) healthy participants/controls (N=21); 2) a “neurologically intact” patient group (N=12); and 3) a “neurologically impaired” patient group (N=40), based on blinded clinical evaluations conducted by the spinal surgery and physiatry teams. In the neurologically impaired group, ESG was repeated 1-3 times during hospitalization, yielding 62 ESG exams in total (Figure 1A). Data collection Digital rectal examination (DRE): DREs were conducted by one of three SCI physiatrists, each with experience over 300 DREs annually. Table 1A outlines the DRE parameters and methods. To reduce bias, physiatrists alternated the order of ESG and DRE administration. DRE interpretation followed current SCI guidelines (Table 1). (4) ElectroSacroGram (ESG) procedure: The ESG assessment was performed in lateral decubitus position using a handheld, point-of-care s-EMG device (NeuroTrac® MyoPlus2, Verity Medical Ltd, UK). Surface electrodes (3.2cm round, gel coated) were placed over one side of the levator ani muscle, and a 5x5cm ground electrode was placed on the greater trochanter (Figure 1B and 1C). Motor function was assessed using delta amplitudes (Max – Min amplitude, µV). Sensory function was evaluated via electrical perceptual threshold (EPT) testing at S4-S5 using pulsed biphasic symmetrical waves (200 µs pulse width, 10Hz frequency, 5s rest, 1mA increments starting from 1 mA). (5) Stimulation was capped at 17mA (the maximal tolerable threshold in healthy participants); if no perception occurred at 17 mA, a value of 18 mA was assigned. Normative ESG values derived from healthy participants were used to classify patient results. Table 1 describes the ESG criteria used for concurrent validity (present/absent) and diagnostic accuracy (normal/abnormal). Spinal radiological abnormalities: Radiological reference standards included magnetic resonance imaging (MRI) or computed tomography scan (CT-scan) (for missing MRI). Radiologists confirmed the presence of spinal cord edema, hemorrhage, or compression or moderate-to-severe spinal stenosis as markers of pathological neural compromise. Statistical analysis Content validity: A nine-member expert panel (4 physiatrists, one senior neurology resident, one urologist and three spinal surgeons) assessed the relevance of each DRE parameter (e.g., resting anal tone, voluntary anal contraction, anal wink, bulbocavernosus or bulbospongious reflex, S4-S5 pinprick and light touch sensory function, and deep anal pressure) for bedside neuro-sacral function. Responses used a 4-point scale (“essential” to “not necessary”). Item and scale content validity indices (I/S-CVI) were calculated, retaining only parameters with an I-CVI >0.78. (6) Descriptive, construct, and dimensionality analysis: Normality was assessed using the Shapiro-Wilk test. Due to non-normal distributions, continuous variables were summarized using medians and 2.5 th - 97.5 th percentiles. Differences between the three participant groups were evaluated with Kruskal-Wallis tests and pairwise post-hoc analysis. To explore ESG’s underlying structure, principal component analysis (PCA) with varimax rotation was performed on six ESG parameters (resting anal tone, VAC ∆amplitude, maxVAC, BSR ∆amplitude, maxBSR, EPT). Sampling adequacy was confirmed via Kaiser Mayer-Olkin and Bartlett’s tests. (7) Components with eigenvalues >1 were retained, and rotated loadings ≥0.4 were deemed meaningful. Concurrent validity: Although DRE is inherently subjective, it remains the clinical reference standard for bedside neuro-sacral evaluation. ESG-DRE agreement was assessed using Cohen's Kappa (κ). Four a priori hypotheses guided interpretation: ESG would detect subclinical VAC missed by DRE. Agreement would be lower for EPT than VAC due to differing sensory modalities. BSR agreement would be moderate due to unstandardized manual stimulus. Anal tone agreement would be limited due to subjective palpation vs. EMG signal detection. Diagnostic accuracy: ESG diagnostic accuracy for radiological abnormalities was assessed using contingency tables, with calculations of sensitivity, specificity, and likelihood ratios (LR+ and LR-). Analyses used IBM SPSS Statistics v29. Statistical significance was set at p £0.05. Sample size considerations Content validity was evaluated using I-CVI and S-CVI based on expert ratings, with a minimum of 5–10 raters, as typically recommended. (6) Principal component analysis (PCA) required ³40 patients (10:1 subject-to-variable ratio). A minimum of 48 patients was needed to detect k=0.6 with 80% power. Diagnostic accuracy analysis was powered to detect an area under the curve (AUC) of 0.80 (vs. null AUC = 0.50), requiring N=54. RESULTS Study population A total of 74 ESG assessments were conducted in the 52 enrolled patients with vertebral injury or lesion. Of these, 16 patients underwent two ESG sessions and 3 patients underwent three, reflecting repeat testing during hospitalization (Table 2, Figure 1A). No patients declined participation in either ESG or DRE (Figure 1A) and no adverse events were reported from either examination. The neurologically impaired group included 40 patients (mean age 56.26±18.48 years, 70% male, 67.5% traumatic etiology), of whom 34 (85.0%) had SCI/L, and 4 (10.00%) had cauda equina syndrome (CES). Among SCI/L patients, 22 (60.71%) sustained a functional motor-incomplete injury (American Spinal Injury Association [ASIA] Impairment Scale [AIS] grade D), 5 (14.71%) had AIS grade A, 2 (5.88%) had AIS grade B, and 5 (14.71%) had AIS grade C injuries. The neurologically intact group included 12 patients (mean age 60.92±18.30 years, 58.0% male), and the healthy participants group included 21 individuals (mean age 39.62±16.97 years, 24.0% male) (Table 2). Content validity Expert evaluation of DRE parameters identified the resting anal tone, VAC, and S4-S5 light touch as highly relevant (I-CV1=1.00). Deep anal pressure (DAP) and bulbospongious reflex (BSR) were also considered relevant (I-CVI= 0.89 and 0.78, respectively). Pinprick and anal wink reflex were rated lower (I-CVI= 0.67) and excluded from ESG. The overall scale-CVI for DRE was 0.43, indicating poor validity, (6) whereas the ESG achieved an excellent scale-CVI at 1.00. Descriptive results Normative ESG values from healthy participants (N=21) were: resting anal tone amplitude = 2.4 µV (range 0.8 – 3.6), maxVAC ∆amplitude = 18.5 µV (range 9 – 50.3), BSR ∆amplitude = 3 µV (range 0.5 – 11.8), and EPT= 4 mA (range: 1– 7) (Figure 1C). Neurologically intact patients (N=12) showed similar resting anal tone (2.15 µV), moderately reduced maxVAC ∆amplitude (11.8 µV), comparable BSR ∆amplitude (3.5 µV), and slightly higher EPT (6 mA). Neurologically impaired patients had similar tone (2.15 µV), lower maxVAC ∆amplitude (5.3 µV), lower BSR ∆amplitude (2.3 µV), and higher EPT (7 mA) (Figure 1C). Group comparisons showed no significant differences in resting tone (p=0.29). MaxVAC ∆amplitude values were significantly lower in the neurologically impaired group compared to neuro-intact (p=0,005) and healthy participants (p<0.001), as well as between healthy and neuro-intact groups (p=0.03). BSR values were significantly lower in the neuro-impaired group compared to healthy (p=0.01) and neuro-intact (p=0.03), but not between healthy and neuro-intact groups (p=1.00). EPT values were significantly higher in the neuro-impaired vs. healthy group (p<0.001), but did not differ significantly between the other comparisons. Concurrent validity Among the neurologically intact group, agreement between ESG and DRE was 100% across all parameters. In the neurologically impaired group (N=62 ESG exams), agreement for resting anal tone was 82% (k=0.205, p<0.05), for VAC 95% (k=0.876, p<0.05), for BSR 91% (k=0.671, p<0.05), and for sensory function (DRE/DAP vs. ESG/EPT) 97% (k=0.881, p<0.05). ESG demonstrated strong agreement for VAC and EPT, moderate agreement for BSR, and limited agreement for resting tone (Table 3). Dimensionality and construct validity Principal component analysis with varimax rotation revealed two components (eigenvalues >1), explaining 76.9% of total variance. All variables showed strong communalities (range: 0.68–0.95). Components were groups as: 1) motor domain (resting tone, maxVAC), and 2) sensory/reflex domain (BSR, EPT). Diagnostic accuracy Among 74 ESG tests, 57 (77.02%) were matched with MRI and 17 (22.97%) with CT. Based on PCA and Spearman correlation, the best performing ESG variables for each domain were maxVAC ∆amplitude (r=-0.43, p<0.001) and EPT (r=0.35, p=0.01). Results were also validated by the clinical authors of this study. This approach allowed for a clinically meaningful and parsimonious evaluation of ESG’s diagnostic performance while minimizing redundancy across the domains. (7) A test was defined as abnormal (ESG-A) if either parameter was outside the normative range (Table 1); otherwise, it was considered normal (ESG-N). ESG demonstrated a sensitivity of 83.3% (50/60), specificity of 100% (14/14), and overall accuracy of 86.5%. Positive predictive value (PPV) was 100% (50/50), while negative predictive value (NPV) was 58.3% (14/24). The positive likelihood ratio (LR+) was infinite, indicating all ESG-A results corresponded to radiological abnormalities. The negative likelihood ratio (LR-) was 0.167, suggesting a normal ESG (ESG-N) result lowered – but did not eliminate- the likelihood of pathology. DISCUSSION This study introduces the ElectroSacroGram (ESG), a novel, digital point-of-care neurophysiological tool designed to quantify sacral motor, reflex and sensory function following spinal cord injury or lesion (SCI/L). ESG leverages surface electromyography (s-EMG) and structured clinical protocols to objectively assess four core components of neuro-sacral integrity: resting anal tone, maximal voluntary anal contraction (maxVAC), bulbospongious reflex (BSR), and electrical perceptual threshold (EPT). Our results demonstrate that ESG provides robust content validity and high diagnostic accuracy (86.5%) in identifying patients with radiologically confirmed sacral spinal pathology. While the digital rectal examination (DRE) remains the clinical reference for neuro-sacral evaluation at bedside, its limitations -subjectivity, low sensitivity for subclinical function, and inter-rater variability – restricts its utility. (8, 9) ESG addresses this gap by offering quantitative, reproducible outputs that align with psychological domains and can be directly interpreted across users and clinical contexts. Crucially, ESG differentiates between neurologically impaired and intact individuals through its motor (maxVAC ∆amplitude) and sensory (EPT) components, supporting its utility as a digital adjunct to traditional evaluation. These digitally captured metrics may be particularly useful in the early characterization of neurogenic dysfunction – such as altered voluntary control or sensory responsiveness- that may not yet be clinically evident or detectable by palpation-based examination. By standardizing sacral assessment at the bedside, ESG holds promise to support earlier diagnosis, improve the granularity of neurological evaluations, and complement radiological imaging in complex SCI/L presentations. Given its portability, real-time feedback, and minimal invasiveness, ESG may also be suited for longitudinal monitoring of sacral function across the different phases of recovery. This aligns with broader goals in digital medicine to create accessible, scalable tools that enable precision assessment at the point of care. ESG parameter domains and clinical significance The ESG digitally captures sacral neurophysiological function through surface EMG recordings of the external anal sphincter, enabling a structured assessment of both motor and sensory-reflex domains. Our analysis supports the content validity of these domains, which reflect two physiologically and clinically distinct aspect of sacral integrity: 1) motor activation and tone, and 2) afferent sensory conduction and reflex loop responsiveness. The motor domain is defined by two complementary parameters: resting anal tone and maxVAC. Resting anal tone, which reflects basal motor output from the external anal sphincter, may serve as a surrogate marker for injury timing (e.g., spinal shock vs. spasticity emergence), upper vs. lower upper motor neuron syndromes, and potential secondary complications such as pelvic floor hypertonicity. (10, 11) Although not strongly discriminatory in the acute phase, this parameter may offer clinical value in chronic monitoring and response to targeted interventions. In contrast, maxVAC offers a robust and quantifiable alternative to the binary assessment of VAC in the DRE. By capturing subclinical volitional recruitment (ESG+/DRE-), ESG enhances the detection of spared motor function, which has been linked to better recovery trajectories for bladder, bowel, and general functional outcomes. (3, 12) As a digital proxy for sacral motor integrity, maxVAC holds promise for prognostication and therapy