A 35-year-old man was hospitalized for a psychotic episode in which he heard voices of God and the devil and believed that his family was plotting to kill him. He improved rapidly with medication therapy and was discharged. Three weeks later, the patient comes to the emergency department due to generalized muscle stiffness and shaking of his right hand. He has no other medical history and takes no other medications. Temperature is 36.7 C (98 F), blood pressure is 110/80 mm Hg, pulse is 68/min, and respirations are 14/min. On mental status examination, he is alert and oriented with mild paranoia but no auditory hallucinations. Which of the following is the best treatment for this patient's current symptoms?
Drug-induced parkinsonism | |
Etiology |
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Symptoms |
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Management |
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This patient's psychotic episode was most likely treated with an antipsychotic, and his current symptoms are consistent with drug-induced parkinsonism, an extrapyramidal side effect of antipsychotics. Symptoms include rigidity (may be experienced as subjective stiffness), resting/postural tremor, masked facies, and bradykinesia and typically occur within the first 3 months of drug initiation. Other extrapyramidal side effects of antipsychotic medications include acute dystonia (sudden, sustained contraction of muscle groups) and akathisia (subjective restlessness and inability to sit still).
Drug-induced parkinsonism is caused by dopamine (D2) receptor blockade in the nigrostriatal pathway. If the antipsychotic cannot be reduced or discontinued, drug-induced parkinsonism is best treated with a centrally acting anticholinergic agent (eg, benztropine). Levodopa should not be used to treat antipsychotic-induced parkinsonism as it can exacerbate or even precipitate psychosis (Choice E).
(Choice B) Dantrolene is a direct-acting skeletal muscle relaxant used in the treatment of neuroleptic malignant syndrome (NMS). NMS presents with diffuse muscle rigidity, high fever, sympathetic hyperactivity (eg, hypertension, tachycardia), and altered mental status and is unlikely in this oriented, afebrile patient with normal vital signs.
(Choices C and F) The benzodiazepine diazepam and the beta blocker propranolol may both be used in the treatment of akathisia. Akathisia is characterized by subjective restless and an inability to sit still rather than rigidity and tremor, as seen in this patient.
(Choice D) Haloperidol is a first-generation antipsychotic and potent D2 blocker that frequently causes extrapyramidal symptoms, including drug-induced parkinsonism. Its use would only exacerbate the patient's parkinsonian symptoms. Use of a second-generation antipsychotic with minimal D2 blockade would be a reasonable long-term alternative if the patient were taking a first-generation antipsychotic.
Educational objective:
Drug-induced parkinsonism is an extrapyramidal side effect caused by medications that block D2 receptors (eg, antipsychotics). Management strategies include decreasing or discontinuing the offending medication and treatment with an anticholinergic medication.