[Scale for the assessment and rating of ataxia (SARA): translation and cultural adaptation to German-speaking areas]

BACKGROUND/OBJECTIVE

The scale for the assessment and rating of ataxia (SARA) is a feasible assessment for the classification and evaluation of therapeutic interventions. In order to provide access to the SARA in German, the aim of this work was to translate the SARA into German and to adapt it according to international guidelines for German-speaking countries.

METHOD

The process involved six steps. The comprehensibility of the scale was assessed using interviews with potential users.

RESULTS

A total of nine physiotherapists and six physicians working in various clinical settings were interviewed, seven of them worked in Germany and four each in Austria and Switzerland. The interviews led to a refined version of the translation. The comprehensibility testing revealed no country-specific differences.

CONCLUSION

A German version of the SARA authorized by the co-author of the original publication, is now available. The results provide methodological insights into the translation process of observation-based standardized assessments.

Neuropathy, ataxia, retinitis pigmentosa: a case of a mother and two siblings

AIM

We describe the ophthalmic manifestations of Neuropathy, ataxia, retinitis pigmentosa (NARP) syndrome in three related patients.

METHODS

We examined a mother and her two children, who were carriers of the mt 8993T>G mutation. The mother, patient I, is the first known carrier within the family pedigree. Patients II and III are her children from a non-carrier father. NARP syndrome and the heteroplasmy levels were established prior to the first referral of the patients to the Ophthalmology department.We performed a visual acuity testing, followed by a biomicroscopic and fundus examination, as well as additional multimodal imaging testing: optical coherence tomography (OCT) and fundus autofluorescence (FAF), and functional testing: electroretinogram and visual field.

RESULTS

All patients had the clinical manifestations of NARP syndrome, which were variably expressed symptomatically, on the fundus exams, electroretinogram, and visual fields.

CONCLUSIONS

Once genetically established, NARP syndrome, as other mitochondrial disorders, has a very variable progression with different degrees of severity. A multimodal approach involving both neurological and ophthalmological diagnosis of NARP syndrome is necessary in order to establish the course of the disease and the measures to be taken.

Uncertainty of Vowel Predictions as a Digital Biomarker for Ataxic Dysarthria

Dysarthria is a common manifestation across cerebellar ataxias leading to impairments in communication, reduced social connections, and decreased quality of life. While dysarthria symptoms may be present in other neurological conditions, ataxic dysarthria is a perceptually distinct motor speech disorder, with the most prominent characteristics being articulation and prosody abnormalities along with distorted vowels. We hypothesized that uncertainty of vowel predictions by an automatic speech recognition system can capture speech changes present in cerebellar ataxia. Speech of participants with ataxia (N=61) and healthy controls (N=25) was recorded during the "picture description" task. Additionally, participants' dysarthric speech and ataxia severity were assessed on a Brief Ataxia Rating Scale (BARS). Eight participants with ataxia had speech and BARS data at two timepoints. A neural network trained for phoneme prediction was applied to speech recordings. Average entropy of vowel tokens predictions (AVE) was computed for each participant's recording, together with mean pitch and intensity standard deviations (MPSD and MISD) in the vowel segments. AVE and MISD demonstrated associations with BARS speech score (Spearman's rho=0.45 and 0.51), and AVE demonstrated associations with BARS total (rho=0.39). In the longitudinal cohort, Wilcoxon pairwise signed rank test demonstrated an increase in BARS total and AVE, while BARS speech and acoustic measures did not significantly increase. Relationship of AVE to both BARS speech and BARS total, as well as the ability to capture disease progression even in absence of measured speech decline, indicates the potential of AVE as a digital biomarker for cerebellar ataxia.

Analysis of static plantar pressure data with capsule networks: Diagnosing ataxia in MS patients with a deep learning-based approach

In this study, it was aimed to detect ataxia in patients with Multiple Sclerosis (MS) by utilizing static plantar pressure data and capsule networks (CapsNet), one of the deep learning (DL) architectures. CapsNet is also equipped with a robust dynamic routing mechanism that determines the output of the next capsule. MS is a chronic nervous system disease that shows its effect in the central nervous system and manifests itself with attacks. One of the most common and challenging symptoms of MS is known as ataxia. Ataxia causes loss of control of limb muscle tone or gait disorders, leading to loss of balance and coordination. The diagnosis of ataxia in MS is applied employing the standard Expanded Disability Status Scale (EDSS) score. However, due to reasons such as physician misconception, diagnosis differences among physicians, and incorrect patient information, more unbiased solutions are required for the diagnosis. The results included Sensitivity at 96.34 % ± 1.71, Specificity at 98.11 % ± 2.04, Precision at 98.08 % ± 2.16, and Accuracy at 97.13 % ± 0.33. The main motivation of the study is to show that these deep learning methods can successfully detect ataxia in MS patients using static plantar pressure data. The high-performance measurements of sensitivity, specificity, precision and accuracy emphasize that the proposed system can be an effective tool in clinical practice. In addition, it was concluded that the proposed autonomous system would be a support mechanism to assist the physician in the detection of ataxia in patients with MS.

Pearls & Oy-sters: CACNA1A-Related Paroxysmal Tonic Upgaze With Ataxia Responsive to Acetazolamide

A 9-month-old male infant was evaluated for sudden onset of paroxysmal episodes of forced, conjugate upward eye deviation. Extensive in-hospital evaluation including electrophysiology and neuroimaging studies were reassuring against seizures or a structural abnormality. Given the clinical presentation of sudden onset intermittent upward eye deviations, downbeating saccades, associated ataxia, and typical development, a clinical diagnosis of paroxysmal tonic upgaze (PTU) with ataxia was made. Targeted genetic testing of CACNA1A was performed, which revealed a variant of undetermined significance, which was later classified as a de novo pathogenic variant after protein modeling and parental testing performed. Off-label use of oral acetazolamide was prescribed, which led to dose-responsive decrease in the frequency and intensity of eye movement episodes. After 6 months of episode freedom at 2 years of age, acetazolamide was discontinued without return of episodes. Neurodevelopmental assessments revealed continued typical development. This case is presented to describe the diagnostic formulation, etiologic evaluation, and symptomatic treatment of CACNA1A-related PTU with ataxia.

