Repetitive transcranial magnetic stimulation normalizes cerebrocerebellar loop functional connectivity in spinocerebellar ataxia type 3: a synthetic control study

Repetitive transcranial magnetic stimulation normalizes cerebrocerebellar loop functional connectivity in spinocerebellar ataxia type 3: a synthetic control study | 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 Repetitive transcranial magnetic stimulation normalizes cerebrocerebellar loop functional connectivity in spinocerebellar ataxia type 3: a synthetic control study Yonghua Huang, Liu Feng, Peiling Ou, Lihua Deng, Linfeng Shi, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7158751/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Background Spinocerebellar ataxia type 3 (SCA3) is a rare neurodegenerative disorder characterized by ataxia; structural and functional damage to the cerebrocerebellar loop play key roles in its pathology. However, effective treatments for SCA3 remain limited. Repetitive transcranial magnetic stimulation (rTMS) modulates cortical plasticity. Here, we investigated the utility of rTMS in SCA3 treatment. Methods This study included 25 confirmed SCA3 patients and 33 age- and sex-matched healthy volunteers as controls. The Scale for the Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS) were used to assess the severity of clinical symptoms in the SCA3 group. Both groups completed neuropsychological evaluations and underwent brain magnetic resonance imaging (MRI) before and after treatment. MRI data were preprocessed using DPABI software to analyze changes in functional connectivity strength, both at the stimulation target and across the whole brain, in SCA3 patients before and after multi-target rTMS therapy based on the cerebrocerebellar loop. Results After multi-target rTMS treatment, SARA ( p < 0.001) and ICARS ( p < 0.001) scores in SCA3 patients were significantly reduced, whereas Montreal Cognitive Assessment ( p < 0.001) scores showed a substantial improvement in cognitive performance. Functional connectivity strengths between the paracentral lobule and cerebellum, and between the cerebellar vermis and paracentral lobule, decreased in SCA3 patients after treatment, gradually approaching levels observed in healthy controls. Discussion A multi-target rTMS treatment strategy targeting the cerebrocerebellar loop may significantly improve motor and cognitive functions in SCA3 patients by effectively regulating functional connectivity within this circuit. Spinocerebellar ataxia type 3 (SCA3) Cerebrocerebellar loop Repetitive transcranial magnetic stimulation (rTMS) Functional connectivity Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Spinocerebellar ataxia type 3 (SCA3) is an autosomal-dominant neurodegenerative disorder characterized by an abnormal expansion of the CAG repeat in the MJD1 gene, leading to the pathological accumulation of ataxin-3 protein in the brain, which causes neuronal degeneration[ 1 ]. SCA3 patients typically exhibit progressive ataxia, dysarthria, and ocular movement disorders[ 1 ]. Studies have shown that several brain regions, including the cerebellum, brainstem, basal ganglia, and thalamus, undergo atrophy in SCA3 patients[ 1 ]. The atrophy process often begins in the cerebellar vermis and gradually extends to areas such as the neostriatum and frontoparietal cortex[ 2 ]. These structural changes directly affect the cerebrocerebellar loop, resulting in decreased cortical inhibition and increased intrinsic connectivity[ 3 , 4 ]. Because no curative treatments for SCA3 currently exist[ 5 ], it is particularly important to identify approaches that can slow SCA3 disease progression. The cerebrocerebellar loop, a critical neural circuit connecting the cerebral cortex and cerebellum, plays a key role in motor coordination, balance, and spatial cognitive processing[ 6 – 9 ]. It is also the loop most affected by the disease. Our previous study of brain structural connectivity in SCA3 revealed significant abnormalities within this loop, including degeneration in the cerebellar-thalamo-cortical tract and increased connectivity in the cortico-ponto-cerebellar tract[ 10 ]. Dysfunction in the cerebrocerebellar loop exacerbates ataxia symptoms in SCA3 patients, greatly affecting their daily activities and social interactions[ 11 ]. Therefore, explorations of treatments that target the cerebrocerebellar loop are critical for efforts to alleviate clinical symptoms and improve quality of life in individuals with SCA3. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulatory technique that has gained prominence in neurological rehabilitation. By delivering rapidly changing magnetic fields to the scalp, rTMS generates electrical currents in cortical brain regions, enabling temporary modulation of brain activity by either exciting or inhibiting targeted areas[ 12 ]. Moreover, rTMS can influence long-term cortical plasticity and alter functional connectivity (FC) among brain regions[ 13 ]. Current evidence suggests that rTMS can be effective in the management of neurodegenerative diseases[ 14 ]. However, data regarding the efficacy of rTMS in SCA3 treatment exhibit moderate quality, and inconsistent therapeutic outcomes highlight variability in the clinical response[ 14 ]. Therefore, more comprehensive studies are needed to clarify the efficacy of rTMS in SCA3 treatment. A key limitation of this approach is the focal stimulation primarily directed at the cerebellum, which may limit its ability to modulate the broader neural networks involved in SCA3 pathogenesis[ 15 ]. Research has indicated that rTMS multi-target therapies are more effective than single-target approaches; loop-based treatment strategies potentially offer greater therapeutic benefits[ 16 ]. There is currently a lack of research investigating rTMS multi-target strategies that specifically target the cerebrocerebellar loop in SCA3. This study utilized rTMS multi-target stimulation with the aim of modulating key nodes within the cerebrocerebellar loop in SCA3 patients. By evaluating changes in clinical symptom severity and cerebrocerebellar FC before and after treatment, we sought to clarify the feasibility and efficacy of this treatment approach, then explore the role of rTMS in regulating FC within the cerebrocerebellar loop. Materials and Methods Participants Between December 2020 and March 2023, we recruited 52 patients at the First Affiliated Hospital of the Chinese Army Medical University who had been diagnosed with SCA3. The inclusion criteria for SCA3 patients included a confirmed diagnosis through genetic testing, symptoms of spinocerebellar ataxia, and an age range of 16 to 75 years. Exclusion criteria for SCA3 patients were: 1) other familial hereditary disorders, such as Parkinson's disease; 2) serious central nervous system conditions, including epilepsy, traumatic brain injury, stroke, or brain tumors; 3) disagree with rTMS treatment (n = 14), 4) contraindications for magnetic resonance imaging (MRI), 5) rTMS treatment was not completed (n = 13). We selected 33 healthy volunteers matched according to age, sex, and handedness from a pool of 200 healthy controls recruited during the same period. All participants provided written informed consent at the First Affiliated Hospital of the Army Medical University. The study protocol was approved by the institutional review committee (KY2020191), and the clinical trial was registered under ChiCTR2000039434 ( http://chictr.org.cn ). The study protocol is illustrated in Fig. 1 . Clinical evaluation The severity of ataxia in SCA3 patients was evaluated using the Scale for the Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS)[ 17 , 18 ]. Healthy controls and SCA3 patients agreed to undergo pre- and post-treatment neuropsychological assessments, including the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) to measure overall cognitive function[ 19 ], the Rapid Verbal Retrieval (RVR) category fluency test[ 20 ], and the Digit Span Test (DST) to assess working memory[ 21 ]. Image data acquisition All participants underwent MRI scans using a Siemens Trio 3T MR scanner (Germany), equipped with a standard eight-channel phased-array head coil. The MRI protocol included high-resolution sagittal T1-weighted imaging (T1WI) and resting-state functional imaging sequences. Sagittal T1WI used the MPRAGE sequence with the following parameters: repetition time of 1900 ms, echo time of 2·52 ms, inversion time of 900 ms, echo train length of 1, flip angle of 9°, slice thickness of 1 mm, matrix size of 256 × 256, voxel size of 1 × 1 × 1 mm, and 176 slices with no interslice gap. Resting-state functional imaging sequence parameters included a repetition time of 2000 ms, echo time of 30 ms, flip angle of 90°, field of view of 240 × 240 mm, matrix size of 64 × 64, 240 slices, slice thickness of 3 mm, no interslice gap, and a voxel size of 3·75 × 3·75 × 3 mm. Transcranial magnetic stimulation The study used the OSF-6 magnetic stimulator, manufactured by Wuhan Yiruide, to treat SCA3 patients. The biconical coil was designed to stimulate