Peripheral Neuropathy in Spinocerebellar Ataxia Type 1, 2, 3, and 6.

Spinocerebellar ataxias (SCAs) are characterized by autosomal dominantly inherited progressive ataxia but are clinically heterogeneous due to variable involvement of non-cerebellar parts of the nervous system. Non-cerebellar symptoms contribute significantly to the burden of SCAs, may guide the clinician to the underlying genetic subtype, and might be useful markers to monitor disease. Peripheral neuropathy is frequently observed in SCA, but subtype-specific features and subclinical manifestations have rarely been evaluated. We performed a multicenter nerve conduction study with 162 patients with genetically confirmed SCA1, SCA2, SCA3, and SCA6. The study proved peripheral nerves to be involved in the neurodegenerative process in 82 % of SCA1, 63 % of SCA2, 55 % of SCA3, and 22 % of SCA6 patients. Most patients of all subtypes revealed affection of both sensory and motor fibers. Neuropathy was most frequently of mixed type with axonal and demyelinating characteristics in all SCA subtypes. However, nerve conduction velocities of SCA1 patients were slower compared to other genotypes. SCA6 patients revealed less axonal damage than patients with other subtypes. No influence of CAG repeat length or biometric determinants on peripheral neuropathy could be identified in SCA1, SCA3, and SCA6. In SCA2, earlier onset and more severe ataxia were associated with peripheral neuropathy. We proved peripheral neuropathy to be a frequent site of the neurodegenerative process in all common SCA subtypes. Since damage to peripheral nerves is readily assessable by electrophysiological means, nerve conduction studies should be performed in a longitudinal approach to assess these parameters as potential progression markers.

Depression comorbidity in spinocerebellar ataxia.

This is a description of the prevalence and profile of depressive symptoms in dominant spinocerebellar ataxia (SCA). Depressive symptoms were assessed in a convenience sample of 526 genetically confirmed and clinically affected patients (117 SCA1, 163 SCA2, 139 SCA3, and 107 SCA6) using the Patient Health Questionnaire (PHQ). In addition, depressive status according to the examiner and the use of antidepressants was recorded. Depression self-assessment was compared with an interview-based psychiatric assessment in a subset of 26 patients. Depression prevalence estimates were 17.1% according to the PHQ algorithm and 15.4% when assessed clinically. The sensitivity of clinical impression compared with PHQ classification was low (0.35), whereas diagnostic accuracy of PHQ compared with psychiatric interview in the subset was high. Antidepressants were used by 17.7% of patients and in >10% of patients without current clinically relevant depressive symptoms. Depression profile in SCA did not differ from a sample of patients with major depressive disorder except for the movement-related item. Neither depression prevalence nor use of antidepressants differed between genetic subtypes, with only sleep disturbance more common in SCA3. In a multivariate analysis, ataxia severity and female sex independently predicted depressive status in SCA. The PHQ algorithmic classification is appropriate for use in SCA but should stimulate further psychiatric evaluation if depression is indicated. Despite a higher risk for depression with more severe disease, the relation of depressive symptoms to SCA neurodegeneration remains to be shown.

Visualization, quantification and correlation of brain atrophy with clinical symptoms in spinocerebellar ataxia types 1, 3 and 6.

BACKGROUND AND OBJECTIVE: Biomarkers to monitor neurological dysfunction in autosomal dominant inherited spinocerebellar ataxias (SCA) are lacking. We therefore aimed to visualize, quantify and correlate localized brain atrophy with clinical symptoms in SCA1, SCA3, and SCA6. METHODS: We compared patients suffering from SCA1 (n=48), SCA3 (n=24), and SCA6 (n=10) with 32 controls using magnetic resonance imaging (MRI) on four different scanners in eight centers followed by voxel-based morphometry (VBM) and quantitative three-dimensional (3D) volumetry. RESULTS: SCA1 and SCA3 patients presented with severe atrophy in total brainstem (consisting of midbrain, pons, and medulla), pons, medulla, total cerebellum, cerebellar hemispheres and cerebellar vermis, putamen and caudate nucleus. Atrophy in the cerebellar hemispheres was less severe in SCA3 than in SCA1 and SCA6. Atrophy in SCA6 was restricted to the grey matter of the cerebellum (VBM and volumetry), total brainstem and pons (volumetry only). Overall, we did not observe substantial atrophy in the cerebral cortex. A discriminant analysis taking into account data from pons, cerebellar hemispheres, medulla, midbrain and putamen achieved a reclassification probability of 81.7% for SCA1, SCA3, and SCA6. The repeat length of the expanded allele showed a weak negative correlation with the volume of the brainstem, pons, caudate nucleus and putamen in SCA3, and a weak correlation with the pons in SCA1, whereas no such correlation was found in SCA6. Clinical dysfunction as measured by the Scale for the Assessment and Rating of Ataxia (SARA) and the Unified Huntington's Disease Rating Scale functional assessment correlated best with the atrophy of pons in SCA1, with total brainstem atrophy in SCA3 and atrophy of total cerebellum in SCA6. CONCLUSIONS: Our data provide strong evidence that MRI is an attractive surrogate marker for clinical studies of SCA. In each SCA genotype clinical dysfunction may be caused by different patho-anatomical processes.

