Spinocerebellar ataxia 31 (SCA31)
General description
Spinocerebellar ataxia type 31 (SCA31) is an autosomal dominant cerebellar ataxia disorder resulting from non-coding pentanucleotide repeat expansions in the BEAN1 gene, located on chromosome 16q21. The clinical phenotype of SCA31 is characterized by a pure cerebellar syndrome with a wide range of age at onset, spanning from early childhood to late adulthood.
The initial manifestation is typically gait instability, though some patients may present with dysarthria as the inaugural symptom. Notably, the disease course of SCA31 is generally slowly progressive.
Cerebellar atrophy
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Cerebellum
While cerebellar atrophy is observed, there is no atrophy in the brainstem and no degeneration of transverse pontine fibers.
Loss of hypointensity in dentate nucleus
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Dentate nucleus
The hypointense signal of the cerebellar dentate nuclei on T2WI is attenuated, resulting in signal intensity comparable to that of the pons.