Alteration of Postural Stability after Cerebrospinal Fluid Tap Test in Patients with Idiopathic Normal Pressure Hydrocephalus

Alteration of Postural Stability after Cerebrospinal Fluid Tap Test in Patients with Idiopathic Normal Pressure Hydrocephalus | 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 Article Alteration of Postural Stability after Cerebrospinal Fluid Tap Test in Patients with Idiopathic Normal Pressure Hydrocephalus Eunhee Park, Sanghyeon Lee, Tae-Du Jung, Ki-Su Park, Jong Taek Lee, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3198125/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background In patients with idiopathic normal pressure hydrocephalus (iNPH), the characteristics of balance disturbance are less understood than those of gait. We examined the changes in postural stability after the cerebrospinal fluid tap test (CSFTT) during quiet standing. Furthermore, we explored the relationship between frontal lobe function and the amount of spontaneous body sway. Methods All patients with iNPH underwent CSFTT and were evaluated using a frontal assessment battery (FAB) and center of pressure (COP) using a force plate during quiet standing before and after CSFTT. After COP measurement, we calculated COP parameters using time and frequency domain analysis. We determined whether there were alterations of COP parameters before and after CSFTT and the relationship between FAB and COP parameters using SPSS. Results In total, 72 patients with iNPH were recruited, and 56 patients who positively responded to CSFTT were finally included. Following CSFTT, there were significantly improved COP parameters using time domain analysis (velocity of COP, vCOP, p = 0.002; root-mean-square of COP, p = 0.032; turn index, p = 0.017; torque, p = 0.003; base of support, BOS, p = 0.014) compared to before CSFTT. In COP parameters using frequency domain analysis after CSFTT, we observed decreased power spectral density (PSD) values in the anteroposterior (peak value, p = 0.049; average value, p = 0.030) and mediolateral (peak value, p = 0.003; average value, p = 0.028) directions at low-frequency oscillation, below 0.5 Hz. In addition, FAB scores were negatively correlated with the vCOP ( r = − 0.359, p = 0.007), BOS ( r = − 0.302, p = 0.025), and the peak PSD value ( r = − 0.464, p = 0.002) and average PSD value ( r = − 0.424, p = 0.004) in anteroposterior direction for iNPH patients, respectively. Conclusions In patients with iNPH who responded to CSFTT, spontaneous body sway during quiet standing improved after CSFTT. The increased spontaneous sway is associated with impaired frontal lobe function, which may be linked to postural control circuits in patients with iNPH. Health sciences/Neurology/Neurological disorders/Hydrocephalus Health sciences/Health care/Health services/Rehabilitation Normal pressure hydrocephalus Postural balance Spinal puncture Figures Figure 1 Figure 2 Introduction Idiopathic normal pressure hydrocephalus (iNPH), with enlarged brain ventricle and normal cerebrospinal fluid (CSF) pressure, is characterized by gait and balance disturbance, cognitive impairment, and urinary incontinence 1,2 . Gait and balance disturbances are often the most prominent clinical features and the first to become apparent 1,3 . Compared with healthy individuals, the gait of patients with iNPH is characterized by a broad base, short stride length, low speed, and increased variability in stride time and length 4 . The CSF tap test (CSFTT) is a widely used diagnostic and therapeutic tool for improving gait disturbance 4–7 . In accordance with the Japanese guideline, clinical improvement after the CSFTT increases diagnostic certainty of iNPH from possible to probable 5 . In patients with iNPH, these gait characteristics are relatively better known than balance characteristics 8 . Postural stability, also referred to as balance, is the ability of the body to maintain the center of gravity (COG) within the base of support (BOS), which is the area of contact with the support surface 9,10 . Force platforms have been used to quantify the characteristics of postural stability and calculate indirect changes in spontaneous body sway, i.e., the center of pressure (COP) calculated from ground reaction force 11,12 . The COP indicates the weighted average of all forces created from the BOS and reflects the trajectory of the COG. When the limit of stability of BOS is exceeded, an individual must take a step to reestablish the BOS below the COG to prevent a fall 13 . Consequently, measuring COP displacement is related to the spontaneous joint movements needed to maintain the body against gravity 14 . Although quiet standing appears still, passive skeletal alignment and muscular and postural tone are needed to prevent collapse against gravity, known as static steady-state balance 9,14 . The power spectral density (PSD) of COP calculated via frequency domain analysis using Fourier transformation is a helpful tool for evaluating the effects of small and rapid movements on spontaneous body sway during quiet standing in older adults 15 , patients with Parkinson’s disease 16,17 , and patients with multiple sclerosis 18 . There have been a few studies on the quantitative measurement of balance disturbance in patients with iNPH. A previous study reported an improvement in the radius and sway area of COP after shunt surgery in nine patients with iNPH 19 . Furthermore, Blomsterwall et al. 20 described that patients with iNPH had a larger sway area and higher COP velocity than those with subcortical arteriosclerotic encephalopathy, but this study was limited by the inclusion of secondary NPH patients. In addition, Nikaido et al. 21 demonstrated that patients with iNPH showed improved COP trajectories after shunt surgery, but this study was limited to only 23 participants with iNPH. The characteristics of imbalance and alteration in postural stability after CSFTT have yet to be elucidated in patients with iNPH. This study aimed to quantitatively measure changes in COP during quiet standing after CSFTT in iNPH patients who responded positively to the CSFTT. We examined alteration in COP parameters using time and frequency domain analysis before and after CSFTT. Furthermore, we investigated the relationship between frontal lobe function and COP during quiet standing at baseline. Our hypotheses were as follows. First, when a patient with iNPH stands quietly, COP parameters improve after CSFTT compared to before CSFTT. Second, the amount of spontaneous body sway is associated with frontal lobe dysfunction, which might affect postural control. Method 1. Participants This study included patients diagnosed with iNPH, using the following criteria proposed by previous diagnostic guidelines: ( 1 ) aged > 40 years, ( 2 ) symptoms that have progressed insidiously over 6 months (i.e., gait disturbance with at least cognitive impairment), ( 3 ) presented with normal CSF opening pressure, ( 4 ) showed enlarged ventricles (Evans’ ratio of > 0.3) and no macroscopic obstruction of CSF flow on brain magnetic resonance imaging, and ( 5 ) positive responsiveness after CSFTT 5,22 . A lumbar tap removed 30–50 ml of CSF on each INPH patient. After the CSFTT, patients were re-evaluated with the Korean-Mini Mental State Examination (K-MMSE), the iNPH Grading Scale (iNPHGS), and the Timed Up and Go Test (TUG). Gait changes were evaluated multiple times over 7 days following the tap, and changes in cognition and urination were assessed at 1 week. CSFTT response was defined using these 3 major scales 23 . INPH patients who had a positive response to the CSFTT according to the Japanese guidelines for iNPH were enrolled 23 . The exclusion criteria were as follows: ( 1 ) history of stroke; ( 2 ) history of heavy alcohol use; ( 3 ) history of hospitalization due to a major psychiatric disorder; ( 4 ) history of other neurologic, metabolic, neoplastic, or musculoskeletal disorder; and ( 5 ) evidence of secondary hydrocephalus after traumatic brain injury, intracerebral hemorrhage, or meningitis. The Frontal Assessment Battery (FAB) scores ranged from 0 to 18, with a higher score indicating better cognitive function associated with the frontal lobe 24 . This prospective study included patients admitted to the Department of Neurology at Kyungpook National University Chilgok Hospital between September 2021 and November 2022. Written informed consent was obtained from all participants. The Institutional Review Board of Kyungpook National University Chilgok Hospital provided ethical approval (No. 2021-07-023). All experiments were performed in accordance with relevant guidelines and regulations. 