deeper brain regions, and the specific coil used was a curved biconical coil. This coil has a winding angle of 135° and a wing diameter of 90 mm. The paracentral lobule and cerebellar vermis play key roles in ataxia and are critical sites within the cerebrocerebellar loop. Before the first rTMS session, the patient's cortical resting motor threshold must be measured[ 22 ]. During each treatment session, surface localization methods are used to separately identify the stimulation targets. When the optimal location for stimulating the leg motor cortex is identified on the scalp of SCA3 patients, standard rTMS treatment is administered. In this study, stimulation was applied at 100% of the resting motor threshold, with a pulse frequency of 10 Hz, delivering 40 stimuli over 4 seconds. The inter-stimulus interval was 26 seconds with 25 repetitions, for a total of 1000 pulses within 12 minutes and 30 seconds. The surface of the cerebellar vermis is located 1 cm below the external occipital protuberance[ 23 ]. Here, the coil was positioned accordingly for treatment. Intermittent theta-burst stimulation (iTBS) was used, with an intensity of 120% of the resting motor threshold. The iTBS parameters included an intra-burst frequency of 50 Hz, intra-burst stimulation time of 0.06 seconds, inter-burst frequency of 5 Hz, and 10 bursts per sequence. Each stimulation lasted for 2 seconds, followed by an 8-second interval; these steps were repeated 20 times for a total of 600 pulses completed within 3 minutes and 20 seconds. After a 5-minute rest, the cerebellar vermis iTBS treatment was repeated. The treatment protocol was conducted once daily, five times per week, for 4 weeks. rTMS treatment outcome measurement Primary outcomes of interest were changes in the SARA and ICARS scores after treatment. All patients who completed the full treatment course and underwent baseline and post-treatment evaluations related to the primary outcomes (n = 25) were included in the primary analysis. Secondary outcomes included cognitive measurements such as the MoCA, RVR, and DST, as well as FC changes within the cerebrocerebellar loop. Image preprocessing Resting-state functional MRI scans were preprocessed using the Brain Imaging Data Processing and Analysis Toolbox (DPABI) software (DPABI: a toolbox for Data Processing & Analysis for Brain Imaging | The R-fMRI Network (rfmri.org)). Preprocessing began by discarding the first 10 time points; this was followed by time point correction to ensure uniformity across scans. Manual head motion correction was performed, and participants with maximum head movement exceeding 5·mm of translation were excluded (due to the movement disorder in SCA3 patients, head movement was more pronounced relative to the healthy control group). Functional and structural images were manually adjusted to align with T1WI templates, using resampled voxel sizes of 2 × 2 × 2 mm. Several covariates, including Friston 24 motion parameters, cerebrospinal fluid, and white matter signals, were regressed out as nuisance variables to minimize spurious differences. To reduce the effects of low-frequency drift and physiological high-frequency noise, further preprocessing involved linear regression and time bandpass filtering (0.01–0.08 Hz). At this stage, linear trends were also removed to mitigate the impact of temperature fluctuations in the MRI equipment. Definition of the region of interest for seed points The region of interest (ROI) for the stimulation target in the midline of the cerebrocerebellar loop was defined using Montreal Neurological Institute (MNI) spatial coordinates. ROI 1, located in the paracentral cortex, was centered at (0, -30, 65), and ROI 2, located in the cerebellar vermis, was centered at (0, -70, -25). A spherical ROI with a 10 mm diameter was generated around each of these points. The mask for each ROI was resampled to a voxel size of 3 × 3 × 3 mm. The blood-oxygen-level-dependent time series from voxels within the ROI was averaged to create a reference time series. Statistical analysis of FC To assess the strength of cerebrocerebellar FC, we conducted FC analysis based on the seed points. We also calculated Pearson correlation coefficients between seed points and whole-brain voxels, then performed z-transformation to improve normality. Group-level statistical comparisons were performed to evaluate FC differences in the two seed ROIs among healthy controls, baseline SCA3 patients, and post-treatment SCA3 patients. The image calculator within the DPABI toolkit was used to compare FC differences between the SCA3_0W (SCA3 patients before treatment, n = 22) and healthy control (HC, n = 33) groups. Independent sample t-tests were performed, controlling for head movement, age, and average frame displacement values. Paired sample t-tests were used to evaluate longitudinal changes in FC differences between SCA3_0W (n = 22) and SCA3_4W (SCA3 patients after treatment, n = 22). Thresholds for statistical significance were defined as voxel-level p < 0.001 and cluster-level p < 0.05, adjusted for Gaussian Random Field correction. Statistical analysis Demographic and clinical characteristics were analyzed using SPSS Statistics for Windows, version 26·0 (IBM, Armonk, NY, USA). Differences in demographic and baseline variables between study groups were evaluated using independent sample t-tests and chi-square tests. The study protocol and statistical analysis plan are available in eSAP 1, eSAP 2, respectively. Results Demographic data In total, 25 SCA3 patients and 33 healthy controls were included in this study (Fig. 2 ). No significant differences were observed in age (44.8 ± 11.22 vs 44.8 ± 9·26, p = 0.991) or sex (15 men vs 11 men, p = 0.912) between SCA3 patients and healthy controls. The average duration of disease onset in SCA3 patients was 9.6 ± 3.9 years. Cognition-related scales, including MoCA ( p < 0.001), MMSE ( p = 0.005), and RVR ( p < 0.001), showed significantly lower scores in SCA3 patients than in healthy controls. However, there was no statistically significant difference in DST score ( p = 0.073) between the two groups. Participant demographic and clinical characteristics are presented in Table 1 . Table 1 Participant demographic and clinical characteristics Characteristics HC SCA3 Statistical analysis (n = 33) (n = 25) t p Age (years) 44·8 ± 9·26 44·8 ± 11·22 -0.011 0·991 a Sex (male) 15 11 0.012 0·912 b Duration of onset 9·60 ± 3·90 SARA 14·02 ± 6·90 ICARS 36·16 ± 17·16 MoCA 26·76 ± 3·36 22·64 ± 4·24 -4·12 < 0.001 a MMSE 28·7 ± 1·74 27·00 ± 2·63 -2·95 0.005 a RVR 48·55 ± 15·44 33·20 ± 12·24 -4·09 < 0.001 a DST 8·88 ± 2·58 7·82 ± 1·49 -1·83 0.073 a Abbreviations: a, two-sample t-test; b, chi-square test; SARA, Scale for the Assessment and Rating of Ataxia; ICARS, International Cooperative Ataxia Rating Scale; MoCA, Montreal Cognitive Assessment; RVR, Rapid Verbal Retrieval; DST, Digit Span Test. Changes in clinical scales pre- and post-treatment After rTMS treatment, SCA3 patients showed significant reductions in disease severity, as reflected by decreased SARA ( p < 0.001) and ICARS ( p < 0.001) scores. Moreover, the MoCA score ( p < 0.001), related to cognitive function, demonstrated a substantial improvement after treatment. However, there were no statistically significant differences between pre- and post-treatment scores on the MMSE ( p = 0.097), RVR ( p = 0.395), or DST ( p = 0.131) assessments (refer to Fig. 2 for details). Resting-state FC based on seed points Three of the 25 SCA3 patients were excluded from the analysis due to poor MRI scan quality caused by motion artifacts. Comparisons of FC in ROI1 and ROI2 within the midline region of the cerebrocerebellar loop between SCA3 patients and healthy controls (as shown in Fig. 3 ) revealed significant increases in FC. Specifically, FC in ROI1 containing the supplementary motor area and cerebellum in SCA3 patients showed a substantial increase (voxel-level p < 0.001, cluster-level p < 0.05, GFR-corrected). Additionally, FC between ROI2 and the cerebellum, occipital lobe, and paracentral lobule showed significant enhancement (voxel-level p < 0.001, cluster-level p < 0.05, GFR-corrected). Comparisons of stimulation targets and global brain FC in SCA3 patients before and after treatment (Fig. 3 ) demonstrated post-treatment decreases in FC. Specifically, FC between the paracentral lobule and the thalamus and cerebellum decreased (voxel-level p < 0.001, cluster-level p < 0.05, GFR-corrected). Similarly, FC between the cerebellar vermis and the occipital lobe and paracentral lobule was reduced (voxel-level p < 0.001, cluster-level p < 0.05, GFR-corrected). Changes in FC between stimulation target ROIs and whole brain in SCA3 patients At baseline and after treatment, changes in FC between stimulation target ROIs and the whole brain encompassed the cerebellum and paracentral lobule (Table 2 ). Prior to rTMS treatment, SCA3 patients exhibited increased FC strength between ROI1 and the cerebellum, as well as between ROI2 and the paracentral lobule (voxel-level p < 0.001, cluster-level p < 