Serotonin Syndrome? Not So Fast, Sherlock

Mark E. Williams, MD

My 72-year-old patient was a new admission to our facility on a Friday afternoon. Donna had a history of bipolar II disorder, anxiety, depression, hypothyroidism, hypoparathyroidism, hypertension, gastric reflux, and collagenous colitis.

During her admission, she was confused and had active hallucinations as well as myoclonic jerking. She could not provide any history. Her husband, Fred, said that 3 weeks earlier, she'd begun experiencing generalized dizziness, decreased concentration, and the slowing of her movements. About a week after that, she'd developed a tremor, increased confusion, and bizarre hallucinations.

Hospitalization and Tests, but No Real Answers

Donna had been taken to the hospital about a week prior to her admission to our facility because she was unstable on her feet. She'd also become more delirious and somnolent and had developed myoclonic jerking. She was admitted to the neurology service and underwent brain imaging to rule out acute processes. An EEG demonstrated moderate encephalopathy, but no seizures or spikes. This led to an initial exclusion of Creutzfeldt-Jakob disease.

Donna's thyroid function tests were normal and cerebral spinal fluid studies after a lumbar puncture showed mildly elevated protein and 10 lymphocytes. Herpes simplex virus and Lyme serologies were negative. Serotonergic medications (escitalopram, duloxetine