2. COP measurement We assessed all participants for measuring COP at pre-CSFTT and the day after the CSFTT. We measured COP using a force-measuring plate sampled at 60 Hz (Zebris FDM-S®, Germany) during quiet standing with eyes opened. We instructed the participants to try to stand with their bare feet as close together as possible. For 30 s, they stood quietly on the force plate and arms held comfortably on their sides. We assessed COP twice before CSFTT (pre-CSFTT) and after CSFTT within 24 to 48 h (post-CSFTT). 3. Data analysis We conducted time and frequency domain analysis of COP using Python 3.7.15 ( https://www.python.org ) and Python signal processing package SciPy 1.9.1 ( https://scipy.org ) and calculated the COP parameters using analytical methods proposed by Palmieri et al. 12 and Kotolova et al. 25 . 3.1. COP parameters using time domain analysis We calculated the velocity of COP (vCOP) by dividing the displacement of the COP trajectory by the recording time, t . The anteroposterior (AP) and mediolateral (ML) directions represent the AP and ML positions, respectively. $$\text{v}\text{C}\text{O}\text{P}=\frac{{\sum }_{\text{n}=1}^{\text{N}}\sqrt{{\left({AP}_{n-1} - {AP}_{n}\right)}^{2} + {\left({ML}_{n-1} - {ML}_{n}\right)}^{2}}}{t} (\text{m}\text{m}/\text{s})$$ We calculated the root mean square COP (rmsCOP) as the distance between the displacement of COP and mean COP position \(\left({{\mu }}_{\text{A}\text{P}}, {{\mu }}_{\text{M}\text{L}}\right)\) . Then, we calculated the sum of the distances and divided it by the number of frames N during the recording time. $$\text{r}\text{m}\text{s}\text{C}\text{O}\text{P}=\frac{{\sum }_{\text{n}=1}^{\text{N}}\sqrt{{\left({AP}_{n} - {\mu }_{AP}\right)}^{2} + {\left({ML}_{n} -{ \mu }_{ML}\right)}^{2}}}{N} (\text{m}\text{m}/\text{f}\text{r}\text{a}\text{m}\text{e})$$ We calculated the turn index by dividing the sum of the COP trajectory length in each direction by its standard deviation ( \({{\sigma }}_{\text{A}\text{P}}, {{\sigma }}_{\text{M}\text{L}})\) in that direction; the obtained value was then divided by the recording time. $$Turn index=\frac{{\sum }_{\text{n}=1}^{\text{N}}\sqrt{{\left(\frac{{AP}_{n-1} - {AP}_{n} }{{\sigma }_{AP}}\right)}^{2} + {\left(\frac{{ML}_{n-1} - {ML}_{n} }{{\sigma }_{ML}}\right)}^{2}}}{t} (\text{m}\text{m}/\text{s})$$ The torque was calculated by multiplying the weight with vCOP, where \({\text{F}}_{\text{G}}\) indicates each patient’s weight. Torque = \(\frac{{\sum }_{n=1}^{N}{F}_{G} \cdot \sqrt{{\left({AP}_{n-1} – {AP}_{n}\right)}^{2} + {\left({ML}_{n-1} – {ML}_{n}\right)}^{2}} }{t} (\text{k}\text{g}\bullet \frac{\text{m}}{\text{s}}\) ) The area of BOS was calculated as the area between both feet in contact with the force plate ( \({\text{c}\text{m}}^{2}\) ), as shown in Supplementary Fig. 1. 3.2. COP parameters using frequency domain analysis We quantified COP oscillations using Fourier analysis and power spectral density (PSD). We calculated the PSD values of COP as follows: the peak PSD in AP and peak PSD in ML indicated the maximum PSD values of the AP and ML direction within the frequency range of interest, and the average PSD in AP and average PSD in ML were calculated as the average value of PSD within the frequency range of interest. Based on previous studies 17,18,26 , we considered the frequency ranges of interest as 0–0.5 Hz and 0.5-1.0 Hz. 4. Statistical analysis We performed all statistical analyses using SPSS software version 23 (SPSS, Inc, Armonk, NY, USA). We confirmed a normal distribution of data using the Shapiro–Wilk test ( p < 0.05). We used a Paired t -test to compare changes in COP parameters using time and frequency domain analysis at pre- and post-CSFTT. Furthermore, we used Pearson’s correlation to evaluate the relationship between FAB and COP parameters. The correlation coefficient ( r ) of ≥ 0.3 was considered to be medically significant 27 . A p value of < 0.05 was considered to indicate statistical significance. Results We recruited 72 patients with iNPH, 3 of whom failed quiet standing for 30 s at pre-CSFTT, and 2 patients were lost to COP measurements after CSFTT. Also, we excluded 11 patients who did not respond to CSFTT. Finally, we included 56 patients with iNPH after positively responding to CSFTT. Of the 56 patients, 36 were male, and 20 were female (mean age 75.45 ± 5.46 years old). The average FAB score was 9.78 ± 3.72 at baseline. COP parameters using time domain analysis The representative data of the COP trajectory and the COP displacements in AP and ML directions before and after CSFTT are shown in Fig. 1 . During quiet standing at post-CSFTT, vCOP ( t = 3.188, p = 0.002), rmsCOP ( t = 2.213, p = 0.032), turn index ( t = 2.483, p = 0.017), torque ( t = 3.102, p = 0.003) and BOS ( t = 2.550, p = 0.014) significantly decreased compared with those at pre-CSFTT (Table 1 ). Table 1 Center of Pressure Parameters Before and After CSFTT in Patients with Idiopathic Normal Pressure Hydrocephalus COP parameters Pre-CSFTT Post-CSFTT t p value Time Domain Analysis vCOP 30.32 (12.78) 25.97 (6.95) 3.188 0.002 * rmsCOP 9.49 (4.87) 8.42 (3.64) 2.213 0.032 * Turns index 286.32 (384.07) 189.76 (150.27) 2.483 0.017 * Torque 1.60 (0.54) 1.43 (0.37) 3.102 0.003 * BOS 666.75 (141.46) 625.40 (96.67) 2.550 0.014 * Frequency Domain Analysis Peak PSD in AP at 0–0.5 Hz 194.39 (301.61) 101.29 (107.74) 2.037 0.049 * at 0.5–1.0 Hz 21.56 (27.22) 14.61 (15.21) 1.716 0.095 Average PSD in AP at 0–0.5 Hz 63.32 (84.16) 35.86 (30.38) 2.262 0.030 * at 0.5–1.0 Hz 9.10 (11.24) 5.98 (5.86) 2.026 0.050 Peak PSD in ML at 0–0.5 Hz 472.97 (679.87) 146.06 (217.07) 3.172 0.003 * at 0.5–1.0 Hz 93.29 (427.88) 11.51 (21.79) 1.236 0.224 Average PSD in ML at 0–0.5 Hz 179.15 (320.19) 61.12 (106.06) 2.289 0.028 * at 0.5–1.0 Hz 39.51 (179.85) 5.99 (14.79) 1.247 0.220 The value of mean (standard deviation). AP: anteroposterior, BOS: base of support, COP: center of pressure, CSFTT: cerebrospinal fluid tap test, rms: root-mean-square, ML: mediolateral, PSD: power spectral density, v: velocity. * represents a significant difference between pre-and post-CSFTT using Paired t-test ( p < 0.05). COP parameters using frequency domain analysis We observed a significant decrease in the peak PSD value in AP direction ( t = 2.037, p = 0.049), the average PSD value in AP direction ( t = 2.262, p = 0.030), the peak PSD value in ML direction ( t = 3.172, p = 0.003), and the average PSD value in ML direction ( t = 2.289, p = 0.028) at 0–0.5 Hz after CSFTT during quiet standing (Table 1 ). Relationship between FAB scores and COP parameters The FAB score was significantly negatively correlated with vCOP ( r = − 0.359, p = 0.007), BOS ( r = − 0.302, p = 0.025), and the peak PSD value ( r = − 0.464, p = 0.002) and average PSD value ( r = − 0.424, p = 0.004) in AP direction at 0-0.5 Hz, respectively (Fig. 2 ). Discussion We investigated alteration in COP parameters, which indicates