Self-rated health status in spinocerebellar ataxia--results from a European multicenter study.

Patient-based measures of subjective health status are increasingly used as outcome measures in interventional trials. We aimed to determine the variability and predictors of subjective health ratings in a possible target group for future interventions: the spinocerebellar ataxias (SCAs). A consecutive sample of 526 patients with otherwise unexplained progressive ataxia and genetic diagnoses of SCA1 (117), SCA2 (163), SCA3 (139), and SCA6 (107) were enrolled at 18 European referral centers. Subjective health status was assessed with a generic measure of health related quality of life, the EQ-5D (Euroqol) questionnaire. In addition, we performed a neurological examination and a screening questionnaire for affective disorders (patient health questionnaire). Patient-reported health status was compromised in patients of all genotypes (EQ-5D visual analogue scale (EQ-VAS) mean 61.45 +/- 20.8). Specifically, problems were reported in the dimensions of mobility (86.9% of patients), usual activities (68%), pain/discomfort (49.4%), depression/anxiety (46.4%), and self care (38.2%). Multivariate analysis revealed three independent predictors of subjective health status: ataxia severity, extent of noncerebellar involvement, and the presence of depressive syndrome. This model explained 30.5% of EQ-VAS variance in the whole sample and might be extrapolated to other SCA genotypes.

Early symptoms in spinocerebellar ataxia type 1, 2, 3, and 6.

Onset of genetically determined neurodegenerative diseases is difficult to specify because of their insidious and slowly progressive nature. This is especially true for spinocerebellar ataxia (SCA) because of varying affection of many parts of the nervous system and huge variability of symptoms. We investigated early symptoms in 287 patients with SCA1, SCA2, SCA3, or SCA6 and calculated the influence of CAG repeat length on age of onset depending on (1) the definition of disease onset, (2) people defining onset, and (3) duration of symptoms. Gait difficulty was the initial symptom in two-thirds of patients. Double vision, dysarthria, impaired hand writing, and episodic vertigo preceded ataxia in 4% of patients, respectively. Frequency of other early symptoms did not differ from controls and was regarded unspecific. Data about disease onset varied between patients and relatives for 1 year or more in 44% of cases. Influence of repeat length on age of onset was maximum when onset was defined as beginning of permanent gait disturbance and cases with symptoms for more than 10 years were excluded. Under these conditions, CAG repeat length determined 64% of onset variability in SCA1, 67% in SCA2, 46% in SCA3, and 41% in SCA6 demonstrating substantial influence of nonrepeat factors on disease onset in all SCA subtypes. Identification of these factors is of interest as potential targets for disease modifying compounds. In this respect, recognition of early symptoms that develop before onset of ataxia is mandatory to determine the shift from presymptomatic to affected status in SCA.

Reliability and validity of the International Cooperative Ataxia Rating Scale: a study in 156 spinocerebellar ataxia patients.

To evaluate the efficacy of treatments in spinocerebellar ataxias (SCAs), appropriate clinical scales are required. This study evaluated metric properties of the International Cooperative Ataxia Rating Scale (ICARS) in 156 SCA patients and 8 controls. ICARS was found to be a reliable scale satisfying accepted criteria for interrater reliability, test-retest reliability, and internal consistency. Although validity testing was limited, we found evidence of validity of ICARS when ataxia disease stages and Barthel index were used as external criteria. On the other hand, our study revealed two major problems associated with the use of ICARS. First, the redundant and overlapping nature of several items gave rise to a considerable number of contradictory ratings. Second, a factorial analysis showed that the rating results were determined by four different factors that did not coincide with the ICARS subscales, thus questioning the justification of ICARS subscore analysis in clinical trials.