Inter-rater reliability of the International Cooperative Ataxia Rating Scale (ICARS)

The Pattern and Staging of Brain Atrophy in Spinocerebellar Ataxia Type 2 (SCA2): MRI Volumetrics from ENIGMA-Ataxia

Objective

Spinocerebellar ataxia type 2 (SCA2) is a rare, inherited neurodegenerative disease characterised by progressive deterioration in both motor coordination and cognitive function. Atrophy of the cerebellum, brainstem, and spinal cord are core features of SCA2, however the evolution and pattern of whole-brain atrophy in SCA2 remain unclear. We undertook a multi-site, structural magnetic resonance imaging (MRI) study to comprehensively characterize the neurodegeneration profile of SCA2.

Methods

Voxel-based morphometry analyses of 110 participants with SCA2 and 128 controls were undertaken to assess groupwise differences in whole-brain volume. Correlations with clinical severity and genotype, and cross-sectional profiling of atrophy patterns at different disease stages, were also performed.

Results

Atrophy in SCA2 relative to controls was greatest (Cohen's d>2.5) in the cerebellar white matter (WM), middle cerebellar peduncle, pons, and corticospinal tract. Very large effects (d>1.5) were also evident in the superior cerebellar, inferior cerebellar, and cerebral peduncles. In cerebellar grey matter (GM), large effects (d>0.8) mapped to areas related to both motor coordination and cognitive tasks. Strong correlations (|r|>0.4) between volume and disease severity largely mirrored these groupwise outcomes. Stratification by disease severity showed a degeneration pattern beginning in cerebellar and pontine WM in pre-clinical subjects; spreading to the cerebellar GM and cerebro-cerebellar/corticospinal WM tracts; then finally involving the thalamus, striatum, and cortex in severe stages.

Interpretation

The magnitude and pattern of brain atrophy evolves over the course of SCA2, with widespread, non-uniform involvement across the brainstem, cerebellar tracts, and cerebellar cortex; and late involvement of the cerebral cortex and striatum.

Effects of Non-invasive Brain Stimulation on Hereditary Ataxia: a Systematic Review and Meta-analysis

Numerous studies have demonstrated the potential of non-invasive brain stimulation (NIBS) techniques as a viable treatment option for cerebellar ataxia. However, there is a notable dearth of research investigating the efficacy of NIBS specifically for hereditary ataxia (HA), a distinct subgroup within the broader category of cerebellar ataxia. This study aims to conduct a comprehensive systematic review and meta-analysis in order to assess the efficacy of various NIBS methods for the treatment of HA. A thorough review of the literature was conducted, encompassing both English and Chinese articles, across eight electrical databases. The focus was on original articles investigating the therapeutic effectiveness of non-invasive brain stimulation for hereditary ataxia, with a publication date prior to March 2023. Subsequently, a meta-analysis was performed specifically on randomized controlled trials (RCTs) that fulfilled the eligibility criteria, taking into account the various modalities of non-invasive brain stimulation. A meta-analysis was conducted, comprising five RCTs, which utilized the Scale for the Assessment and Rating of Ataxia (SARA) as the outcome measure to evaluate the effects of transcranial magnetic stimulation (TMS). The findings revealed a statistically significant mean decrease of 1.77 in the total SARA score following repetitive TMS (rTMS) (p=0.006). Subgroup analysis based on frequency demonstrated a mean decrease of 1.61 in the total SARA score after high-frequency rTMS (p=0.05), while no improvement effects were observed after low-frequency rTMS (p=0.48). Another meta-analysis was performed on three studies, utilizing ICARS scores, to assess the impact of rTMS. The results indicated that there were no statistically significant differences in pooled ICARS scores between the rTMS group and the sham group (MD=0.51, 95%CI: -5.38 to 6.39; p=0.87). These findings align with the pooled results of two studies that evaluated alterations in post-intervention BBS scores (MD=0.74, 95%CI: -5.48 to 6.95; p=0.82). Despite the limited number of studies available, this systematic review and meta-analysis have revealed promising potential benefits of rTMS for hereditary ataxia. However, it is strongly recommended that further high-quality investigations be conducted in this area. Furthermore, the significance of standardized protocols for NIBS in future studies was also emphasized.

Consensus framework for conducting phase I/II clinical trials for children, adolescents, and young adults with pediatric low-grade glioma: Guidelines established by the International Pediatric Low-Grade Glioma Coalition Clinical Trial Working Group

Within the last few decades, we have witnessed tremendous advancements in the study of pediatric low-grade gliomas (pLGG), leading to a much-improved understanding of their molecular underpinnings. Consequently, we have achieved successful milestones in developing and implementing targeted therapeutic agents for treating these tumors. However, the community continues to face many unknowns when it comes to the most effective clinical implementation of these novel targeted inhibitors or combinations thereof. Questions encompassing optimal dosing strategies, treatment duration, methods for assessing clinical efficacy, and the identification of predictive biomarkers remain unresolved. Here, we offer the consensus of the international pLGG coalition (iPLGGc) clinical trial working group on these important topics and comment on clinical trial design and endpoint rationale. Throughout, we seek to standardize the global approach to early clinical trials (phase I and II) for pLGG, leading to more consistently interpretable results as well as enhancing the pace of novel therapy development and encouraging an increased focus on functional endpoints as well and quality of life for children faced with this disease.

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.

Apparent Opportunities and Hidden Pitfalls: The Conflicting Results of Restoring NRF2-Regulated Redox Metabolism in Friedreich's Ataxia Pre-Clinical Models and Clinical Trials

Friedreich's ataxia (FRDA) is an autosomal, recessive, inherited neurodegenerative disease caused by the loss of activity of the mitochondrial protein frataxin (FXN), which primarily affects dorsal root ganglia, cerebellum, and spinal cord neurons. The genetic defect consists of the trinucleotide GAA expansion in the first intron of FXN gene, which impedes its transcription. The resulting FXN deficiency perturbs iron homeostasis and metabolism, determining mitochondrial dysfunctions and leading to reduced ATP production, increased reactive oxygen species (ROS) formation, and lipid peroxidation. These alterations are exacerbated by the defective functionality of the nuclear factor erythroid 2-related factor 2 (NRF2), a transcription factor acting as a key mediator of the cellular redox signalling and antioxidant response. Because oxidative stress represents a major pathophysiological contributor to FRDA onset and progression, a great effort has been dedicated to the attempt to restore the NRF2 signalling axis. Despite this, the beneficial effects of antioxidant therapies in clinical trials only partly reflect the promising results obtained in preclinical studies conducted in cell cultures and animal models. For these reasons, in this critical review, we overview the outcomes obtained with the administration of various antioxidant compounds and critically analyse the aspects that may have contributed to the conflicting results of preclinical and clinical studies.

Neurological and cerebellar soft signs in bipolar disorder: The role of staging, type and history of psychotic symptoms

AIM

Bipolar disorder (BD) patients show neurological abnormalities in form of neurological and cerebellar soft signs (NSS and CSS). NSS represents heterogeneous group of symptoms representing i.a. deficits of motor coordination, sequencing of complex motor acts and sensory integration. CSS were introduced as group of the neurological deficits of posture, gait, kinetic functions, eye movements and speech, associated more specifically to cerebellar abnormalities than NSS. Studies show significant effect size variability of those symptoms in BD group suggesting the existence of differing subpopulations. The aim of our study was to evaluate the effect of BD type, stage and the history of psychotic symptoms (HoPS) on the severity of CSS and NSS as none of the previous studies had verified the role of those categories.

METHODS

This study involved 181 participants: 116 euthymic BD patients (66 BD I, 50 BD II) and 65 healthy controls (HC). CSS was assessed with the International Cooperative Ataxia Rating Scale and NSS with Neurological Evaluation Scale. Patients were divided into early and late stage of the disorder according to Kapczinski's criteria. Rater was blind to patients' stage, type and HoPS.

RESULTS

Staging was related to vast majority of CSS and NSS scores. HoPS was related to oculomotor deficits. The effect of BD type was the least significant. Late stage BD showed more severe CSS and NSS than HC in every measure. There were no differences between early stage BD and HC, apart of posture and gait disturbances. Except of sensory integration scores, late stage BD showed higher CSS and NSS rates than early stage patients.

CONCLUSION

In this hitherto the largest study of neurological abnormalities in BD we have shown significant role of staging in CSS and NSS severity. Progression criteria based on inter-episode psychosocial functioning may stand as unrecognised factor responsible for variability observed in previous studies evaluating neurological abnormalities in BD. Our study suggests that in clinical practice NSS and CSS may be potentially used as easy-to-assess biological marker of BD staging. Observed severity of neurological impairments of BD patients may more likely correspond to the disease progression than to BD type and HoPS.

