A 45-year-old man comes to the physician due to 2 weeks of muscle stiffness and imbalance. He has no fever, headache, joint pain, or muscle soreness. The patient has a history of bipolar disorder and suicidal ideations. He was started on risperidone for a manic episode 2 months ago. He does not use alcohol or tobacco.
His blood pressure is 130/80 mm Hg and pulse is 68/min. On examination, there is a low-amplitude resting tremor of both hands. Finger tapping is slow and irregular on both sides.
Which of the following is the most appropriate next step in management of this patient?

Question

A 45-year-old man comes to the physician due to 2 weeks of muscle stiffness and imbalance.  He has no fever, headache, joint pain, or muscle soreness.  The patient has a history of bipolar disorder and suicidal ideations.  He was started on risperidone for a manic episode 2 months ago.  He does not use alcohol or tobacco.
His blood pressure is 130/80 mm Hg and pulse is 68/min.  On examination, there is a low-amplitude resting tremor of both hands.  Finger tapping is slow and irregular on both sides.
Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

This patient is presenting with drug-induced parkinsonism (DIP) after recently starting risperidone. The symptoms/signs of idiopathic Parkinson disease and DIP may be indistinguishable, and consist of bradykinesia, rigidity, and tremor. Dopamine (D2) receptor antagonists are the most common offending agents and include typical antipsychotics (eg, haloperidol), some atypical antipsychotics (eg, risperidone), and antiemetics (eg, metoclopramide). The mainstay of DIP management is discontinuation of the offending agent. Patients with a psychiatric diagnosis who require treatment should be switched to an antipsychotic with a low potential for causing extrapyramidal effects (eg, quetiapine or clozapine). Evidence supporting the use of anticholinergics (eg, benztropine) or amantadine to control DIP symptoms is limited (Choice D). (Choice B) Brain MRI can be useful in excluding alternate diagnoses (eg, tumor, stroke) in patients presenting with parkinsonism; however, this patient's lack of atherosclerotic risk factors or other symptoms (eg, headache, seizure, nausea/vomiting) make these diagnoses less likely. (Choice C) Though hyperthyroidism may present with tremor and weakness, this patient lacks other features such as weight loss and tachycardia. In addition, hyperthyroidism would not explain his bradykinesia (eg, slow finger tapping) and rigidity. (Choice E) Pramipexole is a dopamine agonist that may be effective in treating idiopathic Parkinson disease; however, this patient's symptoms developed after starting risperidone. The most appropriate next step is to monitor his symptoms after switching to quetiapine as most cases of DIP are reversible. Educational objective: Dopamine receptor antagonists (eg, typical or atypical antipsychotics, antiemetics) may cause secondary parkinsonism. Most cases resolve after discontinuation of the offending agent. Patients that require continued antipsychotic therapy should be switched to a low-risk agent (eg, quetiapine, clozapine). __________ References: Drug-induced parkinsonism. (http://www.ncbi.nlm.nih.gov/pubmed/22523509) Drug-induced parkinsonism. (http://www.ncbi.nlm.nih.gov/pubmed/23540800)

A 45-Year-Old Man Comes to the Physician Due to 2