[Recent clinical advances in hereditary spinocerebellar degeneration].

Spinocerebellar degeneration (SCD) is a neurodegenerative disorder characterized by cerebellar ataxia and other multisystem manifestations, such as Parkinsonism and pyramidal tract symptoms. No effective treatment is available for SCD. Approximately one-third of the cases of SCD are inherited, and the remaining two-third are sporadic, including multiple system atrophy. This article provides an overview of hereditary SCD, its clinical features, recent treatment advances, biomarkers, role of genomic medicine, and future treatment prospects.

Differentiation of speech in Parkinson's disease and spinocerebellar degeneration using deep neural networks.

INTRODUCTION: Assessing dysarthria features in patients with neurodegenerative diseases helps diagnose underlying pathologies. Although deep neural network (DNN) techniques have been widely adopted in various audio processing tasks, few studies have tested whether DNNs can help differentiate neurodegenerative diseases using patients' speech data. This study evaluated whether a DNN model using a transformer architecture could differentiate patients with Parkinson's disease (PD) from patients with spinocerebellar degeneration (SCD) using speech data. METHODS: Speech data were obtained from 251 and 101 patients with PD and SCD, respectively, while they read a passage. We fine-tuned a pre-trained DNN model using log-mel spectrograms generated from speech data. The DNN model was trained to predict whether the input spectrogram was generated from patients with PD or SCD. We used fivefold cross-validation to evaluate the predictive performance using the area under the receiver operating characteristic curve (AUC) and accuracy, sensitivity, and specificity. RESULTS: Average ± standard deviation of the AUC, accuracy, sensitivity, and specificity of the trained model for the fivefold cross-validation were 0.93 ± 0.04, 0.87 ± 0.03, 0.83 ± 0.05, and 0.89 ± 0.05, respectively. CONCLUSION: The DNN model can differentiate speech data of patients with PD from that of patients with SCD with relatively high accuracy and AUC. The proposed method can be used as a non-invasive, easy-to-perform screening method to differentiate PD from SCD using patient speech and is expected to be applied to telemedicine.

Roles of the cerebellum and basal ganglia in temporal integration: Insights from a synchronized tapping task.

OBJECTIVE: The aim of this study was to clarify the roles of the cerebellum and basal ganglia for temporal integration. METHODS: We studied 39 patients with spinocerebellar degeneration (SCD), comprising spinocerebellar atrophy 6 (SCA6), SCA31, Machado-Joseph disease (MJD, also called SCA3), and multiple system atrophy (MSA). Thirteen normal subjects participated as controls. Participants were instructed to tap on a button in synchrony with isochronous tones. We analyzed the inter-tap interval (ITI), synchronizing tapping error (STE), negative asynchrony, and proportion of delayed tapping as indicators of tapping performance. RESULTS: The ITI coefficient of variation was increased only in MSA patients. The standard variation of STE was larger in SCD patients than in normal subjects, especially for MSA. Negative asynchrony, which is a tendency to tap the button before the tones, was prominent in SCA6 and MSA patients, with possible basal ganglia involvement. SCA31 patients exhibited normal to supranormal performance in terms of the variability of STE, which was surprising. CONCLUSIONS: Cerebellar patients generally showed greater STE variability, except for SCA31. The pace of tapping was affected in patients with possible basal ganglia pathology. SIGNIFICANCE: Our results suggest that interaction between the cerebellum and the basal ganglia is essential for temporal processing. The cerebellum and basal ganglia and their interaction regulate synchronized tapping, resulting in distinct tapping pattern abnormalities among different SCD subtypes.

How do patients with Parkinson's disease and cerebellar ataxia read aloud? -Eye-voice coordination in text reading.