Validity and Reliability of the Korean-Translated Version of the International Cooperative Ataxia Rating Scale in Cerebellar Ataxia

OBJECTIVE

The International Cooperative Ataxia Rating Scale (ICARS) is a semiquantitative clinical scale for ataxia that is widely used in numerous countries. The purpose of this study was to investigate the validity and reliability of the Korean-translated version of the ICARS.

METHODS

Eighty-eight patients who presented with cerebellar ataxia were enrolled. We investigated the construct validity using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). We also investigated the internal consistency using Cronbach's α and intrarater and interrater reliability using intraclass correlation coefficients.

RESULTS

The Korean-translated ICARS showed satisfactory construct validity using EFA and CFA. It also revealed good interrater and intrarater reliability and showed acceptable internal consistency. However, subscale 4 for assessing oculomotor disorder showed moderate internal consistency.

CONCLUSION

This is the first report to investigate the validity and reliability of the Korean-translated ICARS. Our results showed excellent construct and convergent validity. The reliability is also acceptable.

A wearable motion capture suit and machine learning predict disease progression in Friedreich's ataxia

Friedreich's ataxia (FA) is caused by a variant of the Frataxin (FXN) gene, leading to its downregulation and progressively impaired cardiac and neurological function. Current gold-standard clinical scales use simplistic behavioral assessments, which require 18- to 24-month-long trials to determine if therapies are beneficial. Here we captured full-body movement kinematics from patients with wearable sensors, enabling us to define digital behavioral features based on the data from nine FA patients (six females and three males) and nine age- and sex-matched controls, who performed the 8-m walk (8-MW) test and 9-hole peg test (9 HPT). We used machine learning to combine these features to longitudinally predict the clinical scores of the FA patients, and compared these with two standard clinical assessments, Spinocerebellar Ataxia Functional Index (SCAFI) and Scale for the Assessment and Rating of Ataxia (SARA). The digital behavioral features enabled longitudinal predictions of personal SARA and SCAFI scores 9 months into the future and were 1.7 and 4 times more precise than longitudinal predictions using only SARA and SCAFI scores, respectively. Unlike the two clinical scales, the digital behavioral features accurately predicted FXN gene expression levels for each FA patient in a cross-sectional manner. Our work demonstrates how data-derived wearable biomarkers can track personal disease trajectories and indicates the potential of such biomarkers for substantially reducing the duration or size of clinical trials testing disease-modifying therapies and for enabling behavioral transcriptomics.

Relationships of Motor Changes with Cognitive and Neuropsychiatric Features in FMR1 Male Carriers Affected with Fragile X-Associated Tremor/Ataxia Syndrome

The premutation expansion of the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene on the X chromosome has been linked to a range of clinical and subclinical features. Nearly half of men with FMR1 premutation develop a neurodegenerative disorder; Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS). In this syndrome, cognitive executive decline and psychiatric changes may co-occur with major motor features, and in this study, we explored the interrelationships between these three domains in a sample of adult males affected with FXTAS. A sample of 23 adult males aged between 48 and 80 years (mean = 62.3; SD = 8.8), carrying premutation expansions between 45 and 118 CGG repeats, and affected with FXTAS, were included in this study. We employed a battery of cognitive assessments, two standard motor rating scales, and two self-reported measures of psychiatric symptoms. When controlling for age and/or educational level, where appropriate, there were highly significant correlations between motor rating score for ICARS gait domain, and the scores representing global cognitive decline (ACE-III), processing speed (SDMT), immediate memory (Digit Span), and depression and anxiety scores derived from both SCL90 and DASS instruments. Remarkably, close relationships of UPDRS scores, representing the contribution of Parkinsonism to FXTAS phenotypes, were exclusive to psychiatric scores. Highly significant relationships between CGG repeat size and most scores for three phenotypic domains suggest a close tracking with genetic liability. These findings of relationships between a constellation of phenotypic domains in male PM carriers with FXTAS are reminiscent of other conditions associated with disruption to cerebro-cerebellar circuits.

Clinical Motor Coordination Tests in Adult Neurology: A Scoping Review

Purpose: This scoping review aimed to identify which clinical tests are used to assess upper limb, lower limb, and trunk motor coordination, and their metric and measurement properties for adult neurological populations. Method: MEDLINE (1946-) and EMBASE (1996-) databases were searched using keywords such as movement quality, motor performance, motor coordination, assessment, and psychometrics. Data regarding the body part assessed, neurological condition, psychometric properties, and scored metrics of spatial and/or temporal coordination were independently extracted by two reviewers. Alternate versions of some tests such as the Finger-to-Nose Test were included. Results: Fifty-one included articles yielded 2 tests measuring spatial coordination, 7 tests measuring temporal coordination, and 10 tests measuring both. Scoring metrics and measurement properties differed between tests, with a majority of tests having good-to-excellent measurement properties. Conclusions: The metrics of motor coordination scored by current tests vary. Since tests do not assess functional task performance, the onus falls on clinicians to infer the connection between coordination impairments and functional deficits. Clinical practice would benefit from the development of a battery of tests that assesses the metrics of coordination related to functional performance.

The Outcomes of an Individualized Physical Therapy Program in CALFAN Syndrome: A Case Report

PURPOSE

This case report investigated the effectiveness of an individualized physical therapy program in CALFAN syndrome.

CASE DESCRIPTION

A 13-year-old girl participated in physical therapy, which included trunk stabilization, balance training, and functional exercises for 12 weeks.

ASSESSMENTS

The International Cooperative Ataxia Rating Scale; Trunk Impairment Scale; Pediatric Quality of Life Inventory; Functional Independence Measure for Children; Quick Disability of the Arm, Shoulder, and Hand Questionnaire; 9-Hole Peg Test; and Cobb measurement were used as outcome measures.

RESULTS

Positive changes were observed in the International Cooperative Ataxia Rating Scale; Quick Disability of the Arm, Shoulder, and Hand Questionnaire; Pediatric Quality of Life Inventory; Trunk Impairment Scale; Functional Independence Measure; and the 9-Hole Peg Test. The Cobb angle was increased by 2° in the thoracic region and reduced by 11° in the lumbar region.

CONCLUSIONS

Physical therapy improved quality of life, functional independence, trunk control, and upper extremity performance.

WHAT THIS ADDS TO EVIDENCE

This case report is the first to support the effectiveness of physical therapy for a child with CALFAN syndrome.

Relationship between neurological and cerebellar soft signs, and implicit motor learning in schizophrenia and bipolar disorder

BACKGROUND

Schizophrenia (SZ) and bipolar disorder (BD) patients share deficits in motor functions in the form of neurological (NSS) and cerebellar soft signs (CSS), and implicit motor learning disturbances. Here, we use cluster analysis method to assess (1) the relationship between those abnormalities in SZ and BD and (2) the differences between those groups.

METHODS

33 SZ patients, 33 BD patients as well as 31 healthy controls (HC) took part in the study. We assessed CSS with the International Cooperative Ataxia Rating Scale (ICARS) and NSS with the Neurological Evaluation Scale (NES). Implicit motor learning was evaluated with the Serial Reaction Time Task (SRTT). Participants were divided into clusters (Ward's method) based on the mean response time and mean error rate in SRTT. The difference in ICARS and NES scores, and SRTT variables between clusters were evaluated. We have measured associations between SRTT parameters and both ICARS and NES total scores and subscores.

RESULTS

Cluster analysis based on the SRTT parameters allowed to extract three clusters. Those were characterized by the increasing disruption of motor functioning (psychomotor retardation, the severity of NSS and CSS) regardless of the diagnosis. Cluster 1 covered almost all of HC and was characterized by faster reaction times and small number of errors. BD and SZ patients represented in cluster 1, although fully functional in performing the SRTT, showed higher rates of NSS and CSS. Patients with BD and SZ were set apart in clusters 2 and 3 in a similar proportion. Cluster 2 presented significantly slower reaction times but with the comparable number of errors to cluster 1. Cluster 3 consisted of participants with normal or decreased reaction time and significantly increased number of errors. None of the clusters were predominantly composed of the patients representing one psychiatric diagnosis.

CONCLUSIONS

To our best knowledge, we are presenting the first data indicating the relationship between implicit motor learning and NSS and CSS in SZ and BD patients' groups. Lack of clusters predominantly represented by patients with the diagnosis of SZ or BD may refer to the model of schizophrenia-bipolar disorder boundary, pointing out the similarities between those two disorders.

Evaluation of upper extremity ataxia through image processing in individuals with multiple sclerosis

BACKGROUND

Impaired dexterity is a frequently reported disability among people with ataxic multiple sclerosis (MS).