Clinical and genetic keys to cerebellar ataxia due to FGF14 GAA expansions

BACKGROUND

SCA27B caused by FGF14 intronic heterozygous GAA expansions with at least 250 repeats accounts for 10-60% of cases with unresolved cerebellar ataxia. We aimed to assess the size and frequency of FGF14 expanded alleles in individuals with cerebellar ataxia as compared with controls and to characterize genetic and clinical variability.

METHODS

We sized this repeat in 1876 individuals from France sampled for research purposes in this cross-sectional study: 845 index cases with cerebellar ataxia and 324 affected relatives, 475 controls, as well as 119 cases with spastic paraplegia, and 113 with familial essential tremor.

FINDINGS

A higher frequency of expanded allele carriers in index cases with ataxia was significant only above 300 GAA repeats (10.1%, n = 85) compared with controls (1.1%, n = 5) (p < 0.0001) whereas GAA250-299 alleles were detected in 1.7% of both groups. Eight of 14 index cases with GAA250-299 repeats had other causal pathogenic variants (4/14) and/or discordance of co-segregation (5/14), arguing against GAA causality. We compared the clinical signs in 127 GAA≥300 carriers to cases with non-expanded GAA ataxia resulting in defining a key phenotype triad: onset after 45 years, downbeat nystagmus, episodic ataxic features including diplopia; and a frequent absence of dysarthria. All maternally transmitted alleles above 100 GAA were unstable with a median expansion of +18 repeats per generation (r2 = 0.44; p < 0.0001). In comparison, paternally transmitted alleles above 100 GAA mostly decreased in size (-15 GAA (r2 = 0.63; p < 0.0001)), resulting in the transmission bias observed in SCA27B pedigrees.

INTERPRETATION

SCA27B diagnosis must consider both the phenotype and GAA expansion size. In carriers of GAA250-299 repeats, the absence of documented familial transmission and a presentation deviating from the key SCA27B phenotype, should prompt the search for an alternative cause. Affected fathers have a reduced risk of having affected children, which has potential implications for genetic counseling.

FUNDING

This work was supported by the Fondation pour la Recherche Médicale, grant number 13338 to JLM, the Association Connaître les Syndrome Cérébelleux - France (to GS) and by the European Union's Horizon 2020 research and innovation program under grant agreement No 779257 ("SOLVE-RD" to GS). DP holds a Fellowship award from the Canadian Institutes of Health Research (CIHR). SK received a grant (01GM1905C) from the Federal Ministry of Education and Research, Germany, through the TreatHSP network. This work was supported by the Australian Government National Health and Medical Research Council grants (GNT2001513 and MRFF2007677) to MB and PJL.

Clinical and genetic analyses of a Swedish patient series diagnosed with ataxia

Hereditary ataxia is a heterogeneous group of complex neurological disorders. Next-generation sequencing methods have become a great help in clinical diagnostics, but it may remain challenging to determine if a genetic variant is the cause of the patient's disease. We compiled a consecutive single-center series of 87 patients from 76 families with progressive ataxia of known or unknown etiology. We investigated them clinically and genetically using whole exome or whole genome sequencing. Test methods were selected depending on family history, clinical phenotype, and availability. Genetic results were interpreted based on the American College of Medical Genetics criteria. For high-suspicion variants of uncertain significance, renewed bioinformatical and clinical evaluation was performed to assess the level of pathogenicity. Thirty (39.5%) of the 76 families had received a genetic diagnosis at the end of our study. We present the predominant etiologies of hereditary ataxia in a Swedish patient series. In two families, we established a clinical diagnosis, although the genetic variant was classified as "of uncertain significance" only, and in an additional three families, results are pending. We found a pathogenic variant in one family, but we suspect that it does not explain the complete clinical picture. We conclude that correctly interpreting genetic variants in complex neurogenetic diseases requires genetics and clinical expertise. The neurologist's careful phenotyping remains essential to confirm or reject a diagnosis, also by reassessing clinical findings after a candidate genetic variant is suggested. Collaboration between neurology and clinical genetics and combining clinical and research approaches optimizes diagnostic yield.

Detection and discovery of repeat expansions in ataxia enabled by next-generation sequencing: present and future

Hereditary cerebellar ataxias are a heterogenous group of progressive neurological disorders that are disproportionately caused by repeat expansions (REs) of short tandem repeats (STRs). Genetic diagnosis for RE disorders such as ataxias are difficult as the current gold standard for diagnosis is repeat-primed PCR assays or Southern blots, neither of which are scalable nor readily available for all STR loci. In the last five years, significant advances have been made in our ability to detect STRs and REs in short-read sequencing data, especially whole-genome sequencing. Given the increasing reliance of genomics in diagnosis of rare diseases, the use of established RE detection pipelines for RE disorders is now a highly feasible and practical first-step alternative to molecular testing methods. In addition, many new pathogenic REs have been discovered in recent years by utilising WGS data. Collectively, genomes are an important resource/platform for further advancements in both the discovery and diagnosis of REs that cause ataxia and will lead to much needed improvement in diagnostic rates for patients with hereditary ataxia.

Machine Learning-Based Scoring System to Predict the Risk and Severity of Ataxic Speech Using Different Speech Tasks

The assessment of speech in Cerebellar Ataxia (CA) is time-consuming and requires clinical interpretation. In this study, we introduce a fully automated objective algorithm that uses significant acoustic features from time, spectral, cepstral, and non-linear dynamics present in microphone data obtained from different repeated Consonant-Vowel (C-V) syllable paradigms. The algorithm builds machine-learning models to support a 3-tier diagnostic categorisation for distinguishing Ataxic Speech from healthy speech, rating the severity of Ataxic Speech, and nomogram-based supporting scoring charts for Ataxic Speech diagnosis and severity prediction. The selection of features was accomplished using a combination of mass univariate analysis and elastic net regularization for the binary outcome, while for the ordinal outcome, Spearman's rank-order correlation criterion was employed. The algorithm was developed and evaluated using recordings from 126 participants: 65 individuals with CA and 61 controls (i.e., individuals without ataxia or neurotypical). For Ataxic Speech diagnosis, the reduced feature set yielded an area under the curve (AUC) of 0.97 (95% CI 0.90-1), the sensitivity of 97.43%, specificity of 85.29%, and balanced accuracy of 91.2% in the test dataset. The mean AUC for severity estimation was 0.74 for the test set. The high C-indexes of the prediction nomograms for identifying the presence of Ataxic Speech (0.96) and estimating its severity (0.81) in the test set indicates the efficacy of this algorithm. Decision curve analysis demonstrated the value of incorporating acoustic features from two repeated C-V syllable paradigms. The strong classification ability of the specified speech features supports the framework's usefulness for identifying and monitoring Ataxic Speech.