spontaneous body sway, after CSFTT during quiet standing in patients with iNPH. The COP displacements associated with time domain analysis reduced after CSFTT. In addition, iNPH patients had low PSD values, indicating less variation in power value of COP in the peak and average in both AP and ML directions at low-frequency oscillation after CSFTT. Interestingly, frontal lobe function was negatively correlated with spontaneous sway. To evaluate balance function in patients with iNPH, we measured COP during quiet standing. Clinically, balance function is classified into static steady-state balance, which is the ability to maintain a steady position, such as standing, and dynamic steady-state balance, which is the ability to maintain a static position with a shift in the COG, such as walking 9,28 . An individual with a good static steady-state balance is expected to perform well in dynamic steady-state balance 28,29 . In practice, gait disturbances in patients with iNPH range from mild imbalance to complete inability to walk. In the case of patients who cannot walk independently or experience frequent falls, measuring the static steady-state balance could be helpful. To the best of our knowledge, this is the first study to compare the changes in static steady-state balance before and after CSFTT in patients with iNPH. Further studies are warranted to confirm the relationship between static and dynamic steady-state balance in patients with iNPH. In our study, iNPH patients showed a decrease in COP parameters using time and frequency domain analysis after CSFTT. These changes could be interpreted as improving the ability to postural control after CSFTT. The PSD value helps evaluate the effect of small and rapid movements on spontaneous body sway 26 . Previous studies have reported higher PSD values of COP in older adults 15 , patients with Parkinson’s disease 16,17 , multiple sclerosis 18 , idiopathic scoliosis 30 , and vestibular disorders 31 than in healthy controls during quiet standing. Furthermore, the range of PSD is closely associated with postural control in older adults and Parkinson’s disease 17,26 . Especially, low-frequency oscillation below 0.5 Hz reflects thought to be part of the descending drive to the motor neuron pool 17,18 . The exacerbation of low-frequency oscillations probably indicates a loss of motor control of the descending drive to the motor control. This decline in motor control is likely caused by the deterioration of neurons in brain regions related to motor control 17 . In this study, lower PSD values in the AP and ML direction below 0.5 Hz suggest a less frequent oscillation of spontaneous body sway during quiet standing after CSFTT. This improvement in low-frequency oscillation may be linked to an improvement in cerebral blood flow in periventricular and frontal white matter regions after CSFTT 32 . Furthermore, it was suggested that motor function recovery in iNPH patients after CSF removal was related to a reversible suppression of frontal periventricular cortico-basal ganglia-thalamo-cortical circuits 33 . However, the mechanisms producing balance recovery in iNPH are still not fully understood, and future studies are warranted to better investigate this aspect. The spontaneous body sway was inversely associated with frontal lobe function; in other words, lower frontal lobe function was related to more frequent oscillations of body sway. Recent studies reported the ability to balance control was related to cognitive impairment in healthy older people 34 , Alzheimer's disease 35 , and Parkinson’s disease 36 . Even though healthy young adults, postural control was attentionally demanding, secondary tasks could increase their spontaneous body sway 37,38 . Postural control is influenced by multifactorial brain areas related to motor control systems, including those associated with higher-level cognitive function (frontal cortex), sensory feedback, coordination (basal ganglia, brainstem, and spinal cord), and generation of forces (motor neurons and muscles) that result in movements that maintain the body’s position 39 . In patients with iNPH, ventricular enlargement may interrupt the cortical-subcortical connections, such as the basal ganglia circuit, which connects the frontal cortex and basal ganglia 40,41 . In our study, severe frontal dysfunction predicted as impaired cortico-subcortical circuits may result in poor balance function in patients with iNPH. This study has several limitations. We measured participants’ ability to maintain a steady position during standing. Although there is a high similarity between static and dynamic steady-state balance, it might be insufficient to explain dynamic parameters related to gait function. Recent studies have attempted to quantitatively assess dynamic characteristics during gait using a triaxial accelerometer of the trunk in patients with iNPH 42,43 . To understand postural instability in patients with iNPH, further large-scale studies are warranted to evaluate the relationship between static and dynamic steady-state balance function in patients with iNPH. Moreover, we did not compare COP parameters between patients with iNPH and healthy older controls. Healthy older adults revealed a difference in spontaneous sway between fallers and non-fallers during quiet standing 44 . Further study is needed to measure alterations of COP parameters in patients with iNPH compared to older adults. Conclusion Spontaneous body sway during quiet standing improved after CSFTT in patients with iNPH. Furthermore, the amount of spontaneous sway is negatively associated with frontal lobe function. Our finding suggested that increased postural instability could be related to impaired frontal lobe functions in iNPH patients who suffered from impaired cortico-subcortical circuits. Declarations Acknowledgements The research was supported by National Research Foundation of Korea (NRF- 2021R1C1C101138713). Author contributions K.K., K.P., and T.J. conceptualized this study. K.K. and E.P. recruited participants and performed clinical assessments. E.P., S.L, and JT.L analyzed and interpreted the data. E.P. and S.L. were major contributors in writing the manuscript. All authors read and approved the final manuscript. Data availability statement The datasets generated and/or analysed during the current study are not publicly available because we did not get permission to disclosure it from the participants. However, it can be available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Ethics declarations The study was conducted with written informed consent obtained from all participants. 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D., Kofman, J. & McIlroy, W. E. J. P. o. Elderly fall risk prediction using static posturography. 