Background: The coordination between gaze and voice is closely linked when reading text aloud, with the gaze leading the reading position by a certain eye-voice lead (EVL). How this coordination is affected is unknown in patients with cerebellar ataxia and parkinsonism, who show oculomotor deficits possibly impacting coordination between different effectors. Objective: To elucidate the role of the cerebellum and basal ganglia in eye-voice coordination during reading aloud, by studying patients with Parkinson's disease (PD) and spinocerebellar degeneration (SCD). Methods: Participants were sixteen SCD patients, 18 PD patients, and 30 age-matched normal subjects, all native Japanese speakers without cognitive impairment. Subjects read aloud Japanese texts of varying readability displayed on a monitor in front of their eyes, consisting of Chinese characters and hiragana (Japanese phonograms). The gaze and voice reading the text was simultaneously recorded by video-oculography and a microphone. A custom program synchronized and aligned the gaze and audio data in time. Results: Reading speed was significantly reduced in SCD patients (3.53 ± 1.81 letters/s), requiring frequent regressions to compensate for the slow reading speed. In contrast, PD patients read at a comparable speed to normal subjects (4.79 ± 3.13 letters/s vs. 4.71 ± 2.38 letters/s). The gaze scanning speed, excluding regressive saccades, was slower in PD patients (9.64 ± 4.26 letters/s) compared to both normal subjects (12.55 ± 5.42 letters/s) and SCD patients (10.81 ± 4.52 letters/s). PD patients' gaze could not far exceed that of the reading speed, with smaller allowance for the gaze to proceed ahead of the reading position. Spatial EVL was similar across the three groups for all texts (normal: 2.95 ± 1.17 letters/s, PD: 2.95 ± 1.51 letters/s, SCD: 3.21 ± 1.35 letters/s). The ratio of gaze duration to temporal EVL was lowest for SCD patients (normal: 0.73 ± 0.50, PD: 0.70 ± 0.37, SCD: 0.40 ± 0.15). Conclusion: Although coordination between voice and eye movements and normal eye-voice span was observed in both PD and SCD, SCD patients made frequent regressions to manage the slowed vocal output, restricting the ability for advance processing of text ahead of the gaze. In contrast, PD patients experience restricted reading speed primarily due to slowed scanning, limiting their maximum reading speed but effectively utilizing advance processing of upcoming text.

Abnormal saccade profiles in hereditary spinocerebellar degeneration reveal cerebellar contribution to visually guided saccades.

OBJECTIVE: To study how the pathophysiology underlying hereditary spinocerebellar degeneration (spinocerebellar ataxia; SCA) with pure cerebellar manifestation evolves with disease progression using saccade recordings. METHODS: We recorded visually- (VGS) and memory-guided saccade (MGS) task performance in a homogeneous population of 20 genetically proven SCA patients (12 SCA6 and eight SCA31 patients) and 19 normal controls. RESULTS: For VGS but not MGS, saccade latency and amplitude were increased and more variable than those in normal subjects, which correlated with cerebellar symptom severity assessed using the International Cooperative Ataxia Rating Scale (ICARS). Parameters with significant correlations with cerebellar symptoms showed an aggravation after disease stage progression (ICARS > 50). The saccade velocity profile exhibited shortened acceleration and prolonged deceleration, which also correlated with disease progression. The main sequence relationship between saccade amplitude and peak velocity as well as saccade inhibitory control were preserved. CONCLUSIONS: The cerebellum may be involved in initiating VGS, which was aggravated acutely during disease stage progression. Dysfunction associated with disease progression occurs mainly in the cerebellum and brainstem interaction but may also eventually involve cortical saccade processing. SIGNIFICANCE: Saccade recording can reveal cerebellar pathophysiology underlying SCA with disease progression.

Home Aerobic Training for Cerebellar Degenerative Diseases: a Randomized Controlled Trial.