An atypical case of hypomagnesemia-induced cerebellar syndrome with literature review

Cerebellar ataxia in adults is always a diagnostic challenge. One of the important causes of late-onset cerebellar ataxia is hypomagnesemia. Hypomagnesemia can have varied manifestations and is attributable to numerous causes. Identification of hypomagnesemia-induced cerebellar syndrome (HiCS) is important as it is reversible but often missed. HiCS has distinct clinical findings and characteristic magnetic resonance imaging (MRI) findings. HiCS presents with distinct clinical, biochemical, and neuroimaging findings, but it cannot be ruled out even in the absence of neuroimaging findings. This condition has to be treated promptly and meticulously to avoid precipitating any serious complications, and a strong suspicion is required for the diagnosis. The underlying cause should be evaluated and managed, as HiCS is a serious but potentially reversible disease with a good prognosis. We present a case of HiCS presenting with a characteristic history of recurrent ataxia, tremor, and vertigo that improved with treatment. Our patient was atypical, as there were no significant MRI findings attributable to hypomagnesemia. Only seven case reports are available throughout the world that show such disparity.

Ataxia Rating Scales Reflect Patient Experience: an Examination of the Relationship Between Clinician Assessments of Cerebellar Ataxia and Patient-Reported Outcomes

Ataxia rating scales are observer administered clinical outcome assessments (COAs) of the cerebellar motor syndrome. It is not known whether these COAs mirror patient experience of their disease. Here we test the hypothesis that ataxia COAs are related to and reflect patient reported symptoms and impact of illness. A concept library of symptoms and activities impacted by ataxia was created by reviewing (a) concept elicitation data from surveys completed by 147 ataxia patients and 80 family members and (b) cognitive debrief data from focus groups of 17 ataxia patients used to develop the Patient Reported Outcome Measure of Ataxia. These findings were mapped across the items on 4 clinical measures of ataxia (SARA, BARS, ICARS and FARS). Symptoms reported most commonly related to balance, gait or walking, speech, tremor and involuntary movements, and vision impairment. Symptoms reported less frequently related to hand coordination, loss of muscle control, dizziness and vertigo, muscle discomfort or pain, swallowing, and incontinence. There was a mosaic mapping of items in the observer-derived ataxia COAs with the subjective reports by ataxia patients/families of the relevance of these items to their daily lives. Most COA item mapped onto multiple real-life manifestations; and most of the real-life impact of disease mapped onto multiple COA items. The 4 common ataxia COAs reflect patient reported symptoms and impact of illness. These results validate the relevance of the COAs to patients' lives and underscore the inadvisability of singling out any one COA item to represent the totality of the patient experience.

Quantification of Upper Limb Movements in Patients with Hereditary or Idiopathic Ataxia

Assessment of ataxic movements is usually based on clinical judgment. Technical devices can be employed in the quantification of ataxic movements in addition to clinical evaluation. The effect of maximal speed in upper limb movements in ataxia patients has not been quantified. The aim was to quantify upper limb movements in patients with hereditary or idiopathic ataxia and to find features of movement that are characteristic for ataxia. We examined 19 patients with degenerative ataxia and 21 healthy controls. An ad hoc system comprising a touch screen, an accelerometer, and a gyroscope was used to measure speed, angular acceleration, consistency, and accuracy of upper limb movements. The movements were quantified during finger-to-nose test that the patients were asked to perform at their own pace and as fast as possible. Disease severity was estimated by using the Scale for the Assessment and Rating of Ataxia (SARA). The mean SARA score of the patients was 13.5. Compared to the controls the performance of the patients was slow (p < 0.001) and arrhythmic (p < 0.001), but end-point accuracy on the touch screen was intact. The SARA score correlated with the standard deviation of amplitude of angular acceleration in Z-axis (F(1,17) = 15.00, p < 0.001 with R2 = 0.47). Upper limb movements of the patients with degenerative ataxia were slower and more arrhythmic than those in the controls. The patients retained spatial end-point accuracy.

Amiodarone-Induced Nystagmus and Ataxia: Case Report and Systematic Review of Case Reports

Amiodarone is an antiarrhythmic drug with a significant adverse effect profile, including neurotoxicity. While ataxia, neuropathy, and tremors are more commonly seen forms of amiodarone neurotoxicity, very few cases of nystagmus are reported. We report the case of an 86-year-old man who presented with abrupt-onset ataxia, dizziness, and inability to ambulate, 10 days after initiating amiodarone for atrial fibrillation. His examination revealed gaze-evoked nystagmus along with features of cerebellar dysfunction. After excluding other etiologies, amiodarone was stopped. His nystagmus resolved, and his ataxia improved within 48 h of stopping amiodarone. Due to the rarity of this drug-induced adverse effect, we performed a systematic review of available case reports in the literature (PubMed and Scopus) using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and presented our findings. Nystagmus is a rarely reported adverse effect of amiodarone, which can occur within days to months of starting the medication. Treatment includes stopping the drug and monitoring for resolution of nystagmus.

Clinical and electrophysiological features of SCN8A variants causing episodic or chronic ataxia

BACKGROUND

Variants in SCN8A are associated with a spectrum of epilepsies and neurodevelopmental disorders. Ataxia as a predominant symptom of SCN8A variation has not been well studied. We set out to investigate disease mechanisms and genotype-phenotype correlations of SCN8A-related ataxia.

METHODS

We collected genetic and electro-clinical data of ten individuals from nine unrelated families carrying novel SCN8A variants associated with chronic progressive or episodic ataxia. Electrophysiological characterizations of these variants were performed in ND7/23 cells and cultured neurons.