monitoring in the early phases of recovery. (13, 14) The sensory-reflex domain integrates the EPT and the BSR, providing complementary views of afferent and reflexive function. (5) EPT quantifies sacral sensory detection thresholds using controlled surface electrical stimulation, primarily targeting Aβ fibers while potentially engaging deeper sensory pathways at higher amplitudes. (15) This contrasts with subjective sensory testing during DRE, which relies on examiner interpretation of patient-reported responses. BSR, although absent from formal classical systems like the ISNCSCI (International Standards for Neurological Classification of SCI), remains a clinically relevant measure of sacral reflex integrity. It probes both afferent pudendal conduction and S2-S4 spinal processing through an involuntary reflex arc. (16) The early reappearance of BSR has been linked to better outcomes in severe SCI and may serve as a physiological marker of reflex circuit preservation. (10) Together, EPT and BSR reflect distinct but converging mechanisms within the sacral sensory-reflex circuitry: EPT captures conscious, ascending sensory pathways, while BSR evaluates spinal-level reflex integrity. Their integration into ESG enables a multidimensional view of sacral function, bridging a long-standing gap in bedside neurophysiological evaluation. Notably, the ability to simultaneously and objectively assess volitional motor control, basal tone, conscious sensory perception, and reflex integrity within a single point-of-care tool represents a significant advance in neurodiagnostics. This comprehensive approach offers new opportunities for earlier characterization of neurogenic dysfunction, more nuanced monitoring of progression or recovery, and standardized comparisons across clinical settings and studies. Normative thresholds and group comparisons This study established preliminary normative thresholds for all ESG parameters using a healthy reference cohort. These thresholds were subsequently validated against a neurologically intact patient group, with strong alignment between blinded assessments and expected values, supporting the clinical utility of ESG in distinguishing normal from impaired sacral function. Although the neurologically intact and impaired groups were comparable in clinical profiles, demographic differences from the healthy reference group – specifically younger age and greater female representation- may account for some intergroup variability, consistent with established effects of age and sex on neuromuscular physiology. (17, 18) Among ESG parameters, resting anal tone did not significantly differ across groups. This may reflect both the inherent variability of this low-amplitude signal and its relative preservation in the acute phase of SCI/L, limiting its value for early discrimination. In contrast, maxVAC and BSR differentiated neurologically impaired patients from both healthy and neurologically intact individuals, but not between the latter two, suggesting high specificity for SCI/L-related dysfunction. EPT also distinguished healthy from neurologically impaired participants, highlighting its potential utility in identifying sensory dysfunction. However, overlap in EPT distributions between neuro-intact and impaired patients (with 53% and 75% of values, respectively, within the normative range) suggests limited sensitivity when used in isolation. Taken together, these findings underscore the need for a multidimensional approach to sacral assessment. No single ESG parameter independently confirmed neurogenic impairment; rather, the combined interpretation of motor and sensory/reflex domains provides a more reliable and nuanced characterization of neuro-sacral integrity following SCI/L. Concurrent validity: agreement between ESG and DRE To assess concurrent validity, ESG outputs were compared against clinical reference standard – expert-performed DRE- using Cohen’s Kappa (k). Agreement was interpreted in the context of four a priori hypotheses, each corresponding to a distinct ESG parameter. MaxVAC: ESG was hypothesized to demonstrate greater sensitivity than DRE for detecting VAC owing its ability to quantify subtle, subclinical motor activity. This was confirmed by the identification of patients with preserved contraction on ESG but undetectable on DRE (ESG+/DRE-), supporting prior findings that surface EMG can capture low-amplitude contractions associated with better functional recovery. (19) This highlights ESG’s capacity to detect residual motor function not apparent through manual assessment. Electrical perceptual threshold (EPT) : Lower agreement was anticipated for sacral sensory function due to the difference in modalities: EPT targets Aβ-mediated light touch via surface electrical stimulation, whereas DRE relies on subjective perception of broad afferent input. As expected, agreement for EPT was lower than for maxVAC, likely reflecting both neuroanatomical pathways and perceptual differences in stimulus detection. Bulbocavernosus/bulbospongious reflex (BSR) : We hypothesized reduced concordance between ESG and DRE for reflex testing, due to variability in manual stimulation during bedside exams. ESG reflex recordings were elicited via standardized manual techniques, but not via electrical stimulation, which was incompatible with real-time bedside use. The moderate κ observed supports the need for future studies employing automated stimulation to improve reproducibility in reflex assessment. Resting anal tone : Lower agreement was also anticipated for this parameter, as s-EMG quantifies low-level basal activity that may not correlate with the subjective tactile perception of the baseline tone on DRE. The limited concordance observed likely stems from low signal amplitude and inter-examiner variability.(8, 20, 21) ESG’s objective capture of continuous baseline activity represents a potential advantage for longitudinal monitoring of sacral motor tone. (22) Together, these findings support ESG’s concurrent validity, particularly for VAC and sensory threshold assessment. Discrepancies between ESG and DRE underscore the complementary nature of the two tools: while DRE offers a quick qualitative snapshot, ESG provides reproducible, quantifiable metrics that may detect subclinical or early changes in sacral neurophysiology. These attributes position ESG as a valuable adjunct in neuro-sacral assessment, particularly in contexts requiring objective and standardized data acquisition. Diagnostic performance and clinical implications Our findings confirm that the ESG demonstrates strong diagnostic accuracy in detecting radiological evidence of spinal pathology. With high sensitivity (83.3%), ESG successfully identified the majority of patients with MRI/CT-confirmed neurogenic lesions. Its perfect specificity (100%), indicating no false positives – supports its reliability as a confirmatory tool (PPV=100%). However, ESG’s diagnostic applicability is currently limited to patients able to fully collaborate with testing procedures (same as for DRE). Individuals with cognitive impairment, altered consciousness, or significant pain (preventing maxVAC generation) may not be appropriate candidates, as ESG requires active participation and comprehension of instruction. The negative predictive value (NPV=58.3%) suggests that while ESG helps rule in neurological impairment, a normal result (ESG-N) does not fully exclude pathology, particularly in milder cases. The positive likelihood ratio (LR + =¥) reflects that abnormal ESG findings (VAC and/or EPT dysfunction) are exclusively associated with radiological abnormalities, reinforcing its role in confirming neurogenic dysfunction. Conversely, the negative likelihood ratio (LR ⁻ = 0.167) indicates that a normal ESG decreases—but does not eliminate—the likelihood of underlying pathology . These findings underscore ESG’s potential utility as a confirmatory test in SCI/L assessment , rather than a rule-out tool. The ESG can also be used from admission to the acute care center and throughout the different phases of care. Given the subjectivity of DRE, ESG offers a quantitative, standardized approach to neuro-sacral evaluation, with applications in triaging, monitoring recovery, and informing long-term management. Beyond its immediate clinical utility, the ESG provides a standardized and quantifiable framework, laying the groundwork for future integration with digital health technologies and predictive analytics. Its structured EMG signal outputs enable the development of clinical decision support systems and remote monitoring applications for patients with SCI/L and cauda equina syndrome. Importantly, the ESG’s digital architecture also opens the door to future machine learning applications . By leveraging large-scale ESG datasets, predictive models could be trained to stratify neurogenic bladder risk, anticipate surgical urgency, or forecast neurological recovery. These capabilities would support more personalized care and optimize resource allocation across the continuum of SCI management. Future research should explore the integration of ESG data into algorithm-based diagnostic platforms, ideally through multicenter studies with longitudinal follow-up. Limitations This study focused on the development and preliminary validation of ESG as a point-of care s-EMG tool for bedside neuro-sacral assessment. To maintain clinical feasibility, electrical stimulation for BSR assessment was not employed; instead, manual stimulation was used, which may have introduced variability due to the lack of standardized stimulus intensity. Although electrode placement can influence EMG recordings, (23) the study demonstrated strong content and concurrent validity. Nonetheless, formal reliability testing is necessary to confirm ESG’s utility for longitudinal follow-up. Future work should also consider bilateral electrode placement to detect asymmetric dysfunction, which may be particularly relevant in cauda equina syndrome. Concurrent validity was evaluated by a single expert physiatrist alternating between ESG and DRE. While this design minimized inter-examiner variability, it introduces potential assessor bias. Future studies should involve multiple blind raters to enhance reproducibility and generalizability. As with DRE, ESG requires full patient cooperation, limiting its applicability in patients with cognitive impairments or pain-related restrictions. Finally, larger-scale, multi-center validation studies are essential before ESG can be broadly recommended for clinical use. Conclusion Neuro-sacral assessment remains a critical yet under standardized component of SCI/L evaluation. The current standard – the digital rectal examination (DRE) – is subjective, invasive, and highly dependent on examiner expertise. In response, we developed the ElectroSacroGram (ESG), a novel bedside-compatible s-EMG tool that enables real-time, objective evaluation of sacral sensory and motor function. Developed with input from a multidisciplinary panel of SCI experts, ESG showed strong content validity and promising diagnostic performance. Principal component analysis identified two clinically relevant domains: 1) motor (resting anal tone, maxVAC ∆amplitude), and 2) sensory/reflex (EPT, BSR) – supporting the construct validity. With excellent specificity (100%), high sensitivity (83.3%), and overall accuracy of 86.5%, ESG effectively detects neuro-sacral dysfunction associated with spinal pathology. In cooperative patients, abnormal ESG results were exclusively associated with radiological evidence of injury/evidence (PPV=100%). While a normal ESG results does not fully exclude pathology (NPV = 58.3%), its objective metrics offer a valuable complement to imaging and clinical examination. Although not suited for uncooperative patients, ESG holds strong promise as a precision medicine tool in acute SCI/L care. Further validation is warranted to support its integration into diagnostic algorithms, guide individualized rehabilitation strategies and prognostic assessment, as well as enhance our understanding of neurophysiological recovery. Abbreviations AIS: ASIA impairment scale AUC: Area under the curve ASIA: American Spinal Injury Association BSR: Bulbospongious sacral reflex CES: Cauda equina syndrome CT: Computed tomography DRE: Digital rectal examination EAS: External anal sphincter EMG: Electromyography EPT: Electrical perceptual threshold ESG: ElectroSacroGram I/S-CVI: Item/scale content validity indices ISNCSCI: International Standards for Neurological Classification of SCI LR: Likelihood ratio MRI: Magnetic resonance imaging NPV: Negative predictive value PCA: Principal component analysis PPV: Positive predictive value SCI: Spinal cord injury SCI/L: Spinal cord injury/lesion s-EMG: surface electromyography VAC: Voluntary anal contraction Declarations Ethics approval and consent to participate Ethics clearance by the institutional review board of the Centre Intégré Universitaire de Santé et de Services Sociaux (CIUSSS) du Nord-de-l’Île-de Montréal - Hôpital du Sacré-Coeur de Montréal and written informed consent from each patient were duly obtained for this study. Availability of data and materials Data is not openly accessible; inquiries should be directed to the corresponding authors and reasonable requests will be evaluated. Competing Interests The authors declare no competing interests. Funding This work was supported by the Chaire de recherche Medtronic en traumatologie spinale (JMMT), grants from the Canadian Institutes of Health Research (CIHR) and the Craig H. Neilsen Foundation (ARD). Funders played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript. Author Contribution Statement MD contributed to patient recruitment, data collection, extraction, and analysis, interpreting results, redaction of the first draft of the manuscript and editing. JDHC and NB contributed to patient recruitment, data collection, result interpretation and manuscript editing. JMMT contributed to patient recruitment, designing the protocol, result interpretation, funding of the study and manuscript editing. ARD participated in designing the protocol, patient recruitment, data collection, result interpretation, funding of this study and manuscript editing. Acknowledgements The authors would like to deeply thank the research team in spinal cord injury of the Centre de recherche du CIUSS-NIM (NeuroTrauma Reamed and OrthoS teams), as well as the clinical multidisciplinary team in spinal cord injury care at the Hôpital du Sacré-Coeur de Montréal for their help in making this project come to fruition. We would like to particularly thank Dr Paul Khoueir, Dr Étienne Bourassa-Moreau and Dr Gilles Maurais for their help in patient recruitment. References Rupp R, Biering-Sørensen F, Burns SP, Graves DE, Guest J, Jones L, et al. International Standards for Neurological Classification of Spinal Cord Injury: Revised 2019. 