Balance training has shown some benefits in cerebellar ataxia whereas the effects of aerobic training are relatively unknown. To determine whether a phase III trial comparing home aerobic to balance training in ambulatory patients with cerebellar ataxia is warranted, we conducted a single-center, assessor-blinded, randomized controlled trial. Nineteen subjects were randomized to aerobic training and 17 subjects to balance training. The primary outcome was improvement in ataxia as measured by the Scale for the Assessment and Rating of Ataxia (SARA). Secondary outcomes included safety, training adherence, and balance improvements. There were no differences between groups at baseline. Thirty-one participants completed the trial, and there were no training-related serious adverse events. Compliance to training was over 70%. There was a mean improvement in ataxia symptoms of 1.9 SARA points (SD 1.62) in the aerobic group compared to an improvement of 0.6 points (SD 1.34) in the balance group. Although two measures of balance were equivocal between groups, one measure of balance showed greater improvement with balance training compared to aerobic training. In conclusion, this 6-month trial comparing home aerobic versus balance training in cerebellar ataxia had excellent retention and adherence to training. There were no serious adverse events, and training was not interrupted by minor adverse events like falls or back pain. There was a significant improvement in ataxia symptoms with home aerobic training compared to balance training, and a phase III trial is warranted. Clinical trial registration number: NCT03701776 on October 8, 2018.

Changes in Standing Postural Control Ability in a Case of Spinocerebellar Ataxia Type 31 With Physical Therapy Focusing on the Center of Gravity Sway Variables and Lower Leg Muscle Activity.

Spinocerebellar degeneration (SCD) is a progressive disease characterized by cerebellar ataxia or the posterior spinal cord. Among these, spinocerebellar ataxia type 31 (SCA31) is genetically more common in the Japanese population and is characterized by pure ataxia, resulting in severe disturbances in postural balance, with common falls. Therefore, rehabilitation is important to improve postural balance. Light touch is a known method of reducing postural sway, which acts with the light touching of an object with the body. We herein present a case of a patient with SCA31 who was trained in a standing position by lightly touching the back of the body to a wall surface. Dynamic interarticular coordination exercises were also performed as part of the rehabilitation program. As a result, even in the progressive SCA31, improvements in standing postural balance and activities of daily living contributed to improvements in the patient's postural balance. We followed the progress of postural control ability using the center of gravity sway measurement and electromyography and described some interesting characteristics of the patient's postural control ability in this report.

Altered cerebral blood flow in patients with spinocerebellar degeneration.

Objectives: Spinocerebellar degeneration (SCD) comprises a multitude of disorders with sporadic and hereditary forms, including spinocerebellar ataxia (SCA). Except for progressive cerebellar ataxia and structural atrophy, hemodynamic changes have also been observed in SCD. This study aimed to explore the whole-brain patterns of altered cerebral blood flow (CBF) and its correlations with disease severity and psychological abnormalities in SCD via arterial spin labeling (ASL). Methods: Thirty SCD patients and 30 age- and sex-matched healthy controls (HC) were prospectively recruited and underwent ASL examination on a 3.0T MR scanner. The Scale for Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS) scores were used to evaluate the disease severity in SCD patients. Additionally, the status of anxiety, depression and sleep among all patients were, respectively, evaluated by the Self-Rating Anxiety Scale (SAS), Self-Rating Depression Scale (SDS) and Self-Rating Scale of Sleep (SRSS). We compared the whole-brain CBF value between SCD group and HC group at the voxel level. Then, the correlation analyses between CBF and disease severity, and psychological abnormalities were performed on SCD group. Results: Compared with HC, SCD patients demonstrated decreased CBF value in two clusters (FWE corrected P < 0.05), covering bilateral dentate and fastigial nuclei, bilateral cerebellar lobules I-IV, V and IX, left lobule VI, right lobule VIIIb, lobules IX and X of the vermis in the cerebellar Cluster 1 and the dorsal part of raphe nucleus in the midbrain Cluster 2. The CBF of cerebellar Cluster 1 was negatively correlated with SARA scores (Spearman's rho = -0.374, P = 0.042) and SDS standard scores (Spearman's rho = -0.388, P = 0.034), respectively. And, the CBF of midbrain Cluster 2 also had negative correlations with SARA scores (Spearman's rho = -0.370, P = 0.044) and ICARS scores (Pearson r = -0.464, P = 0.010). Conclusion: The SCD-related whole-brain CBF changes mainly involved in the cerebellum and the midbrain of brainstem, which are partially overlapped with the related function cerebellar areas of hand, foot and tongue movement. Decreased CBF was related to disease severity and depression status in SCD. Therefore, CBF may be a promising neuroimaging biomarker to reflect the severity of SCD and suggest mental changes.