12, e0172398 (2017). Additional Declarations No competing interests reported. Supplementary Files SupplementaryFigure1.tif Supplementary Figure 1. Calculating method of the base of support (BOS) Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-3198125","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":222582669,"identity":"f21ae7bd-beb8-4193-a25a-62f3f7adf3ac","order_by":0,"name":"Eunhee Park","email":"","orcid":"","institution":"Kyungpook National University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Eunhee","middleName":"","lastName":"Park","suffix":""},{"id":222582670,"identity":"6052401d-fa4d-46f7-9e4b-523583e2ede6","order_by":1,"name":"Sanghyeon Lee","email":"","orcid":"","institution":"Kyungpook National University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Sanghyeon","middleName":"","lastName":"Lee","suffix":""},{"id":222582671,"identity":"ed109868-c5fa-4cdb-a312-b4191bae5deb","order_by":2,"name":"Tae-Du Jung","email":"","orcid":"","institution":"Kyungpook National University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Tae-Du","middleName":"","lastName":"Jung","suffix":""},{"id":222582672,"identity":"e9da2cb6-3907-4b86-852d-7dc5fbcb5a22","order_by":3,"name":"Ki-Su Park","email":"","orcid":"","institution":"Kyungpook National University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Ki-Su","middleName":"","lastName":"Park","suffix":""},{"id":222582673,"identity":"4716e41d-984f-41fb-adf1-36ea4352e25c","order_by":4,"name":"Jong Taek Lee","email":"","orcid":"","institution":"Kyungpook National University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jong","middleName":"Taek","lastName":"Lee","suffix":""},{"id":222582674,"identity":"49f5c30b-3a6f-4c42-938f-0fb5994af4bf","order_by":5,"name":"Kyunghun Kang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYBACCRDB2AAkeECsigNg0QMPiNdy5gCYPpBAtBbGNogWBnxaJGfkmD38uuNwHgPP4WcPv867I2cvdvgh0BY7Od0G7FqkJXLMjWXPHC5m4G0DMrY9M+aRTjMAakk2NjuAXYucRI6ZtGTb4cQGfgYgY9vhxB7pBJCWA4nbCGth/yYtOQekJf0DXi1Ah5lJfgRp4e0BMhpAWnLw2yLZ86xMmrEtPbGN50yZNMOxw8Y8t3MKDiQY4PaLxPHkbZI/26wT+3nSt0n+qDksxz47ffOHDxV2cri0MAgkMDCDooINiMEMCDDAoRwE+A8wMP6AsuGMUTAKRsEoGAXIAAAPn2DYmhoZOgAAAABJRU5ErkJggg==","orcid":"","institution":"Kyungpook National University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Kyunghun","middleName":"","lastName":"Kang","suffix":""}],"badges":[],"createdAt":"2023-07-24 06:15:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3198125/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3198125/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":41037571,"identity":"7d31ca7e-c0a3-4eb4-a5ec-5c665aadf107","added_by":"auto","created_at":"2023-08-03 20:40:42","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":56832,"visible":true,"origin":"","legend":"\u003cp\u003eThe representative data of the center of pressure (COP) trajectory and the COP displacements in anteroposterior (AP) and mediolateral (ML) directions before and after the cerebrospinal fluid tap test (CSFTT). The data correspond to three participants: (a) a 69-year-old man; (b) a 75-year-old man; (c) an 81-year-old man. The blue line represents COP trajectory according to time during quiet standing, and the red spot represents the center of COP displacement during quiet standing.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3198125/v1/1dd38b1811b49eff3315f161.png"},{"id":41037572,"identity":"7a6a2517-b621-483b-a635-535a1aa42f0b","added_by":"auto","created_at":"2023-08-03 20:40:42","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":30509,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship between center of pressure (COP) parameters and frontal assessment battery (FAB) score. (a) velocity of COP (vCOP) and FAB; (b) area of the base of support (BOS) and FAB; (c) the peak of power spectral density (PSD) value in anteroposterior (AP) direction at 0-0.5 Hz and FAB; (d) the average of PSD value in AP direction at 0-0.5 Hz and FAB. *Significant difference in Pearson’s correlation (coefficient \u003cem\u003er\u003c/em\u003e \u0026gt; 0.3).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3198125/v1/cc29cd08a3d9d38117a7c5ed.png"},{"id":47850466,"identity":"c6d7c399-9427-436b-8a3f-c52f94eb1b99","added_by":"auto","created_at":"2023-12-08 11:15:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":481867,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3198125/v1/f0ecd44d-786c-4b7e-a70d-2927c323348c.pdf"},{"id":41037573,"identity":"d09a57ac-d7d3-43fb-829e-4305feee41e0","added_by":"auto","created_at":"2023-08-03 20:40:42","extension":"tif","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":77244,"visible":true,"origin":"","legend":"\u003cp\u003eSupplementary Figure 1. Calculating method of the base of support (BOS)\u003c/p\u003e","description":"","filename":"SupplementaryFigure1.tif","url":"https://assets-eu.researchsquare.com/files/rs-3198125/v1/13a8c822ec26255de120f43a.tif"}],"financialInterests":"No competing interests reported.","formattedTitle":"Alteration of Postural Stability after Cerebrospinal Fluid Tap Test in Patients with Idiopathic Normal Pressure Hydrocephalus","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIdiopathic normal pressure hydrocephalus (iNPH), with enlarged brain ventricle and normal cerebrospinal fluid (CSF) pressure, is characterized by gait and balance disturbance, cognitive impairment, and urinary incontinence\u003csup\u003e1,2\u003c/sup\u003e. Gait and balance disturbances are often the most prominent clinical features and the first to become apparent\u003csup\u003e1,3\u003c/sup\u003e. Compared with healthy individuals, the gait of patients with iNPH is characterized by a broad base, short stride length, low speed, and increased variability in stride time and length\u003csup\u003e4\u003c/sup\u003e. The CSF tap test (CSFTT) is a widely used diagnostic and therapeutic tool for improving gait disturbance\u003csup\u003e4\u0026ndash;7\u003c/sup\u003e. In accordance with the Japanese guideline, clinical improvement after the CSFTT increases diagnostic certainty of iNPH from possible to probable\u003csup\u003e5\u003c/sup\u003e. In patients with iNPH, these gait characteristics are relatively better known than balance characteristics\u003csup\u003e8\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePostural stability, also referred to as balance, is the ability of the body to maintain the center of gravity (COG) within the base of support (BOS), which is the area of contact with the support surface\u003csup\u003e9,10\u003c/sup\u003e. Force platforms have been used to quantify the characteristics of postural stability and calculate indirect changes in spontaneous body sway, i.e., the center of pressure (COP) calculated from ground reaction force\u003csup\u003e11,12\u003c/sup\u003e. The COP indicates the weighted average of all forces created from the BOS and reflects the trajectory of the COG. When the limit of stability of BOS is exceeded, an individual must take a step to reestablish the BOS below the COG to prevent a fall\u003csup\u003e13\u003c/sup\u003e. Consequently, measuring COP displacement is related to the spontaneous joint movements needed to maintain the body against gravity\u003csup\u003e14\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAlthough quiet standing appears still, passive skeletal alignment and muscular and postural tone are needed to prevent collapse against gravity, known as static steady-state balance\u003csup\u003e9,14\u003c/sup\u003e. The power spectral density (PSD) of COP calculated via frequency domain analysis using Fourier transformation is a helpful tool for evaluating the effects of small and rapid movements on spontaneous body sway during quiet standing in older adults\u003csup\u003e15\u003c/sup\u003e, patients with Parkinson\u0026rsquo;s disease\u003csup\u003e16,17\u003c/sup\u003e, and patients with multiple sclerosis\u003csup\u003e18\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThere have been a few studies on the quantitative measurement of balance disturbance in patients with iNPH. A previous study reported an improvement in the radius and sway area of COP after shunt surgery in nine patients with iNPH\u003csup\u003e19\u003c/sup\u003e. Furthermore, Blomsterwall et al.\u003csup\u003e20\u003c/sup\u003e described that patients with iNPH had a larger sway area and higher COP velocity than those with subcortical arteriosclerotic encephalopathy, but this study was limited by the inclusion of secondary NPH patients. In addition, Nikaido et al.\u003csup\u003e21\u003c/sup\u003e demonstrated that patients with iNPH showed improved COP trajectories after shunt surgery, but this study was limited to only 23 participants with iNPH. The characteristics of imbalance and alteration in postural stability after CSFTT have yet to be elucidated in patients with iNPH.