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Critique and recommendations. Res Nurs Health. 2006;29(5):489-97. Terwee CB, Bot SD, de Boer MR, van der Windt DA, Knol DL, Dekker J, et al. Quality criteria were proposed for measurement properties of health status questionnaires. J Clin Epidemiol. 2007;60(1):34-42. Kava BR DA, Heaney JA. Reproducibility of the digital rectal examination in assessment of anal sphincter tone. . Tech Coloproctol. 2002;6(2):83-6. Guldner GT, Brzenski AB. The sensitivity and specificity of the digital rectal examination for detecting spinal cord injury in adult patients with blunt trauma. Am J Emerg Med. 2006;24(1):113-7. Greciet N, Mac-Thiong JM, Nguyen BH, Richard-Denis A. The Functional Impact of the Absence of a Bulbocavernosus Reflex in the Postoperative Period After a Motor-Complete Traumatic Spinal Cord Injury. Am J Phys Med Rehabil. 2020;99(8):712-8. Previnaire JG. The importance of the bulbocavernosus reflex. Spinal Cord Ser Cases. 2018;4:2. van Middendorp JJ, Hosman AJ, Pouw MH, Van de Meent H. Is determination between complete and incomplete traumatic spinal cord injury clinically relevant? Validation of the ASIA sacral sparing criteria in a prospective cohort of 432 patients. Spinal Cord. 2009;47(11):809-16. Wyndaele JJ. Correlation between clinical neurological data and urodynamic function in spinal cord injured patients. Spinal Cord. 1997;35(4):213-6. Previnaire JG, Soler JM, Alexander MS, Courtois F, Elliott S, McLain A. Prediction of sexual function following spinal cord injury: a case series. Spinal Cord Ser Cases. 2017;3:17096. Tashani O, Johnson M. Transcutaneous Electrical Nerve Stimulation (TENS) A Possible Aid for Pain Relief in Developing Countries? Libyan J Med. 2009;4(2):62-5. Blaivas JG, Zayed AA, Labib KB. The bulbocavernosus reflex in urology: a prospective study of 299 patients. J Urol. 1981;126(2):197-9. Ansdell P, Brownstein CG, Skarabot J, Hicks KM, Simoes DCM, Thomas K, et al. Menstrual cycle-associated modulations in neuromuscular function and fatigability of the knee extensors in eumenorrheic women. J Appl Physiol (1985). 2019;126(6):1701-12. Dedek A, Xu J, Lorenzo LE, Godin AG, Kandegedara CM, Glavina G, et al. Sexual dimorphism in a neuronal mechanism of spinal hyperexcitability across rodent and human models of pathological pain. Brain. 2022;145(3):1124-38. Duguay M, Mac-Thiong J-M, Richard-Denis A. Bedside electromyography for clinical assessment of sacral motor and reflex activity adapted for patients hospitalized with acute neurological conditions: a pilot study. Spinal Cord Series and Cases. 2024;10(1):47. Enck P, Eggers E, Koletzko S, Erckenbrecht JF. Spontaneous variation of anal "resting" pressure in healthy humans. Am J Physiol. 1991;261(5 Pt 1):G823-6. Enck P vdHC, Müller-Lissner S. Function of the external anal sphincter: quantification with surface electromyography. Dis Colon Rectum. 1991;34(5):397-403. Grasland M, Turmel N, Pouyau C, Leroux C, Charlanes A, Chesnel C, et al. External Anal Sphincter Fatigability: An Electromyographic and Manometric Study in Patients With Anorectal Disorders. J Neurogastroenterol Motil. 2021;27(1):119-26. Ken N, Takuya I. Location of Electrodes in Surface EMG. In: Mark S, editor. EMG Methods for Evaluating Muscle and Nerve Function. Rijeka: IntechOpen; 2012. p. Ch. 2. Ltd. VM. NeuroTrac MyoPlus 2Pro - Operators Manual 2016. Available from: https://parsenn-produkte.ch/wp-content/uploads/2022/11/MYO220P-OM-EN04-12-08-21.pdf. Tables Table 1. Description of the digital rectal examination (DRE) and ElectroSacroGram (ESG) procedures and data handling approach. Assessment of DRE parameters based on current standards of care ESG proposed method and threshold values Anal resting tone Resistance of the EAS to passive stretch by the examiner's finger, marked as either: Normal (DRE/tone-N): defined as a firm, uniform and consistent resistance. Abnormal (DRE/tone- A): either diminished (not perceptible or weaker than expected) or increased (resists the insertion of the finger more strongly than expected). Amplitude of the EAS motor activity at rest was noted (in µV), and was also treated for sensitivity and specificity analysis as: Normal (ESG/tone-N): from 0.8 to 3.6 µV. Abnormal (ESG/tone- A): either 3.6 µV. Voluntary Anal Contraction (VAC) Tested by asking the patient to maximally squeeze the finger as if they were holding back a bowel movement (1), marked as either: Preserved (DRE/VAC+) Absent (DRE/VAC-) Amplitude of the EAS motor activity measured by asking the patient to maximally squeeze the anus as if they were holding back a bowel movement (1). The highest value maintained across the 3 trials was noted (in µV). The maxVAC was also treated for concurrent validity analysis as: Preserved VAC (ESG/VAC+): ∆Amplitude (maxVAC-resting tone) ≥0.2µV (device margin of error). Absent VAC (ESG/VAC-): <0.2 µV ESG’s maxVAC ∆amplitude thresholds for sensibility and specificity analysis: Normal (ESG/deltaVAC-N): from 9 to 50.3 µV. Abnormal (ESG/deltaVAC-A): <9 µV. Values exceeding 50.3 µV were not observed but would be considered outliers. Sacral spinal reflex: bulbospongious reflex (BSR) Contraction of the EAS as felt by the examiner’s finger in response to stimulus of the sensory receptors in the urethra and genitals (slightly tugging the indwelling catheter in patients or squeezing the glans of penis or clitoris in healthy participants), and dichotomized as: Preserved (DRE/BSR+) Absent (DRE/BSR-) Amplitude of the EAS motor activity in response to the same stimulus. The highest value maintained across the 3 trials was noted (in µV). The BSR was also treated for concurrent validity analysis as: Preserved BSR (ESG/BSR+): if the ∆Amplitude was ≥0.2µV (device margin of error) (24) Absent BSR (ESG/BSR-): <0.2 µV S4-S5 Sensory function Deep anal pressure was tested by applying gentle pressure against the anorectal wall and asking the patient whether they sense it or not. Light touch and pinprick sensation at S4-S5 key sensory point were also performed and graded as absent (0), altered (1) or normal (2). Sacral sensory function was then dichotomized as: Preserved sensory function (DRE/SS+) : defined as preserved sensation in deep anal pressure. Absent sensory function (DRE/SS-): no sensation at deep anal pressure, light touch or pinprick examination. Electrical perceptual threshold (EPT) was noted (in mA). The EPT was also treated for concurrent validity analysis as: Preserved sensory function (ESG/EPT+): Impulse is felt at maximal impulse or below £17 mA Absent sensory function (ESG/EPT-): no feeling until maximal impulse (17 mA). ESG’s EPT thresholds for sensibility and specificity analysis: Normal (ESG/maxVAC-N): from 1 to 7 mA. Abnormal (ESG/maxVAC-A): >7 mA. DRE: digital rectal examination. ESG: ElectroSacroGram. EAS: External anal sphincter. EPT: Electrical perceptual threshold. MicroVolts ( µV); MilliAmpere (mA) Table 2. Cohort description for the three groups of patients A) Neurologically impaired (N=40) & neurologically intact (N=12) Clinical characteristics Neurologically impaired (N=40) Neuro-intact (N=12) Age at injury in years (mean±SD)) 56.23±18.48 60.92±18.30 Sex (N, % male) 28 (70.0) 7 (58.3) Initial AIS (N, %) AIS A AIS B AIS C AIS D CES 5 (12.5) 2 (5.0) 5 (12.5) 22 (55.0) 4 (10.0) N/A Etiology of SCI/L (N,%) Traumatic Non-traumatic 27 (67.5) 13 (32.5) N/A B) Healthy participants (N=21) Clinical characteristics Healthy participants (N=21) Age at injury in years (mean±SD)) 39.62±16.97 Sex (N, % male) 5 (23.8) CES: Cauda equina syndrome. F: Female. M: Male. AIS: ASIA [American Spinal Injury Association] Impairment Scale. Table 3. Concurrent validity analysis between the ESG and DRE for testing the four key parameters of neuro-sacral function in the neurologically impaired group (N=62). ESG Resting anal tone (N=62) maxVAC (N=62) BSR (N=46) EPT (N=62) A N - + - + - + DRE A 2 1 - 15 0 5 1 9 2 N 10 49 + 3 44 3 37 0 51 Agreement 82% (k=0.205) 95% (k=0.876) 91% (k=0.671) 97% (k=0.881) ESG: ElectroSacroGram. DRE: Digital rectal examination. maxVAC: maximum voluntary anal contraction. BSR: Bulbospongious Sacral Reflex. Sensory: Sensory preservation testing. N: normal. A: abnormal. +: present. -: absent. EPT: Electrical Perceptual Threshold (sensory function). Table 4. Capacity of the ESG to accurately (accuracy analysis) classify neurological impairment in the patient group (N=74). Radiological abnormality condition present (+) absent (-) ESG A 50 0 N 10 14 ESG: ElectroSacroGram. SCI/L +: Spinal Cord Injury/lesion present. SCI/L -: Spinal Cord Injury/lesion absent. N: normal. A: abnormal motor and/or sensory sacral function Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 11 Dec, 2025 Read the published version in Journal of NeuroEngineering and Rehabilitation → Version 1 posted Editorial decision: Revision requested 11 Sep, 2025 Reviews received at journal 09 Sep, 2025 Reviewers agreed at journal 20 Aug, 2025 Reviews received at journal 18 Aug, 2025 Reviewers agreed at journal 30 Jul, 2025 Reviewers invited by journal 25 Jul, 2025 Editor assigned by journal 17 Jul, 2025 Submission checks completed at journal 17 Jul, 2025 First submitted to journal 15 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7135084","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":490988667,"identity":"1b6d4b40-df3b-4d6b-8291-ac8d7f462c73","order_by":0,"name":"Maude Duguay","email":"","orcid":"","institution":"University of Montreal","correspondingAuthor":false,"prefix":"","firstName":"Maude","middleName":"","lastName":"Duguay","suffix":""},{"id":490988668,"identity":"65358b14-a6cd-4bf3-80e1-5986ad638dc0","order_by":1,"name":"Jean-Marc Mac-Thiong","email":"","orcid":"","institution":"University of Montreal","correspondingAuthor":false,"prefix":"","firstName":"Jean-Marc","middleName":"","lastName":"Mac-Thiong","suffix":""},{"id":490988669,"identity":"ba9812d3-5bcc-43d8-a4a0-457f67fdffa2","order_by":2,"name":"Juan-David Cifuentes-Hernandez","email":"","orcid":"","institution":"Hôpital du Sacré-Cœur de Montréal","correspondingAuthor":false,"prefix":"","firstName":"Juan-David","middleName":"","lastName":"Cifuentes-Hernandez","suffix":""},{"id":490988670,"identity":"713d763d-b30e-4d3a-81e1-22de7dd632c9","order_by":3,"name":"Natan Bensoussan","email":"","orcid":"","institution":"University of Montreal","correspondingAuthor":false,"prefix":"","firstName":"Natan","middleName":"","lastName":"Bensoussan","suffix":""},{"id":490988671,"identity":"df68c9e6-f9f6-4fbe-a5f9-8cec0e22c4cd","order_by":4,"name":"Andréane Richard-Denis","email":"data:image/png;base64,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","orcid":"","institution":"University of Montreal","correspondingAuthor":true,"prefix":"","firstName":"Andréane","middleName":"","lastName":"Richard-Denis","suffix":""}],"badges":[],"createdAt":"2025-07-16 02:53:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7135084/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7135084/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12984-025-01797-4","type":"published","date":"2025-12-11T15:58:51+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":87832377,"identity":"c223e729-0d79-4181-bc9c-9d2d0d1ca6c1","added_by":"auto","created_at":"2025-07-29 12:39:09","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":77348,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePatient recruitment and schematic representation of electrodes and patient placement\u003c/strong\u003e. A) Participant recruitment and division into the study’s three groups: Healthy participants, Neurologically impaired and Neurologically intact. \u0026nbsp;B) To perform the DRE and ESG, the patient is positioned in lateral decubitus. A ground electrode is placed over the greater trochanter. Two recording electrodes are placed next to the margin of the EAS at 6 and 9 o’clock over the \u003cem\u003elevator ani\u003c/em\u003e muscle.