Spino-cerebellar Ataxia 31 presenting as a demyelinating disease: a case report.

Spinocerebellar ataxia (SCA) is a group of inherited disorders that encompasses different types and presentations. One of its types, SCA31, is a rare ataxia that has a wide spectrum of presentations. Therefore, it may be mistakenly diagnosed with another neurological disorder. Here we describe a 52-year-old woman with progressive imbalance and lower limb weakness who was initially diagnosed with multiple sclerosis (MS) based on periventricular MRI lesions and cerebrospinal fluid oligoclonal bands. She received interferon-beta for four years without improvement. After mistreatment for years, she was reassessed and, due to a strong family history of similar ataxic symptoms, was prompted to undergo genetic testing, which confirmed SCA31. This case highlights the diagnostic challenges associated with SCA31 that can mimic MS because of overlapping clinical and radiological features, potentially leading to misdiagnosis and inappropriate treatment. Therefore, clinicians should exercise caution and consider alternative diagnoses, particularly in the presence of poor response to immunotherapy, a progressive disease course, and a positive family history, all of which may indicate an inherited ataxia.