\u003c/p\u003e \u003cp\u003eThis study aimed to quantitatively measure changes in COP during quiet standing after CSFTT in iNPH patients who responded positively to the CSFTT. We examined alteration in COP parameters using time and frequency domain analysis before and after CSFTT. Furthermore, we investigated the relationship between frontal lobe function and COP during quiet standing at baseline. Our hypotheses were as follows. First, when a patient with iNPH stands quietly, COP parameters improve after CSFTT compared to before CSFTT. Second, the amount of spontaneous body sway is associated with frontal lobe dysfunction, which might affect postural control.\u003c/p\u003e "},{"header":"Method","content":"\u003ch2\u003e1. Participants\u003c/h2\u003e\u003cp\u003eThis study included patients diagnosed with iNPH, using the following criteria proposed by previous diagnostic guidelines: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) aged\u0026thinsp;\u0026gt;\u0026thinsp;40 years, (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) symptoms that have progressed insidiously over 6 months (i.e., gait disturbance with at least cognitive impairment), (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) presented with normal CSF opening pressure, (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) showed enlarged ventricles (Evans\u0026rsquo; ratio of \u0026gt;\u0026thinsp;0.3) and no macroscopic obstruction of CSF flow on brain magnetic resonance imaging, and (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) positive responsiveness after CSFTT\u003csup\u003e5,22\u003c/sup\u003e. A lumbar tap removed 30\u0026ndash;50 ml of CSF on each INPH patient. After the CSFTT, patients were re-evaluated with the Korean-Mini Mental State Examination (K-MMSE), the iNPH Grading Scale (iNPHGS), and the Timed Up and Go Test (TUG). Gait changes were evaluated multiple times over 7 days following the tap, and changes in cognition and urination were assessed at 1 week. CSFTT response was defined using these 3 major scales\u003csup\u003e23\u003c/sup\u003e. INPH patients who had a positive response to the CSFTT according to the Japanese guidelines for iNPH were enrolled\u003csup\u003e23\u003c/sup\u003e. The exclusion criteria were as follows: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) history of stroke; (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) history of heavy alcohol use; (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) history of hospitalization due to a major psychiatric disorder; (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) history of other neurologic, metabolic, neoplastic, or musculoskeletal disorder; and (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) evidence of secondary hydrocephalus after traumatic brain injury, intracerebral hemorrhage, or meningitis. The Frontal Assessment Battery (FAB) scores ranged from 0 to 18, with a higher score indicating better cognitive function associated with the frontal lobe\u003csup\u003e24\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis prospective study included patients admitted to the Department of Neurology at Kyungpook National University Chilgok Hospital between September 2021 and November 2022. Written informed consent was obtained from all participants. The Institutional Review Board of Kyungpook National University Chilgok Hospital provided ethical approval (No. 2021-07-023). All experiments were performed in accordance with relevant guidelines and regulations.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2. COP measurement\u003c/h2\u003e \u003cp\u003eWe assessed all participants for measuring COP at pre-CSFTT and the day after the CSFTT. We measured COP using a force-measuring plate sampled at 60 Hz (Zebris FDM-S\u0026reg;, Germany) during quiet standing with eyes opened. We instructed the participants to try to stand with their bare feet as close together as possible. For 30 s, they stood quietly on the force plate and arms held comfortably on their sides. We assessed COP twice before CSFTT (pre-CSFTT) and after CSFTT within 24 to 48 h (post-CSFTT).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3. Data analysis\u003c/h2\u003e \u003cp\u003eWe conducted time and frequency domain analysis of COP using Python 3.7.15 (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.python.org\u003c/span\u003e\u003cspan address=\"https://www.python.org\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) and Python signal processing package SciPy 1.9.1 (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://scipy.org\u003c/span\u003e\u003cspan address=\"https://scipy.org\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) and calculated the COP parameters using analytical methods proposed by Palmieri et al.\u003csup\u003e12\u003c/sup\u003e and Kotolova et al.\u003csup\u003e25\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.1. COP parameters using time domain analysis\u003c/h2\u003e \u003cp\u003eWe calculated the velocity of COP (vCOP) by dividing the displacement of the COP trajectory by the recording time, \u003cem\u003et\u003c/em\u003e. The anteroposterior (AP) and mediolateral (ML) directions represent the AP and ML positions, respectively.\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\text{v}\\text{C}\\text{O}\\text{P}=\\frac{{\\sum }_{\\text{n}=1}^{\\text{N}}\\sqrt{{\\left({AP}_{n-1} - {AP}_{n}\\right)}^{2} + {\\left({ML}_{n-1} - {ML}_{n}\\right)}^{2}}}{t} (\\text{m}\\text{m}/\\text{s})$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWe calculated the root mean square COP (rmsCOP) as the distance between the displacement of COP and mean COP position \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\left({{\\mu }}_{\\text{A}\\text{P}}, {{\\mu }}_{\\text{M}\\text{L}}\\right)\\)\u003c/span\u003e\u003c/span\u003e. Then, we calculated the sum of the distances and divided it by the number of frames N during the recording time.\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\text{r}\\text{m}\\text{s}\\text{C}\\text{O}\\text{P}=\\frac{{\\sum }_{\\text{n}=1}^{\\text{N}}\\sqrt{{\\left({AP}_{n} - {\\mu }_{AP}\\right)}^{2} + {\\left({ML}_{n} -{ \\mu }_{ML}\\right)}^{2}}}{N} (\\text{m}\\text{m}/\\text{f}\\text{r}\\text{a}\\text{m}\\text{e})$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWe calculated the turn index by dividing the sum of the COP trajectory length in each direction by its standard deviation (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({{\\sigma }}_{\\text{A}\\text{P}}, {{\\sigma }}_{\\text{M}\\text{L}})\\)\u003c/span\u003e\u003c/span\u003ein that direction; the obtained value was then divided by the recording time.\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$Turn index=\\frac{{\\sum }_{\\text{n}=1}^{\\text{N}}\\sqrt{{\\left(\\frac{{AP}_{n-1} - {AP}_{n} }{{\\sigma }_{AP}}\\right)}^{2} + {\\left(\\frac{{ML}_{n-1} - {ML}_{n} }{{\\sigma }_{ML}}\\right)}^{2}}}{t} (\\text{m}\\text{m}/\\text{s})$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe torque was calculated by multiplying the weight with vCOP, where \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{F}}_{\\text{G}}\\)\u003c/span\u003e\u003c/span\u003e indicates each patient\u0026rsquo;s weight.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003e\u003cem\u003eTorque\u003c/em\u003e = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\frac{{\\sum }_{n=1}^{N}{F}_{G} \\cdot \\sqrt{{\\left({AP}_{n-1} \u0026ndash; {AP}_{n}\\right)}^{2} + {\\left({ML}_{n-1} \u0026ndash; {ML}_{n}\\right)}^{2}} }{t} (\\text{k}\\text{g}\\bullet \\frac{\\text{m}}{\\text{s}}\\)\u003c/span\u003e\u003c/span\u003e)\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe area of BOS was calculated as the area between both feet in contact with the force plate (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{c}\\text{m}}^{2}\\)\u003c/span\u003e\u003c/span\u003e), as shown in Supplementary Fig.