\u003c/p\u003e\n\u003cp\u003eEAS: External anal sphincter. DRE: Digital rectal examination. ESG: ElectroSacroGram. Tone: Resting anal tone\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7135084/v1/c71435aca0f92cbc5b004885.png"},{"id":87832380,"identity":"945038d3-17d1-4ced-b698-5a9081e06a6d","added_by":"auto","created_at":"2025-07-29 12:39:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":149384,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eESG values for key parameters of the neuro-sacral examination\u003c/strong\u003e. ESG values for each ESG parameter in individuals admitted for a spinal/vertebral injury/lesion (N=52) classified in the neuro-intact group (N=12) or the neurologically impaired (neuro-impaired) group (N=40), as well as in healthy participants (N=21). Values are presented in this violon plot for each parameter of the neuro-sacral examination: A) Resting anal tone, B) maxVAC, C) BSR and D) EPT, showing individual values for each ESG performed as well as median and range.\u003c/p\u003e\n\u003cp\u003eHorizontal red line: median. Upper horizontal black line: 97.5\u003csup\u003eth\u003c/sup\u003e percentile. Lower horizontal black line: 2.5\u003csup\u003eth\u003c/sup\u003e percentile. maxVAC: maximal Voluntary Anal Contraction. BSR: Bulbospongious Reflex. EPT: Electrical Perceptual Threshold. MicroVolts (uV); MilliAmpere (mA). * : p\u0026lt;0.05.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7135084/v1/79bb0100054f9c23f81f521c.png"},{"id":98243982,"identity":"7a4dc4bf-0f95-45a4-85a4-601aef697e9f","added_by":"auto","created_at":"2025-12-15 16:11:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1600305,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7135084/v1/976d0337-73ce-4448-925b-cd3bf2180449.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Development and Validation of the ElectroSacroGram (ESG): A Digital Point-of-Care Tool for Real- time Neuro-Sacral Assessment After Spinal Cord Injury","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThe digital rectal examination (DRE) is a cornerstone of neuro-sacral function assessment and spinal cord integrity evaluation following spinal cord injury/lesion (SCI/L). While essential,\u0026nbsp;DRE\u0026nbsp;is inherently subjective, invasive, and highly dependent\u0026nbsp;on examiner expertise, limiting its ability to provide quantitative and reproducible assessments.\u0026nbsp;(1)\u0026nbsp;As a result, subtle neurogenic dysfunction may go undetected, and inter-examiner variability can impact clinical decision-making.\u003c/p\u003e\n\u003cp\u003eNeurophysiological testing offers a more objective approach by measuring the electrical activity of sacral-nerve-innervated muscles. (2) However, conventional electromyography (EMG) has not been widely adopted in clinical practice due to several limitations, including offline analysis, incomplete assessment of neuro-sacral parameters (e.g., resting anal tone, voluntary motor and reflex activity, and sensory function), and reliance on needle electrodes, which reduces patient acceptability.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSurface electromyography (s-EMG) has recently emerged as a non-invasive,\u0026nbsp;quantitative alternative for neuro-sacral function. (3) Notably, s-EMG has demonstrated the ability to detect voluntary anal contractions (VAC) that are undetected by expert-performed DRE, suggesting its potential to enhance early detection of neurological improvement. (3) However, existing s-EMG methods are not optimized for real-time, point-of-care use, limiting their integration into acute care settings.\u003c/p\u003e\n\u003cp\u003eTo address this gap, we developed the\u0026nbsp;ElectroSacroGram (ESG): a digital neurophysiological tool designed for bedside use, which combines real-time surface EMG recording with automated sacral function assessment. ESG captures motor, reflex, and sensory data relevant to the sacral spinal cord and generates interpretable digital outputs suitable for rapid clinical decision-making. By transforming a subjective exam into an objective digital signal, ESG has the potential to improve the standardization and scalability of neuro-sacral assessment in SCI.\u003c/p\u003e\n\u003cp\u003eAlthough DRE is limited in reliability, it remains the current clinical reference standard; therefore, evaluating the ESG\u0026rsquo;s agreement with DRE is necessary to establish concurrent validity within the existing diagnostic framework. In parallel, we assessed the ESG\u0026rsquo;s diagnostic performance against imaging-confirmed spinal pathology, to examine its potential as digital screening tool for early neurogenic dysfunction.\u003c/p\u003e\n\u003cp\u003eThis study aimed to 1) define and validate the ESG protocol based on expert consensus; 2) evaluate its content and concurrent validity in comparison with DRE; and 3) assess its diagnostic accuracy in identifying radiological abnormalities following SCI/L using normative data derived from healthy participants.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003e\u003cstrong\u003eDesign and population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis prospective diagnostic accuracy study represents the first validation of the ElectroSacroGram (ESG), a digital neurophysiological assessment tool, conducted at a Level 1 trauma center specializing in spinal cord injury (SCI) care. A total of 73 participants were enrolled, including 21 healthy controls and 52 adult patients (\u0026sup3;18 years) with acute spinal vertebral injuries or lesions\u0026ndash; with or without neurological involvement- recruited between March 1\u003csup\u003est\u003c/sup\u003e, 2023, and January 31\u003csup\u003est\u003c/sup\u003e, 2024. To be eligible, patients had to undergo a physiatry consultation, provide written informed consent, and demonstrate full cooperation for neuro-sacral assessments using both ESG and the digital rectal examination (DRE). Patients who refused either test were excluded.\u003c/p\u003e\n\u003cp\u003eParticipants were divided into three groups: 1) healthy participants/controls (N=21); 2) a \u0026ldquo;neurologically intact\u0026rdquo; patient group (N=12); and 3) a \u0026ldquo;neurologically impaired\u0026rdquo; patient group (N=40), based on blinded clinical evaluations conducted by the spinal surgery and physiatry teams. In the neurologically impaired group, ESG was repeated 1-3 times during hospitalization, yielding 62 ESG exams in total (Figure 1A).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData collection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eDigital rectal examination (DRE):\u0026nbsp;\u003c/em\u003eDREs were conducted by one of three SCI physiatrists, each with experience over 300 DREs annually. Table 1A outlines the DRE parameters and methods. To reduce bias, physiatrists alternated the order of ESG and DRE administration. DRE interpretation followed current SCI guidelines (Table 1). (4)\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eElectroSacroGram (ESG) procedure:\u0026nbsp;\u003c/em\u003eThe ESG assessment was performed in lateral decubitus position using a handheld, point-of-care s-EMG device (NeuroTrac\u0026reg; MyoPlus2, Verity Medical Ltd, UK). Surface electrodes (3.2cm round, gel coated) were placed over one side of the levator ani muscle, and a 5x5cm ground electrode was placed on the greater trochanter (Figure 1B and 1C).\u0026nbsp;\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eMotor function was assessed using delta amplitudes (Max \u0026ndash; Min amplitude,\u0026nbsp;\u0026micro;V).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSensory function was evaluated via electrical perceptual threshold (EPT) testing at S4-S5 using pulsed biphasic symmetrical waves (200 \u0026micro;s pulse width, 10Hz frequency, 5s rest, 1mA increments starting from 1 mA). (5)\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eStimulation was capped at 17mA (the maximal tolerable threshold in healthy participants); if no perception occurred at 17 mA, a value of 18 mA was assigned.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eNormative ESG values derived from healthy participants were used to classify patient results. Table 1 describes the ESG criteria used for concurrent validity (present/absent) and diagnostic accuracy (normal/abnormal).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSpinal radiological abnormalities:\u0026nbsp;\u003c/em\u003eRadiological reference standards included magnetic resonance imaging (MRI) or computed tomography scan (CT-scan) (for missing MRI). Radiologists confirmed the presence of spinal cord edema, hemorrhage, or compression or moderate-to-severe spinal stenosis as markers of pathological neural compromise.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eContent validity:\u0026nbsp;\u003c/em\u003eA nine-member expert panel (4 physiatrists, one senior neurology resident, one urologist and three spinal surgeons) assessed the relevance of each DRE parameter (e.g., resting anal tone, voluntary anal contraction, anal wink, bulbocavernosus or bulbospongious reflex, S4-S5 pinprick and light touch sensory function, and deep anal pressure) for bedside neuro-sacral function. Responses used a 4-point scale (\u0026ldquo;essential\u0026rdquo; to \u0026ldquo;not necessary\u0026rdquo;). Item and scale content validity indices (I/S-CVI) were calculated, retaining only parameters with an I-CVI \u0026gt;0.78. (6)\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eDescriptive, construct, and dimensionality analysis:\u0026nbsp;\u003c/em\u003eNormality was assessed using the Shapiro-Wilk test. Due to non-normal distributions, continuous variables were summarized using medians and 2.5\u003csup\u003eth\u003c/sup\u003e - 97.5\u003csup\u003eth\u003c/sup\u003e percentiles. Differences between the three participant groups were evaluated with Kruskal-Wallis tests and pairwise post-hoc analysis.\u003c/p\u003e\n\u003cp\u003eTo explore ESG\u0026rsquo;s underlying structure, principal component analysis (PCA) with varimax rotation was performed on six ESG parameters (resting anal tone, VAC ∆amplitude, maxVAC, BSR ∆amplitude, maxBSR, EPT). Sampling adequacy was confirmed via Kaiser Mayer-Olkin and Bartlett\u0026rsquo;s tests. (7) Components with eigenvalues \u0026gt;1 were retained, and rotated loadings \u0026ge;0.4 were deemed meaningful.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConcurrent validity:\u003c/em\u003e Although DRE is inherently subjective, it remains the clinical reference standard for bedside neuro-sacral evaluation. ESG-DRE agreement was assessed using Cohen\u0026apos;s Kappa (\u0026kappa;). Four a priori hypotheses guided interpretation:\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003eESG would detect subclinical VAC missed by DRE.\u003c/li\u003e\n \u003cli\u003eAgreement would be lower for EPT than VAC due to differing sensory modalities.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eBSR agreement would be moderate due to unstandardized manual stimulus.\u003c/strong\u003e\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAnal tone agreement would be limited due to subjective palpation vs. EMG signal detection.\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003e\u003cem\u003eDiagnostic accuracy:\u0026nbsp;\u003c/em\u003eESG diagnostic accuracy for radiological abnormalities was assessed using contingency tables, with calculations of sensitivity, specificity, and likelihood ratios (LR+ and LR-). Analyses used IBM SPSS Statistics v29. Statistical significance was set at p\u0026nbsp;\u0026pound;0.05.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSample size considerations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eContent validity was evaluated using I-CVI and S-CVI based on expert ratings, with a minimum of 5\u0026ndash;10 raters, as typically recommended. (6) Principal component analysis (PCA) required \u0026sup3;40 patients (10:1 subject-to-variable ratio). A minimum of 48 patients was needed to detect k=0.6 with 80% power. Diagnostic accuracy analysis was powered to detect an area under the curve (AUC) of 0.80 (vs. null AUC = 0.50), requiring N=54.