The Impact of the COVID-19 Pandemic on Three Domains of Functioning of ICF in Participants with Spinocerebellar Degeneration and Multiple System Atrophy in Japan / The Japanese Journal of Rehabilitation Medicine

Objective：We aimed to determine the impact of the COVID-19 pandemic on the “body function”, “activity”, and “participation” domains of functioning as defined in the International Classification of Functioning (ICF) for individuals with spinocerebellar degeneration (SCD) and multiple system atrophy (MSA).Methods：A questionnaire survey was administered to 1,000 members of the SCD/MSA patient association in Japan between November and December 2020. Questions related to COVID-19 were extracted from the multipurpose data, and the degree of COVID-19-related effects on each life function was assessed using a 7-point scale. Results were stratified into two groups based on age, care needs based on long-term care insurance coverage, and limited opportunities for rehabilitation. The χ2 test was used to examine differences between pairs of groups regarding impacts on functioning.Results：Data from 460 participants with SCD and MSA were analyzed. Participation restriction was reported in 54％ of participants with SCD and 46％ of participants with MSA, and impairment and activity limitation in approximately 20％ of participants with both conditions resulting from the COVID-19 pandemic. Participants with low care needs reported more impairment in SCD and more participation restriction in MSA. About 24％ of subjects reported limited opportunities for rehabilitation. MSA participants with these limitations reported greater impairment.Conclusion：The COVID-19 pandemic has had a particular impact on the participation domain of functioning in participants with SCD and MSA. The domains of body function and participation were found to be affected in participants with low care needs or limited opportunities for rehabilitation.

The History of Gene Hunting in Hereditary Spinocerebellar Degeneration: Lessons From the Past and Future Perspectives.

Hereditary spinocerebellar degeneration (SCD) encompasses an expanding list of rare diseases with a broad clinical and genetic heterogeneity, complicating their diagnosis and management in daily clinical practice. Correct diagnosis is a pillar for precision medicine, a branch of medicine that promises to flourish with the progressive improvements in studying the human genome. Discovering the genes causing novel Mendelian phenotypes contributes to precision medicine by diagnosing subsets of patients with previously undiagnosed conditions, guiding the management of these patients and their families, and enabling the discovery of more causes of Mendelian diseases. This new knowledge provides insight into the biological processes involved in health and disease, including the more common complex disorders. This review discusses the evolution of the clinical and genetic approaches used to diagnose hereditary SCD and the potential of new tools for future discoveries.

Premature saccades: A detailed physiological analysis.

OBJECTIVE: Premature saccades (PSs) are those made with latencies too short for the direction and amplitude to be specifically programmed. We sought to determine the minimum latency needed to establish accurate direction and amplitude, and observed what occurs when saccades are launched before this minimum latency. METHODS: In Experiment 1, 249 normal subjects performed the gap saccade task with horizontal targets. In Experiment 2, 28 normal subjects performed the gap saccade task with the targets placed in eight directions. In Experiment 3, 38 normal subjects, 49 patients with Parkinson's disease (PD), and 10 patients with spinocerebellar degeneration (SCD) performed the gap saccade task with horizontal targets. RESULTS: In Experiment 1, it took 100 ms to accurately establish saccade amplitudes and directions. In Experiment 2, however, the latencies needed for accurate amplitude and direction establishment were both approximately 150 ms. In Experiment 3, the frequencies of PSs in patients with PD and SCD were lower than those of normal subjects. CONCLUSIONS: The saccade amplitudes and directions are determined simultaneously, 100-150 ms after target presentation. PSs may result from prediction of the oncoming target direction or latent saccade activities in the superior colliculus. SIGNIFICANCE: Saccade direction and amplitude are determined simultaneously.

