Movement Disorders USMLE Step 1 Practice Question
A 65-year-old woman with a 10-year history of Parkinson disease on levodopa develops sudden fluctuations in motor control—periods of excellent mobility ('on' states) alternating with severe bradykinesia and rigidity ('off' states). The duration of benefit from each dose decreases despite escalating doses. Which of the following best describes this phenomenon?
Answer choices
- ALevodopa-induced dyskinesia
- BMotor fluctuations (wearing-off effect)Correct answer
- CNeuroleptic malignant syndrome
- DDisease progression resistant to medication
- EMedication nonadherence
- FOn-off phenomenon due to dopamine agonist sensitivity
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