\u0026nbsp;\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003e\u003cstrong\u003eStudy population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 74 ESG assessments were conducted in the 52 enrolled patients with vertebral injury or lesion. Of these, 16 patients underwent two ESG sessions and 3 patients underwent three, reflecting repeat testing during hospitalization (Table 2, Figure 1A). No patients declined participation in either ESG or DRE (Figure 1A) and no adverse events were reported from either examination.\u003c/p\u003e\n\u003cp\u003eThe neurologically impaired group included 40 patients (mean age 56.26\u0026plusmn;18.48 years, 70% male,\u0026nbsp;67.5% traumatic etiology), of whom 34 (85.0%) had SCI/L, and 4 (10.00%) had cauda equina syndrome (CES). Among SCI/L patients, 22 (60.71%) sustained a functional motor-incomplete injury (American Spinal Injury Association [ASIA] Impairment Scale [AIS] grade D), 5 (14.71%) had AIS grade A, 2 (5.88%) had AIS grade B, and 5 (14.71%) had AIS grade C injuries. The neurologically intact group included 12 patients (mean age 60.92\u0026plusmn;18.30 years, 58.0% male), and the healthy participants group included 21 individuals\u0026nbsp;(mean age 39.62\u0026plusmn;16.97 years, 24.0% male) (Table 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eContent validity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eExpert evaluation of DRE parameters identified the resting anal tone, VAC, and S4-S5 light touch as highly relevant (I-CV1=1.00). Deep anal pressure (DAP) and bulbospongious reflex (BSR) were also considered relevant (I-CVI= 0.89 and 0.78, respectively). Pinprick and anal wink reflex were rated lower (I-CVI= 0.67) and excluded from ESG. The overall scale-CVI for DRE was 0.43, indicating poor validity, (6) whereas the ESG achieved an excellent scale-CVI at 1.00.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDescriptive results\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNormative ESG values from healthy participants (N=21) were: resting anal tone amplitude = 2.4 \u0026micro;V (range 0.8 \u0026ndash; 3.6), maxVAC ∆amplitude = 18.5 \u0026micro;V (range 9 \u0026ndash; 50.3), BSR ∆amplitude = 3 \u0026micro;V (range 0.5 \u0026ndash; 11.8), and EPT= 4 mA (range: 1\u0026ndash; 7) (Figure 1C). Neurologically intact patients (N=12) showed similar resting anal tone (2.15 \u0026micro;V), moderately reduced maxVAC ∆amplitude (11.8 \u0026micro;V), comparable BSR ∆amplitude (3.5 \u0026micro;V), and slightly higher EPT (6 mA). Neurologically impaired patients had similar tone (2.15 \u0026micro;V), lower maxVAC ∆amplitude (5.3 \u0026micro;V), lower BSR ∆amplitude (2.3 \u0026micro;V), and higher EPT (7 mA) (Figure 1C).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eGroup comparisons showed no significant differences in resting tone (p=0.29). MaxVAC ∆amplitude values were significantly lower in the neurologically impaired group compared to neuro-intact (p=0,005) and healthy participants (p\u0026lt;0.001), as well as between healthy and neuro-intact groups (p=0.03). BSR values were significantly lower in the neuro-impaired group compared to healthy (p=0.01) and neuro-intact (p=0.03), but not between healthy and neuro-intact groups (p=1.00). EPT values were significantly higher in the neuro-impaired vs. healthy group (p\u0026lt;0.001), but did not differ significantly between the other comparisons.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConcurrent validity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAmong the neurologically intact group, agreement between ESG and DRE was 100% across all parameters. In the neurologically impaired group (N=62 ESG exams), agreement for resting anal tone was 82% (k=0.205, p\u0026lt;0.05), for VAC 95% (k=0.876, p\u0026lt;0.05), for BSR 91% (k=0.671, p\u0026lt;0.05), and for sensory function (DRE/DAP vs. ESG/EPT) 97% (k=0.881, p\u0026lt;0.05). ESG demonstrated strong agreement for VAC and EPT, moderate agreement for BSR, and limited agreement for resting tone (Table 3).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDimensionality and construct validity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePrincipal component analysis with varimax rotation revealed two components (eigenvalues \u0026gt;1), explaining 76.9% of total variance. All variables showed strong communalities (range: 0.68\u0026ndash;0.95). Components were groups as: 1) motor domain (resting tone, maxVAC), and 2) sensory/reflex domain (BSR, EPT).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiagnostic accuracy\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAmong 74 ESG tests, 57 (77.02%) were matched with MRI and 17 (22.97%) with CT. Based on PCA and Spearman correlation, the best performing ESG variables for each domain were maxVAC ∆amplitude (r=-0.43, p\u0026lt;0.001) and EPT (r=0.35, p=0.01). Results were also validated by the clinical authors of this study. This approach allowed for a clinically meaningful and parsimonious evaluation of ESG\u0026rsquo;s diagnostic performance while minimizing redundancy across the domains. (7) A test was defined as abnormal (ESG-A) if either parameter was outside the normative range (Table 1); otherwise, it was considered normal (ESG-N).\u003c/p\u003e\n\u003cp\u003eESG demonstrated a sensitivity of 83.3% (50/60), specificity of 100% (14/14), and overall accuracy of 86.5%. Positive predictive value (PPV) was 100% (50/50), while negative predictive value (NPV) was 58.3% (14/24). The positive likelihood ratio (LR+) was infinite, indicating all ESG-A results corresponded to radiological abnormalities. The negative likelihood ratio (LR-) was 0.167, suggesting a normal ESG (ESG-N) result lowered \u0026ndash; but did not eliminate- the likelihood of pathology.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study introduces the ElectroSacroGram (ESG), a novel, digital\u0026nbsp;point-of-care neurophysiological tool designed to quantify sacral motor, reflex and sensory function following spinal cord injury or lesion (SCI/L). ESG leverages surface electromyography (s-EMG) and structured clinical protocols to objectively assess four core components of neuro-sacral integrity: resting anal tone, maximal voluntary anal contraction (maxVAC), bulbospongious reflex (BSR), and electrical perceptual threshold (EPT).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur results demonstrate that ESG provides robust content validity and high diagnostic accuracy (86.5%) in identifying patients with radiologically confirmed sacral spinal pathology. While the digital rectal examination (DRE) remains the clinical reference for neuro-sacral evaluation at bedside, its limitations -subjectivity, low sensitivity for subclinical function, and inter-rater variability \u0026ndash; restricts its utility. (8, 9) ESG addresses this gap by offering quantitative, reproducible outputs that align with psychological domains and can be directly interpreted across users and clinical contexts.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCrucially, ESG differentiates between neurologically impaired and intact individuals through its motor (maxVAC\u0026nbsp;∆amplitude) and sensory (EPT) components, supporting its utility as a digital adjunct to traditional evaluation. These digitally captured metrics may be particularly useful in the early characterization of neurogenic dysfunction \u0026ndash; such as altered voluntary control or sensory responsiveness- that may not yet be clinically evident or detectable by palpation-based examination. By standardizing sacral assessment at the bedside, ESG holds promise to support earlier diagnosis, improve the granularity of neurological evaluations, and complement radiological imaging in complex SCI/L presentations.\u003c/p\u003e\n\u003cp\u003eGiven its portability, real-time feedback, and minimal invasiveness, ESG may also be suited for longitudinal monitoring of sacral function across the different phases of recovery. This aligns with broader goals in digital medicine to create accessible, scalable tools that enable precision assessment at the point of care.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eESG parameter domains and clinical significance\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe ESG digitally captures sacral neurophysiological function through surface EMG recordings of the external anal sphincter, enabling a structured assessment of both motor and sensory-reflex domains. Our analysis supports the content validity of these domains, which reflect two physiologically and clinically distinct aspect of sacral integrity: 1) motor activation and tone, and 2) afferent sensory conduction and reflex loop responsiveness.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe motor domain is defined by two complementary parameters: resting anal tone and maxVAC. Resting anal tone, which reflects basal motor output from the external anal sphincter, may serve as a surrogate marker for injury timing (e.g., spinal shock vs. spasticity emergence), upper vs. lower upper motor neuron syndromes, and potential secondary complications such as pelvic floor hypertonicity. (10, 11) Although not strongly discriminatory in the acute phase, this parameter may offer clinical value in chronic monitoring and response to targeted interventions. In contrast, maxVAC offers a robust and quantifiable alternative to the binary assessment of VAC in the DRE. By capturing subclinical volitional recruitment (ESG+/DRE-), ESG enhances the detection of spared motor function, which has been linked to better recovery trajectories for bladder, bowel, and general functional outcomes. (3, 12) As a digital proxy for sacral motor integrity, maxVAC holds promise for prognostication and therapy monitoring in the early phases of recovery. (13, 14)\u003c/p\u003e\n\u003cp\u003eThe sensory-reflex domain integrates the EPT and the BSR, providing complementary views of afferent and reflexive function. (5) EPT quantifies sacral sensory detection thresholds using controlled surface electrical stimulation, primarily targeting A\u0026beta; fibers while potentially engaging deeper sensory pathways at higher amplitudes. (15) This contrasts with subjective sensory testing during DRE, which relies on examiner interpretation of patient-reported responses. BSR, although absent from formal classical systems like the ISNCSCI (International Standards for Neurological Classification of SCI), remains a clinically relevant measure of sacral reflex integrity. It probes both afferent pudendal conduction and S2-S4 spinal processing through an involuntary reflex arc. (16) The early reappearance of BSR has been linked to better outcomes in severe SCI and may serve as a physiological marker of reflex circuit preservation. (10)\u003c/p\u003e\n\u003cp\u003eTogether, EPT and BSR reflect distinct but converging mechanisms within the sacral sensory-reflex circuitry: EPT captures conscious, ascending sensory pathways, while BSR evaluates spinal-level reflex integrity. Their integration into ESG enables a multidimensional view of sacral function, bridging a long-standing gap in bedside neurophysiological evaluation. Notably, the ability to simultaneously and objectively assess volitional motor control, basal tone, conscious sensory perception, and reflex integrity within a single point-of-care tool represents a significant advance in neurodiagnostics. This comprehensive approach offers new opportunities for earlier characterization of neurogenic dysfunction, more nuanced monitoring of progression or recovery, and standardized comparisons across clinical settings and studies.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNormative thresholds and group comparisons\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study established preliminary normative thresholds for all ESG parameters using a healthy reference cohort. These thresholds were subsequently validated against a neurologically intact patient group, with strong alignment between blinded assessments and expected values, supporting the clinical utility of ESG in distinguishing normal from impaired sacral function.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAlthough the neurologically intact and impaired groups were comparable in clinical profiles, demographic differences from the healthy reference group \u0026ndash; specifically younger age and greater female representation- may account for some intergroup variability, consistent with established effects of age and sex on neuromuscular physiology.\u0026nbsp;(17, 18)\u003c/p\u003e\n\u003cp\u003eAmong ESG parameters, resting anal tone did not significantly differ across groups. This may reflect both the inherent variability of this low-amplitude signal and its relative preservation in the acute phase of SCI/L, limiting its value for early discrimination. In contrast, maxVAC and BSR differentiated neurologically impaired patients from both healthy and neurologically intact individuals, but not between the latter two, suggesting high specificity for SCI/L-related dysfunction. EPT also distinguished healthy from neurologically impaired participants, highlighting its potential utility in identifying sensory dysfunction. However, overlap in EPT distributions between neuro-intact and impaired patients (with 53% and 75% of values, respectively, within the normative range) suggests limited sensitivity when used in isolation.