OBJECTIVE

To quantify and standardize the evaluation of upper extremity coordination disorder among patients with multiple sclerosis (MS), using the Tablet Ataxia Assessment Program (TAAP).

METHODS

The X and Y axis movements of 50 MS patients and 30 healthy individuals who were evaluated using the International Cooperative Ataxia Rating Scale (ICARS) were also assessed using TAAP. The functional times of the participants' right and left hands were recorded using the nine-hole peg test (NHPT). The upper extremity coordination of individuals with MS was evaluated using the upper extremity kinetic functions section of ICARS.

RESULTS

The deviations for the X and Y axis movements of the MS group were greater than those of the control group (p<0.05). Significant correlations were shown between TAAP scores and NHPT and ICARS scores. The strongest correlation was found between NHPT and ICARS in the dominant hand (rnhpt=0.356, pnhpt=0.001; ricars=0.439, picars=0.000). In correlating the Y axis with ICARS, the deviations in the Y axis were found to be greater in the non-dominant hand than those in the X axis (ryright=0.402, pyright=0.004; ryleft=0.691, pyleft=0.000).

CONCLUSION

Measurement using TAAP is more sensitive than other classical and current methods for evaluating ataxia. We think that TAAP is an objective tool that will allow neurorehabilitation professionals and clinicians to evaluate upper extremity coordination.

Objective Assessment of Progression and Disease Characterization of Friedreich Ataxia via an Instrumented Drinking Cup: Preliminary Results

The monitoring of disease progression in certain neurodegenerative conditions can significantly be quantified with the help of objective assessments. The severity assessment of diseases like Friedreich ataxia (FRDA) are usually based on different subjective measures. The ability of a participant with FRDA to perform standard neurological tests is the most common way of assessing disease progression. In this feasibility study, an Ataxia Instrumented Measurement-Cup (AIM-C) is proposed to quantify the disease progression of 10 participants (mean age 39 years, onset of disease 16.3 years) in longitudinal timepoints. The device consists of a sensing system with the provision of extracting both kinetic and kinematic information while engaging in an activity closely associated with activities of daily living (ADL). A common functional task of simulated drinking was used to capture features that possesses disease progression information as well as certain other features which intrinsically correlate with commonly used clinical scales such as the modified Friedreich Ataxia Rating Scale (mFARS), the Functional Staging of Ataxia score and the ADL scale. Frequency and time-frequency domain features allowed the longitudinal assessment of participants with FRDA. Furthermore, both kinetic and kinematic measures captured clinically relevant features and correlated 85% with clinical assessments.

Assessment of gait and balance impairment in people with spinocerebellar ataxia using wearable sensors

OBJECTIVE

To explore the use of wearable sensors for objective measurement of motor impairment in spinocerebellar ataxia (SCA) patients during clinical assessments of gait and balance.

METHODS

In total, 14 patients with genetically confirmed SCA (mean age 61.6 ± 8.6 years) and 4 healthy controls (mean age 49.0 ± 16.4 years) were recruited through the Massachusetts General Hospital (MGH) Ataxia Center. Participants donned seven inertial sensors while performing two independent trials of gait and balance assessments from the Scale for the Assessment and Rating of Ataxia (SARA) and Brief Ataxia Rating Scale (BARS2). Univariate analysis was used to identify sensor-derived metrics from wearable sensors that discriminate motor function between the SCA and control groups. Multivariate linear regression models were used to estimate the subjective in-person SARA/BARS2 ratings. Spearman correlation coefficients were used to evaluate the performance of the model.

RESULTS

Stride length variability, stride duration, cadence, stance phase, pelvis sway, and turn duration were different between SCA and controls (p < 0.05). Similarly, sway and sway velocity of the ankle, hip, and center of mass differentiated SCA and controls (p < 0.05). Using these features, linear regression models showed moderate-to-strong correlation with clinical scores from the in-person rater during SARA assessments of gait (r = 0.73, p = 0.003) and stance (r = 0.90, p < 0.001) and the BARS2 gait assessment (r = 0.74, p = 0.003).

CONCLUSION

This study demonstrates that sensor-derived metrics can potentially be used to estimate the level of motor impairment in patient with SCA quickly and objectively. Thus, digital biomarkers from wearable sensors have the potential to be an integral tool for SCA clinical trials and care.

Is the dynamic gait index a useful outcome to measure balance and ambulation in patients with cerebellar ataxia?

BACKGROUND

Ataxia can adversely affect balance and gait and increase the incidence of falls, which puts individuals at greater risk for injury. Thus, interventions focused on balance and gait are integral in rehabilitation training. In order to determine if rehabilitation interventions are effective, we need an outcome measure to detect change. To our knowledge, no activity level outcome measures have been established for balance and gait in cerebellar ataxia.

OBJECTIVE

The aim of the current study is to determine the reliability and validity of the Dynamic Gait Index (DGI) for ataxia.

DESIGN

Twenty adult participants (23-84 years) with ataxia were evaluated to assess construct validity, inter-rater reliability, and same day test-retest reliability of the DGI.

METHODS

Participants completed ataxia-specific impairment level outcome measures, as well as the DGI. In addition to the in-person rater, three additional physical therapists scored video recordings of DGI test and retests. Construct validity was assessed via Spearman's rank order correlation coefficient (Spearman's rho) between the impairment measures (Scale for Assessment and Rating of Ataxia (SARA), International Cooperative of Ataxia Rating Scale (ICARS) and the DGI. Reliability was assessed by Spearman's rho and Intraclass Correlation Coefficient ICC (2,1).

RESULTS

In terms of construct validity, we found significant correlations between the activity level DGI and impairment level outcome measures (-0.81 for SARA; -0.88 with ICARS). The interrater reliability of the DGI applied to participants with ataxia was high (Spearman rho: range 0.71-0.98; ICC (2,1) 0.98) as was test-retest reliability (Spearman rho: 0.95; ICC (2,1) 0.98).

CONCLUSION

We showed that the DGI is a reliable and valid outcome measure to be used in the clinic for individuals with cerebellar ataxia. The DGI had excellent inter-rater and test-retest reliability for raters with varying years of clinical experience. Therefore, the DGI can be a useful clinical outcome measure for assessing balance and ambulation for individuals with cerebellar ataxia.

Relationships between motor scores and cognitive functioning in FMR1 female premutation X carriers indicate early involvement of cerebello-cerebral pathways

BACKGROUND

Smaller expansions of CGG trinucleotide repeats in the FMR1 X-linked gene termed 'premutation' lead to a neurodegenerative disorder: Fragile X Associated Tremor/Ataxia Syndrome (FXTAS) in nearly half of aged carrier males, and 8-16% females. Core features include intention tremor, ataxia, and cognitive decline, and white matter lesions especially in cerebellar and periventricular locations. A 'toxic' role of elevated and expanded FMR1 mRNA has been linked to the pathogenesis of this disorder. The emerging issue concerns the trajectory of the neurodegenerative changes: is the pathogenetic effect confined to overt clinical manifestations? Here we explore the relationships between motor and cognitive scale scores in a sample of 57 asymptomatic adult female premutation carriers of broad age range.

METHODS

Three motor scale scores (ICARS-for tremor/ataxia, UPDRS-for parkinsonism, and Clinical Tremor) were related to 11 cognitive tests using Spearman's rank correlations. Robust regression, applied in relationships between all phenotypic measures, and genetic molecular and demographic data, identified age and educational levels as common correlates of these measures, which were then incorporated as confounders in correlation analysis.

RESULTS

Cognitive tests demonstrating significant correlations with motor scores were those assessing non-verbal reasoning on Matrix Reasoning (p-values from 0.006 to 0.011), and sequencing and alteration on Trails-B (p-values from 0.008 to 0.001). Those showing significant correlations with two motor scores-ICARS and Clinical Tremor- were psychomotor speed on Symbol Digit Modalities (p-values from 0.014 to 0.02) and working memory on Digit Span Backwards (p-values from 0.024 to 0.011).

CONCLUSIONS

Subtle motor impairments correlating with cognitive, particularly executive, deficits may occur in female premutation carriers not meeting diagnostic criteria for FXTAS. This pattern of cognitive deficits is consistent with those seen in other cerebellar disorders. Our results provide evidence that more than one category of clinical manifestation reflecting cerebellar changes - motor and cognitive - may be simultaneously affected by premutation carriage across a broad age range in asymptomatic carriers.

