Non-ataxic manifestations of Spinocerebellar ataxia-2, their determinants and predictors

Introduction: To evaluate the non-ataxic clinical manifestations in genetically proven Spinocerebellar ataxia 2 (SCA2) and identify their determinants and predictors.

Methods: Seventy-three subjects with genetically proven SCA2 were evaluated clinically for the common non-ataxic manifestations. Based on the presence or absence of non-ataxic manifestations, patients were classified into groups and then compared for significant differences in the CAG repeat length, age at onset (AAO), duration of disease, and ataxia rating score. Predictors of non-ataxic symptoms were identified using multivariable binary logistic regression.

Results: The most common non-ataxic clinical manifestations were peripheral neuropathy, extrapyramidal features, pyramidal signs, cognitive impairment and lower motor neuron signs. The CAG repeat length was inversely related to the AAO of symptoms (r = -0.46, p < .001). Patients with peripheral neuropathy and psychiatric symptoms had earlier AAO. Patients with cognitive impairment and extrapyramidal symptoms had higher CAG repeat length whereas presence of lower motor neuron signs was more common in patients with lower CAG repeat length.

Conclusion: The lower strength of association between CAG repeat length and AAO in our cohort suggests the presence of additional factors underlying the variability in AAO. Both CAG repeat length and AAO were identified as significant determinants and predictors of non-ataxic symptoms.