\u003c/p\u003e\n\u003cp\u003eTaken together, these findings underscore the need for a multidimensional approach to sacral assessment. No single ESG parameter independently confirmed neurogenic impairment; rather, the combined interpretation of motor and sensory/reflex domains provides a more reliable and nuanced characterization of neuro-sacral integrity following SCI/L.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConcurrent validity: agreement between ESG and DRE\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTo assess concurrent validity, ESG outputs were compared against clinical reference standard \u0026ndash; expert-performed DRE- using Cohen\u0026rsquo;s Kappa (k). Agreement was interpreted in the context of four a priori hypotheses, each corresponding to a distinct ESG parameter.\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003e\u003cu\u003eMaxVAC:\u003c/u\u003e ESG was hypothesized to demonstrate greater sensitivity than DRE for detecting VAC owing its ability to quantify subtle, subclinical motor activity. This was confirmed by the identification of patients with preserved contraction on ESG but undetectable on DRE (ESG+/DRE-), supporting prior findings that surface EMG can capture low-amplitude contractions associated with better functional recovery. (19) This highlights ESG\u0026rsquo;s capacity to detect residual motor function not apparent through manual assessment.\u003c/li\u003e\n \u003cli\u003e\u003cu\u003eElectrical perceptual threshold (EPT)\u003c/u\u003e: Lower agreement was anticipated for sacral sensory function due to the difference in modalities: EPT targets A\u0026beta;-mediated light touch via surface electrical stimulation, whereas DRE relies on subjective perception of broad afferent input. As expected, agreement for EPT was lower than for maxVAC, likely reflecting both neuroanatomical pathways and perceptual differences in stimulus detection.\u003c/li\u003e\n \u003cli\u003e\u003cu\u003eBulbocavernosus/bulbospongious reflex (BSR)\u003c/u\u003e: We hypothesized reduced concordance between ESG and DRE for reflex testing, due to variability in manual stimulation during bedside exams. ESG reflex recordings were elicited via standardized manual techniques, but not via electrical stimulation, which was incompatible with real-time bedside use. The moderate \u0026kappa; observed supports the need for future studies employing automated stimulation to improve reproducibility in reflex assessment.\u003c/li\u003e\n \u003cli\u003e\u003cu\u003eResting anal tone\u003c/u\u003e: Lower agreement was also anticipated for this parameter, as s-EMG quantifies low-level basal activity that may not correlate with the subjective tactile perception of the baseline tone on DRE. The limited concordance observed likely stems from low signal amplitude and inter-examiner variability.(8, 20, 21) ESG\u0026rsquo;s objective capture of continuous baseline activity represents a potential advantage for longitudinal monitoring of sacral motor tone. (22)\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eTogether, these findings support ESG\u0026rsquo;s concurrent validity, particularly for VAC and sensory threshold assessment. Discrepancies between ESG and DRE underscore the complementary nature of the two tools: while DRE offers a quick qualitative snapshot, ESG provides reproducible, quantifiable metrics that may detect subclinical or early changes in sacral neurophysiology. These attributes position ESG as a valuable adjunct in neuro-sacral assessment, particularly in contexts requiring objective and standardized data acquisition.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eDiagnostic performance and clinical implications\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eOur findings confirm that the ESG demonstrates strong diagnostic accuracy in detecting radiological evidence of spinal pathology. With high sensitivity (83.3%), ESG successfully identified the majority of patients with MRI/CT-confirmed neurogenic lesions. Its perfect specificity (100%), indicating no false positives \u0026ndash; supports its reliability as a confirmatory tool (PPV=100%).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHowever, ESG\u0026rsquo;s diagnostic applicability is currently limited to patients able to fully collaborate with testing procedures (same as for DRE). Individuals with cognitive impairment, altered consciousness, or significant pain (preventing maxVAC generation) may not be appropriate candidates, as ESG requires active participation and comprehension of instruction.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe negative predictive value (NPV=58.3%) suggests that while ESG helps rule in neurological impairment, a normal result (ESG-N) does not fully exclude pathology, particularly in milder cases. The positive likelihood ratio (LR\u003csup\u003e+\u003c/sup\u003e=\u0026yen;) reflects that abnormal ESG findings (VAC and/or EPT dysfunction) are exclusively associated with radiological abnormalities, reinforcing its role in confirming neurogenic dysfunction. Conversely, the negative likelihood ratio\u0026nbsp;\u003cstrong\u003e(LR\u003c/strong\u003e\u003cstrong\u003e⁻\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;= 0.167)\u003c/strong\u003e indicates that \u003cstrong\u003ea normal ESG decreases\u0026mdash;but does not eliminate\u0026mdash;the likelihood of underlying pathology\u003c/strong\u003e\u003cstrong\u003e.\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThese findings underscore ESG\u0026rsquo;s \u003cstrong\u003epotential utility as a confirmatory test in SCI/L assessment\u003c/strong\u003e, rather than a rule-out tool. The ESG can also be used from admission to the acute care center and throughout the different phases of care. Given the subjectivity of DRE, ESG offers a quantitative, standardized approach to neuro-sacral evaluation, with applications in triaging, monitoring recovery, and informing long-term management.\u003c/p\u003e\n\u003cp\u003eBeyond its immediate clinical utility, the ESG provides a standardized and quantifiable framework, laying the groundwork for future integration with digital health technologies and predictive analytics. Its structured EMG signal outputs enable the development of clinical decision support systems and remote monitoring applications for patients with SCI/L and cauda equina syndrome. Importantly, the ESG\u0026rsquo;s digital architecture also opens the door to future \u003cstrong\u003emachine learning applications\u003c/strong\u003e. By leveraging large-scale ESG datasets, predictive models could be trained to stratify neurogenic bladder risk, anticipate surgical urgency, or forecast neurological recovery. These capabilities would support more personalized care and optimize resource allocation across the continuum of SCI management. Future research should explore the integration of ESG data into algorithm-based diagnostic platforms, ideally through multicenter studies with longitudinal follow-up.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLimitations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study focused on the development and preliminary validation of ESG as a point-of care s-EMG tool for bedside neuro-sacral assessment. To maintain clinical feasibility, electrical stimulation for BSR assessment was not employed; instead, manual stimulation was used, which may have introduced variability due to the lack of standardized stimulus intensity.\u003c/p\u003e\n\u003cp\u003eAlthough electrode placement can influence EMG recordings, (23) the study demonstrated strong content and concurrent validity. Nonetheless, formal reliability testing is necessary to confirm ESG\u0026rsquo;s utility for longitudinal follow-up. Future work should also consider bilateral electrode placement to detect asymmetric dysfunction, which may be particularly relevant in cauda equina syndrome.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConcurrent validity was evaluated by a single expert physiatrist alternating between ESG and DRE. While this design minimized inter-examiner variability, it introduces potential assessor bias. Future studies should involve multiple blind raters to enhance reproducibility and generalizability.\u003c/p\u003e\n\u003cp\u003eAs with DRE, ESG requires full patient cooperation, limiting its applicability in patients with cognitive impairments or pain-related restrictions. Finally, larger-scale, multi-center validation studies are essential before ESG can be broadly recommended for clinical use.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eNeuro-sacral assessment remains a critical yet under standardized component of SCI/L evaluation. The current standard \u0026ndash; the digital rectal examination (DRE) \u0026ndash; is subjective, invasive, and highly dependent on examiner expertise. In response, we developed the ElectroSacroGram (ESG), a novel bedside-compatible s-EMG tool that enables real-time, objective evaluation of sacral sensory and motor function.\u003c/p\u003e\n\u003cp\u003eDeveloped with input from a multidisciplinary panel of SCI experts, ESG showed strong content validity and promising diagnostic performance. Principal component analysis identified two clinically relevant domains: 1) motor (resting anal tone, maxVAC ∆amplitude), and 2) sensory/reflex (EPT, BSR) \u0026ndash; supporting the construct validity.\u003c/p\u003e\n\u003cp\u003eWith excellent specificity (100%), high sensitivity (83.3%), and overall accuracy of 86.5%, ESG effectively detects neuro-sacral dysfunction associated with spinal pathology. In cooperative patients, abnormal ESG results were exclusively associated with radiological evidence of injury/evidence (PPV=100%). While a normal ESG results does not fully exclude pathology (NPV = 58.3%), its objective metrics offer a valuable complement to imaging and clinical examination.\u003c/p\u003e\n\u003cp\u003eAlthough not suited for uncooperative patients, ESG holds strong promise as a precision medicine tool in acute SCI/L care. Further validation is warranted to support its integration into diagnostic algorithms, guide individualized rehabilitation strategies and prognostic assessment, as well as enhance our understanding of neurophysiological recovery.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eAIS: ASIA impairment scale\u003c/p\u003e\n\u003cp\u003eAUC: Area under the curve\u003c/p\u003e\n\u003cp\u003eASIA: American Spinal Injury Association\u003c/p\u003e\n\u003cp\u003eBSR: Bulbospongious sacral reflex\u003c/p\u003e\n\u003cp\u003eCES: Cauda equina syndrome\u003c/p\u003e\n\u003cp\u003eCT: Computed tomography\u003c/p\u003e\n\u003cp\u003eDRE: Digital rectal examination\u003c/p\u003e\n\u003cp\u003eEAS: External anal sphincter\u003c/p\u003e\n\u003cp\u003eEMG: Electromyography\u003c/p\u003e\n\u003cp\u003eEPT: Electrical perceptual threshold\u003c/p\u003e\n\u003cp\u003eESG: ElectroSacroGram\u003c/p\u003e\n\u003cp\u003eI/S-CVI: Item/scale content validity indices\u003c/p\u003e\n\u003cp\u003eISNCSCI: International Standards for Neurological Classification of SCI\u003c/p\u003e\n\u003cp\u003eLR: Likelihood ratio\u003c/p\u003e\n\u003cp\u003eMRI: Magnetic resonance imaging\u003c/p\u003e\n\u003cp\u003eNPV: Negative predictive value\u003c/p\u003e\n\u003cp\u003ePCA: Principal component analysis\u003c/p\u003e\n\u003cp\u003ePPV: Positive predictive value\u003c/p\u003e\n\u003cp\u003eSCI: Spinal cord injury\u003c/p\u003e\n\u003cp\u003eSCI/L: Spinal cord injury/lesion\u003c/p\u003e\n\u003cp\u003es-EMG: surface electromyography\u003c/p\u003e\n\u003cp\u003eVAC: Voluntary anal contraction\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthics clearance by the institutional review board of the\u0026nbsp;\u003cstrong\u003e\u003cem\u003eCentre Int\u0026eacute;gr\u0026eacute; Universitaire de Sant\u0026eacute; et de Services Sociaux (CIUSSS) du Nord-de-l\u0026rsquo;\u0026Icirc;le-de Montr\u0026eacute;al -\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cem\u003eH\u0026ocirc;pital du Sacr\u0026eacute;-Coeur de Montr\u0026eacute;al\u003c/em\u003e and written informed consent from each patient were duly obtained for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData is not openly accessible; inquiries should be directed to the corresponding authors and reasonable requests will be evaluated.