FINDINGS

Variants associated with chronic progressive ataxia either decreased Na+ current densities and shifted activation curves towards more depolarized potentials (p.Asn995Asp, p.Lys1498Glu and p.Trp1266Cys) or resulted in a premature stop codon (p.Trp937Ter). Three variants (p.Arg847Gln and biallelic p.Arg191Trp/p.Asp1525Tyr) were associated with episodic ataxia causing loss-of-function by decreasing Na+ current densities or a hyperpolarizing shift of the inactivation curve. Two additional episodic ataxia-associated variants caused mixed gain- and loss-of function effects in ND7/23 cells and were further examined in primary murine hippocampal neuronal cultures. Neuronal firing in excitatory neurons was increased by p.Arg1629His, but decreased by p.Glu1201Lys. Neuronal firing in inhibitory neurons was decreased for both variants. No functional effect was observed for p.Arg1913Trp. In four individuals, treatment with sodium channel blockers exacerbated symptoms.

INTERPRETATION

We identified episodic or chronic ataxia as predominant phenotypes caused by variants in SCN8A. Genotype-phenotype correlations revealed a more pronounced loss-of-function effect for variants causing chronic ataxia. Sodium channel blockers should be avoided under these conditions.

FUNDING

BMBF, DFG, the Italian Ministry of Health, University of Tuebingen.

Immune-mediated ataxias: Guide to clinicians

Immune-mediated cerebellar ataxias were initially described as a clinical entity in the 1980s, and since then, an expanding body of evidence has contributed to our understanding of this topic. These ataxias encompass various etiologies, including postinfectious cerebellar ataxia, gluten ataxia, paraneoplastic cerebellar degeneration, opsoclonus-myoclonus-ataxia syndrome and primary autoimmune cerebellar ataxia. The increased permeability of the brain-blood barrier could potentially explain the vulnerability of the cerebellum to autoimmune processes. In this manuscript, our objective is to provide a comprehensive review of the most prevalent diseases within this group, emphasizing clinical indicators, pathogenesis, and current treatment approaches.

A Novel c.3636-4 A&gt;G Mutation in the CCDC88C Plays a Causative Role in Familial Spinocerebellar Ataxia

INTRODUCTION

Spinocerebellar ataxia (SCA) is an autosomal dominant genetic disease characterized by cerebellar neurological deficits. Specifically, its primary clinical manifestation is ataxia accompanied by peripheral nerve damage. A total of 48 causative genes of SCA have been identified. This study aimed to identify causative genes of autosomal dominant SCA in a four-generation Chinese kindred comprising eight affected individuals.

METHODS

Genomic DNA samples were extracted from the pedigree members, and genomic whole-exome sequencing was performed, followed by bidirectional Sanger sequencing, and minigene assays to identify mutation sites.

RESULTS

A novel pathogenic heterozygous mutation in the splice region of the coiled-coil domain containing the 88C (CCDC88C) gene (NM_001080414:c.3636-4 A>G) was identified in four affected members. The minigene assay results indicated that this mutation leads to the insertion of CAG bases (c.3636-1_3636-3 insCAG).

CONCLUSION

CCDC88C gene mutation leads to SCA40 (OMIM:616053), which is a rare subtype of SCA without symptoms during childhood. Our findings further demonstrated the role of the CCDC88C gene in SCA and indicated that the c.3636-4 A>G (NM_001080414) variant of CCDC88C is causative for a later-onset phenotype of SCA40. Our findings enrich the mutation spectrum of CCDC88C gene and provide a theoretical basis for the genetic counseling of SCA40.

Instrumented Gait Classification Using Meaningful Features in Patients with Impaired Coordination

Early onset ataxia (EOA) and developmental coordination disorder (DCD) both affect cerebellar functioning in children, making the clinical distinction challenging. We here aim to derive meaningful features from quantitative SARA-gait data (i.e., the gait test of the scale for the assessment and rating of ataxia (SARA)) to classify EOA and DCD patients and typically developing (CTRL) children with better explainability than previous classification approaches. We collected data from 18 EOA, 14 DCD and 29 CTRL children, while executing both SARA gait tests. Inertial measurement units were used to acquire movement data, and a gait model was employed to derive meaningful features. We used a random forest classifier on 36 extracted features, leave-one-out-cross-validation and a synthetic oversampling technique to distinguish between the three groups. Classification accuracy, probabilities of classification and feature relevance were obtained. The mean classification accuracy was 62.9% for EOA, 85.5% for DCD and 94.5% for CTRL participants. Overall, the random forest algorithm correctly classified 82.0% of the participants, which was slightly better than clinical assessment (73.0%). The classification resulted in a mean precision of 0.78, mean recall of 0.70 and mean F1 score of 0.74. The most relevant features were related to the range of the hip flexion-extension angle for gait, and to movement variability for tandem gait. Our results suggest that classification, employing features representing different aspects of movement during gait and tandem gait, may provide an insightful tool for the differential diagnoses of EOA, DCD and typically developing children.

Parkinsonism in complex neurogenetic disorders: lessons from hereditary dementias, adult-onset ataxias and spastic paraplegias

Parkinsonism is a syndrome characterized by bradykinesia in combination with either rest tremor, rigidity, or both. These features are the cardinal manifestations of Parkinson's disease, the most common cause of parkinsonism, and atypical parkinsonian disorders. However, parkinsonism can be a manifestation of complex neurological and neurodegenerative genetically determined disorders, which have a vast and heterogeneous motor and non-motor phenotypic features. Hereditary dementias, adult-onset ataxias and spastic paraplegias represent only few of this vast group of neurogenetic diseases. This review will provide an overview of parkinsonism's clinical features within adult-onset neurogenetic diseases which a neurologist could face with. Understanding parkinsonism and its characteristics in the context of the aforementioned neurological conditions may provide insights into pathophysiological mechanisms and have important clinical implications, including diagnostic and therapeutic aspects.

Frontal ataxia: historical aspects and clinical definition

Frontal ataxia, originally described by Bruns, is characterized by the presence of signs of frontal lobe dysfunction, such as perseveration, paratonia, frontal release signs, cognitive changes, and urinary difficulty, associated with imbalance, slow gait, broad-based, the presence of postural instability and falls, retropulsion, and bradykinesia in the lower limbs. The goal of the present study is to recall the historical aspects of this condition, to draw attention to the importance of this clinical finding for the differential diagnosis of ataxias and to review the main semiological differences between primary ataxias (frontal, cerebellar, and sensory ataxia).