0.05, GFR-corrected). However, after rTMS treatment targeting the cerebrocerebellar loop, the FC strength in these regions decreased ( p = 0.01) (Fig. 4 ). Table 2 Changes in FC within brain regions of SCA3 patients before and after treatment ROI Brain region Cluster size AAL MNI (x, y, z) t value ( df ) SCA3_0W VS HC ROI1 Cerebellum 595 91–94 -27, -66, -60 4·93 (52) ROI2 Paracentral lobule 37 70 4, -35, 60 4·41 (52) SCA3_4W VS SCA3_0W ROI1 Cluster 1 Cerebellum 80 92–94 9, -81, -24 -4·71 (41) Cluster 2 Thalamus 50 77,78 12, -18, 6 -3·85 (41) ROI2 Cluster 1 Paracentral lobule 60 69,70 3, -30, 63 -4·21 (41) Cluster 2 Lingual 55 48 18, -93, -6 -4·03 (41) Abbreviations: SCA3_0W, SCA3 patients before treatment; SCA3_4W, SCA3 patients after treatment Relationship between longitudinal FC changes and clinical symptoms Correlation analysis was performed to examine the relationship between changes in FC and improvements in clinical symptoms. The results indicated that the reduction in FC between the paracentral lobule and cerebellum was positively correlated with decreases in SARA scores (r = 0·845, p < 0.001) and ICARS scores (r = 0·912, p < 0.001). Similarly, the decrease in FC between the cerebellar vermis and paracentral lobule was positively correlated with reductions in SARA scores (r = 0·611, p = 0.003) and ICARS scores (r = 0.609, p = 0.003) (Fig. 5 ). Discussion As one of the most prevalent subtypes of SCA, SCA3 requires further exploration of interventions that can modify the disease course by delaying onset or slowing progression. To our knowledge, this is the first study to apply rTMS to SCA3 patients, focusing on the midline region of the cerebrocerebellar loop and utilizing a multi-target treatment strategy. Moreover, through functional MRI, we conducted an in-depth analysis of how rTMS modulates FC within the cerebrocerebellar loop in SCA3 patients. The findings demonstrate that rTMS significantly improves both motor and cognitive functions in SCA3 patients; it also effectively alters FC patterns within the cerebrocerebellar loop, bringing them closer to the normalized patterns observed in healthy individuals. The results of this study suggest that multi-target rTMS therapy focused on the midline of the cerebrocerebellar loop has dual benefits on motor function and cognitive performance in SCA3 patients. Improvements in SARA and ICARS scores post-treatment are consistent with outcomes in previous randomized controlled trials, which showed the efficacy of iTBS treatment in the cerebellum for SCA3 patients[ 24 , 25 ]. Additionally, neuroregulation of the cerebellum improves motor function in ataxia model mice[ 26 ]. However, clinical treatment of SCA3 has historically emphasized motor symptom management, often overlooking the cognitive decline that accompanies the disease[ 27 , 28 ]. Therefore, the study also evaluated cognitive function pre- and post-treatment, revealing a significant increase in MoCA scores after rTMS therapy. The increased FC strength observed between the paracentral lobules and cerebellum, as well as between the cerebellar vermis and paracentral lobules, indicates impairment in the cerebrocerebellar loop in SCA3 patients. This finding aligns with previous studies showing structural and functional damage to cerebrocerebellar connections in SCA3 patients[ 3 , 4 ]. After rTMS treatment, the FC between the paracentral lobule and cerebellum, as well as between the cerebellar vermis and paracentral lobule, weakened and began to normalize in SCA3 patients (Fig. 4 ). These observations suggest that rTMS can effectively modulate the FC of the cerebrocerebellar loop in SCA3, thereby improving symptoms. Notably, rTMS targeting brain circuits has been used in motor disorders such as spinocerebellar ataxia; it provides greater benefits relative to single-target rTMS strategies[ 29 – 32 ]. The cerebral cortex → pontine nucleus → cerebellar cortex → dentate nucleus → ventrolateral nucleus of the thalamus → cerebral cortex pathway is a key circuit connecting the cerebral and cerebellar cortices[ 33 ]. Structural or functional disruptions within this circuit can lead to ataxia symptoms. Furthermore, the cerebellum’s connections with various supratentorial motor regions underscore its involvement in the cerebrocerebellar loop, particularly with regard to the paracentral lobule, which is responsible for motor and sensory functions related to the lower limbs[ 34 – 39 ]. Cerebellar iTBS likely enhances the excitability of Purkinje cells, which modulate activity in deep cerebellar nuclei and ultimately influence the motor cortex. 48 Consequently, high-frequency excitatory rTMS in the paracentral region may facilitate limb function recovery by increasing the excitability of the corticospinal tract[ 40 , 41 ]. Additionally, rTMS may regulate local neurotransmitter levels and enhance synaptic plasticity, improving transmission efficiency and neural recovery. The observed FC changes in the paracentral region likely reflect these underlying mechanisms. 51 In summary, rTMS targeting the midline of the cerebrocerebellar loop may optimize motor function and improve both motor dysfunction and cognitive abilities in SCA3 patients[ 42 ][ 43 ]. This study had some limitations. First, the single-arm design did not include a sham-stimulation control group, primarily due to the difficulty in achieving reliable sham conditions. Second, the lack of follow-up assessments prevented evaluations regarding the long-term stability and persistence of the treatment effects. Finally, the study was conducted at a single center, limiting the diversity and representativeness of the sample. This constraint was largely due to the rarity of the disease and the small number of available patients. In conclusion, this study employed multi-target rTMS therapy focused on the midline of the cerebrocerebellar loop in SCA3 patients, demonstrating that this approach improves both motor and cognitive functions. Additionally, it effectively regulates and normalizes FC within the cerebrocerebellar loop. Multi-target rTMS therapy based on the cerebrocerebellar loop is a feasible and effective treatment option for SCA3; it may be useful as a combination therapy in the future. Abbreviations Repetitive Transcranial Magnetic Stimulation, rTMS; Functional Connectivity, FC; Spinocerebellar Ataxia Type 3, SCA3; Scale for the Assessment and Rating of Ataxia, SARA; International Cooperative Ataxia Rating Scale, ICARS; Magnetic Resonance Imaging, Montreal Cognitive Assessment, MoCA; Mini-Mental State Examination, MMSE; Rapid Verbal Retrieval, RVR; Digit Span Test, DST; MRI; Intermittent theta-burst stimulation, iTBS; Region of Interest, ROI. Declarations Ethics approval : This study was approved by the Medical Ethical Committee of the Third Military Medical University. Consent to participate : Informed consent was obtained from all individual participants included in the study. Consent for publication : The authors affirm that human research participants provided informed consent for publication of the images. Availability of data and materials: The data presented in this study are available on reasonable request from the corresponding author. Competing interests: The authors declare that they have no competing interests. Funding: This research was supported by grants from the Young Middle-aged Senior Medical Talents studio of Chongqing (524Z28921), Senior Medical Talents Program of Chongqing for Young and Middle-aged (514Z395), Excellent Young Talent Fund of the First Affiliated Hospital of the Army Medical University (2024YQBJ-2), Chongqing City Key Medical Research Program of Science-Health Collaboration (2025GGXM005) and Natural Science Foundation of China (82071910, 81601478) provided funding for this study. Author contributions : Yonghua Huang : Writing-original draft, Methodology; Liu Feng , Data curation, Formal analysis; Peiling Ou: Data curation, Formal analysis; Lihua Deng: Data curation, Formal analysis; Linfeng Shi : Software, Supervision; He Liu : Software, Supervision; Zhiming Zhen : Supervision, Validation; Chen Wei : Supervision, Validation; Huafu Chen : Supervision, Validation; Xingang Wang : Validation, Visualization; Jian Wang : Writing-review & editing; Chen Liu : Writing-review & editing, Conceptualization, Funding acquisition. Acknowledgments: We are indebted to the patients and their families for their enthusiastic cooperation. References Klockgether T, Mariotti C, Paulson HL: Spinocerebellar ataxia . Nat Rev Dis Primers 2019, 5 (1):24. Guo J, Chen H, Biswal BB, Guo X, Zhang H, Dai L, Zhang Y, Li L, Fan Y, Han S et al : Gray matter atrophy patterns within the cerebellum-neostriatum-cortical network in SCA3 . Neurology 2020, 95 (22):e3036-e3044. 