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Chaire de recherche Medtronic en traumatologie spinale (JMMT), grants from the Canadian Institutes of Health Research (CIHR) and the Craig H. Neilsen Foundation (ARD). Funders played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMD contributed to patient recruitment, data collection, extraction, and analysis, interpreting results, redaction of the first draft of the manuscript and editing. JDHC and NB contributed to patient recruitment, data collection, result interpretation and manuscript editing. JMMT contributed to patient recruitment, designing the protocol, result interpretation, funding of the study and manuscript editing. ARD participated in designing the protocol, patient recruitment, data collection, result interpretation, funding of this study and manuscript editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to deeply thank the research team in spinal cord injury of the Centre de recherche du CIUSS-NIM (NeuroTrauma Reamed and OrthoS teams), as well as the clinical multidisciplinary team in spinal cord injury care at the H\u0026ocirc;pital du Sacr\u0026eacute;-Coeur de Montr\u0026eacute;al for their help in making this project come to fruition. We would like to particularly thank Dr Paul Khoueir, Dr \u0026Eacute;tienne Bourassa-Moreau and Dr Gilles Maurais for their help in patient recruitment.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eRupp R, Biering-S\u0026oslash;rensen F, Burns SP, Graves DE, Guest J, Jones L, et al. International Standards for Neurological Classification of Spinal Cord Injury: Revised 2019. Topics in Spinal Cord Injury Rehabilitation. 2021;27(2):1-22.\u003c/li\u003e\n\u003cli\u003ePodnar S. Clinical and neurophysiologic testing of the penilo-cavernosus reflex. Neurourol Urodyn. 2008;27(5):399-402.\u003c/li\u003e\n\u003cli\u003eDuguay M, Mac-Thiong JM, Richard-Denis A. Bedside electromyography for clinical assessment of sacral motor and reflex activity adapted for patients hospitalized with acute neurological conditions: a pilot study. Spinal Cord Ser Cases. 2024;10(1):47.\u003c/li\u003e\n\u003cli\u003eAsia, Committee ISIS. The 2019 revision of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI)-What\u0026apos;s new? Spinal Cord. 2019;57(10):815-7.\u003c/li\u003e\n\u003cli\u003eHuang YN, Meftah EM, Pion CH, Mac-Thiong JM, Cohen-Adad J, Barthelemy D. Quantitative electrophysiological assessments as predictive markers of lower limb motor recovery after spinal cord injury: a pilot study with an adaptive trial design. Spinal Cord Ser Cases. 2022;8(1):26.\u003c/li\u003e\n\u003cli\u003ePolit DF, Beck CT. The content validity index: are you sure you know what\u0026apos;s being reported? Critique and recommendations. Res Nurs Health. 2006;29(5):489-97.\u003c/li\u003e\n\u003cli\u003eTerwee CB, Bot SD, de Boer MR, van der Windt DA, Knol DL, Dekker J, et al. Quality criteria were proposed for measurement properties of health status questionnaires. J Clin Epidemiol. 2007;60(1):34-42.\u003c/li\u003e\n\u003cli\u003eKava BR DA, Heaney JA. Reproducibility of the digital rectal examination in assessment of anal sphincter tone. . Tech Coloproctol. 2002;6(2):83-6.\u003c/li\u003e\n\u003cli\u003eGuldner GT, Brzenski AB. The sensitivity and specificity of the digital rectal examination for detecting spinal cord injury in adult patients with blunt trauma. Am J Emerg Med. 2006;24(1):113-7.\u003c/li\u003e\n\u003cli\u003eGreciet N, Mac-Thiong JM, Nguyen BH, Richard-Denis A. The Functional Impact of the Absence of a Bulbocavernosus Reflex in the Postoperative Period After a Motor-Complete Traumatic Spinal Cord Injury. Am J Phys Med Rehabil. 2020;99(8):712-8.\u003c/li\u003e\n\u003cli\u003ePrevinaire JG. The importance of the bulbocavernosus reflex. Spinal Cord Ser Cases. 2018;4:2.\u003c/li\u003e\n\u003cli\u003evan Middendorp JJ, Hosman AJ, Pouw MH, Van de Meent H. Is determination between complete and incomplete traumatic spinal cord injury clinically relevant? Validation of the ASIA sacral sparing criteria in a prospective cohort of 432 patients. Spinal Cord. 2009;47(11):809-16.\u003c/li\u003e\n\u003cli\u003eWyndaele JJ. Correlation between clinical neurological data and urodynamic function in spinal cord injured patients. Spinal Cord. 1997;35(4):213-6.\u003c/li\u003e\n\u003cli\u003ePrevinaire JG, Soler JM, Alexander MS, Courtois F, Elliott S, McLain A. Prediction of sexual function following spinal cord injury: a case series. Spinal Cord Ser Cases. 2017;3:17096.\u003c/li\u003e\n\u003cli\u003eTashani O, Johnson M. Transcutaneous Electrical Nerve Stimulation (TENS) A Possible Aid for Pain Relief in Developing Countries? Libyan J Med. 2009;4(2):62-5.\u003c/li\u003e\n\u003cli\u003eBlaivas JG, Zayed AA, Labib KB. The bulbocavernosus reflex in urology: a prospective study of 299 patients. J Urol. 1981;126(2):197-9.\u003c/li\u003e\n\u003cli\u003eAnsdell P, Brownstein CG, Skarabot J, Hicks KM, Simoes DCM, Thomas K, et al. Menstrual cycle-associated modulations in neuromuscular function and fatigability of the knee extensors in eumenorrheic women. J Appl Physiol (1985). 2019;126(6):1701-12.\u003c/li\u003e\n\u003cli\u003eDedek A, Xu J, Lorenzo LE, Godin AG, Kandegedara CM, Glavina G, et al. Sexual dimorphism in a neuronal mechanism of spinal hyperexcitability across rodent and human models of pathological pain. Brain. 2022;145(3):1124-38.\u003c/li\u003e\n\u003cli\u003eDuguay M, Mac-Thiong J-M, Richard-Denis A. Bedside electromyography for clinical assessment of sacral motor and reflex activity adapted for patients hospitalized with acute neurological conditions: a pilot study. Spinal Cord Series and Cases. 2024;10(1):47.\u003c/li\u003e\n\u003cli\u003eEnck P, Eggers E, Koletzko S, Erckenbrecht JF. Spontaneous variation of anal \u0026quot;resting\u0026quot; pressure in healthy humans. Am J Physiol. 1991;261(5 Pt 1):G823-6.\u003c/li\u003e\n\u003cli\u003eEnck P vdHC, M\u0026uuml;ller-Lissner S. Function of the external anal sphincter: quantification with surface electromyography. Dis Colon Rectum. 1991;34(5):397-403.\u003c/li\u003e\n\u003cli\u003eGrasland M, Turmel N, Pouyau C, Leroux C, Charlanes A, Chesnel C, et al. External Anal Sphincter Fatigability: An Electromyographic and Manometric Study in Patients With Anorectal Disorders. J Neurogastroenterol Motil. 2021;27(1):119-26.\u003c/li\u003e\n\u003cli\u003eKen N, Takuya I. Location of Electrodes in Surface EMG. In: Mark S, editor. EMG Methods for Evaluating Muscle and Nerve Function. Rijeka: IntechOpen; 2012. p. Ch. 2.\u003c/li\u003e\n\u003cli\u003eLtd. VM. NeuroTrac MyoPlus 2Pro - Operators Manual 2016. Available from: https://parsenn-produkte.ch/wp-content/uploads/2022/11/MYO220P-OM-EN04-12-08-21.pdf.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1. Description of the digital rectal examination (DRE) and ElectroSacroGram (ESG) procedures and data handling approach.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.1538%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003col\u003e\n \u003cli\u003e\u003cstrong\u003eAssessment of DRE parameters based on current standards of care\u003c/strong\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003col start=\"2\"\u003e\n \u003cli\u003e\u003cstrong\u003eESG proposed method and threshold values\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.1538%;\"\u003e\n \u003col\u003e\n \u003cli\u003e\u003cstrong\u003eAnal resting tone\u003c/strong\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eResistance of the EAS to passive stretch by the examiner\u0026apos;s finger, marked as either:\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eNormal (DRE/tone-N):\u003c/strong\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003edefined as a firm, uniform and consistent resistance.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbnormal (DRE/tone- A):\u0026nbsp;\u003c/strong\u003eeither diminished (not perceptible or weaker than expected) or increased (resists the insertion of the finger more strongly than expected).\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eAmplitude of the EAS motor activity at rest\u0026nbsp;was noted (in\u0026nbsp;\u0026micro;V), and\u0026nbsp;was also treated for sensitivity and specificity analysis as:\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eNormal (ESG/tone-N):\u003c/strong\u003e from 0.8 to 3.6 \u0026micro;V.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbnormal (ESG/tone- A):\u0026nbsp;\u003c/strong\u003eeither\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u0026lt;0.8 \u0026micro;V or \u0026gt;3.6 \u0026micro;V.\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.1538%;\"\u003e\n \u003col start=\"2\"\u003e\n \u003cli\u003e\u003cstrong\u003eVoluntary Anal Contraction (VAC)\u003c/strong\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eTested by asking the patient to maximally squeeze the finger as if they were holding back a bowel movement (1), marked as either:\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003ePreserved (DRE/VAC+)\u003c/strong\u003e\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbsent (DRE/VAC-)\u003c/strong\u003e\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eAmplitude of the EAS motor activity measured by asking the patient to maximally squeeze the anus as if they were holding back a bowel movement (1). The highest value maintained across the 3 trials was noted (in \u0026micro;V).\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eThe maxVAC was also treated for concurrent validity analysis as:\u0026nbsp;\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003ePreserved VAC (ESG/VAC+):\u003c/strong\u003e ∆Amplitude (maxVAC-resting tone) \u0026ge;0.2\u0026micro;V (device margin of error).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbsent VAC (ESG/VAC-):\u003c/strong\u003e \u0026lt;0.2 \u0026micro;V\u003c/li\u003e\n \u003c/ul\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eESG\u0026rsquo;s maxVAC ∆amplitude thresholds for sensibility and specificity analysis:\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eNormal (ESG/deltaVAC-N):\u003c/strong\u003e from 9 to 50.3 \u0026micro;V.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbnormal (ESG/deltaVAC-A):\u0026nbsp;\u003c/strong\u003e\u0026lt;9 \u0026micro;V. Values exceeding 50.3 \u0026micro;V were not observed but would be considered outliers.\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.1538%;\"\u003e\n \u003col start=\"3\"\u003e\n \u003cli\u003e\u003cstrong\u003eSacral spinal reflex: bulbospongious reflex (BSR)\u003c/strong\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eContraction of the EAS\u003cem\u003e\u0026nbsp;\u003c/em\u003eas felt by the examiner\u0026rsquo;s finger in response to stimulus of the sensory receptors in the urethra and genitals (slightly tugging the indwelling catheter in patients or squeezing the glans of penis or clitoris in healthy participants), and dichotomized as:\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003ePreserved (DRE/BSR+)\u003c/strong\u003e\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbsent (DRE/BSR-)\u003c/strong\u003e\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eAmplitude of the EAS motor activity in response to the same stimulus. The highest value\u0026nbsp;maintained across\u0026nbsp;the 3 trials was noted (in\u0026nbsp;\u0026micro;V).\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eThe BSR was also treated for concurrent validity analysis as:\u0026nbsp;\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003ePreserved BSR (ESG/BSR+):\u003c/strong\u003e if the ∆Amplitude was \u0026ge;0.2\u0026micro;V (device margin of error) (24)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbsent BSR (ESG/BSR-):\u003c/strong\u003e \u0026lt;0.2 \u0026micro;V\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.1538%;\"\u003e\n \u003col start=\"4\"\u003e\n \u003cli\u003e\u003cstrong\u003eS4-S5 Sensory function\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eDeep anal pressure was tested by applying gentle pressure against the anorectal wall and asking the patient whether they sense it or not. Light touch and pinprick sensation at S4-S5 key sensory point were also performed and graded as absent (0), altered (1) or normal (2). Sacral sensory function was then dichotomized as:\u0026nbsp;\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003ePreserved sensory function (DRE/SS+)\u003c/strong\u003e: defined as preserved sensation in deep anal pressure.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbsent\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003esensory function\u0026nbsp;\u003cbr\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(DRE/SS-):\u0026nbsp;\u003c/strong\u003eno sensation at deep anal pressure, light touch or pinprick examination.\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 39.4231%;\"\u003e\n \u003cp\u003eElectrical perceptual threshold (EPT) was noted (in mA).\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eThe EPT was also treated for concurrent validity analysis as:\u0026nbsp;\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003ePreserved sensory function (ESG/EPT+):\u003c/strong\u003e Impulse is felt at maximal impulse or below \u0026pound;17 mA\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbsent\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003esensory function\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003cbr\u003e\u0026nbsp;(ESG/EPT-):\u003c/strong\u003e no feeling until maximal impulse (17 mA).