Effects of Short-term Intensive Rehabilitation in Patients with Ambulatory Spinocerebellar Degeneration：Total Score and Sub-score Change of Scale for the Assessment and Rating of Ataxia / The Japanese Journal of Rehabilitation Medicine

Objective：The purpose of this study was to evaluate the effectiveness of a four-week short-term intensive rehabilitation on ataxia in patients with ambulatory spinocerebellar degeneration (SCD), using the Scale for the Assessment and Rating of Ataxia (SARA) total score and sub-score.Methods：This study included 23 SCD patients；we considered those with a SARA gait score of＜3 points. Our program included a one-hour training session with individualized instructions and a one-hour self-balance training session. Additionally, occupational or speech-language-hearing therapy was performed for one hour daily. Our program was conducted five days weekly for four weeks. We assessed the SARA total score and sub-score findings immediately, before the first and after the last interventions.Results：The SARA total, gait, stance, and heel-shin scores showed more significant improvement after intervention than before intervention (p＜0.05). The other SARA sub-scores were not significantly different between “before and after” interventions.Conclusion：The four-week short-term intensive rehabilitation on ataxia in patients with ambulatory spinocerebellar degeneration improved the SARA total score and ataxia of the trunk and lower limbs.

Mediastinal tumor resection in a patient with spinocerebellar degeneration.

BACKGROUND: In spinocerebellar degeneration (SCD) patients, general and regional anesthesia may cause postoperative dysfunction of respiratory, nerve and muscle systems. We present the surgical case of thymoma developed in patient with SCD. CASE PRESENTATION: A 47-year-old woman with spinocerebellar degeneration was admitted because of a well-defined mass measuring 48 × 31 mm in anterior mediastinum. She showed limb, truncal, ocular, and speech ataxia; hypotonia; areflexia; sensory disturbances; and muscle weakness. Her eastern cooperative oncology group performance status was 4. Surgical resection was performed via video-assisted thoracic surgery and under general anesthesia only without epidural analgesia. The mass was diagnosed as type B1 thymoma without capsular invasion (Masaoka stage I). The patients got a good postoperative course by cooperation with anesthesiologists and neurologists in perioperative managements. She has been well over 3 years of follow-up. CONCLUSIONS: In conclusion, careful surgical and anesthesia management is essential for providing an uneventful postoperative course in patients with SCD. Especially, selection of minimal invasive approach and avoid diaphragmatic nerve damage are the most important points in surgical procedures.

Differential effects of thyrotropin releasing hormone (TRH) on motor execution and motor adaptation process in patients with spinocerebellar degeneration.

BACKGROUND: The cerebellum is known to play a crucial role in sensori-motor adaptation, which includes the prism adaptation. TRH has been widely used as a treatment for cerebellar ataxia in Japan, however effects of TRH on cerebellar adaptation process have not been studied. Here, we studied effects of TRH treatment on the prism adaptation task. METHODS: Eighteen spinocerebellar degeneration (SCD) patients participated in this study. The participants received intravenous injection of 2 mg/day protirelin tartrate once a day for 14 days. In the prism adaptation task, the participants reached to the target on the screen wearing wedge prisms. We compared the Scale for Assessment and Rating of Ataxia (SARA), baseline errors and the aftereffect (AE) of the prism adaptation task between before and after TRH therapy. RESULTS: TRH therapy improved SARA significantly (p = .005). Multiple regression analysis revealed that improvement of SARA score was mainly due to improvement of "Stance" category score. TRH decreased baseline errors of the prism adaptation task (p = .021), while unaffected AEs (p = .252). CONCLUSION: TRH differentially affected clinical cerebellar ataxia including baseline reaching performance in the prism adaptation task, whereas TRH did not affect the learning process of prism adaptation. Different cerebellar functional aspects may underlie the learning process of sensori-motor adaptation and simple motor execution (clinically evaluated cerebellar ataxia).

