A 75-year-old man with a history of Parkinson disease, bipolar disorder, and hypertension is brought to the emergency department with confusion and fever. His caregivers report that last week he complained of stomach cramps and diarrhea and stopped taking his medications as he thought they were worsening his symptoms. His medications include carbidopa/levodopa, sertraline, lithium, lisinopril, and amlodipine. He does not use tobacco or illicit drugs but drinks 2 or 3 beers on weekends.
On evaluation, the patient is diaphoretic and confused. Temperature is 38.3 C (101 F), blood pressure is 180/95 mm Hg, pulse is 114/min, and respirations are 20/min. The mucous membranes are dry. He has prominent generalized muscular rigidity and bilateral tremor. The abdomen is nontender and bowel sounds are present.
Laboratory results are as follows:
ECG shows sinus tachycardia and nonspecific T-wave changes. Spinal fluid evaluation shows no abnormalities. Which of the following is the most likely diagnosis?

Question

A 75-year-old man with a history of Parkinson disease, bipolar disorder, and hypertension is brought to the emergency department with confusion and fever.  His caregivers report that last week he complained of stomach cramps and diarrhea and stopped taking his medications as he thought they were worsening his symptoms.  His medications include carbidopa/levodopa, sertraline, lithium, lisinopril, and amlodipine.  He does not use tobacco or illicit drugs but drinks 2 or 3 beers on weekends.
On evaluation, the patient is diaphoretic and confused.  Temperature is 38.3 C (101 F), blood pressure is 180/95 mm Hg, pulse is 114/min, and respirations are 20/min.  The mucous membranes are dry.  He has prominent generalized muscular rigidity and bilateral tremor.  The abdomen is nontender and bowel sounds are present.
Laboratory results are as follows:
 ECG shows sinus tachycardia and nonspecific T-wave changes.  Spinal fluid evaluation shows no abnormalities.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec193a_9693_f8a4_853d_75bee24fd145_MD0002_00 Although rigidity can be seen in Parkinson disease, the combination of this patient's confusion, fever, diffuse rigidity, and autonomic instability (eg, diaphoresis, hypertension, tachycardia) in the context of recently stopping his Parkinson medication is suggestive of neuroleptic malignant syndrome (NMS). NMS most commonly occurs as an idiosyncratic adverse effect of antipsychotic medications, but it can also occur in patients with Parkinson disease after withdrawal, dose reduction, or a switch in dopamine agents (where it is also referred to as parkinsonism-hyperpyrexia syndrome). The key features of NMS are altered sensorium, hyperthermia, autonomic instability, and generalized muscular (lead-pipe) rigidity. Muscle rigidity is often severe and leads to elevated creatine kinase levels (typically more than 1,000 IU/L). Severe cases can result in rhabdomyolysis with complications of myoglobinuria and acute renal failure. Other common laboratory findings include leukocytosis and electrolyte abnormalities. Treatment involves immediate discontinuation of antipsychotic medication or reinstitution of dopamine agents, as well as supportive care (eg, rehydration, cooling body temperature). NMS has a mortality rate of 10%-20% with admission to the intensive care unit commonly necessary. Muscle relaxants (eg, dantrolene) or dopamine agonists (eg, bromocriptine) are reserved for patients who do not improve with restarting dopaminergic medication and supportive care. (Choice A) Lithium toxicity can present with confusion and neuromuscular symptoms such as slurred speech, tremor, and ataxia. Diffuse rigidity and hyperpyrexia, however, would not be expected. This patient has stopped taking his lithium, making toxicity unlikely. (Choice B) Malignant hyperthermia is seen in the context of procedures requiring the use of halogenated inhalant anesthetics plus succinylcholine. (Choice D) Patients who have taken levodopa for long periods may experience fluctuations in motor symptoms with periods of increased rigidity and bradykinesia. This is known as the "on-off" phenomenon. It is not associated with fever, confusion, or autonomic instability. (Choice E) Serotonin syndrome presents similarly to NMS; however, hyperreflexia and myoclonus, rather than diffuse muscle rigidity, would be expected. This patient stopped taking his sertraline last week, making serotonin syndrome unlikely. The presence of generalized rigidity and the onset of symptoms after stopping Parkinson medication make NMS more likely. Educational objective: Neuroleptic malignant syndrome presents with mental status changes, fever, muscle rigidity, and autonomic instability after starting antipsychotics or withdrawing dopamine agonists. Treatment includes withdrawal of a neuroleptic agent or reinstitution of a dopamine agonist, as well as supportive care. __________ References: Management of serotonin syndrome and neuroleptic malignant syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/27469512) What to do when people with Parkinson's disease cannot take their usual oral medications. (http://www.ncbi.nlm.nih.gov/pubmed/26719485) The parkinsonism-hyperpyrexia syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/18712508)

A 75-Year-Old Man with a History of Parkinson Disease, Bipolar