\u0026nbsp;1.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.2. COP parameters using frequency domain analysis\u003c/h2\u003e \u003cp\u003eWe quantified COP oscillations using Fourier analysis and power spectral density (PSD). We calculated the PSD values of COP as follows: the peak PSD in AP and peak PSD in ML indicated the maximum PSD values of the AP and ML direction within the frequency range of interest, and the average PSD in AP and average PSD in ML were calculated as the average value of PSD within the frequency range of interest. Based on previous studies\u003csup\u003e17,18,26\u003c/sup\u003e, we considered the frequency ranges of interest as 0\u0026ndash;0.5 Hz and 0.5-1.0 Hz.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e4. Statistical analysis\u003c/h2\u003e \u003cp\u003eWe performed all statistical analyses using SPSS software version 23 (SPSS, Inc, Armonk, NY, USA). We confirmed a normal distribution of data using the Shapiro\u0026ndash;Wilk test (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). We used a Paired \u003cem\u003et\u003c/em\u003e-test to compare changes in COP parameters using time and frequency domain analysis at pre- and post-CSFTT. Furthermore, we used Pearson\u0026rsquo;s correlation to evaluate the relationship between FAB and COP parameters. The correlation coefficient (\u003cem\u003er\u003c/em\u003e) of \u0026ge;\u0026thinsp;0.3 was considered to be medically significant\u003csup\u003e27\u003c/sup\u003e. A \u003cem\u003ep\u003c/em\u003e value of \u0026lt;\u0026thinsp;0.05 was considered to indicate statistical significance.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eWe recruited 72 patients with iNPH, 3 of whom failed quiet standing for 30 s at pre-CSFTT, and 2 patients were lost to COP measurements after CSFTT. Also, we excluded 11 patients who did not respond to CSFTT. Finally, we included 56 patients with iNPH after positively responding to CSFTT. Of the 56 patients, 36 were male, and 20 were female (mean age 75.45\u0026thinsp;\u0026plusmn;\u0026thinsp;5.46 years old). The average FAB score was 9.78\u0026thinsp;\u0026plusmn;\u0026thinsp;3.72 at baseline.\u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eCOP parameters using time domain analysis\u003c/h2\u003e \u003cp\u003eThe representative data of the COP trajectory and the COP displacements in AP and ML directions before and after CSFTT are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. During quiet standing at post-CSFTT, vCOP (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.188, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002), rmsCOP (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.213, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032), turn index (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.483, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.017), torque (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.102, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003) and BOS (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.550, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014) significantly decreased compared with those at pre-CSFTT (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\u003eCenter of Pressure Parameters Before and After CSFTT in Patients with Idiopathic Normal Pressure Hydrocephalus\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=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eCOP parameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePre-CSFTT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePost-CSFTT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003et\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eTime Domain Analysis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003evCOP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e30.32 (12.78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e25.97 (6.95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.188\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.002\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ermsCOP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.49 (4.87)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8.42 (3.64)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.213\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.032\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTurns index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e286.32 (384.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e189.76 (150.27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.483\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.017\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTorque\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.60 (0.54)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.43 (0.37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.003\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBOS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e666.75 (141.46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e625.40 (96.67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.550\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.014\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003eFrequency Domain Analysis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePeak PSD in AP\u003c/p\u003e \u003cp\u003eat 0\u0026ndash;0.5 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e194.39 (301.61)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e101.29 (107.74)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.037\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.049\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eat 0.5\u0026ndash;1.0 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e21.56 (27.22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e14.61 (15.21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.716\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.095\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAverage PSD in AP\u003c/p\u003e \u003cp\u003eat 0\u0026ndash;0.5 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e63.32 (84.16)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e35.86 (30.38)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.262\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.030\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eat 0.5\u0026ndash;1.0 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.10 (11.24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.98 (5.86)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.050\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePeak PSD in ML\u003c/p\u003e \u003cp\u003eat 0\u0026ndash;0.5 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e472.97 (679.87)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e146.06 (217.