Clinical Reasoning: A 38-Year-Old Man With Involuntary Jerk-Like Movements and Ataxia

A 38-year-old male patient with no personal or family history of neurologic disease presented with a 1-year history of chronic, progressive gait instability and predominantly right-sided involuntary jerk-like movements. A brain MRI revealed diffuse cerebellar atrophy on T2 fluid-attenuated inversion recovery and T1-weighted sequences. Laboratory and diagnostic investigations focused on identifying acquired etiologies. This case explores the differential diagnosis of myoclonus-ataxia syndrome, emphasizing its progression and the distinct underlying causes. It also presents a structured approach to a potentially treatable cause of an uncommon neurologic disorder.