A 62-year-old woman with no significant past medical history presents to neurology with a 18-month history of progressive gait ataxia, lower extremity incoordination, and dysarthria. She denies alcohol use, recent infections, or toxic exposures. Her son was diagnosed with a similar condition at age 55. On examination, she has nystagmus, dysmetria on finger-to-nose testing bilaterally, and a wide-based gait. Vital signs are stable. Brain MRI shows selective cerebellar vermis and hemisphere atrophy with normal brainstem and cerebral white matter. Genetic testing reveals a CAG repeat expansion of 42 in the SCA1 gene. Which of the following is the most likely diagnosis?
- A)Friedreich ataxia
- B)Spinocerebellar ataxia type 1GABARITO
- C)Spinocerebellar ataxia type 3
- D)Multiple sclerosis with cerebellar involvement
- E)Chronic alcohol-related cerebellar degeneration
Explicação
SCA1 is an autosomal dominant trinucleotide repeat disorder caused by CAG expansion (typically 39-82 repeats; >40 is pathogenic) in the ATXN1 gene. The clinical presentation of progressive cerebellar signs (ataxia, dysarthria, nystagmus) with pure cerebellar a... Ver explicação completa e trilha adaptativa →