Quantitative Assessment of Friedreich Ataxia via Self-Drinking Activity

Effective monitoring of the progression of neurodegenerative conditions can be significantly improved by objective assessments. Clinical assessments of conditions such as Friedreich's Ataxia (FA), currently rely on subjective measures commonly practiced in clinics as well as the ability of the affected individual to perform conventional tests of the neurological examination. In this study, we propose an ataxia measuring device, in the form of a pressure canister capable of sensing certain kinetic and kinematic parameters of interest to quantify the impairment levels of participants particularly when engaged in an activity that is closely associated with daily living. In particular, the functional task of simulated drinking was utilised to capture characteristic features of disability manifestation in terms of diagnosis (separation of individuals with FA and controls) and severity assessment of individuals diagnosed with the debilitating condition of FA. Time and frequency domain analysis of these biomarkers enabled the classification of individuals with FA and control subjects to reach an accuracy of 98% and a correlation level reaching 96% with the clinical scores.

Expanding the β-III Spectrin-Associated Phenotypes toward Non-Progressive Congenital Ataxias with Neurodegeneration

(1) Background: A non-progressive congenital ataxia (NPCA) phenotype caused by β-III spectrin (SPTBN2) mutations has emerged, mimicking spinocerebellar ataxia, autosomal recessive type 14 (SCAR14). The pattern of inheritance, however, resembles that of autosomal dominant classical spinocerebellar ataxia type 5 (SCA5). (2) Methods: In-depth phenotyping of two boys studied by a customized gene panel. Candidate variants were sought by structural modeling and protein expression. An extensive review of the literature was conducted in order to better characterize the SPTBN2-associated NPCA. (3) Results: Patients exhibited an NPCA with hypotonia, developmental delay, cerebellar syndrome, and cognitive deficits. Both probands presented with progressive global cerebellar volume loss in consecutive cerebral magnetic resonance imaging studies, characterized by decreasing midsagittal vermis relative diameter measurements. Cortical hyperintensities were observed on fluid-attenuated inversion recovery (FLAIR) images, suggesting a neurodegenerative process. Each patient carried a novel de novo SPTBN2 substitution: c.193A > G (p.K65E) or c.764A > G (p.D255G). Modeling and protein expression revealed that both mutations might be deleterious. (4) Conclusions: The reported findings contribute to a better understanding of the SPTBN2-associated phenotype. The mutations may preclude proper structural organization of the actin spectrin-based membrane skeleton, which, in turn, is responsible for the underlying disease mechanism.

Validation of new measures of arm coordination impairment in Wheelchair Rugby

This study aims were twofold: (1) to evaluate the construct validity of the Repetitive Movement Test (RMT) a novel test developed for Wheelchair Rugby classification which evaluates arm coordination impairment at five joints - shoulder, elbow, forearm, wrist and fingers - and (2), pending sufficiently positive results, propose objective minimum impairment criteria (MIC). Forty-two WR athletes with an eligible coordination impairment, and 20 volunteers without impairment completed the RMT and two clinically established coordination tests: the finger-nose test (FNT) and the spiral test (ST). Coordination deduction (CD), an ordinal observational coordination scale, currently used in WR classification, was obtained. Spearman-rank correlation coefficients (SCC) between RMT and ST (0.40 to 0.67) and between RMT and CD (0.31 to 0.53) generally supported RMT construct validity, SCC between RMT and FNT were lower (0.12-0.31). When the scores on ST, FNT and RMT from the sample of WR players were compared with the scores from volunteers without impairment, 93.5% to 100% of WR players had scores > 2SD below the mean of volunteers without impairment on the same test. In conclusion, RMT at the elbow, forearm, wrist and fingers have sufficient construct validity for use in WR. MIC were recommended with ST and RMT.

Differential Progression of Motor Dysfunction Between Male and Female Fragile X Premutation Carriers Reveals Novel Aspects of Sex-Specific Neural Involvement

Expansions of the CGG repeat in the non-coding segment of the FMR1 X-linked gene are associated with a variety of phenotypic changes. Large expansions (>200 repeats), which cause a severe neurodevelopmental disorder, the fragile x syndrome (FXS), are transmitted from the mothers carrying smaller, unstable expansions ranging from 55 to 200 repeats, termed the fragile X premutation. Female carriers of this premutation may themselves experience a wide range of clinical problems throughout their lifespan, the most severe being the late onset neurodegenerative condition called "Fragile X-Associated Tremor Ataxia Syndrome" (FXTAS), occurring between 8 and 16% of these carriers. Male premutation carriers, although they do not transmit expanded alleles to their daughters, have a much higher risk (40-50%) of developing FXTAS. Although this disorder is more prevalent and severe in male than female carriers, specific sex differences in clinical manifestations and progress of the FXTAS spectrum have been poorly documented. Here we compare the pattern and rate of progression (per year) in three motor scales including tremor/ataxia (ICARS), tremor (Clinical Tremor Rating scale, CRST), and parkinsonism (UPDRS), and in several cognitive and psychiatric tests scores, between 13 female and 9 male carriers initially having at least one of the motor scores ≥10. Moreover, we document the differences in each of the clinical and cognitive measures between the cross-sectional samples of 21 female and 24 male premutation carriers of comparable ages with FXTAS spectrum disorder (FSD), that is, who manifest one or more features of FXTAS. The results of progression assessment showed that it was more than twice the rate in male than in female carriers for the ICARS-both gait ataxia and kinetic tremor domains and twice as high in males on the CRST scale. In contrast, sex difference was negligible for the rate of progress in UPDRS, and all the cognitive measures. The overall psychiatric pathology score (SCL-90), as well as Anxiety and Obsessive/Compulsive domain scores, showed a significant increase only in the female sample. The pattern of sex differences for progression in motor scores was consistent with the results of comparison between larger, cross-sectional samples of male and female carriers affected with the FSD. These results were in concert with sex-specific distribution of MRI T2 white matter hyperintensities: all males, but no females, showed the middle cerebellar peduncle white matter hyperintensities (MCP sign), although the distribution and severity of these hyperintensities in the other brain regions were not dissimilar between the two sexes. In conclusion, the magnitude and specific pattern of sex differences in manifestations and progression of clinically recorded changes in motor performance and MRI lesion distribution support, on clinical grounds, the possibility of certain sex-limited factor(s) which, beyond the predictable effect of the second, normal FMR1 alleles in female premutation carriers, may have neuroprotective effects, specifically concerning the cerebellar circuitry.

Delineating the Relationships Between Motor, Cognitive-Executive and Psychiatric Symptoms in Female FMR1 Premutation Carriers

Introduction: Premutation expansions (55-200 CGG repeats) of the Fragile X Mental Retardation 1 (FMR1) gene on the X chromosome are associated with a range of clinical features. Apart from the most severe - Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) - where the most typical white matter changes affect cerebellar peduncles, more subtle changes may include impairment of executive functioning, affective disorders and/or subtle motor changes. Here we aimed to examine whether performance in selected components of executive functioning is associated with subclinical psychiatric symptoms in non-FXTAS, adult females carrying the FMR1 premutation. Methods and Sample: A total of 47 female premutation carriers (sub-symptomatic for FXTAS) of wide age range (26-77 years; M = 50.3; SD = 10.9) were assessed using standard neuropsychological tests, three motor rating scales and self-reported measures of psychiatric symptoms using the Symptom Checklist-90-Revised (SCL-90-R). Results: After adjusting for age and educational level where appropriate, both non-verbal reasoning and response inhibition as assessed on the Stroop task (i.e., the ability to resolve cognitive interference) were associated with a range of primary psychiatric symptom dimensions, and response inhibition uniquely predicted some primary symptoms and global psychiatric features. Importantly, lower scores (worse performance) in response inhibition were also strongly correlated with higher (worse) scores on standard motor rating scales for tremor-ataxia and for parkinsonism. Conclusion: These results provide evidence for the importance of response inhibition in the manifestation of psychiatric symptoms and subtle tremor-ataxia motor features, suggestive of the presence of early cerebellar changes in female premutation carriers.

Assessment of Ataxia Rating Scales and Cerebellar Functional Tests: Critique and Recommendations

BACKGROUND

We assessed the clinimetric properties of ataxia rating scales and functional tests, and made recommendations regarding their use.

METHODS

A systematic literature search was conducted to identify the instruments used to rate ataxia symptoms. The identified rating scales and functional ability tests were reviewed and ranked by the panel as "recommended," "suggested," or "listed" for the assessment of patients with discrete cerebellar disorders, using previously established criteria.