Phase I randomized single-blinded controlled study investigating the potential benefit of aerobic exercise in degenerative cerebellar disease.

OBJECTIVES: To investigate whether people with cerebellar degeneration can perform rigorous aerobic exercise and to assess the clinical impact of training. DESIGN: Randomized single-blinded controlled, feasibility study comparing aerobic training to no training. SETTING: Home intervention, assessments conducted at an academic medical center. SUBJECTS: Twenty individuals with cerebellar degeneration caused by a range of genetic disorders. INTERVENTION: Aerobic training consisted of four weeks of stationary bicycle training, five times per week for 30-minute sessions. Intensity ranged from 65% to 80% of the participant's maximal heart rate determined during cardiopulmonary exercise testing. MAIN MEASURES: Primary outcome measure was change in the Scale for the Assessment and Rating of Ataxia scores. Recruitment rate, adherence, drop-out, and adverse events were also determined. The treatment was considered technically feasible if participants achieved target training frequency, duration, and intensity. RESULTS: The 20 participants mean age was 50 years (standard deviation 15.65 years) and average Scale for the Assessment and Rating of Ataxia score was 9.6 (standard deviation 3.13). Ten participants were randomized to aerobic training and 10 to no training. Seven participants in the aerobic group attained target training duration, frequency, and intensity. There was a mean reduction in ataxia severity of 2.1 points (standard deviation 1.26) with four weeks of aerobic training, whereas ataxia severity increased by 0.3 (standard deviation 0.62) in the control group over the same period. Walking speed, balance measures, and fitness also improved in individuals who performed aerobic exercise. CONCLUSIONS: Rigorous aerobic training is feasible in people with cerebellar degeneration. Improvements in ataxia, balance, and gait are promising.

Progressive Supranuclear Palsy with Predominant Cerebellar Ataxia.

Progressive supranuclear palsy (PSP) is characterized by supranuclear gaze palsy, dystonic rigidity of the neck and upper trunk, frequent falls and mild cognitive impairment. Cerebellar ataxia is one of the exclusion criteria given by the National Institute of Neurological Disorders and Stroke and the Society for Progressive Supranuclear Palsy. As a result, pathologically proven PSP patients exhibiting cerebellar ataxia have often been misdiagnosed with spinocerebellar degeneration, specifically multiple system atrophy with predominant cerebellar ataxia (MSA-C). However, more recently, it has been recognized that patients with PSP can present with truncal and limb ataxia as their initial symptom and/or main manifestation. These patients can be classified as having PSP with predominant cerebellar ataxia (PSP-C), a new subtype of PSP. Since the development of this classification, patients with PSP-C have been identified primarily in Asian countries, and it has been noted that this condition is very rare in Western communities. Furthermore, the clinical features of PSP-C have been identified, enabling it to be distinguished from other subtypes of PSP and MSA-C. In this review, we describe the clinical and neuropathological features of PSP-C. The hypothesized pathophysiology of cerebellar ataxia in PSP-C is also discussed.

Frequency analyses of posturography using logarithmic translation.