A patient with neuropathy and ataxia: what do I have to consider?

PURPOSE OF REVIEW

An increasing number of peripheral neuro(no)pathies are identified as involving other components of the neurological system, particularly those that further impair balance. Here we aim to outline an evidence-based approach to the diagnosis of patients who present with a somatosensory disorder which also involves at least one other area of neurological impairment such as the vestibular, auditory, or cerebellar systems.

RECENT FINDINGS

Detailed objective investigation of patients who present with sensory impairment, particularly where the degree of imbalance is greater than would be expected, aids the accurate diagnosis of genetic, autoimmune, metabolic, and toxic neurological disease.

SUMMARY

Diagnosis and management of complex somatosensory disorders benefit from investigation which extends beyond the presenting sensory impairment.

FDXR-associated disease: a challenging differential diagnosis with inflammatory peripheral neuropathy

BACKGROUND AND AIMS

Mutations in FDXR gene, involved in mitochondrial pathway, cause a rare recessive neurological disorder with variable severity of phenotypes. The most common presentation includes optic and/or auditory neuropathy, variably associated to developmental delay or regression, global hypotonia, pyramidal, cerebellar signs, and seizures. The review of clinical findings in previously described cases from literature reveals also a significant incidence of sensorimotor peripheral polyneuropathy (22.72%) and ataxia (43.18%). To date, 44 patients with FDXR mutations have been reported. We describe here on two new patients, siblings, who presented with a quite different phenotype compared to previously described patients.

METHODS

Clinical, neurophysiological, and genetic features of two siblings and a systematic literature review focused on the clinical spectrum of the disease are described.

RESULTS

Both patients presented with an acute-sub-acute onset of peripheral neuropathy and only in later stages of the disease developed the typical features of FDXR-associated disease.

INTERPRETATION

The peculiar clinical presentation at onset and the evolution of the disease in our patients and in some cases revised from the literature shed lights on a new possible phenotype of FDXR-associated disease: a peripheral neuropathy which can mimic an acute inflammatory disease.

Scale for the assessment and rating of ataxia: Age-dependent performance of healthy adults

BACKGROUND AND PURPOSE

The Scale for Assessment and Rating of Ataxia (SARA) is a widely used clinical scale. The objective was to study the age dependence of SARA in healthy adults and to define age-specific cut-off values to differentiate healthy from ataxic individuals.

METHODS

Data from 390 healthy individuals and 119 spinocerebellar ataxia patients were analyzed. SARA scores were mapped on functional SARA (fSARA). Age-adjusted cut-off values were determined by receiver operating characteristic curve analysis.

RESULTS

The cut-off value was 3 for SARA and 1.5 for fSARA. Older patients had higher SARA cut-off values (4.5 for 60-69 years and 6.5 for 70-79 years). Age-adjusted cut-off values for fSARA are 1 for 18-29, 30-39 and 50-59 years, 2 for 40-49 and 60-69 years and 3 for 70-79 years. Sensitivity and specificity were higher for SARA than for fSARA.

CONCLUSION

In this study, age-dependent cut-off values were defined for SARA and fSARA. The results may be relevant for the design of future preventive trials in spinocerebellar ataxias that use conversion to ataxia as an outcome.

[Novel heterozygous STUB1 gene mutation causes SCA48 in a Hungarian patient]

Autosomal dominant cerebellar ataxias (ADCA), also known as spinocerebellar ataxias (SCA) are a group of progressive neurodegenerative diseases with remarkable clinical and genetic heterogeneity. In the last ten years 20 genes were identified in the background of SCAs. One of these genes was STUB1 (STIP1 homology and U-box containing protein 1) (chromosome 16p13, NM_005861.4) encoding a multifunctional E3 ubiquitine ligase (CHIP)1. In 2013, STUB1 was identified as a causative gene of autosomal recessive spinocerebellar ataxia 16 (SCAR16), but in 2018 Genis et al. published that heterozygous mutations of this gene can cause the autosomal dominantly inherited SCA48 as well1,2. 28 French, twelve Italian, three Belgian, two North-American, one Spanish, one Turkish, one Dutch, one German and one British SCA48 families have been reported so far2-9. Based on these publications, SCA48 is a late-onset, progressive disorder characterized by cerebellar dysfunction, cognitive impairment, psychiatric features, dysphagia, hyperreflexia, urinary tract symptoms and movement disorders including Parkinsonism, chorea, dystonia and rarely tremor. The brain MRI in all SCA48 patients demonstrated vermian and hemispheric cerebellar atrophy which was more pronounced in the posterior areas (lobules VI and VII) of the cerebellum in most of the cases2-9. Besides this, T2- weighted imaging (T2WI) hyperintensity of dentate nuclei (DN) was reported in some Italian patients10. Moreover, the most recent publication described alterations on DAT-scan imaging in some French families9. Neurophysiological examinations did not find any central or peripheral nervous system abnormalities2,3,5. Neuropathologic findings revealed definite cerebellar atrophy and cortical shrinkage with variable severity6,7. The histopathological assessment denoted Purkinje cell loss, p62-positive neuronal intranuclear inclusions in some cases and tau pathology in one patient6-7. In this paper we describe the clinical and genetic characterization of the first Hungarian SCA48 case with a novel heterozygous STUB1 gene missense mutation.

To what extent are anorectal function tests comparable? A study comparing digital rectal examination, anal electromyography, 3-dimensional high-resolution anal manometry, and transperineal ultrasound

BACKGROUND

Anorectal function tests are helpful for objective investigation of anorectal (dys)function. A variety of tests are available, but there is no recommendation when to perform which test. Furthermore, which test is the most accurate is controversial and the correlation between these tests is not very clear. The aim of our study was to examine the correlation of anal pressures and the possibility to diagnose pelvic floor dyssynergia between digital rectal examination (DRE) and several anorectal function tests.

METHODS

Between January 2020 and April 2022, all men and women aged 18 to 80 years, treated at the Proctos Clinic, who were referred for pelvic floor physical therapy (PFPT) by the surgeon and underwent anorectal function tests, were included. DRE was performed to establish the anal pressure at rest and during squeeze and straining. Anorectal function tests included 3D high-resolution anal manometry (3D-HRAM), balloon expulsion test (BET), transperineal ultrasound (TPUS), and surface electromyography (s-EMG).