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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-7158751","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":532932529,"identity":"42432bcc-8948-46a4-a690-40e8618c3b80","order_by":0,"name":"Yonghua Huang","email":"","orcid":"","institution":"Third Military Medical University Southwest Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yonghua","middleName":"","lastName":"Huang","suffix":""},{"id":532932530,"identity":"6dfa5106-a9ad-4b56-86da-5180c3e4cfc6","order_by":1,"name":"Liu Feng","email":"","orcid":"","institution":"Third Military Medical University Southwest 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1","display":"","copyAsset":false,"role":"figure","size":417973,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlowchart of the study protocol\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAbbreviations: SCA3, Spinocerebellar ataxia type 3; MRI, Magnetic Resonance Imaging; rTMS, repetitive transcranial magnetic stimulation\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/94fdcebd81559afca4c586f3.png"},{"id":94874844,"identity":"f0438dd9-0027-4be3-896a-35ed62cee3e7","added_by":"auto","created_at":"2025-10-31 15:32:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":527409,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eClinical assessment scale scores before and after rTMS treatment in SCA3 patients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAbbreviations: Pre, SCA3 patients before treatment; Post, SCA3 patients after treatment; SARA, Scale for the Assessment and Rating of Ataxia; ICARS, International Cooperative Ataxia Rating Scale; MoCA, Montreal Cognitive Assessment; RVR, Rapid Verbal Retrieval; DST, Digit Span Test. *\u003cem\u003ep\u003c/em\u003e\u0026lt;0.05, **\u003cem\u003ep\u003c/em\u003e\u0026lt;0.01, ***\u003cem\u003ep\u003c/em\u003e\u0026lt;0.001, ns: not significant.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/3bb1da98813d5a079cc64c10.png"},{"id":94874846,"identity":"f003a7bf-6fd9-4066-bc16-58dec17e18dd","added_by":"auto","created_at":"2025-10-31 15:32:57","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3240696,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFC in ROIs across the whole brain\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA: Comparison of FC between two groups of ROIs and the whole brain. B: Changes in FC in SCA3 patients before and after treatment. Red indicates an increase in FC strength, whereas blue indicates a decrease. Color brightness corresponds to the magnitude of change in FC.\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/7feafcb203f8c720e1c70661.png"},{"id":94874849,"identity":"b4733eee-e19b-4661-9c66-2517a36dbf57","added_by":"auto","created_at":"2025-10-31 15:32:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1752896,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSignificant changes in FC of seed points before and after treatment in SCA3 patients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA-C show FC changes from the paracentral lobule to the cerebellum, whereas D-F illustrate FC changes from the cerebellar vermis to the paracentral lobule. *\u003cem\u003ep\u003c/em\u003e\u0026lt;0.05, **\u003cem\u003ep\u003c/em\u003e\u0026lt;0.01, ***\u003cem\u003ep\u003c/em\u003e\u0026lt;0.001.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/2efedfa60c9f9648caf270ad.png"},{"id":94874850,"identity":"ab8b262e-81e5-403e-9782-313a707c811a","added_by":"auto","created_at":"2025-10-31 15:32:57","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1469159,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe relationship between longitudinal FC changes and clinical symptom progression in SCA3 patients.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e△ represents the difference between pre- and post-treatment, FC_ROI1 refers to functional connectivity from the paracentral lobule to the cerebellum, and △FC_ROI2 refers to the connectivity from the cerebellar vermis to the paracentral lobule. *\u003cem\u003ep\u003c/em\u003e\u0026lt;0.05, **\u003cem\u003ep\u003c/em\u003e\u0026lt;0.01, ***\u003cem\u003ep\u003c/em\u003e\u0026lt;0.001. Red indicates a positive correlation, and blue denotes a negative correlation; darker colors represent stronger correlations.\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/6e49400194cbbab0811fdd09.png"},{"id":95000475,"identity":"9514d755-0b92-4ff6-8fb2-c204ee6d052e","added_by":"auto","created_at":"2025-11-03 08:58:13","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":10078525,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/5c9834bd-965e-4dfd-84c1-3d9e991a15e5.pdf"},{"id":94874873,"identity":"3b0004d5-ddf0-4e91-aa41-51ce13aff932","added_by":"auto","created_at":"2025-10-31 15:32:58","extension":"mp4","order_by":10,"title":"","display":"","copyAsset":false,"role":"supplement","size":8709539,"visible":true,"origin":"","legend":"","description":"","filename":"Gaitvideosbeforeandaftertreatment.mp4","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/8faa5a6c711269c4f1f1b31e.mp4"},{"id":94874863,"identity":"b5c5ab81-2dab-4dd9-86df-21e2ddb60afc","added_by":"auto","created_at":"2025-10-31 15:32:57","extension":"jpg","order_by":11,"title":"","display":"","copyAsset":false,"role":"supplement","size":1052909,"visible":true,"origin":"","legend":"","description":"","filename":"PrevsPostGaitParameters.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7158751/v1/4c7b9b14be9e70ccd29670a0.jpg"}],"financialInterests":"","formattedTitle":"\u003cp\u003eRepetitive transcranial magnetic stimulation normalizes cerebrocerebellar loop functional connectivity in spinocerebellar ataxia type 3: a synthetic control study\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSpinocerebellar ataxia type 3 (SCA3) is an autosomal-dominant neurodegenerative disorder characterized by an abnormal expansion of the CAG repeat in the \u003cem\u003eMJD1\u003c/em\u003e gene, leading to the pathological accumulation of ataxin-3 protein in the brain, which causes neuronal degeneration[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. SCA3 patients typically exhibit progressive ataxia, dysarthria, and ocular movement disorders[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Studies have shown that several brain regions, including the cerebellum, brainstem, basal ganglia, and thalamus, undergo atrophy in SCA3 patients[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The atrophy process often begins in the cerebellar vermis and gradually extends to areas such as the neostriatum and frontoparietal cortex[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. These structural changes directly affect the cerebrocerebellar loop, resulting in decreased cortical inhibition and increased intrinsic connectivity[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Because no curative treatments for SCA3 currently exist[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], it is particularly important to identify approaches that can slow SCA3 disease progression.\u003c/p\u003e\u003cp\u003eThe cerebrocerebellar loop, a critical neural circuit connecting the cerebral cortex and cerebellum, plays a key role in motor coordination, balance, and spatial cognitive processing[\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. It is also the loop most affected by the disease. Our previous study of brain structural connectivity in SCA3 revealed significant abnormalities within this loop, including degeneration in the cerebellar-thalamo-cortical tract and increased connectivity in the cortico-ponto-cerebellar tract[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Dysfunction in the cerebrocerebellar loop exacerbates ataxia symptoms in SCA3 patients, greatly affecting their daily activities and social interactions[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Therefore, explorations of treatments that target the cerebrocerebellar loop are critical for efforts to alleviate clinical symptoms and improve quality of life in individuals with SCA3.\u003c/p\u003e\u003cp\u003eRepetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulatory technique that has gained prominence in neurological rehabilitation. By delivering rapidly changing magnetic fields to the scalp, rTMS generates electrical currents in cortical brain regions, enabling temporary modulation of brain activity by either exciting or inhibiting targeted areas[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Moreover, rTMS can influence long-term cortical plasticity and alter functional connectivity (FC) among brain regions[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Current evidence suggests that rTMS can be effective in the management of neurodegenerative diseases[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, data regarding the efficacy of rTMS in SCA3 treatment exhibit moderate quality, and inconsistent therapeutic outcomes highlight variability in the clinical response[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Therefore, more comprehensive studies are needed to clarify the efficacy of rTMS in SCA3 treatment. A key limitation of this approach is the focal stimulation primarily directed at the cerebellum, which may limit its ability to modulate the broader neural networks involved in SCA3 pathogenesis[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Research has indicated that rTMS multi-target therapies are more effective than single-target approaches; loop-based treatment strategies potentially offer greater therapeutic benefits[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. There is currently a lack of research investigating rTMS multi-target strategies that specifically target the cerebrocerebellar loop in SCA3.