RESULTS

We reviewed 14 instruments (9 rating scales and 5 functional tests). "Recommended" rating scales for the assessment of symptoms severity were: for Friedreich's ataxia, the Friedreich's Ataxia Rating Scale, the International Cooperative Ataxia Rating Scale (ICARS), and the Scale for the Assessment and Rating of Ataxia (SARA); for spinocerebellar ataxias, ICARS and SARA; for ataxia telangiectasia: ICARS and SARA; for brain tumors, SARA; for congenital disorder of glycosylation-phosphomannomutase-2 deficiency, ICARS; for cerebellar symptoms in multiple sclerosis, ICARS; for cerebellar symptoms in multiple system atrophy: Unified Multiple System Atrophy Rating Scale and ICARS; and for fragile X-associated tremor ataxia syndrome, ICARS. "Recommended" functional tests were: for Friedreich's ataxia, Ataxia Functional Composite Score and Composite Cerebellar Functional Severity Score; and for spinocerebellar ataxias, Ataxia Functional Composite Score, Composite Cerebellar Functional Severity Score, and SCA Functional Index.

CONCLUSIONS

We identified some "recommended" scales and functional tests for the assessment of patients with major hereditary ataxias and other cerebellar disorders. The main limitations of these instruments include the limited assessment of patients in the more severe end of the spectrum and children. Further research in these populations is warranted. © 2020 International Parkinson and Movement Disorder Society.

Vestibular impairment in Charcot-Marie-Tooth disease

OBJECTIVE

To find out if Charcot-Marie-Tooth (CMT) patients, who have peripheral vestibular as well as peripheral somatosensory impairment, have worse postural balance than those who do not.

METHODS

We studied 32 patients with various CMT phenotypes and genotypes. Vestibular function was measured with the video head impulse test (vHIT) which tests vestibulo-ocular reflex (VOR) gain from each of the six semicircular canals in response to rapid head rotations. Postural balance was evaluated with a battery of four postural tests with emphasis on the modified clinical test of sensory integration in balance (mCTSIB).

RESULTS

Half of the 32 patients had some impairment of vestibular function ranging from mild, affecting only 1-2 semicircular canals, to almost total affecting all 6 semicircular canals. Their mCTSIB scores correlated with VOR gain from the vertical rather than from the lateral semicircular canals. The worse the vertical VOR gain the worse the mCTSIB score.

CONCLUSION

We propose that any CMT patient could have clinically inapparent vestibular impairment that can be easily measured with the vHIT. This vestibular impairment could be contributing to their imbalance and could respond to a focused vestibular rehabilitation program.

Quantitative assessment of postural instability in spinocerebellar ataxia type 3 patients

Objective

Spinocerebellar ataxia type 3 (SCA3) is one of the most common hereditary neurodegenerative diseases, with balance instability as main symptom. Balance quantification is crucial for evaluating the efficacy of therapeutic interventions. However, balance evaluation in SCA3 is often subject to bias. Here, we aimed to quantitatively evaluate postural instability and investigate the relationship between postural instability and clinical characteristics in SCA3 patients.

Methods

Sixty‐two SCA3 patients and 62 normal controls were recruited, and their postural balance was measured using a posturographic platform. Principal component analysis was performed as data reduction to identify postural instability factors. Multivariable linear regression was used to investigate potential risk factors for postural instability and to explore whether postural instability predicts the severity and progression of ataxia in SCA3 patients.

Results

We found SCA3 patients experience postural instability characterized by significant impairment in static and dynamic stability. The condition without visual feedback was the most sensitive measure in differentiating SCA3 from controls. Regression analyses revealed that ataxia severity predicted both static (P = 0.014) and dynamic stability (P = 0.001). Likewise, along with expanded CAG repeats (P < 0.001), both static (P < 0.001) and dynamic stability (P < 0.001) predicted ataxia severity, but not ataxia progression.

Interpretation

Our findings demonstrate the validity of using the Pro‐kin system for assessing postural instability in SCA3 patients. This type of quantitative assessment of balance dysfunction can contribute to clinical trials and balance rehabilitation in SCA3 patients.

Neurologic outcomes in Friedreich ataxia: Study of a single-site cohort

Objective

To investigate the pattern of progression of neurologic impairment in Friedreich ataxia (FRDA) and identify patients with fast disease progression as detected by clinical rating scales.

Methods

Clinical, demographic, and genetic data were analyzed from 54 patients with FRDA included at the Brussels site of the European Friedreich's Ataxia Consortium for Translational Studies, with an average prospective follow-up of 4 years.

Results

Afferent ataxia predated other features of FRDA, followed by cerebellar ataxia and pyramidal weakness. The Scale for the Assessment and Rating of Ataxia (SARA) best detected progression in ambulatory patients and in the first 20 years of disease duration but did not effectively capture progression in advanced disease. Dysarthria, sitting, and upper limb coordination items kept worsening after loss of ambulation. Eighty percent of patients needing support to walk lost ambulation within 2 years. Age at onset had a strong influence on progression of neurologic and functional deficits, which was maximal in patients with symptom onset before age 8 years. All these patients became unable to walk by 15 years after onset, significantly earlier than patients with later onset. Progression in the previous 1 or 2 years was not predictive of progression in the subsequent year.

Conclusions

The SARA is a sensitive outcome measure in ambulatory patients with FRDA and has an excellent correlation with functional capabilities. Ambulatory patients with onset before age 8 years showed the fastest measurable worsening. Loss of ambulation in high-risk patients is a disease milestone that should be considered as an end point in clinical trials.

Cerebellar lesions at a young age predict poorer long-term functional recovery

Early studies on long-term functional recovery after motor and premotor lesions showed better outcomes in younger monkeys than in older monkeys. This finding led to the widespread belief that brain injuries cause less impairment in children than adults. However, this view has limitations and a large body of evidence now indicates that cerebral damages can be more harmful when inflicted at young age, during critical periods of neural development. To date, this issue has been mainly investigated in the context of focal and diffuse cortical lesions. Much less is known about the potential influence of early cerebellar damages. Several studies exist in survivor of posterior fossa tumours. However, in these studies, critical confounders were not always considered and contradictory conclusions were provided. We studied the impact or early cerebellar damage on long-term functional recovery in three groups of 15 posterior fossa survivors, comparable with respect to their tumour characteristics (type, size and location) but operated at different ages: young (≤7 years), middle (>7 and ≤13 years) and older (>13 years). Daily (health-related quality of life scale, performance status scale), motor (International Cooperative Ataxia Rating Scale, Pegboard Purdue Test) and cognitive (full-scale intelligence quotient) functioning were assessed. A general linear model controlling for age at surgery, radiotherapy, preservation of deep cerebellar nuclei, tumour volume and delay between surgery and assessment was used to investigate significant variations in outcome measures. Early age at surgery, lesion of deep cerebellar nuclei and postoperative radiotherapy had a significant, independent negative influence on long-term recovery. Tumour volume and delay between surgery and assessment had no statistically detectable impact. The negative influence of early age at surgery was significant in all domains: daily functioning (health-related quality of life scale, performance status scale), motor functioning (International Cooperative Ataxia Rating Scale, Pegboard Purdue Test) and cognitive functioning (full-scale intelligence quotient). These results support the existence of an early critical period of development during which the cerebellar ‘learning machine’ is of critical importance. Although the extent to which the early deficits here observed can be reversed needs now to be established, our data plead for the implementation of prompt and intense rehabilitation interventions in children operated before 7 years of age.

Temporal Invariance in SCA6 Is Related to Smaller Cerebellar Lobule VI and Greater Disease Severity

Regulating muscle force and timing are fundamental for accurate motor performance. In spinocerebellar ataxia type 6 (SCA6), there is evidence that individuals have greater force dysmetria but display better temporal accuracy during fast goal directed contractions. Here, we test whether greater temporal accuracy occurs in all individuals with SCA6, and can be explained by lesser temporal variability. Further we examine whether it is linked to disease severity and specific degenerative changes in the cerebellum. Nineteen human participants with SCA6 (13 woman) and 18 healthy controls performed fast goal-directed ankle dorsiflexion contractions aiming at a spatiotemporal target. We quantified the endpoint control of these contractions, gray matter (GM) integrity of the cerebellum, and disease severity using the International Cooperative Ataxia Rating Scale (ICARS). SCA6 individuals exhibited lower temporal endpoint error and variability than the healthy controls (p = 0.008). Statistically, SCA6 clustered into two distinct groups for temporal variability. A group with low temporal variability ranging from 10 to 19% (SCA6a) and a group with temporal variability similar to healthy controls (SCA6b; 19-40%).SCA6a exhibited greater disease severity than SCA6b, as assessed with ICARS (p < 0.001). Lower temporal variability, which was not associated with disease duration (R ² = 0.1, p > 0.2), did correlate with both greater ICARS (R ² = 0.3) and reduced GM volume in cerebellar lobule VI (R ² = 0.35). Other cerebellar lobules did not relate to temporal variability. We provide new evidence that a subset of SCA6 with greater loss of GM in cerebellum lobule VI exhibit temporal invariance and more severe ataxia than other SCA6 individuals.SIGNIFICANCE STATEMENT Variability is an inherent feature of voluntary movement, and traditionally more variability in the targeted output infers impaired performance. For example, cerebellar patients present exacerbated temporal variability during multijoint movements, which is thought to contribute to their motor deficits. In the current work, we show that in a subgroup of spinocerebellar ataxia type 6 individuals, temporal variability is lower than that of healthy controls when performing single-joint fast-goal directed movements. This invariance related to exacerbated atrophy of lobule VI of the cerebellum and exacerbated disease severity. The relation between invariance and disease severity suggests that pathological motor variability can manifest not only as an exacerbation but also as a reduction relative to healthy controls.

