American Board of Internal Medicine (ABIM) Certification Practice Exam

Which condition is characterized by the combination of parkinsonism, cerebellar ataxia, and early postural instability?

1. Wilson's disease

2. Multiple system atrophy

3. Parkinson's disease

4. Huntington's disease

The correct answer is: Multiple system atrophy

The condition characterized by the combination of parkinsonism, cerebellar ataxia, and early postural instability is multiple system atrophy (MSA). MSA is a neurodegenerative disorder that affects the autonomic nervous system and movement. In MSA, patients typically experience parkinsonian symptoms, which may include rigidity, bradykinesia, and tremor. The presence of cerebellar ataxia indicates coordination and balance issues due to the involvement of the cerebellum in the disease process. Early postural instability is particularly significant in MSA, as patients often have difficulty maintaining their posture and may experience falls early in the course of the disease. The other conditions listed do not present with this specific combination of symptoms. For instance, Wilson's disease primarily involves copper accumulation leading to hepatic and neurological manifestations but doesn’t typically present with prominent ataxia early on. Parkinson's disease presents primarily with motor symptoms without the early onset of cerebellar ataxia or significant postural instability, which often develops later in the disease. Huntington's disease is primarily characterized by chorea and psychiatric symptoms, with less emphasis on ataxia or early postural instability. In summary, the unique combination of parkinsonism,