RESULTS

A total of 50 patients, 37 (74%) females, were included. Median age was 51 years. Twenty-three (62%) females had a history of two or more vaginal deliveries. The most frequent reason for referral for PFPT was fecal incontinence in 27 (54%) patients. The assessed pressures and pelvic floor function measured with DRE by the surgeon and the pelvic floor physical therapist during rest, squeeze, and straining correlated in 78%, 78%, and 84%, respectively. Correlation between DRE and 3D-HRAM or s-EMG was better for squeeze pressures than resting pressures. The correlation between s-EMG and 3D-HRAM was better during squeeze than at rest with an agreement of 59% and 37%, respectively.

CONCLUSION

DRE by an experienced investigator is of sufficient value for daily clinical practice to detect dyssynergia and to measure sphincter tone. Commonly performed anorectal function tests correlate poorly with DRE and with other anorectal function tests. When conservative treatment fails, further investigation is warranted; however, these results should be interpreted with caution. WHAT DOES THIS PAPER ADD TO THE LITERATURE?: Anorectal function tests such as the 3D high-resolution anorectal manometry, balloon expulsion test, surface electromyography, and transperineal ultrasound are all frequently performed in the diagnostic workup in patients with defecation disorders. No previous study has compared these tests regarding their outcomes, nor has the interrater agreement been measured regarding the digital rectal examination by two experienced observers. Furthermore, transperineal ultrasound is in all probability not frequently used and therefore underexposed in the diagnostic workup of patients with dyssynergic defecation.

Suspected Autosomal Recessive Polycystic Kidney Disease but Cerebellar Vermis Hypoplasia, Oligophrenia Ataxia, Coloboma, and Hepatic Fibrosis (COACH) Syndrome in Retrospect, A Delayed Diagnosis Aided by Genotyping and Reverse Phenotyping: A Case Report and A Review of the Literature

The clinical features of cerebellar vermis hypoplasia, oligophrenia, ataxia, coloboma, and hepatic fibrosis (COACH) characterize the rare autosomal recessive multisystem disorder called COACH syndrome. COACH syndrome belongs to the spectrum of Joubert syndrome and related disorders (JSRDs) and liver involvement distinguishes COACH syndrome from the rest of the JSRD spectrum. Developmental delay and oculomotor apraxia occur early but with time, these can improve and may not be readily apparent or no longer need active medical management. Congenital hepatic fibrosis and renal disease, on the other hand, may develop late, and the temporal incongruity in organ system involvement may delay the recognition of COACH syndrome. We present a case of a young adult presenting late to a Renal Genetics Clinic for evaluation of renal cystic disease with congenital hepatic fibrosis, clinically suspected to have autosomal recessive polycystic kidney disease. Following genetic testing, a reevaluation of his medical records from infancy, together with reverse phenotyping and genetic phasing, led to a diagnosis of COACH syndrome.

CACNA1A-Related Channelopathies: Clinical Manifestations and Treatment Options

In the last decade, variants in the Ca2+ channel gene CACNA1A emerged as a frequent aetiology of rare neurological phenotypes sharing a common denominator of variable paroxysmal manifestations and chronic cerebellar dysfunction. The spectrum of paroxysmal manifestations encompasses migraine with hemiplegic aura, episodic ataxia, epilepsy and paroxysmal non-epileptic movement disorders. Additional chronic neurological symptoms range from severe developmental phenotypes in early-onset cases to neurobehavioural disorders and chronic cerebellar ataxia in older children and adults.In the present review we systematically approach the clinical manifestations of CACNA1A variants, delineate genotype-phenotype correlations and elaborate on the emerging concept of an age-dependent phenotypic spectrum in CACNA1A disease. We furthermore reflect on different therapy options available for paroxysmal symptoms in CACNA1A and address open issues to prioritize in the future clinical research.

Objective Assessment of Upper-Extremity Motor Functions in Spinocerebellar Ataxia Using Wearable Sensors

The study presents a novel approach to objectively assessing the upper-extremity motor symptoms in spinocerebellar ataxia (SCA) using data collected via a wearable sensor worn on the patient's wrist during upper-extremity tasks associated with the Assessment and Rating of Ataxia (SARA). First, we developed an algorithm for detecting/extracting the cycles of the finger-to-nose test (FNT). We extracted multiple features from the detected cycles and identified features and parameters correlated with the SARA scores. Additionally, we developed models to predict the severity of symptoms based on the FNT. The proposed technique was validated on a dataset comprising the seventeen (n = 17) participants' assessments. The cycle detection technique showed an accuracy of 97.6% in a Bland-Altman analysis and a 94% accuracy (F1-score of 0.93) in predicting the severity of the FNT. Furthermore, the dependency of the upper-extremity tests was investigated through statistical analysis, and the results confirm dependency and potential redundancies in the upper-extremity SARA assessments. Our findings pave the way to enhance the utility of objective measures of SCA assessments. The proposed wearable-based platform has the potential to eliminate subjectivity and inter-rater variabilities in assessing ataxia.

Phenytoin-induced ataxia mimicking a stroke: A case report

Acute ataxia is commonly the chief complaint among patients visiting the emergency department (ED). It has multiple causes including infection and immunity-related, metabolic, vascular, and organic causes. Therefore, treating physicians should consider the severity and timing of onset in relation to the initial screening tests when making a differential diagnosis, and must be careful not to miss cases that require urgent treatment, such as stroke and drug-induced ataxia. In this report, we describe the case of a 53-year-old woman with recurrent acute ataxia. She had a history of epilepsy but had not had a seizure for over 10 years. She presented to the ED with ataxia that had started the previous evening. She reported two previous episodes of acute ataxia 14 and 4 days previously. She had visited two different hospitals, and undergone two head magnetic resonance imaging (MRI) scans which showed no evidence of a stroke, and had been diagnosed with transient ischemic attacks (TIAs) at both hospitals. She underwent a third head MRI during the ED visit, which again revealed no evidence of a stroke. The plasma levels of phenytoin, carbamazepine, and valproic acid were 21.2 μg/mL (normal range: 7-20 μg/mL), 2.1 μg/mL (normal range: 5-10 μg/mL), and 33.5 μg/mL (normal range: 50-100 μg/mL), respectively. She was finally diagnosed with ataxia due to phenytoin toxicity. Her symptoms improved soon after the phenytoin dose was reduced and did not recur during a year of follow-up.