\u003c/p\u003e\u003cp\u003eThis study utilized rTMS multi-target stimulation with the aim of modulating key nodes within the cerebrocerebellar loop in SCA3 patients. By evaluating changes in clinical symptom severity and cerebrocerebellar FC before and after treatment, we sought to clarify the feasibility and efficacy of this treatment approach, then explore the role of rTMS in regulating FC within the cerebrocerebellar loop.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e\u003cb\u003eParticipants\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBetween December 2020 and March 2023, we recruited 52 patients at the First Affiliated Hospital of the Chinese Army Medical University who had been diagnosed with SCA3. The inclusion criteria for SCA3 patients included a confirmed diagnosis through genetic testing, symptoms of spinocerebellar ataxia, and an age range of 16 to 75 years. Exclusion criteria for SCA3 patients were: 1) other familial hereditary disorders, such as Parkinson's disease; 2) serious central nervous system conditions, including epilepsy, traumatic brain injury, stroke, or brain tumors; 3) disagree with rTMS treatment (n\u0026thinsp;=\u0026thinsp;14), 4) contraindications for magnetic resonance imaging (MRI), 5) rTMS treatment was not completed (n\u0026thinsp;=\u0026thinsp;13). We selected 33 healthy volunteers matched according to age, sex, and handedness from a pool of 200 healthy controls recruited during the same period. All participants provided written informed consent at the First Affiliated Hospital of the Army Medical University. The study protocol was approved by the institutional review committee (KY2020191), and the clinical trial was registered under ChiCTR2000039434 (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://chictr.org.cn\u003c/span\u003e\u003cspan address=\"http://chictr.org.cn\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). The study protocol is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eClinical evaluation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe severity of ataxia in SCA3 patients was evaluated using the Scale for the Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS)[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Healthy controls and SCA3 patients agreed to undergo pre- and post-treatment neuropsychological assessments, including the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) to measure overall cognitive function[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], the Rapid Verbal Retrieval (RVR) category fluency test[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], and the Digit Span Test (DST) to assess working memory[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cb\u003eImage data acquisition\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAll participants underwent MRI scans using a Siemens Trio 3T MR scanner (Germany), equipped with a standard eight-channel phased-array head coil. The MRI protocol included high-resolution sagittal T1-weighted imaging (T1WI) and resting-state functional imaging sequences. Sagittal T1WI used the MPRAGE sequence with the following parameters: repetition time of 1900 ms, echo time of 2\u0026middot;52 ms, inversion time of 900 ms, echo train length of 1, flip angle of 9\u0026deg;, slice thickness of 1 mm, matrix size of 256 \u0026times; 256, voxel size of 1 \u0026times; 1 \u0026times; 1 mm, and 176 slices with no interslice gap. Resting-state functional imaging sequence parameters included a repetition time of 2000 ms, echo time of 30 ms, flip angle of 90\u0026deg;, field of view of 240 \u0026times; 240 mm, matrix size of 64 \u0026times; 64, 240 slices, slice thickness of 3 mm, no interslice gap, and a voxel size of 3\u0026middot;75 \u0026times; 3\u0026middot;75 \u0026times; 3 mm.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTranscranial magnetic stimulation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe study used the OSF-6 magnetic stimulator, manufactured by Wuhan Yiruide, to treat SCA3 patients. The biconical coil was designed to stimulate deeper brain regions, and the specific coil used was a curved biconical coil. This coil has a winding angle of 135\u0026deg; and a wing diameter of 90 mm.\u003c/p\u003e\u003cp\u003eThe paracentral lobule and cerebellar vermis play key roles in ataxia and are critical sites within the cerebrocerebellar loop. Before the first rTMS session, the patient's cortical resting motor threshold must be measured[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. During each treatment session, surface localization methods are used to separately identify the stimulation targets. When the optimal location for stimulating the leg motor cortex is identified on the scalp of SCA3 patients, standard rTMS treatment is administered. In this study, stimulation was applied at 100% of the resting motor threshold, with a pulse frequency of 10 Hz, delivering 40 stimuli over 4 seconds. The inter-stimulus interval was 26 seconds with 25 repetitions, for a total of 1000 pulses within 12 minutes and 30 seconds. The surface of the cerebellar vermis is located 1 cm below the external occipital protuberance[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Here, the coil was positioned accordingly for treatment. Intermittent theta-burst stimulation (iTBS) was used, with an intensity of 120% of the resting motor threshold. The iTBS parameters included an intra-burst frequency of 50 Hz, intra-burst stimulation time of 0.06 seconds, inter-burst frequency of 5 Hz, and 10 bursts per sequence. Each stimulation lasted for 2 seconds, followed by an 8-second interval; these steps were repeated 20 times for a total of 600 pulses completed within 3 minutes and 20 seconds. After a 5-minute rest, the cerebellar vermis iTBS treatment was repeated. The treatment protocol was conducted once daily, five times per week, for 4 weeks.\u003c/p\u003e\u003cp\u003e\u003cb\u003erTMS treatment outcome measurement\u003c/b\u003e\u003c/p\u003e\u003cp\u003ePrimary outcomes of interest were changes in the SARA and ICARS scores after treatment. All patients who completed the full treatment course and underwent baseline and post-treatment evaluations related to the primary outcomes (n\u0026thinsp;=\u0026thinsp;25) were included in the primary analysis. Secondary outcomes included cognitive measurements such as the MoCA, RVR, and DST, as well as FC changes within the cerebrocerebellar loop.\u003c/p\u003e\u003cp\u003e\u003cb\u003eImage preprocessing\u003c/b\u003e\u003c/p\u003e\u003cp\u003eResting-state functional MRI scans were preprocessed using the Brain Imaging Data Processing and Analysis Toolbox (DPABI) software (DPABI: a toolbox for Data Processing \u0026amp; Analysis for Brain Imaging | The R-fMRI Network (rfmri.org)). Preprocessing began by discarding the first 10 time points; this was followed by time point correction to ensure uniformity across scans. Manual head motion correction was performed, and participants with maximum head movement exceeding 5\u0026middot;mm of translation were excluded (due to the movement disorder in SCA3 patients, head movement was more pronounced relative to the healthy control group). Functional and structural images were manually adjusted to align with T1WI templates, using resampled voxel sizes of 2 \u0026times; 2 \u0026times; 2 mm. Several covariates, including Friston 24 motion parameters, cerebrospinal fluid, and white matter signals, were regressed out as nuisance variables to minimize spurious differences. To reduce the effects of low-frequency drift and physiological high-frequency noise, further preprocessing involved linear regression and time bandpass filtering (0.01\u0026ndash;0.08 Hz). At this stage, linear trends were also removed to mitigate the impact of temperature fluctuations in the MRI equipment.\u003c/p\u003e\u003cp\u003e\u003cb\u003eDefinition of the region of interest for seed points\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe region of interest (ROI) for the stimulation target in the midline of the cerebrocerebellar loop was defined using Montreal Neurological Institute (MNI) spatial coordinates. ROI 1, located in the paracentral cortex, was centered at (0, -30, 65), and ROI 2, located in the cerebellar vermis, was centered at (0, -70, -25). A spherical ROI with a 10 mm diameter was generated around each of these points. The mask for each ROI was resampled to a voxel size of 3 \u0026times; 3 \u0026times; 3 mm. The blood-oxygen-level-dependent time series from voxels within the ROI was averaged to create a reference time series.