A 32-year-old man is brought to the emergency department due to confusion and fever for 2 days. Medical history is significant for bipolar disorder diagnosed a year ago. The patient has been treated with lithium and an antipsychotic medication, and the doses have not changed over the last 2 months. In the emergency department, temperature is 38.8 C (101.8 F), blood pressure is 160/100 mm Hg, pulse is 116/min, and respirations are 22/min. Pulse oximetry is 99% on room air. The patient is not oriented to time, place, or person. Mucous membranes are dry. The lungs are clear to auscultation. Muscle tone is markedly increased. Deep tendon reflexes are 2+. Mild dysarthria and hand tremors are present. Laboratory results are as follows: Serum lithium level is 0.9 mEq/L (normal: 0.6-1.2). Which of the following is the most appropriate next step in management of this patient?

Question

A 32-year-old man is brought to the emergency department due to confusion and fever for 2 days.  Medical history is significant for bipolar disorder diagnosed a year ago.  The patient has been treated with lithium and an antipsychotic medication, and the doses have not changed over the last 2 months.  In the emergency department, temperature is 38.8 C (101.8 F), blood pressure is 160/100 mm Hg, pulse is 116/min, and respirations are 22/min.  Pulse oximetry is 99% on room air.  The patient is not oriented to time, place, or person.  Mucous membranes are dry.  The lungs are clear to auscultation.  Muscle tone is markedly increased.  Deep tendon reflexes are 2+.  Mild dysarthria and hand tremors are present.  Laboratory results are as follows:  Serum lithium level is 0.9 mEq/L (normal: 0.6-1.2).  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d795_8519_bc81_93681cc3a06f_MD0003_00 This patient taking antipsychotic medications has fever, altered mental status, autonomic dysregulation (eg, tachycardia, hypertension), and muscular rigidity. These findings are consistent with neuroleptic malignant syndrome (NMS), an idiosyncratic drug reaction to dopamine antagonists. Although symptoms of NMS typically begin within 2 weeks of initiation of the precipitating agent, they can occur at any time during treatment. Sustained muscle contraction can lead to muscle breakdown that results in many of the observed laboratory abnormalities, including elevated creatine kinase, electrolyte abnormalities (eg, hypocalcemia, metabolic acidosis), and elevated blood urea nitrogen and creatinine (ie, acute kidney injury due to rhabdomyolysis). Nonspecific laboratory abnormalities can include leukocytosis with a left shift, slight protein elevation in the cerebrospinal fluid (possibly reflecting increased neurometabolites), and elevated liver enzymes. Discontinuation of the antipsychotic is the single most important intervention. Additional treatment often includes hydration (eg, intravenous fluids), cooling, and medications to control agitation (eg, benzodiazepines) and decrease muscle contraction (eg, benzodiazepines, dantrolene). (Choices B and C) Lithium toxicity is treated with cessation of lithium and hemodialysis. Like NMS, it can present with confusion, ataxia, and neuromuscular excitability (eg, tremor). Unlike NMS, which is an idiosyncratic reaction (ie, not dose-dependent), lithium toxicity is unlikely when the therapeutic range (0.6-1.2 mEq/L) is maintained. In this patient, lithium could be discontinued to prevent synergistic effects, but it is not as critical as stopping the antipsychotic. (Choice D) Benztropine is used to treat the extrapyramidal adverse effects (eg, rigidity, acute dystonic reactions) of antipsychotics. Although extrapyramidal effects may include rigidity, the hyperthermia, hypertension, altered mental status, and tachycardia are more concerning for NMS. (Choice E) Herpes encephalitis, treated with acyclovir, can present with fever, altered mental status, and leukocytosis. Cerebral spinal fluid may also reveal elevated protein, as in this patient; however, mononuclear pleocytosis and red blood cells would also be expected. Educational objective: Neuroleptic malignant syndrome typically presents with altered mental status, fever, neuromuscular abnormalities (eg, muscular rigidity), and autonomic instability. The most critical intervention is cessation of antipsychotic medications. References: Management of serotonin syndrome and neuroleptic malignant syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/27469512) Neuroleptic malignant syndrome: a review from a clinically oriented perspective. (http://www.ncbi.nlm.nih.gov/pubmed/26411967)

A 32-Year-Old Man Is Brought to the Emergency Department Due