Detection and differentiation of ataxic and hypokinetic dysarthria in cerebellar ataxia and parkinsonian disorders via wave splitting and integrating neural networks

Dysarthria may present during the natural course of many degenerative neurological conditions. Hypokinetic and ataxic dysarthria are common in movement disorders and represent the underlying neuropathology. We developed an artificial intelligence (AI) model to distinguish ataxic dysarthria and hypokinetic dysarthria from normal speech and differentiate ataxic and hypokinetic speech in parkinsonian diseases and cerebellar ataxia. We screened 804 perceptual speech analyses performed in the Samsung Medical Center Neurology Department between January 2017 and December 2020. The data of patients diagnosed with parkinsonian disorders or cerebellar ataxia were included. Two speech tasks (numbering from 1 to 50 and reading nine sentences) were analyzed. We adopted convolutional neural networks and developed a patch-wise wave splitting and integrating AI system for audio classification (PWSI-AI-AC) to differentiate between ataxic and hypokinetic speech. Of the 395 speech recordings for the reading task, 76, 112, and 207 were from normal, ataxic dysarthria, and hypokinetic dysarthria subjects, respectively. Of the 409 recordings of the numbering task, 82, 111, and 216 were from normal, ataxic dysarthria, and hypokinetic dysarthria subjects, respectively. The reading and numbering task recordings were classified with 5-fold cross-validation using PWSI-AI-AC as follows: hypokinetic dysarthria vs. others (area under the curve: 0.92 ± 0.01 and 0.92 ± 0.02), ataxia vs. others (0.93 ± 0.04 and 0.89 ± 0.02), hypokinetic dysarthria vs. ataxia (0.96 ± 0.02 and 0.95 ± 0.01), hypokinetic dysarthria vs. none (0.86 ± 0.03 and 0.87 ± 0.05), and ataxia vs. none (0.87 ± 0.07 and 0.87 ± 0.09), respectively. PWSI-AI-AC showed reliable performance in differentiating ataxic and hypokinetic dysarthria and effectively augmented data to classify the types even with limited training samples. The proposed fully automatic AI system outperforms neurology residents. Our model can provide effective guidelines for screening related diseases and differential diagnosis of neurodegenerative diseases.

Instrumented gait analysis defines the walking signature of CACNA1A disorders

BACKGROUND

Gait disturbances are a frequent symptom in CACNA1A disorders. Even though, data about their severity and progression are lacking and no CACNA1A-specific scale or assessment for gait is available.

METHODS

We applied a gait assessment protocol in 20 ambulatory patients with genetically confirmed CACNA1A disorders and 39 matched healthy controls. An instrumented gait analysis (IGA) was performed by means of wearable sensors in basal condition and after a treadmill/cycloergometer challenge in selected cases.

RESULTS

CACNA1A patients displayed lower gait speed, shorter steps with increased step length variability, a reduced landing acceleration as well as a reduced range of ankle motion compared to controls. Furthermore, gait-width in patients with episodic CACNA1A disorders was narrower as compared to controls. In one patient experiencing mild episodic symptoms after the treadmill challenge, the IGA was able to detect a deterioration over all gait parameters.

CONCLUSIONS

In CACNA1A patients, the IGA with wearable sensors unravels specific gait signatures which are not detectable at naked eye. These features (narrow-based gait, lower landing acceleration) distinguish these patients from other ataxic disorders and may be target of focused rehabilitative interventions. IGA can potentially be applied to monitor the neurological fluctuations associated with CACNA1A disorders.

Phenotype assessment for neurodegenerative murine models with ataxia and application to Niemann-Pick disease, type C1

Identifying meaningful predictors of therapeutic efficacy from preclinical studies is challenging. However, clinical manifestations occurring in both patients and mammalian models offer significant translational value. Many neurological disorders, including inherited, metabolic Niemann-Pick disease, type C (NPC), exhibit ataxia. Both individuals with NPC and murine models manifest ataxia, and investigational therapies impacting this phenotype in mice have been reported to slow disease progression in patients (e.g. miglustat, intrathecal 2-hydroxypropyl-beta-cyclodextrin, and acetyl-L-leucine). Reproducible phenotypic scoring of animal models can facilitate comparisons between genotypes, sexes, disease course, and therapies. Previously, other groups have developed a composite phenotypic scoring system (CPSS), which was subsequently used to distinguish strain-dependent phenotypes and, with modifications, to evaluate potential therapies. However, high inter-rater reliability is paramount to widespread use. We have created a comprehensive, easy-to-follow phenotypic assessment based on the CPSS and have verified its reproducibility using murine models of NPC disease. Application of this scoring system is not limited to NPC disease and may be applicable to other models of neurodegeneration exhibiting motor incoordination, thereby increasing its utility in translational studies.

Detection of ataxia with hybrid convolutional neural network using static plantar pressure distribution model in patients with multiple sclerosis

OBJECTIVE

In this study, it is aimed to detect ataxia for Persons with Multiple Sclerosis (PwMS) through a deep learning-based approach using an image dataset containing static plantar pressure distribution. Here, an alternative and objective method will be proposed to assist physicians who diagnose PwMS in the early stages.

METHODS

A total of 406 static bipedal pressure distribution image data for 43 ataxic PwMS and 62 healthy individuals were used in the study. After preprocessing, these images were given as input to pre-trained deep learning models such as VGG16, VGG19, ResNet, DenseNet, MobileNet, and NasNetMobile. The data of each model is utilized to generate its feature vectors. Finally, feature vectors obtained from static pressure distribution images were classified by SVM (Support Vector Machine), K-NN (K-Nearest Neighbors), and ANN (Artificial Neural Network). In addition, a cross-validation method was used to examine the validity of the classifier.

RESULTS

The performance of the proposed models was evaluated with accuracy, sensitivity, specificity, and F1-measure criteria. The VGG19-SVM hybrid model showed the best performance with 95.12% acc, 94.91% sen, 95.31% spe, and 94.44% F1.