\u003c/p\u003e\u003cp\u003e\u003cb\u003eStatistical analysis of FC\u003c/b\u003e\u003c/p\u003e\u003cp\u003eTo assess the strength of cerebrocerebellar FC, we conducted FC analysis based on the seed points. We also calculated Pearson correlation coefficients between seed points and whole-brain voxels, then performed z-transformation to improve normality. Group-level statistical comparisons were performed to evaluate FC differences in the two seed ROIs among healthy controls, baseline SCA3 patients, and post-treatment SCA3 patients. The image calculator within the DPABI toolkit was used to compare FC differences between the SCA3_0W (SCA3 patients before treatment, n\u0026thinsp;=\u0026thinsp;22) and healthy control (HC, n\u0026thinsp;=\u0026thinsp;33) groups. Independent sample t-tests were performed, controlling for head movement, age, and average frame displacement values.\u003c/p\u003e\u003cp\u003ePaired sample t-tests were used to evaluate longitudinal changes in FC differences between SCA3_0W (n\u0026thinsp;=\u0026thinsp;22) and SCA3_4W (SCA3 patients after treatment, n\u0026thinsp;=\u0026thinsp;22). Thresholds for statistical significance were defined as voxel-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001 and cluster-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, adjusted for Gaussian Random Field correction.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eDemographic and clinical characteristics were analyzed using SPSS Statistics for Windows, version 26\u0026middot;0 (IBM, Armonk, NY, USA). Differences in demographic and baseline variables between study groups were evaluated using independent sample t-tests and chi-square tests.\u003c/p\u003e\u003cp\u003eThe study protocol and statistical analysis plan are available in eSAP 1, eSAP 2, respectively.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eDemographic data\u003c/b\u003e\u003c/p\u003e\u003cp\u003eIn total, 25 SCA3 patients and 33 healthy controls were included in this study (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). No significant differences were observed in age (44.8\u0026thinsp;\u0026plusmn;\u0026thinsp;11.22 vs 44.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9\u0026middot;26, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.991) or sex (15 men vs 11 men, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.912) between SCA3 patients and healthy controls. The average duration of disease onset in SCA3 patients was 9.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9 years. Cognition-related scales, including MoCA (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), MMSE (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005), and RVR (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), showed significantly lower scores in SCA3 patients than in healthy controls. However, there was no statistically significant difference in DST score (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.073) between the two groups. Participant demographic and clinical characteristics are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e\u003cb\u003eParticipant demographic and clinical characteristics\u003c/b\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eCharacteristics\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHC\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSCA3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eStatistical analysis\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;33)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;25)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e44\u0026middot;8\u0026thinsp;\u0026plusmn;\u0026thinsp;9\u0026middot;26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e44\u0026middot;8\u0026thinsp;\u0026plusmn;\u0026thinsp;11\u0026middot;22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.011\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u0026middot;991 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex (male)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.012\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u0026middot;912\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDuration of onset\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9\u0026middot;60\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u0026middot;90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSARA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14\u0026middot;02\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u0026middot;90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eICARS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e36\u0026middot;16\u0026thinsp;\u0026plusmn;\u0026thinsp;17\u0026middot;16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMoCA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e26\u0026middot;76\u0026thinsp;\u0026plusmn;\u0026thinsp;3\u0026middot;36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22\u0026middot;64\u0026thinsp;\u0026plusmn;\u0026thinsp;4\u0026middot;24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-4\u0026middot;12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMMSE\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28\u0026middot;7\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u0026middot;74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27\u0026middot;00\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026middot;63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-2\u0026middot;95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.005 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRVR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e48\u0026middot;55\u0026thinsp;\u0026plusmn;\u0026thinsp;15\u0026middot;44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e33\u0026middot;20\u0026thinsp;\u0026plusmn;\u0026thinsp;12\u0026middot;24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-4\u0026middot;09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDST\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8\u0026middot;88\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026middot;58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u0026middot;82\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u0026middot;49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-1\u0026middot;83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.073 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eAbbreviations: a, two-sample t-test; b, chi-square test; SARA, Scale for the Assessment and Rating of Ataxia; ICARS, International Cooperative Ataxia Rating Scale; MoCA, Montreal Cognitive Assessment; RVR, Rapid Verbal Retrieval; DST, Digit Span Test.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eChanges in clinical scales pre- and post-treatment\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAfter rTMS treatment, SCA3 patients showed significant reductions in disease severity, as reflected by decreased SARA (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and ICARS (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) scores. Moreover, the MoCA score (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), related to cognitive function, demonstrated a substantial improvement after treatment. However, there were no statistically significant differences between pre- and post-treatment scores on the MMSE (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.097), RVR (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.395), or DST (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.131) assessments (refer to Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e for details).\u003c/p\u003e\u003cp\u003e\u003cb\u003eResting-state FC based on seed points\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThree of the 25 SCA3 patients were excluded from the analysis due to poor MRI scan quality caused by motion artifacts. Comparisons of FC in ROI1 and ROI2 within the midline region of the cerebrocerebellar loop between SCA3 patients and healthy controls (as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) revealed significant increases in FC. Specifically, FC in ROI1 containing the supplementary motor area and cerebellum in SCA3 patients showed a substantial increase (voxel-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, cluster-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, GFR-corrected). Additionally, FC between ROI2 and the cerebellum, occipital lobe, and paracentral lobule showed significant enhancement (voxel-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, cluster-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, GFR-corrected).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eComparisons of stimulation targets and global brain FC in SCA3 patients before and after treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) demonstrated post-treatment decreases in FC. Specifically, FC between the paracentral lobule and the thalamus and cerebellum decreased (voxel-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, cluster-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, GFR-corrected). Similarly, FC between the cerebellar vermis and the occipital lobe and paracentral lobule was reduced (voxel-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, cluster-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, GFR-corrected).