\u003c/li\u003e\n \u003c/ul\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eESG\u0026rsquo;s EPT thresholds for sensibility and specificity analysis:\u003c/p\u003e\n \u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eNormal (ESG/maxVAC-N):\u003c/strong\u003e from 1 to 7 mA.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbnormal (ESG/maxVAC-A):\u0026nbsp;\u003c/strong\u003e\u0026gt;7 mA.\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003eDRE: digital rectal examination. ESG: ElectroSacroGram. EAS: External anal sphincter. EPT: Electrical perceptual threshold.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eMicroVolts (\u003c/em\u003e\u003cem\u003e\u0026micro;V); MilliAmpere (mA)\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTable 2. Cohort description for the three groups of patients\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA) Neurologically impaired (N=40) \u0026amp; neurologically intact (N=12)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 43.8326%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eClinical characteristics\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 29.0749%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNeurologically impaired\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e(N=40)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 27.0925%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNeuro-intact\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(N=12)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 43.8326%;\"\u003e\n \u003cp\u003eAge at injury in years (mean\u0026plusmn;SD))\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 29.0749%;\"\u003e\n \u003cp\u003e56.23\u0026plusmn;18.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 27.0925%;\"\u003e\n \u003cp\u003e60.92\u0026plusmn;18.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 43.8326%;\"\u003e\n \u003cp\u003eSex (N, % male)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 29.0749%;\"\u003e\n \u003cp\u003e28 (70.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 27.0925%;\"\u003e\n \u003cp\u003e7 (58.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 43.8326%;\"\u003e\n \u003cp\u003eInitial AIS (N, %)\u003c/p\u003e\n \u003cp\u003eAIS A\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eAIS B\u003c/p\u003e\n \u003cp\u003eAIS C\u003c/p\u003e\n \u003cp\u003eAIS D\u003c/p\u003e\n \u003cp\u003eCES\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 29.0749%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e5 (12.5)\u003c/p\u003e\n \u003cp\u003e2 (5.0)\u003c/p\u003e\n \u003cp\u003e5 (12.5)\u003c/p\u003e\n \u003cp\u003e22 (55.0)\u003c/p\u003e\n \u003cp\u003e4 (10.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 27.0925%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eN/A\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 43.8326%;\"\u003e\n \u003cp\u003eEtiology of SCI/L (N,%)\u003c/p\u003e\n \u003cp\u003eTraumatic\u003c/p\u003e\n \u003cp\u003eNon-traumatic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 29.0749%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e27 (67.5)\u003c/p\u003e\n \u003cp\u003e13 (32.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 27.0925%;\"\u003e\n \u003cp\u003eN/A\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB) Healthy participants (N=21)\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 60.1208%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eClinical characteristics\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39.8792%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHealthy participants (N=21)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 60.1208%;\"\u003e\n \u003cp\u003eAge at injury in years (mean\u0026plusmn;SD))\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39.8792%;\"\u003e\n \u003cp\u003e39.62\u0026plusmn;16.97\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 60.1208%;\"\u003e\n \u003cp\u003eSex (N, % male)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39.8792%;\"\u003e\n \u003cp\u003e5 (23.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003eCES: Cauda equina syndrome. F: Female.\u0026nbsp;\u003c/em\u003e\u003cem\u003eM: Male. AIS: ASIA [American Spinal Injury Association] Impairment Scale.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTable 3. Concurrent validity analysis between the ESG and DRE for testing the four key parameters of neuro-sacral function in the neurologically impaired group (N=62).\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"9\" valign=\"top\" style=\"width: 493px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eESG\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eResting anal tone\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(N=62)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003emaxVAC\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(N=62)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBSR\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(N=46)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eEPT\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(N=62)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDRE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e-\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e+\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 109px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAgreement\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 110px;\"\u003e\n \u003cp\u003e82% (k=0.205)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 110px;\"\u003e\n \u003cp\u003e95% (k=0.876)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 110px;\"\u003e\n \u003cp\u003e91% (k=0.671)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 110px;\"\u003e\n \u003cp\u003e97% (k=0.881)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003eESG: ElectroSacroGram. DRE: Digital rectal examination. maxVAC: maximum voluntary anal contraction. BSR: Bulbospongious Sacral Reflex. Sensory: Sensory preservation testing. N: normal. A: abnormal. +: present. -: absent. EPT: Electrical Perceptual Threshold (sensory function).\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 4. Capacity of the ESG to accurately (accuracy analysis) classify neurological impairment in the patient group (N=74).\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 184px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRadiological abnormality condition\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003epresent (+)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eabsent (-)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eESG\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eA\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cem\u003eESG: ElectroSacroGram. SCI/L +: Spinal Cord Injury/lesion present. SCI/L -: Spinal Cord Injury/lesion absent. N: normal. A: abnormal motor and/or sensory sacral function\u0026nbsp;\u003c/em\u003e\u003cu\u003e\u003c/u\u003e\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-neuroengineering-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jner","sideBox":"Learn more about [Journal of NeuroEngineering and Rehabilitation](http://jneuroengrehab.biomedcentral.com/)","snPcode":"12984","submissionUrl":"https://submission.nature.com/new-submission/12984/3","title":"Journal of NeuroEngineering and Rehabilitation","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"digital diagnostics, digital neurophysiology, spinal cord injury, surface electromyography, point-of-care technology, neuro-sacral assessment","lastPublishedDoi":"10.21203/rs.3.rs-7135084/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7135084/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eAccurate assessment of neuro-sacral function after spinal cord injury or lesion (SCI/L) is critical for diagnosis, prognosis, and early management. However, current bedside methods such as the digital rectal examination (DRE) remain subjective, invasive, and examiner-dependent. Surface electromyography (s-EMG) offers a quantitative alternative but lacks point-of-care integration. We developed and validated the ElectroSacroGram (ESG), a digital, surface-EMG-based tool for real-time sacral neurophysiological assessment.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis study aimed to 1) develop the ESG protocol based on clinical consensus; and 2) evaluate its diagnostic performance compared to radiological findings and expert-performed DRE. In this prospective diagnostic accuracy study at a specialized Level 1 trauma center, 52 adult patients with suspected SCI/L and 21 healthy participants underwent ESG and DRE assessments. ESG captured sacral motor (resting anal tone, maximal voluntary anal contraction (maxVAC), reflex (bulbospongious or bulbocavernosus reflex [BSR]), and sensory (electrical perceptual threshold [EPT]) function using s-EMG and electrical stimulation. Clinically relevant DRE parameters were selected by a nine-member expert panel. Content validity was quantified using item and scale content validity indices (I/S-CVI). Although DRE is inherently subjective, it is the current bedside reference standard; therefore, agreement with ESG was evaluated using Cohen\u0026rsquo;s kappa (k) to assess concurrent validity. Diagnostic accuracy was assessed using contingency tables with imaging-confirmed spinal lesions as reference.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eNormative ESG values were defined in healthy participants. Neurologically impaired patients had lower maxVAC and BSR amplitudes and higher EPT. ESG showed excellent content validity (S-CVI\u0026thinsp;=\u0026thinsp;1) versus DRE (S-CVI\u0026thinsp;=\u0026thinsp;0.43). Agreement with DRE was almost perfect for VAC (κ\u0026thinsp;=\u0026thinsp;0.876) and EPT (κ\u0026thinsp;=\u0026thinsp;0.881), moderate for BSR (κ\u0026thinsp;=\u0026thinsp;0.671), and slight for resting anal tone (κ\u0026thinsp;=\u0026thinsp;0.205). ESG showed 83.3% sensitivity, 100% specificity, and 86.5% overall accuracy for detecting radiological abnormalities.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eESG is a novel digital diagnostic tool that enables objective, real-time neuro-sacral assessment at bedside. By overcoming the limitations of DRE, ESG may improve diagnostic precision and early decision-making in SCI/L. Its point-of-care digital format supports future integration with clinical decision support systems, remote monitoring platforms, and machine learning models for predictive neurodiagnostic. Multicenter validation and longitudinal modeling are warranted.\u003c/p\u003e","manuscriptTitle":"Development and Validation of the ElectroSacroGram (ESG): A Digital Point-of-Care Tool for Real- time Neuro-Sacral Assessment After Spinal Cord Injury","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-29 12:38:46","doi":"10.21203/rs.3.rs-7135084/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-11T18:45:55+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-09T16:59:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"233830501251632250381864387317531123914","date":"2025-08-20T16:57:49+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-18T19:49:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"245230839363467917666419039685646098866","date":"2025-07-30T17:03:15+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-25T16:49:56+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-17T23:30:05+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-17T23:29:40+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of NeuroEngineering and Rehabilitation","date":"2025-07-16T02:45:26+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-neuroengineering-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jner","sideBox":"Learn more about [Journal of NeuroEngineering and Rehabilitation](http://jneuroengrehab.biomedcentral.com/)","snPcode":"12984","submissionUrl":"https://submission.nature.com/new-submission/12984/3","title":"Journal of NeuroEngineering and Rehabilitation","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9d491201-31e3-4869-ba1c-b407221020c9","owner":[],"postedDate":"July 29th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-15T16:04:28+00:00","versionOfRecord":{"articleIdentity":"rs-7135084","link":"https://doi.org/10.1186/s12984-025-01797-4","journal":{"identity":"journal-of-neuroengineering-and-rehabilitation","isVorOnly":false,"title":"Journal of NeuroEngineering and Rehabilitation"},"publishedOn":"2025-12-11 15:58:51","publishedOnDateReadable":"December 11th, 2025"},"versionCreatedAt":"2025-07-29 12:38:46","video":"","vorDoi":"10.1186/s12984-025-01797-4","vorDoiUrl":"https://doi.org/10.1186/s12984-025-01797-4","workflowStages":[]},"version":"v1","identity":"rs-7135084","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7135084","identity":"rs-7135084","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}