Determine the most likely diagnosis for a 50-year-old woman presenting with disorientation, tremors, diaphoresis, abdominal cramps, diarrhea, and abnormal vital signs after being prescribed tramadol. Do you know the answer? Let’s find out!
A 50-year-old woman is brought to the emergency department by her son after being found lying on the bedroom floor. She appears disoriented, tremulous, diaphoretic, and complains of abdominal cramps and diarrhea. She visited the emergency department yesterday for evaluation of severe back pain and was prescribed tramadol by the ED physician. Past medical history is significant for major depressive disorder and type II diabetes mellitus. Current medications include metformin, atorvastatin, and escitalopram. She occasionally drinks alcohol on weekends; her last drink was two weeks ago. Her temperature is 38.9 C (102 F°), pulse is 118/min, respirations are 18/min, and blood pressure is 150/92 mm Hg. Physical examination shows dilated pupils bilaterally, flushed skin, dry mucous membranes, and a positive Babinski sign.
Which of the following is the most likely diagnosis?
A. Neuroleptic malignant syndrome
B. Hypertensive crisis
C. Serotonin syndrome
D. Delirium tremens
E. Acute dystonia
Scroll down for the correct answer!
The correct answer to today’s USMLE® Step 1 Question is…
C. Serotonin syndrome
Correct: See Main Explanation.
Incorrect Answer Explanations
A. Neuroleptic malignant syndrome
Incorrect: Neuroleptic malignant syndrome is a rare but serious complication of antipsychotic medications and classically presents with mental status changes, muscular rigidity, and autonomic instability, including fever (hyperthermia >38°C). Serum creatine kinase >1000 IU/L suggests the diagnosis.
B. Hypertensive crisis
Incorrect: Hypertensive crisis refers to a blood pressure of ≥180/120 mm Hg and can occur in patients on monoamine oxidase inhibitors (MAOI) following ingestion of tyramine-containing foods. Neither tramadol nor escitalopram is an MAOI.
D. Delirium tremens
Incorrect: Delirium tremens can present with altered mental status and autonomic and neuromuscular hyperactivity; however, it occurs in heavy alcohol users 2-4 days after their last drink.
E. Acute dystonia
Incorrect: Acute dystonia refers to involuntary contractions of muscles characterized by sudden onset muscle spasm, stiffness, and oculogyric crisis occurring hours to days after the use of typical antipsychotics, anticonvulsants, or metoclopramide. Altered mental status and autonomic hyperactivity are atypical.
Main Explanation
This patient presents with increased neuromuscular activity (e.g., tremors, positive Babinski sign), autonomic instability, and altered mental status in the setting of tramadol ingestion with escitalopram consistent with serotonin syndrome.
Serotonin syndrome is a life-threatening condition caused by the overstimulation of central and peripheral serotonin receptors. It presents with a triad of mental status changes, autonomic hyperactivity (e.g., hyperthermia, diaphoresis, and diarrhea), and neuromuscular abnormalities (clonus, hyperreflexia, hypertonia, tremor, and seizure).
It results from an interaction between multiple medications that increase serotonergic neurotransmission. Treatment consists of immediate discontinuation of all serotonergic medications, supportive care (oxygen, intravenous fluids), benzodiazepines, and administration of cyproheptadine (serotonin antagonist that blocks 5HT2 receptors).
Before prescribing an SSRI or a serotonergic medication, potential medication interactions should be considered to avoid serotonin syndrome. When switching between serotonergic medications, adequate washout periods should be allowed to prevent the accumulation of excessive serotonin.
Major Takeaway
Serotonin syndrome is caused by overstimulation of central and peripheral serotonin receptors and presents a triad of mental status changes, autonomic hyperactivity, and neuromuscular abnormalities. It results from an interaction between multiple medications that increase serotonergic neurotransmission, most commonly SSRIs.
Want to learn more about this topic?
Read this Osmosis Answer page: Serotonin Syndrome
References
- Lommel K.M., & Meadows A.L., & Chopra N, & Thompson S (2017). Psychiatric emergencies. Stone C, & Humphries R.L.(Eds.), CURRENT Diagnosis & Treatment: Emergency Medicine, 8e. McGraw-Hill.
- Mason, P. J., Morris, V. A., & Balcezak, T. J. (2000). Serotonin syndrome. Presentation of 2 cases and review of the literature. Medicine, 79(4), 201-209.
- Ganetsky, M., & Brush, D. E. (2005). Serotonin syndrome—what have we learned?. Clinical Pediatric Emergency Medicine, 6(2), 103-108.
- Mossop E, & DiBlasio F (). Overdose, poisoning, and withdrawal. Oropello J.M., & Pastores S.M., & Kvetan V(Eds.), Critical Care. McGraw-Hill.
Want more USMLE® Step 1 practice questions? Try Osmosis by Elsevier today! Access your free trial and discover why millions of current and future clinicians and caregivers love learning with us.
Leave a Reply