\u003c/p\u003e\u003cp\u003e\u003cb\u003eChanges in FC between stimulation target ROIs and whole brain in SCA3 patients\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAt baseline and after treatment, changes in FC between stimulation target ROIs and the whole brain encompassed the cerebellum and paracentral lobule (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Prior to rTMS treatment, SCA3 patients exhibited increased FC strength between ROI1 and the cerebellum, as well as between ROI2 and the paracentral lobule (voxel-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, cluster-level \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, GFR-corrected). However, after rTMS treatment targeting the cerebrocerebellar loop, the FC strength in these regions decreased (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e\u003cb\u003eChanges in FC within brain regions of SCA3 patients before and after treatment\u003c/b\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026minus;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eROI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBrain region\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCluster size\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAAL\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMNI\u003c/p\u003e\u003cp\u003e(x, y, z)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003et\u003c/em\u003e value (\u003cem\u003edf\u003c/em\u003e)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSCA3_0W\u003c/p\u003e\u003cp\u003eVS HC\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eROI1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCerebellum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e595\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e91\u0026ndash;94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c5\"\u003e\u003cp\u003e-27, -66, -60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4\u0026middot;93 (52)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eROI2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eParacentral lobule\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c5\"\u003e\u003cp\u003e4, -35, 60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4\u0026middot;41 (52)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSCA3_4W\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eVS SCA3_0W\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eROI1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eCluster 1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCerebellum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e92\u0026ndash;94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c5\"\u003e\u003cp\u003e9, -81, -24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-4\u0026middot;71 (41)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eCluster 2\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThalamus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e77,78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c5\"\u003e\u003cp\u003e12, -18, 6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-3\u0026middot;85 (41)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eROI2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eCluster 1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eParacentral lobule\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e69,70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c5\"\u003e\u003cp\u003e3, -30, 63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-4\u0026middot;21 (41)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003eCluster 2\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLingual\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026minus;\" colname=\"c5\"\u003e\u003cp\u003e18, -93, -6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-4\u0026middot;03 (41)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eAbbreviations: SCA3_0W, SCA3 patients before treatment; SCA3_4W, SCA3 patients after treatment\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eRelationship between longitudinal FC changes and clinical symptoms\u003c/b\u003e\u003c/p\u003e\u003cp\u003eCorrelation analysis was performed to examine the relationship between changes in FC and improvements in clinical symptoms. The results indicated that the reduction in FC between the paracentral lobule and cerebellum was positively correlated with decreases in SARA scores (r\u0026thinsp;=\u0026thinsp;0\u0026middot;845, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and ICARS scores (r\u0026thinsp;=\u0026thinsp;0\u0026middot;912, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Similarly, the decrease in FC between the cerebellar vermis and paracentral lobule was positively correlated with reductions in SARA scores (r\u0026thinsp;=\u0026thinsp;0\u0026middot;611, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003) and ICARS scores (r\u0026thinsp;=\u0026thinsp;0.609, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAs one of the most prevalent subtypes of SCA, SCA3 requires further exploration of interventions that can modify the disease course by delaying onset or slowing progression. To our knowledge, this is the first study to apply rTMS to SCA3 patients, focusing on the midline region of the cerebrocerebellar loop and utilizing a multi-target treatment strategy. Moreover, through functional MRI, we conducted an in-depth analysis of how rTMS modulates FC within the cerebrocerebellar loop in SCA3 patients. The findings demonstrate that rTMS significantly improves both motor and cognitive functions in SCA3 patients; it also effectively alters FC patterns within the cerebrocerebellar loop, bringing them closer to the normalized patterns observed in healthy individuals.\u003c/p\u003e\u003cp\u003eThe results of this study suggest that multi-target rTMS therapy focused on the midline of the cerebrocerebellar loop has dual benefits on motor function and cognitive performance in SCA3 patients. Improvements in SARA and ICARS scores post-treatment are consistent with outcomes in previous randomized controlled trials, which showed the efficacy of iTBS treatment in the cerebellum for SCA3 patients[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Additionally, neuroregulation of the cerebellum improves motor function in ataxia model mice[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. However, clinical treatment of SCA3 has historically emphasized motor symptom management, often overlooking the cognitive decline that accompanies the disease[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Therefore, the study also evaluated cognitive function pre- and post-treatment, revealing a significant increase in MoCA scores after rTMS therapy.\u003c/p\u003e\u003cp\u003eThe increased FC strength observed between the paracentral lobules and cerebellum, as well as between the cerebellar vermis and paracentral lobules, indicates impairment in the cerebrocerebellar loop in SCA3 patients. This finding aligns with previous studies showing structural and functional damage to cerebrocerebellar connections in SCA3 patients[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. After rTMS treatment, the FC between the paracentral lobule and cerebellum, as well as between the cerebellar vermis and paracentral lobule, weakened and began to normalize in SCA3 patients (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). These observations suggest that rTMS can effectively modulate the FC of the cerebrocerebellar loop in SCA3, thereby improving symptoms. Notably, rTMS targeting brain circuits has been used in motor disorders such as spinocerebellar ataxia; it provides greater benefits relative to single-target rTMS strategies[\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe cerebral cortex \u0026rarr; pontine nucleus \u0026rarr; cerebellar cortex \u0026rarr; dentate nucleus \u0026rarr; ventrolateral nucleus of the thalamus \u0026rarr; cerebral cortex pathway is a key circuit connecting the cerebral and cerebellar cortices[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Structural or functional disruptions within this circuit can lead to ataxia symptoms. Furthermore, the cerebellum\u0026rsquo;s connections with various supratentorial motor regions underscore its involvement in the cerebrocerebellar loop, particularly with regard to the paracentral lobule, which is responsible for motor and sensory functions related to the lower limbs[\u003cspan additionalcitationids=\"CR35 CR36 CR37 CR38\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Cerebellar iTBS likely enhances the excitability of Purkinje cells, which modulate activity in deep cerebellar nuclei and ultimately influence the motor cortex.\u003csup\u003e48\u003c/sup\u003e Consequently, high-frequency excitatory rTMS in the paracentral region may facilitate limb function recovery by increasing the excitability of the corticospinal tract[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Additionally, rTMS may regulate local neurotransmitter levels and enhance synaptic plasticity, improving transmission efficiency and neural recovery. The observed FC changes in the paracentral region likely reflect these underlying mechanisms.