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.172\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.003\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eat 0.5\u0026ndash;1.0 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e93.29 (427.88)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11.51 (21.79)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.236\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.224\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAverage PSD in ML\u003c/p\u003e \u003cp\u003eat 0\u0026ndash;0.5 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e179.15 (320.19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e61.12 (106.06)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.289\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.028\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eat 0.5\u0026ndash;1.0 Hz\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e39.51 (179.85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.99 (14.79)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.247\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.220\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eThe value of mean (standard deviation). AP: anteroposterior, BOS: base of support, COP: center of pressure, CSFTT: cerebrospinal fluid tap test, rms: root-mean-square, ML: mediolateral, PSD: power spectral density, v: velocity. \u003csup\u003e*\u003c/sup\u003e represents a significant difference between pre-and post-CSFTT using Paired t-test (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eCOP parameters using frequency domain analysis\u003c/h2\u003e \u003cp\u003eWe observed a significant decrease in the peak PSD value in AP direction (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.037, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.049), the average PSD value in AP direction (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.262, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.030), the peak PSD value in ML direction (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.172, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003), and the average PSD value in ML direction (\u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.289, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.028) at 0\u0026ndash;0.5 Hz after CSFTT during quiet standing (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eRelationship between FAB scores and COP parameters\u003c/h2\u003e \u003cp\u003eThe FAB score was significantly negatively correlated with vCOP (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.359, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007), BOS (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.302, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.025), and the peak PSD value (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.464, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002) and average PSD value (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.424, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004) in AP direction at 0-0.5 Hz, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eWe investigated alteration in COP parameters, which indicates spontaneous body sway, after CSFTT during quiet standing in patients with iNPH. The COP displacements associated with time domain analysis reduced after CSFTT. In addition, iNPH patients had low PSD values, indicating less variation in power value of COP in the peak and average in both AP and ML directions at low-frequency oscillation after CSFTT. Interestingly, frontal lobe function was negatively correlated with spontaneous sway.\u003c/p\u003e \u003cp\u003eTo evaluate balance function in patients with iNPH, we measured COP during quiet standing. Clinically, balance function is classified into static steady-state balance, which is the ability to maintain a steady position, such as standing, and dynamic steady-state balance, which is the ability to maintain a static position with a shift in the COG, such as walking\u003csup\u003e9,28\u003c/sup\u003e. An individual with a good static steady-state balance is expected to perform well in dynamic steady-state balance\u003csup\u003e28,29\u003c/sup\u003e. In practice, gait disturbances in patients with iNPH range from mild imbalance to complete inability to walk. In the case of patients who cannot walk independently or experience frequent falls, measuring the static steady-state balance could be helpful. To the best of our knowledge, this is the first study to compare the changes in static steady-state balance before and after CSFTT in patients with iNPH. Further studies are warranted to confirm the relationship between static and dynamic steady-state balance in patients with iNPH.\u003c/p\u003e \u003cp\u003eIn our study, iNPH patients showed a decrease in COP parameters using time and frequency domain analysis after CSFTT. These changes could be interpreted as improving the ability to postural control after CSFTT. The PSD value helps evaluate the effect of small and rapid movements on spontaneous body sway\u003csup\u003e26\u003c/sup\u003e. Previous studies have reported higher PSD values of COP in older adults\u003csup\u003e15\u003c/sup\u003e, patients with Parkinson\u0026rsquo;s disease\u003csup\u003e16,17\u003c/sup\u003e, multiple sclerosis\u003csup\u003e18\u003c/sup\u003e, idiopathic scoliosis\u003csup\u003e30\u003c/sup\u003e, and vestibular disorders\u003csup\u003e31\u003c/sup\u003e than in healthy controls during quiet standing. Furthermore, the range of PSD is closely associated with postural control in older adults and Parkinson\u0026rsquo;s disease\u003csup\u003e17,26\u003c/sup\u003e. Especially, low-frequency oscillation below 0.5 Hz reflects thought to be part of the descending drive to the motor neuron pool\u003csup\u003e17,18\u003c/sup\u003e. The exacerbation of low-frequency oscillations probably indicates a loss of motor control of the descending drive to the motor control. This decline in motor control is likely caused by the deterioration of neurons in brain regions related to motor control\u003csup\u003e17\u003c/sup\u003e. In this study, lower PSD values in the AP and ML direction below 0.5 Hz suggest a less frequent oscillation of spontaneous body sway during quiet standing after CSFTT. This improvement in low-frequency oscillation may be linked to an improvement in cerebral blood flow in periventricular and frontal white matter regions after CSFTT\u003csup\u003e32\u003c/sup\u003e. Furthermore, it was suggested that motor function recovery in iNPH patients after CSF removal was related to a reversible suppression of frontal periventricular cortico-basal ganglia-thalamo-cortical circuits\u003csup\u003e33\u003c/sup\u003e. However, the mechanisms producing balance recovery in iNPH are still not fully understood, and future studies are warranted to better investigate this aspect.\u003c/p\u003e \u003cp\u003eThe spontaneous body sway was inversely associated with frontal lobe function; in other words, lower frontal lobe function was related to more frequent oscillations of body sway. Recent studies reported the ability to balance control was related to cognitive impairment in healthy older people\u003csup\u003e34\u003c/sup\u003e, Alzheimer's disease\u003csup\u003e35\u003c/sup\u003e, and Parkinson\u0026rsquo;s disease\u003csup\u003e36\u003c/sup\u003e. Even though healthy young adults, postural control was attentionally demanding, secondary tasks could increase their spontaneous body sway\u003csup\u003e37,38\u003c/sup\u003e. Postural control is influenced by multifactorial brain areas related to motor control systems, including those associated with higher-level cognitive function (frontal cortex), sensory feedback, coordination (basal ganglia, brainstem, and spinal cord), and generation of forces (motor neurons and muscles) that result in movements that maintain the body\u0026rsquo;s position\u003csup\u003e39\u003c/sup\u003e. In patients with iNPH, ventricular enlargement may interrupt the cortical-subcortical connections, such as the basal ganglia circuit, which connects the frontal cortex and basal ganglia\u003csup\u003e40,41\u003c/sup\u003e. In our study, severe frontal dysfunction predicted as impaired cortico-subcortical circuits may result in poor balance function in patients with iNPH.