From Pathogenesis to Novel Therapeutics for Spinocerebellar Ataxia Type 3: Evading Potholes on the Way to Translation

Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is a neurodegenerative disorder caused by a polyglutamine expansion in the ATXN3 gene. In spite of the identification of a clear monogenic cause 25 years ago, the pathological process still puzzles researchers, impairing prospects for an effective therapy. Here, we propose the disruption of protein homeostasis as the hub of SCA3 pathogenesis, being the molecular mechanisms and cellular pathways that are deregulated in SCA3 downstream consequences of the misfolding and aggregation of ATXN3. Moreover, we attempt to provide a realistic perspective on how the translational/clinical research in SCA3 should evolve. This was based on molecular findings, clinical and epidemiological characteristics, studies of proposed treatments in other conditions, and how that information is essential for their (re-)application in SCA3. This review thus aims i) to critically evaluate the current state of research on SCA3, from fundamental to translational and clinical perspectives; ii) to bring up the current key questions that remain unanswered in this disorder; and iii) to provide a frame on how those answers should be pursued.

Cross-cultural adaptation and validation of the International Cooperative Ataxia Rating Scale (ICARS) to Brazilian Portuguese

OBJECTIVE

The clinical assessment of patients with ataxias requires reliable scales. We aimed to translate, adapt and validate the International Cooperative Ataxia Rating Scale (ICARS) into Brazilian Portuguese.

METHODS

The steps of this study were forward translation, translation synthesis, backward translation, expert committee meeting, preliminary pilot testing and final assessment. Thirty patients were enrolled in the preliminary pilot testing and 61 patients were evaluated for construct validity, internal consistency, intra- and inter-rater reliability and external consistency.

RESULTS

This study showed good validity of the construct and high internal consistency for the full scale, except for the oculomotor domain (Cronbach's alpha = 0.316, intraclass correlation coefficients intra- = 82.4% and inter- = 79.2%). A high correlation with the Scale for the Assessment and Rating of Ataxia was observed. We found good intra-rater agreement and relative inter-rater disagreement, except in the posture and gait domain.

CONCLUSION

The present ICARS version is adapted for the Brazilian culture and can be used to assess our ataxic patients.

The Spectrum of Neurological and White Matter Changes and Premutation Status Categories of Older Male Carriers of the FMR1 Alleles Are Linked to Genetic (CGG and FMR1 mRNA) and Cellular Stress (AMPK) Markers

The fragile X premutation (PM) allele contains a CGG expansion of 55-200 repeats in the FMR1 gene's promoter. Male PM carriers have an elevated risk of developing neurological and psychiatric changes, including an approximately 50% risk of the fragile X-associated tremor/ataxia syndrome (FXTAS). The aim of this study was to assess the relationships of regional white matter hyperintensities (wmhs) semi-quantitative scores, clinical status, motor (UPDRS, ICARS, Tremor) scales, and cognitive impairments, with FMR1-specific genetic changes, in a sample of 32 unselected male PM carriers aged 39-81 years. Half of these individuals were affected with FXTAS, while the non-FXTAS group comprised subcategories of non-affected individuals and individuals affected with non-syndromic changes. The dynamics of pathological processes at the cellular level relevant to the clinical status of PM carriers was investigated using the enzyme AMP-activated protein kinase (AMPK), which is a highly sensitive cellular stress-sensing alarm protein. This enzyme, as well as genetic markers - CGG repeat number and the levels of the FMR1 mRNA - were assessed in blood lymphoblasts. The results showed that the repeat distribution for FXTAS individuals peaked at 85-90 CGGs; non-FXTAS carriers were distributed within the lowest end of the PM repeat range, and non-syndromic carriers assumed an intermediate position. The size of the CGG expansion was significantly correlated, across all three categories, with infratentorial and total wmhs and with all motor scores, and the FMR1 mRNA levels with all the wmh scores, whilst AMPK activity showed considerable elevation in the non-FXTAS combined group, decreasing in the FXTAS group, proportionally to increasing severity of the wmhs and tremor/ataxia. We conclude that the size of the CGG expansion relates to the risk for FXTAS, to severity of infratentorial wmhs lesions, and to all three motor scale scores. FMR1 mRNA shows a strong association with the extent of wmhs, which is the most sensitive marker of the pathological process. However, the AMPK activity findings - suggestive of a role of this enzyme in the risk of FXTAS - need to be verified and expanded in future studies using larger samples and longitudinal assessment.

Less is more - Pulse width dependent therapeutic window in deep brain stimulation for essential tremor

BACKGROUND

Shorter pulse widths than conventional pulse width settings may lead to reduction of side effects and therefore be a valuable therapeutic option for deep brain stimulation (DBS) in patients with essential tremor (ET).

OBJECTIVE

To compare the DBS effect of shorter pulse width at 40 μs (DBS-40 μs) to conventional pulse width at 60 μs (DBS-60 μs) on the therapeutic window in ET patients.

METHODS

For this prospective, randomized, double-blind, crossover study 9 ET patients with chronic DBS of the ventral intermediate nucleus (VIM)/posterior subthalamic area (PSA) were recruited. Therapeutic window was calculated by determining efficacy and side effect thresholds for DBS-40 μs and DBS-60 μs. Tremor Rating Scales and Kinesia tremor analyses were used to compare clinical efficacy between the considered settings and deactivated DBS (DBS-OFF). Volume of neural activation (VNA) was calculated for both efficacy and side effect thresholds at each pulse width.

RESULTS

DBS-40 μs showed a significantly larger therapeutic window than DBS-60 μs mainly due to higher side-effect thresholds. Both conditions significantly improved tremor compared to DBS-OFF, while efficacy was comparable between DBS-40 μs and DBS-60 μs. Moreover, VNA at efficacy threshold was smaller and less energy was required for tremor suppression with DBS-40 μs compared to DBS-60 μs.

CONCLUSIONS

VIM/PSA-DBS with short pulse width represents a promising programming option for DBS in ET as it reduces side effects while maintaining efficient tremor suppression. Furthermore, our data support the notion of pulse width dependent selective modulation of distinct fiber tracts leading to widening of the therapeutic window.

Psychometric properties of outcome measures evaluating decline in gait in cerebellar ataxia: A systematic review

Cerebellar ataxia often results in impairment in ambulation secondary to gait pattern dysfunction and compensatory gait adjustments. Pharmaceutical and therapy-based interventions with potential benefit for gait in ataxia are starting to emerge, however evaluation of such interventions is hampered by the lack of outcome measures that are responsive, valid and reliable for measurement of gait decline in cerebellar ataxia. This systematic review aimed for the first time to evaluate the psychometric properties of gait and walking outcomes applicable to individuals with cerebellar ataxia. Only studies evaluating straight walking were included. A comprehensive search of three databases (MEDLINE, CINAHL and EMBASE) identified 53 studies meeting inclusion criteria. Forty-nine were rated as 'poor' as assessed by the COnsensus-based Standards for the selection of health Measurement INstruments checklist. The primary objective of most studies was to explore changes in gait related to ataxia, rather than to examine psychometric properties of outcomes. This resulted in methodologies not specific for psychometric assessment. Thirty-nine studies examined validity, 11 examined responsiveness and 12 measured reliability. Review of the data identified double and single support and swing percentage of the gait cycle, velocity, step length and the Scale for Assessment and Rating of Ataxia (SARA) gait item as the most valid and responsive measures of gait in cerebellar ataxia. However, further evaluation to establish their reliability and applicability for use in clinical trials is clearly warranted. We recommend that inter-session reliability of gait outcomes should be evaluated to ensure changes are reflective of intervention effectiveness in cerebellar ataxia.

Progress in the treatment of Friedreich ataxia

Friedreich ataxia (FRDA) is a progressive neurological disorder affecting approximately 1 in 29,000 individuals of European descent. At present, there is no approved pharmacological treatment for this condition however research into treatment of FRDA has advanced considerably over the last two decades since the genetic cause was identified. Current proposed treatment strategies include decreasing oxidative stress, increasing cellular frataxin, improving mitochondrial function as well as modulating frataxin controlled metabolic pathways. Genetic and cell based therapies also hold great promise. Finally, physical therapies are being explored as a means of maximising function in those affected by FRDA.

