Delayed Progression of Ataxia with a Static Cerebellar Lesion- Consider SCA27B.

Repeat expansions in the fibroblast growth factor 14 gene (FGF14), associated with spinocerebellar ataxia type 27B (SCA27B), have emerged as a prevalent cause of previously unexplained late-onset cerebellar ataxia. Here, we present a patient with residual symptom of gait ataxia after complicated meningioma surgery, who presented with progressive symptoms of oculomotor disturbances, speech difficulties, vertigo and worsening of gait imbalance, twelve years post-resection. Neuroimaging revealed a surgical resection cavity in the dorsolateral side of the left cerebellar hemisphere, accompanied by gliosis in left cerebellar hemisphere extending into the vermis, extensive non-specific supratentorial periventricular white matter abnormalities, and mild atrophy of the cerebellar vermis. Initially, her symptoms were attributed to re-emergence of her cerebellar symptoms related to the static cerebellar lesion, and due to a failure of compensatory mechanisms with aging. However, the progressive nature of her cerebellar symptoms and the emergence of novel downbeat nystagmus prompted genetic testing for FGF14 repeat expansion, confirming SCA27B as a significant contributor to her delayed, progressive cerebellar symptoms. This case highlights the significance of considering SCA27B in the differential diagnosis of delayed progressive cerebellar ataxia with oculomotor abnormalities in the presence of a static cerebellar lesion.