\u003c/p\u003e \u003cp\u003eThis study has several limitations. We measured participants\u0026rsquo; ability to maintain a steady position during standing. Although there is a high similarity between static and dynamic steady-state balance, it might be insufficient to explain dynamic parameters related to gait function. Recent studies have attempted to quantitatively assess dynamic characteristics during gait using a triaxial accelerometer of the trunk in patients with iNPH\u003csup\u003e42,43\u003c/sup\u003e. To understand postural instability in patients with iNPH, further large-scale studies are warranted to evaluate the relationship between static and dynamic steady-state balance function in patients with iNPH. Moreover, we did not compare COP parameters between patients with iNPH and healthy older controls. Healthy older adults revealed a difference in spontaneous sway between fallers and non-fallers during quiet standing\u003csup\u003e44\u003c/sup\u003e. Further study is needed to measure alterations of COP parameters in patients with iNPH compared to older adults.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eSpontaneous body sway during quiet standing improved after CSFTT in patients with iNPH. Furthermore, the amount of spontaneous sway is negatively associated with frontal lobe function. Our finding suggested that increased postural instability could be related to impaired frontal lobe functions in iNPH patients who suffered from impaired cortico-subcortical circuits.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe research was supported by National Research Foundation of Korea (NRF- 2021R1C1C101138713).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eK.K., K.P., and T.J. conceptualized this study. K.K. and E.P. recruited participants and performed clinical assessments. E.P., S.L, and JT.L analyzed and interpreted the data. E.P. and S.L. were major contributors in writing the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analysed during the current study are not publicly available because we did not get permission to disclosure it from the participants. However, it can be available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted with written informed consent obtained from all participants. The Institutional Review Board of Kyungpook National University Chilgok Hospital provided ethical approval (No. 2021-07-023).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHakim, S. \u0026amp; Adams, R. J. J. o. t. n. s. The special clinical problem of symptomatic hydrocephalus with normal cerebrospinal fluid pressure: observations on cerebrospinal fluid hydrodynamics. 2, 307\u0026ndash;327 (1965).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdams, R., Fisher, C., Hakim, S., Ojemann, R. \u0026amp; Sweet, W. Symptomatic occult hydrocephalus with normal cerebrospinal-fluid pressure: a treatable syndrome. New England Journal of Medicine 273, 117\u0026ndash;126 (1965).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFisher, C. Hydrocephalus as a cause of disturbances of gait in the elderly. 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Journal of neurology 252, 958\u0026ndash;963 (2005).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYamada, S. \u003cem\u003eet al.\u003c/em\u003e Gait assessment using three-dimensional acceleration of the trunk in idiopathic normal pressure hydrocephalus. Frontiers in Aging Neuroscience 13, 653964 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNikaido, Y. \u003cem\u003eet al.\u003c/em\u003e Associations among falls, gait variability, and balance function in idiopathic normal pressure hydrocephalus. Clinical Neurology and Neurosurgery 183, 105385 (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHowcroft, J., Lemaire, E. D., Kofman, J. \u0026amp; McIlroy, W. E. J. P. o. Elderly fall risk prediction using static posturography. 12, e0172398 (2017).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Normal pressure hydrocephalus, Postural balance, Spinal puncture","lastPublishedDoi":"10.21203/rs.3.rs-3198125/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3198125/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eIn patients with idiopathic normal pressure hydrocephalus (iNPH), the characteristics of balance disturbance are less understood than those of gait. We examined the changes in postural stability after the cerebrospinal fluid tap test (CSFTT) during quiet standing. Furthermore, we explored the relationship between frontal lobe function and the amount of spontaneous body sway.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eAll patients with iNPH underwent CSFTT and were evaluated using a frontal assessment battery (FAB) and center of pressure (COP) using a force plate during quiet standing before and after CSFTT. After COP measurement, we calculated COP parameters using time and frequency domain analysis. We determined whether there were alterations of COP parameters before and after CSFTT and the relationship between FAB and COP parameters using SPSS.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eIn total, 72 patients with iNPH were recruited, and 56 patients who positively responded to CSFTT were finally included. Following CSFTT, there were significantly improved COP parameters using time domain analysis (velocity of COP, vCOP, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002; root-mean-square of COP, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032; turn index, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.017; torque, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003; base of support, BOS, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014) compared to before CSFTT. In COP parameters using frequency domain analysis after CSFTT, we observed decreased power spectral density (PSD) values in the anteroposterior (peak value, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.049; average value, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.030) and mediolateral (peak value, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003; average value, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.028) directions at low-frequency oscillation, below 0.5 Hz. In addition, FAB scores were negatively correlated with the vCOP (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.359, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007), BOS (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.302, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.025), and the peak PSD value (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.464, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002) and average PSD value (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.424, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004) in anteroposterior direction for iNPH patients, respectively.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eIn patients with iNPH who responded to CSFTT, spontaneous body sway during quiet standing improved after CSFTT. The increased spontaneous sway is associated with impaired frontal lobe function, which may be linked to postural control circuits in patients with iNPH.\u003c/p\u003e","manuscriptTitle":"Alteration of Postural Stability after Cerebrospinal Fluid Tap Test in Patients with Idiopathic Normal Pressure Hydrocephalus","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-08-03 20:40:37","doi":"10.21203/rs.3.rs-3198125/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"0f34814e-3880-493d-ae61-aa833a7b62eb","owner":[],"postedDate":"August 3rd, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":23657989,"name":"Health sciences/Neurology/Neurological disorders/Hydrocephalus"},{"id":23657990,"name":"Health sciences/Health care/Health services/Rehabilitation"}],"tags":[],"updatedAt":"2023-12-08T11:14:49+00:00","versionOfRecord":[],"versionCreatedAt":"2023-08-03 20:40:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3198125","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3198125","identity":"rs-3198125","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}