A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 45-year-old woman comes to the physician because of a 6-month history of worsening involuntary movement of the left hand. Her symptoms are worse when she feels stressed at work. She has no history of serious illness and takes no medications. Neurological examination shows difficulty initiating movement and a tremor in the left hand at rest. The tremor decreases when the patient is asked to draw a circle. Which of the following is the most appropriate pharmacotherapy?
-
A
MethimazoleIncorrect. Methimazole treats hyperthyroidism, which can produce a fine action tremor - but not a resting pill-rolling tremor with bradykinesia.
-
B
TrihexyphenidylIncorrect. Trihexyphenidyl is an anticholinergic used for tremor-predominant Parkinson disease in young patients, but it is not the broad first-line therapy because it does not treat bradykinesia or rigidity and has poor tolerability in older patients.
-
C
DonepezilIncorrect. Donepezil is an acetylcholinesterase inhibitor for Alzheimer dementia and would not treat parkinsonian motor symptoms.
-
D
PramipexoleCorrect. Pramipexole is a dopamine agonist used as first-line therapy in younger Parkinson disease patients to reduce tremor and bradykinesia while delaying levodopa-related motor complications.
-
E
PropranololIncorrect. Propranolol treats essential tremor, which is an action tremor that improves with alcohol and worsens with movement, not the resting tremor with bradykinesia of Parkinson disease.
↑ Tap an answer to reveal the reasoning
Answer: D. A middle-aged woman with a unilateral resting tremor that worsens with stress and decreases with intentional movement, plus bradykinesia (difficulty initiating movement), has Parkinson disease. Parkinson disease is a neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra pars compacta, with intracellular alpha-synuclein-rich Lewy bodies. The resulting dopamine deficiency in the nigrostriatal pathway produces the cardinal motor signs: tremor at rest (pill-rolling), rigidity (cogwheel), bradykinesia, and postural instability.
The pharmacotherapy choice depends on age and disease severity. In younger patients (under 65) with mild-to-moderate disease, a dopamine agonist such as pramipexole or ropinirole is preferred first-line. Dopamine agonists delay the need for levodopa and reduce the risk of motor complications (dyskinesias, on-off fluctuations) that develop after prolonged levodopa use. In older patients or those with severe symptoms, levodopa/carbidopa is first-line because it is the most effective agent and dyskinesia risk is less of a long-term concern.
Dopamine agonists do carry side effects: impulse control disorders (gambling, hypersexuality, binge eating), somnolence/sleep attacks, hallucinations, and orthostatic hypotension. Other Parkinson therapies include MAO-B inhibitors (selegiline, rasagiline), COMT inhibitors (entacapone), and amantadine.
**Why each option:**
**A.** Methimazole treats hyperthyroidism, which can produce a fine action tremor - but not a resting pill-rolling tremor with bradykinesia.
**B.** Trihexyphenidyl is an anticholinergic used for tremor-predominant Parkinson disease in young patients, but it is not the broad first-line therapy because it does not treat bradykinesia or rigidity and has poor tolerability in older patients.
**C.** Donepezil is an acetylcholinesterase inhibitor for Alzheimer dementia and would not treat parkinsonian motor symptoms.
**D.** Correct. Pramipexole is a dopamine agonist used as first-line therapy in younger Parkinson disease patients to reduce tremor and bradykinesia while delaying levodopa-related motor complications.