\u003csup\u003e51\u003c/sup\u003e In summary, rTMS targeting the midline of the cerebrocerebellar loop may optimize motor function and improve both motor dysfunction and cognitive abilities in SCA3 patients[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e][\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThis study had some limitations. First, the single-arm design did not include a sham-stimulation control group, primarily due to the difficulty in achieving reliable sham conditions. Second, the lack of follow-up assessments prevented evaluations regarding the long-term stability and persistence of the treatment effects. Finally, the study was conducted at a single center, limiting the diversity and representativeness of the sample. This constraint was largely due to the rarity of the disease and the small number of available patients.\u003c/p\u003e\u003cp\u003eIn conclusion, this study employed multi-target rTMS therapy focused on the midline of the cerebrocerebellar loop in SCA3 patients, demonstrating that this approach improves both motor and cognitive functions. Additionally, it effectively regulates and normalizes FC within the cerebrocerebellar loop. Multi-target rTMS therapy based on the cerebrocerebellar loop is a feasible and effective treatment option for SCA3; it may be useful as a combination therapy in the future.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eRepetitive Transcranial Magnetic Stimulation, rTMS; Functional Connectivity, FC;\u0026nbsp;Spinocerebellar Ataxia Type 3, SCA3; Scale for the Assessment and Rating of Ataxia, SARA; International Cooperative Ataxia Rating Scale, ICARS; Magnetic Resonance Imaging, Montreal Cognitive Assessment, MoCA; Mini-Mental State Examination, MMSE; Rapid Verbal Retrieval, RVR; Digit Span Test, DST; MRI;\u0026nbsp;Intermittent theta-burst stimulation, iTBS; Region of Interest, ROI.\u003c/p\u003e\n"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003cstrong\u003e:\u0026nbsp;\u003c/strong\u003eThis study was approved by the Medical Ethical Committee of the Third Military Medical University.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003cstrong\u003e:\u0026nbsp;\u003c/strong\u003eInformed consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003cstrong\u003e:\u0026nbsp;\u003c/strong\u003eThe authors affirm that human research participants provided informed consent for publication of the images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eThe data presented in this study are available on reasonable request from the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThis research was supported by grants from the Young Middle-aged Senior Medical Talents studio of Chongqing (524Z28921), Senior Medical Talents Program of Chongqing for Young and Middle-aged (514Z395), Excellent Young Talent Fund of the First Affiliated Hospital of the Army Medical University (2024YQBJ-2), Chongqing City Key Medical Research Program of Science-Health Collaboration (2025GGXM005) and Natural Science Foundation of China (82071910, 81601478) provided funding for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e: \u003cstrong\u003eYonghua Huang\u003c/strong\u003e: Writing-original draft, Methodology; \u003cstrong\u003eLiu Feng\u003c/strong\u003e, Data curation, Formal analysis; \u003cstrong\u003ePeiling Ou:\u0026nbsp;\u003c/strong\u003eData curation, Formal analysis; \u003cstrong\u003eLihua Deng:\u003c/strong\u003e Data curation, Formal analysis; \u003cstrong\u003eLinfeng Shi\u003c/strong\u003e: Software, Supervision; \u003cstrong\u003eHe Liu\u003c/strong\u003e: Software, Supervision; \u003cstrong\u003eZhiming Zhen\u003c/strong\u003e: Supervision, Validation; \u003cstrong\u003eChen Wei\u003c/strong\u003e: Supervision, Validation; \u003cstrong\u003eHuafu Chen\u003c/strong\u003e: Supervision, Validation; \u003cstrong\u003eXingang Wang\u003c/strong\u003e: Validation, Visualization; \u003cstrong\u003eJian Wang\u003c/strong\u003e: Writing-review \u0026amp; editing; \u003cstrong\u003eChen Liu\u003c/strong\u003e: Writing-review \u0026amp; editing, Conceptualization, Funding acquisition.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u003c/strong\u003e We are indebted to the patients and their families for their enthusiastic cooperation.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKlockgether T, Mariotti C, Paulson HL: \u003cstrong\u003eSpinocerebellar ataxia\u003c/strong\u003e. \u003cem\u003eNat Rev Dis Primers \u003c/em\u003e2019, 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\u003cstrong\u003e11\u003c/strong\u003e(1):14777.\u003c/li\u003e\n\u003c/ol\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":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"orphanet-journal-of-rare-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ojrd","sideBox":"Learn more about [Orphanet Journal of Rare Diseases](http://ojrd.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ojrd/default.aspx","title":"Orphanet Journal of Rare Diseases","twitterHandle":"@bmc","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Spinocerebellar ataxia type 3 (SCA3), Cerebrocerebellar loop, Repetitive transcranial magnetic stimulation (rTMS), Functional connectivity","lastPublishedDoi":"10.21203/rs.3.rs-7158751/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7158751/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eSpinocerebellar ataxia type 3 (SCA3) is a rare neurodegenerative disorder characterized by ataxia; structural and functional damage to the cerebrocerebellar loop play key roles in its pathology. However, effective treatments for SCA3 remain limited. Repetitive transcranial magnetic stimulation (rTMS) modulates cortical plasticity. Here, we investigated the utility of rTMS in SCA3 treatment.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis study included 25 confirmed SCA3 patients and 33 age- and sex-matched healthy volunteers as controls. The Scale for the Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS) were used to assess the severity of clinical symptoms in the SCA3 group. Both groups completed neuropsychological evaluations and underwent brain magnetic resonance imaging (MRI) before and after treatment. MRI data were preprocessed using DPABI software to analyze changes in functional connectivity strength, both at the stimulation target and across the whole brain, in SCA3 patients before and after multi-target rTMS therapy based on the cerebrocerebellar loop.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eAfter multi-target rTMS treatment, SARA (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and ICARS (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) scores in SCA3 patients were significantly reduced, whereas Montreal Cognitive Assessment (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) scores showed a substantial improvement in cognitive performance. Functional connectivity strengths between the paracentral lobule and cerebellum, and between the cerebellar vermis and paracentral lobule, decreased in SCA3 patients after treatment, gradually approaching levels observed in healthy controls.\u003c/p\u003e\u003ch2\u003eDiscussion\u003c/h2\u003e\u003cp\u003eA multi-target rTMS treatment strategy targeting the cerebrocerebellar loop may significantly improve motor and cognitive functions in SCA3 patients by effectively regulating functional connectivity within this circuit.\u003c/p\u003e","manuscriptTitle":"Repetitive transcranial magnetic stimulation normalizes cerebrocerebellar loop functional connectivity in spinocerebellar ataxia type 3: a synthetic control study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-31 15:32:52","doi":"10.21203/rs.3.rs-7158751/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-01-02T09:56:14+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-21T15:10:40+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Orphanet Journal of Rare Diseases","date":"2025-07-22T06:34:49+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-22T04:55:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"Orphanet Journal of Rare Diseases","date":"2025-07-21T11:16:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"orphanet-journal-of-rare-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ojrd","sideBox":"Learn more about [Orphanet Journal of Rare Diseases](http://ojrd.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ojrd/default.aspx","title":"Orphanet Journal of Rare Diseases","twitterHandle":"@bmc","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"027b38cf-bfb0-4c8b-bd14-636d863015e8","owner":[],"postedDate":"October 31st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-12T10:30:02+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-31 15:32:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7158751","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7158751","identity":"rs-7158751","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}