A 66-year-old man with a known history of Parkinson disease complains of very painful involuntary contractions affecting the toes of both feet. The contractions occur in the morning, soon after he wakes up, and occasionally wake him from sleep. The episodes last about 15-20 minutes. His other medical problems include acid reflux disease and hypertension. He has been taking immediate-release carbidopa/levodopa twice daily for the last 5 years. He has no history of falls.
Vital signs are within normal limits. Examination shows a 3-4 Hz resting tremor in both hands that is exacerbated by distraction and decreased with action. There is mild rigidity of the upper and lower extremities bilaterally. His gait is stable.
Which of the following is most likely to improve this patient's current symptoms?

Question

A 66-year-old man with a known history of Parkinson disease complains of very painful involuntary contractions affecting the toes of both feet.  The contractions occur in the morning, soon after he wakes up, and occasionally wake him from sleep.  The episodes last about 15-20 minutes.  His other medical problems include acid reflux disease and hypertension.  He has been taking immediate-release carbidopa/levodopa twice daily for the last 5 years.  He has no history of falls.
Vital signs are within normal limits.  Examination shows a 3-4 Hz resting tremor in both hands that is exacerbated by distraction and decreased with action.  There is mild rigidity of the upper and lower extremities bilaterally.  His gait is stable.
Which of the following is most likely to improve this patient's current symptoms?

Quizplus · Accepted Answer

Carbidopa/levodopa is the most effective medical therapy for idiopathic Parkinson disease (PD) because it relieves the motor symptoms (eg, tremor, rigidity, bradykinesia). However, about 50% of patients develop motor fluctuations after taking levodopa for 5-10 years. Motor fluctuations occur as episodes between levodopa doses when the drug "wears off" and patients develop symptoms of their underlying PD. These symptoms can occur after awakening, during a specific part of the day, or in the middle of the night. Dystonia is a common painful symptom that can occur spontaneously in the early disease stages or as part of motor fluctuations. Morning dystonia of the feet usually occurs due to low levels of levodopa during sleep. Akathisia (motor restlessness) can also result from levodopa withdrawal and usually occurs at night. Given that this patient's symptoms are worse in the middle of the night and morning hours, it is reasonable to start a longer-acting carbidopa/levodopa at night to ensure steadier levels. Other considerations include taking levodopa or a dopamine agonist at night or first thing in the morning before arising. (Choice A) Benztropine is an anti-cholinergic agent useful for treating tremors seen in PD or drug-induced dystonic reactions. This patient's dystonia is the result of lack of dopamine from his PD rather than from drug-induced dopamine blockade. (Choice B) Decreasing the dose of carbidopa/levodopa can improve dyskinesia but can worsen dystonia. (Choice C) A split night sleep study can identify underlying sleep disorders such as a parasomnia presenting as undesirable physical events (eg, movements, behaviors) or experiences (eg, emotions, perceptions, dreams) during sleep or arousal from sleep. However, patients usually have no awareness of these movements. (Choice E) Vitamin B6 or pyridoxine does not increase the levels of dopamine in the central nervous system and will likely not benefit this patient. Educational objective: Extrapyramidal symptoms such as dystonia in patients with Parkinson disease are the result of insufficient dopamine in the central nervous system. Patients on immediate-release carbidopa/levodopa may need longer-acting carbidopa/levodopa at night to maintain steady levels of dopamine and to avoid unwanted extrapyramidal symptoms. __________ References: Long-acting carbidopa-levodopa in the management of moderate and advanced Parkinson's disease. (http://www.ncbi.nlm.nih.gov/pubmed/1549202)

A 66-Year-Old Man with a Known History of Parkinson Disease