Spinocerebellar ataxias (SCAs) comprise a large and expanding group of neurogenetic diseases characterized by degeneration of the spinal cord and cerebellum. There are over 50 individual spinocerebellar ataxias, referred to sequentially as SCA1, SCA2, ..., etc., roughly in their order of discovery and genetic characterization ².

Epidemiology

As a group, spinocerebellar ataxias are rare. The most common forms vary depending on geographic region, but generally include SCA1, SCA2, SCA3, and SCA6 ^3,4. Most present in early adulthood, but there is considerable variability ⁴.

Clinical presentation

The clinical presentation varies depending on the exact type of spinocerebellar ataxia. Common clinical features among these conditions, unsurprisingly, include progressive cerebellar ataxia ⁴. However, variably patients may have movement disorders, spasticity, sensory symptoms, and ocular anomalies ⁴.

Pathology

Spinocerebellar ataxias are inherited conditions ⁴. Many, including the common types, are repeat expansion disorders ⁴. Among the repeat expansion spinocerebellar ataxias, the common forms (i.e. SCA1, SCA2, SCA3, and SCA6) are specifically CAG repeat expansion disorders ⁴.

Radiographic features

Although individual spinocerebellar ataxias vary in morphological changes, atrophy of the cerebellum is a relatively constant finding. Extracerebellar regions are also affected, depending on the specific SCA ¹.

Treatment and prognosis

Management is generally supportive, with no disease-modifying treatments available ⁴. Among therapies trialed, riluzole may have modest benefit ⁵, but this benefit has not been replicated across all forms of spinocerebellar ataxia ⁶.

Differential diagnosis

• Friedreich ataxia

• dentatorubral-pallidoluysian atrophy

• multiple system atrophy

• ataxia-telangiectasia