CONCLUSIONS

In this study, a specific and sensitive automatic test evaluation system was proposed for Ataxic syndromes using digital images to observe the motor skills of the subjects. Comparative results show that the proposed method can be applied in practice for ataxia that is clinically difficult to detect or not yet symptomatic. It can be defined using only static plantar pressure distribution in the early stage and it can be recommended as an assistant system to physicians in clinical practice.

A first description of ataxia with vitamin E deficiency associated with MT-TG gene mutation

Ataxia with isolated vitamin E deficiency (AVED) is a rare autosomal recessive cerebellar ataxia disorder that is caused by a mutation in the alpha-tocopherol transfer protein gene TTPA, leading to a lower level of serum vitamin E. Although it is almost clinically similar to Friedreich's ataxia, its devastating neurological features can be prevented with appropriate treatment. In this study, we present a patient who was initially diagnosed with Friedreich's ataxia, but was later found to have AVED. Frataxin gene screening revealed the absence of GAA expansion in homozygous or heterozygous state. However, TTPAgene sequencing showed the presence of the c.744delA mutation, leading to a premature stop codon (p.E249fx). In addition, the result of mutational analysis of MT-DNA genes revealed the presence of several variants, including the m.10044A>G mutation in MT-TG gene. Here, we report for the first time the coexistence of both mitochondrial and nuclear genes mutations in AVED.

Eye Movements in Fragile X-Associated Tremor/Ataxia Syndrome

BACKGROUND

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder characterized by ataxia, tremor, and parkinsonism. Eye motility abnormalities on the clinical examination of FXTAS patients have not been formally studied.

METHODS

A case-control study with fragile X gene mutation carriers with and without FXTAS and normal controls was conducted and included a videotaping of ocular items of the International Cooperative Ataxia Rating Scale (ICARS). A neuro-ophthalmologist blinded to gene status rated nystagmus, ocular pursuit, and saccades.

RESULTS

Forty-four cases and controls were recruited, with an average age of 55.2 years (±7.4) and 57% women. Gaze-evoked nystagmus was increased in fragile X gene carriers (odds ratio 1.44, 95% confidence interval: 0.33-7.36) but was not statistically significant. There was no difference in ocular pursuit nor saccade dysmetria between cases and controls.

CONCLUSION

The results show that clinical examination findings of ocular abnormalities, using the ICARS oculomotor disorders movement subscale, are not more common in FXTAS or FMR1 premutation carriers than normal controls on examination in the clinic. Examining a larger cohort of patients with FXTAS would be an ideal next step.

Anorectal manometry to diagnose dyssynergic defecation: Systematic review and meta-analysis of diagnostic test accuracy

BACKGROUND

Chronic constipation is a common condition, and dyssynergic defecation underlies up to 40% of cases. Anorectal manometry is recommended to assess for dyssynergic defecation among chronically constipated patients but remains poorly standardized. We aimed to evaluate the diagnostic accuracy of anorectal manometry and determine optimal testing parameters.

METHODS

We performed a systematic review with meta-analysis of diagnostic test accuracy including cohort studies of chronically constipated patients and case-control studies of patients with dyssynergic defecation or healthy controls. Meta-analysis was performed to determine summary sensitivity, specificity, and area under the curve (AUC) with 95% confidence intervals (CI).

KEY RESULTS

A total of 15 studies comprising 2140 patients were included. Including all studies (estimating optimal diagnostic accuracy), the AUC was 0.78 [95% CI 0.72-0.82], summary sensitivity was 79% [61%-90%], and summary specificity was 64% [44%-79%] to diagnose dyssynergic defecation. In cohort studies only (estimating real-world diagnostic accuracy), the AUC was 0.72 [0.66-0.77], summary sensitivity was 86% [64%-95%], and summary specificity was 49% [30%-68%]. Employing three consecutive simulated defecation attempts improved sensitivity to 94%. A fourth simulated defecation maneuver with air insufflation may improve accuracy. Measuring anorectal pressures to identify complex dyssynergic patterns did not improve real-world diagnostic accuracy estimates over anal pressure measurement alone. Choice of manometry system did not impact diagnostic accuracy.

CONCLUSIONS & INFERENCES

Following the current iteration of the London consensus protocol (three simulated defecation attempts measuring anal relaxation), the role of anorectal manometry in evaluating dyssynergic defecation appears limited. Future iterations of this protocol may improve diagnostic accuracy.

[Paroxysmal dysarthria and ataxia - unusual MS manifestation]

Multiple sclerosis is a common inflammatory demyelinating disease of the central nervous system. Although many patients present permanent symptoms, a number of them suffer of deficits of paroxysmal character. One unusual manifestation of paroxysmal nature is episodes of dysarthria and ataxia known as PDA (paroxysmal dysarthria and ataxia).  The mechanism behind this phenomenon, although not well understood, is hypothesised to relate with ephaptic activation of the neuroaxons within the demyelination plaques. Just a few patients worldwide have been reported at present. These symptoms can be effectively treated with anti-seizure medicines. We present the case of a female 48-year-old patient who shortly after an MS diagnosis developed paroxysmal dysarthria and ataxia related to a midbrain lesion and was eventually treated with carbamazepine.

Classification of Ataxic Gait

Gait disorders accompany a number of neurological and musculoskeletal disorders that significantly reduce the quality of life. Motion sensors enable high-quality modelling of gait stereotypes. However, they produce large volumes of data, the evaluation of which is a challenge. In this publication, we compare different data reduction methods and classification of reduced data for use in clinical practice. The best accuracy achieved between a group of healthy individuals and patients with ataxic gait extracted from the records of 43 participants (23 ataxic, 20 healthy), forming 418 segments of straight gait pattern, is 98% by random forest classifier preprocessed by t-distributed stochastic neighbour embedding.

Novel c.1505_1509dupCTGCC pathogenic variation in a male case with Christianson syndrome

Pathogenic variations in the SLC9A6 gene are associated with an X-linked disorder Christianson syndrome characterized by developmental delay, microcephaly, intellectual disability, autistic-like behavior and epilepsy. We identified a novel pathogenic variation in the SLC9A6 gene in a boy with developmental delay and microcephaly. Herein we report the clinical findings of the case diagnosed as Christianson syndrome; his mother was found to carry the same variant.