Cerebellar ataxia

The cerebellum plays an integral role in the control of limb and ocular movements, balance, and walking. Cerebellar disorders may be classified as sporadic or hereditary with clinical presentation varying with the extent and site of cerebellar damage and extracerebellar signs. Deficits in balance and walking reflect the cerebellum's proposed role in coordination, sensory integration, coordinate transformation, motor learning, and adaptation. Cerebellar dysfunction results in increased postural sway, hypermetric postural responses to perturbations and optokinetic stimuli, and postural responses that are poorly coordinated with volitional movement. Gait variability is characteristic and may arise from a combination of balance impairments, interlimb incoordination, and incoordination between postural activity and leg movement. Intrinsic problems with balance lead to a high prevalence of injurious falls. Evidence for pharmacologic management is limited, although aminopyridines reduce attacks in episodic ataxias and may have a role in improving gait ataxia in other conditions. Intensive exercises targeting balance and coordination lead to improvements in balance and walking but require ongoing training to maintain/maximize any effects. Noninvasive brain stimulation of the cerebellum may become a useful adjunct to therapy in the future. Walking aids, orthoses, specialized footwear and seating may be required for more severe cases of cerebellar ataxia.

Scales for the clinical evaluation of cerebellar disorders

Clinical scales represent an important tool not only for the initial grading/scoring of disease and assessment of progression, but also for the quantification of therapeutic effects in clinical trials. There are several scales available for the clinical evaluation of cerebellar symptoms. While some scales have been developed and evaluated for specific cerebellar disorders such as Friedreich ataxia, others reliably capture cerebellar symptoms with no respect to the underlying etiology. Each scale has its strengths and weaknesses. Extensive scales are certainly useful for thorough documentation of specific features of certain phenotypes, but this gain of information is not always essential for the purpose of a study. Therefore, compact and manageable scales like the Scale for the Assessment and Rating of Ataxia (SARA) or Brief Ataxia Rating Scale (BARS) are often preferred compared to more complex scales in observational and therapeutic studies.

Evaluation and treatment of Langerhans cell histiocytosis patients with central nervous system abnormalities: Current views and new vistas

Central nervous system (CNS) involvement in Langerhans cell histiocytosis (LCH) can include mass lesions of the hypothalamic pituitary axis, choroid plexus, cerebrum, and cerebellum or magnetic resonance imaging (MRI) signal abnormalities of the cerebellum, pons, and basal ganglia. The term neurodegenerative (ND) CNS-LCH has been given to the MRI signal abnormalities and neurologic dysfunction, although initially patients may have no clinical symptoms. Standardized evaluations to better understand the natural history and response to therapy are needed. We propose guidelines for clinical, radiologic, and physiologic tests as a framework for developing the best methods of evaluation, which can then be tested in prospective treatment protocols.

Vestibular impairment in chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a common, treatable, autoimmune peripheral neuropathy considered to produce imbalance by weakness and proprioceptive impairment rather than vestibular impairment. We measured semicircular canal vestibular function in 21 CIDP patients (15M/6F) by the video head impulse test and postural stability with a battery comprising the modified Clinical Test of Sensory Integration and Balance, the Berg Balance Scale, the Dynamic Gait Index, the Fall Efficiency Scale, and the International Cooperative Ataxia Rating Scale. Of the 21 patients, 16 had vestibular impairment, ranging from mild-affecting just a single semicircular canal, to severe-affecting all 6 canals. Although the severity of the vestibular impairment did not correlate either with the severity of the postural imbalance or of the peripheral neuropathy, our data show that vestibular impairment is an additional challenge to balance that some CIDP patients will face.

Stratification of disease progression in a broad spectrum of degenerative cerebellar ataxias with a clustering method using MRI-based atrophy rates of brain structures

BACKGROUND

The rate of disease progression differs among patients with degenerative cerebellar ataxia. The uncertain natural course in individual patients hinders clinical trials of promising treatments. In this study, we analyzed atrophy changes in brain structures with cluster analysis to find sub-groups of patients with homogenous symptom progression in a broad spectrum of degenerative cerebellar ataxias.

METHODS

We examined 48 patients including 21 cases of spinocerebellar ataxia (SCA), 17 cases of the cerebellar type of multiple system atrophy (MSA-C), and 10 cases of cortical cerebellar ataxia (CCA). In all patients, at least two sets of evaluations including magnetic resonance imaging (MRI) and the International Cooperative Ataxia Rating Scale (ICARS) scoring were performed. The median number (min-max) of follow-up studies in each patient was three (2-6), and the mean follow-up period was 3.1 ± 1.6 years. The area of the corpus callosum on midsagittal images and the cerebellar volume were measured using MRI, and these values were divided by the cranial antero-posterior diameter of each patient to correct for individual head size differences as an area index (Adx) and a volume index (Vdx), respectively. The annual changes in Adx, Vdx, and ICARS score were calculated in each patient, and atrophy patterns in patients were categorized with cluster analysis.

RESULTS

The annual atrophy rates for the corpus callosum (Adx) and cerebellum (Vdx) and symptom progression differed significantly by subtype of cerebellar ataxia (p = 0.026, 0.019, and 0.021, respectively). However, neither the annual atrophy rate of Adx nor Vdx was significantly correlated with the annual increase in the ICARS score. When the patients were categorized into three clusters based on the annual changes in Adx and Vdx, the annual increase in the ICARS score was significantly different among clusters (2.9 ± 1.7/year in Cluster 1, 4.8 ± 3.2/year in Cluster 2, and 8.7 ± 6.1/year in Cluster 3; p = 0.014).

CONCLUSIONS

The annual increase in the ICARS score can be stratified by cluster analysis based on the atrophy rates of the corpus callosum and cerebellum. Further studies are warranted to explore whether these simple MRI methods could be used for random allocation of a broad spectrum of patients with degenerative cerebellar ataxia in clinical trials.

Structural cerebellar correlates of cognitive and motor dysfunctions in cerebellar degeneration

See King et al. (doi:10.1093/aww348) for a scientific commentary on this article.Detailed mapping of clinical dysfunctions to the cerebellar lobules in disease populations is necessary to establish the functional significance of lobules implicated in cognitive and motor functions in normal subjects. This study constitutes the first quantitative examination of the lobular correlates of a broad range of cognitive and motor phenomena in cerebellar disease. We analysed cross-sectional data from 72 cases with cerebellar disease and 36 controls without cerebellar disease. Cerebellar lobule volumes were derived from a graph-cut based segmentation algorithm. Sparse partial least squares, a variable selection approach, was used to identify lobules associated with motor function, language, executive function, memory, verbal learning, perceptual organization and visuomotor coordination. Motor dysfunctions were chiefly associated with the anterior lobe and posterior lobule HVI. Confrontation naming, noun fluency, recognition, and perceptual organization did not have cerebellar associations. Verb and phonemic fluency, working memory, cognitive flexibility, immediate and delayed recall, verbal learning, and visuomotor coordination were variably associated with HVI, Crus I, Crus II, HVII B and/or HIX. Immediate and delayed recall also showed associations with the anterior lobe. These findings provide preliminary anatomical evidence for a functional topography of the cerebellum first defined in task-based functional magnetic resonance imaging studies of normal subjects and support the hypotheses that (i) cerebellar efferents target frontal lobe neurons involved in forming action representations and new search strategies; (ii) there is greater involvement of the cerebellum when immediate recall tasks involve more complex verbal stimuli (e.g. longer words versus digits); and (iii) it is involved in spontaneous retrieval of long-term memory. More generally, they provide an anatomical background for studies that seek the mechanisms by which cognitive and motor dysfunctions arise from cerebellar degeneration. Beyond replicating these findings, future research should employ experimental tasks to probe the integrity of specific functions in cerebellar disease, and new imaging methods to quantitatively map atrophy across the cerebellum.

Cerebellar Symptoms Are Associated With Omission Errors and Variability of Response Time in Children With ADHD

OBJECTIVE

We examined the presence of cerebellar symptoms in ADHD and their association with behavioral markers of this disorder.

METHOD

Sixty-two children with ADHD and 62 typically developing (TD) children were examined for cerebellar symptoms using the ataxia rating scale and tested using Conners' Continuous Performance Test.