Background: Power-spectral analysis of the centre of pressure (CoP) frequencies of posturography provides exponentially approximated distributions, whereas logarithmic translation enables linear approximation.Objectives: Frequency analyses were adopted for posturography of healthy subjects and patients with spinocerebellar degeneration (SCD) using logarithmic translation to determine its clinical usefulness for managing the elderly and patients with disequilibrium.Material and methods: We included 172 healthy subjects and 47 SCD patients. Posturography was performed with the eyes fixated and closed, with and without foam rubber. The power-spectral data of the CoP were obtained with the maximum entropy method. Power-spectral data were logarithmically translated for quantitative evaluation.Results: For teenagers, high-frequency fluctuations were dominant and attributable to proprioceptive compensation due to immature postural control. In elderly populations, the increased frequency in the lateral direction was characterised by three peaks indicating postural disturbances attributed to three sensory inputs. The disappearance of one peak in the anteroposterior fluctuation indicates a decrease in vestibular contribution. The foam rubber and the closed-eye condition enhanced fluctuations in two peaks. There were differences in power-spectral distributions of two peaks between the healthy subjects and SCD patients.Conclusions: Logarithmic power-spectral data distribution could provide an age- and disease-specific novel and visually-comprehensible parameter.

Effects of Short-term Intensive Rehabilitation in Patients with Ambulatory Spinocerebellar Degeneration：Total Score and Sub-score Change of Scale for the Assessment and Rating of Ataxia / The Japanese Journal of Rehabilitation Medicine

Objective：The purpose of this study was to evaluate the effectiveness of a four-week short-term intensive rehabilitation on ataxia in patients with ambulatory spinocerebellar degeneration (SCD), using the Scale for the Assessment and Rating of Ataxia (SARA) total score and sub-score.Methods：This study included 23 SCD patients；we considered those with a SARA gait score of＜3 points. Our program included a one-hour training session with individualized instructions and a one-hour self-balance training session. Additionally, occupational or speech-language-hearing therapy was performed for one hour daily. Our program was conducted five days weekly for four weeks. We assessed the SARA total score and sub-score findings immediately, before the first and after the last interventions.Results：The SARA total, gait, stance, and heel-shin scores showed more significant improvement after intervention than before intervention (p＜0.05). The other SARA sub-scores were not significantly different between “before and after” interventions.Conclusion：The four-week short-term intensive rehabilitation on ataxia in patients with ambulatory spinocerebellar degeneration improved the SARA total score and ataxia of the trunk and lower limbs.

Impaired Adaptive Motor Learning Is Correlated With Cerebellar Hemispheric Gray Matter Atrophy in Spinocerebellar Ataxia Patients: A Voxel-Based Morphometry Study.

Objective: To evaluate the degree to which recently proposed parameters measured via a prism adaptation task are correlated with changes in cerebellar structure, specifically gray matter volume (GMV), in patients with spinocerebellar degeneration (SCD). Methods: We performed whole-brain voxel-based morphometry (VBM) analysis on 3-dimensional T1-weighted images obtained from 23 patients with SCD [Spinocerebellar ataxia type 6 (SCA6), 31 (SCA31), 3/Machado-Joseph disease (SCA3/MJD), and sporadic cortical cerebellar atrophy (CCA)] and 21 sex- and age-matched healthy controls (HC group). We quantified a composite index representing adaptive motor learning abilities in a hand-reaching task with prism adaptation. After controlling for age, sex, and total intracranial volume, we analyzed group-wise differences in GMV and regional GMV correlations with the adaptive learning index. Results: Compared with the HC group, the SCD group showed reduced adaptive learning abilities and smaller GMV widely in the lobules IV-VIII in the bilateral cerebellar hemispheres. In the SCD group, the adaptive learning index was correlated with cerebellar hemispheric atrophy in the right lobule VI, the left Crus I. Additionally, GMV of the left supramarginal gyrus showed a correlation with the adaptive learning index in the SCD group, while the supramarginal region did not accompany reduction of GMV. Conclusions: This study indicated that a composite index derived from a prism adaptation task was correlated with GMV of the lateral cerebellum and the supramarginal gyrus in patients with SCD. This study should contribute to the development of objective biomarkers for disease severity and progression in SCD.