RESULTS

Children with ADHD had significantly more cerebellar symptoms compared with the TD children. Cerebellar symptom scores decreased with age in the ADHD group; in the TD group remained stable. In both groups, cerebellar symptoms were associated with parent-rated hyperactive/impulsive symptoms, variability of response time standard error (RT-SE) and increase of RT-SE as the test progresses. More variables were associated with cerebellar symptoms in the ADHD group including omission errors, overall RT-SE and its increase for prolonged interstimulus intervals.

CONCLUSION

Our results highlight the importance of research into motor functions in children with ADHD and indicate a role for cerebellar impairment in this disorder.

Dynamic balance in children with attention-deficit hyperactivity disorder and its relationship with cognitive functions and cerebellum

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is linked to the presence of motor deficiencies, including balance deficits. The cerebellum serves as an integrative structure for balance control and is also involved in cognition, including timing and anticipatory regulation. Cerebellar development may be delayed in children and adolescents with ADHD, and inconsistent reaction time is commonly seen in ADHD. We hypothesized that dynamic balance deficits would be present in children with ADHD and they would correlate with attention and cerebellar functions.

METHODS

Sixty-two children with ADHD and no other neurological conditions and 62 typically developing (TD) children were examined with five trials of the Phyaction Balance Board, an electronic balancing platform. Cerebellar clinical symptoms were evaluated using an international ataxia rating scale. Conners' Continuous Performance Test was used to evaluate patterns of reaction.

RESULTS

Children with ADHD had poorer performance on balancing tasks, compared to TD children (P<0.001). They exhibited significantly greater sway amplitudes than TD children (P<0.001) in all of the five balancing trials. The effect size of the difference between the groups increased continuously from the first to the last trial. Balance score in both groups was related to the variation in the reaction time, including reaction time standard error (r =0.25; P=0.0409, respectively, r =0.31; P=0.0131) and Variability of Standard Error (r =0.28; P=0.0252, respectively, r =0.41; P<0.001). The burden of cerebellar symptoms was strongly related to balance performance in both groups (r =0.50, P<0.001; r =0.49, P=0.001).

CONCLUSION

This study showed that ADHD may be associated with poor dynamic balance control. Furthermore, we showed that maintaining balance correlates with neuropsychological measures of consistency of reaction time. Balance deficits and impaired cognitive functioning could reflect a common cerebellar dysfunction in ADHD children.

Neurobehavioral deficits in the KIKO mouse model of Friedreich's ataxia

Friedreich's Ataxia (FA) is a pediatric neurodegenerative disease whose clinical presentation includes ataxia, muscle weakness, and peripheral sensory neuropathy. The KIKO mouse is an animal model of FA with frataxin deficiency first described in 2002, but neurobehavioral deficits have never been described in this model. The identification of robust neurobehavioral deficits in KIKO mice could support the testing of drugs for FA, which currently has no approved therapy. We tested 13 neurobehavioral tasks to identify a robust KIKO phenotype: Open Field, Grip Strength Test(s), Cylinder, Skilled Forelimb Grasp Task(s), Treadmill Endurance, Locotronic Motor Coordination, Inverted Screen, Treadscan, and Von Frey. Of these, Inverted Screen, Treadscan and Von Frey produced significant neurobehavioral deficits at >8 months of age, and relate to the clinically relevant endpoints of muscle strength and endurance, gait ataxia, and peripheral insensitivity. Thus we identify robust phenotypic measures related to Friedreich's ataxia clinical endpoints which could be used to test effectiveness of potential drug therapy.

Standardized Assessment of Hereditary Ataxia Patients in Clinical Studies

BACKGROUND

Hereditary ataxias are a heterogeneous group of degenerative diseases of the cerebellum, brainstem, and spinal cord. They may present with isolated ataxia or with additional symptoms going beyond cerebellar deficits. There are an increasing number of clinical studies with the goal to define the natural history of these disorders, develop biomarkers, and investigate therapeutic interventions. Especially, early and preclinical disease stages are currently of particular interest.

METHODS AND RESULTS

Evidence-based, we review standards for sampling and storage of biomaterials, clinical and neuropsychological assessment, as well as neurophysiology and neuroimaging and recommendations for standardized assessment of ataxia patients in multicenter studies.

CONCLUSIONS

DNA, RNA, serum, and, if possible, cerebrospinal fluid samples should be processed following established standards. Clinical assessment in ataxia studies must include use of a validated clinical ataxia scale. There are several validated clinical ataxia scales available. There are no instruments that were specifically designed for assessing neuropsychological and psychiatric symptoms in ataxia disorders. We provide a list of tests that may prove valuable. Quantitative performance tests have the potential to supplement clinical scales. They provide additional objective and quantitative information. Posturography and quantitative movement analysis-despite valid approaches-require standardization before implemented in multicenter studies. Standardization of neurophysiological tools, as required for multicenter interventional trials, is still lacking. Future multicenter neuroimaging studies in ataxias should implement quality assurance measures as defined by the ADNI or other consortia. MRI protocols should allow morphometric analyses.

Neurological and cerebellar soft signs do not discriminate schizophrenia from bipolar disorder patients

Patients with schizophrenia (SZ) and bipolar disorder (BD) share subtle motor abnormalities called the neurological soft signs (NSS). Since in both diseases there is evidence for alterations in cerebellar functions, structure and connectivity, we expected that the cerebellar soft signs (CSS), analogue of NSS focusing strictly on cerebellar symptoms, would be also a common trait in SZ and BD. We examined 30 patients with BD, 30 patients with SZ and 28 control subjects using the Neurological Evaluation Scale (NES, for NSS) and International Cooperative Ataxia Rating Scale (ICARS, for CSS). SZ and BD did not differ in total and subscales' scores in both NES and ICARS. Subscale analysis revealed that SZ performed significantly worse than controls in all the subscales of both NES and ICARS. BD patients scored significantly worse than controls in all NES subscales and in oculomotor and kinetic subscales of the ICARS, while other ICARS subscales did not differentiate those two groups. To our knowledge this is the first study to show that CSS constitute common symptoms in BD and SZ. We recommend a special focus on those diseases in further research regarding structural and functional changes of cerebellum and their clinical outcome.

A study of up to 12 years of follow-up of Friedreich ataxia utilising four measurement tools

OBJECTIVE

To explore the progression of Friedreich ataxia by analysing the change in scores of four clinical measures (the Friedreich Ataxia Rating Scale (FARS), the International Cooperative Ataxia Rating Scale (ICARS), the Functional Independence Measure (FIM) and the Modified Barthel Index (MBI)) over a period of up to 12 years, to ascertain the effects of clinical variables on performance of these measures, and to determine the most sensitive rating scale for measuring disease progression.

METHODS

We measured the disease progression of up to 147 individuals against disease duration grouped into 5-year intervals. Additional subgroups were created to study the effects of the size of the smaller FXN intron 1 GAA repeat size (GAA1) and onset age on rating scale performance.

RESULTS

Both the FARS and ICARS demonstrated greater change in the first 20 years post disease onset than in the subsequent 20 years during which there was little change in the mean score. While the FIM and MBI continued to deteriorate beyond 20 years post disease onset, floor effects were noted. As measured by the FARS, individuals with a larger GAA1 repeat were found to progress more quickly in the first 20 years of disease.

CONCLUSIONS

Individuals with larger GAA1 repeat sizes and earlier ages of disease onset were shown to deteriorate at a faster rate and were associated with greater FARS and ICARS scores and lower FIM and MBI scores, which are indicative of greater disease severity.

Force dysmetria in spinocerebellar ataxia 6 correlates with functional capacity

Spinocerebellar ataxia type 6 (SCA6) is a genetic disease that causes pure cerebellar degeneration affecting walking, balance, and coordination. One of the main symptoms of SCA6 is dysmetria. The magnitude of dysmetria and its relation to functional capacity in SCA6 has not been studied. Our purpose was to quantify dysmetria and determine the relation between dysmetria and functional capacity in SCA6. Ten individuals diagnosed and genetically confirmed with SCA6 (63.7 ± 7.02 years) and nine age-matched healthy controls (65.9 ± 8.5 years) performed goal-directed isometric contractions with the ankle joint. Dysmetria was quantified as the force and time error during goal-directed contractions. SCA6 functional capacity was determined by ICARS and SARA clinical assessments. We found that SCA6 participants exhibited greater force dysmetria than healthy controls (P < 0.05), and reduced time dysmetria than healthy controls (P < 0.05). Only force dysmetria was significantly related to SCA6 functional capacity, as measured with ICARS kinetic score (R² = 0.63), ICARS total score (R² = 0.43), and SARA total score (R² = 0.46). Our findings demonstrate that SCA6 exhibit force dysmetria and that force dysmetria is associated to SCA6 functional capacity. Quantifying force and time dysmetria in individuals with SCA6 could provide a more objective evaluation of the functional capacity and disease state in SCA6.