Understanding NMS & Serotonin Syndrome: Similarities and Differences

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The content provided in this Substack post is for entertainment and informational purposes only and is not intended to serve as medical advice. The views and opinions expressed herein are those of the writer and should not be taken as definitive or authoritative. Readers should not rely solely on the information provided in this post to make decisions about patient care. Instead, use this content as a starting point for further research and consult a qualified healthcare professional before making any changes to treatment or medication regimens.

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To begin, let's consider the fictional case of Mr. J, a 46-year-old man with a dual diagnosis of schizophrenia and major depressive disorder. He arrived at the emergency department exhibiting hyperthermia, severe muscle rigidity, and marked confusion. He appeared disoriented and agitated, sweating profusely. His vitals indicated a temperature of 40°C (104°F), blood pressure of 160/90 mmHg, heart rate of 120 bpm, and respiratory rate of 24 breaths per minute.

Mr. J had been on a regimen of a high-potency typical antipsychotic, haloperidol, for his schizophrenia and a selective serotonin reuptake inhibitor (SSRI) for his depression. These circumstances raised the suspicion of two serious conditions, Neuroleptic Malignant Syndrome (NMS) and Serotonin Syndrome.

The clinical overlap between NMS and Serotonin Syndrome, such as hyperthermia, altered mental status, and autonomic dysregulation, can make the differential diagnosis challenging. However, certain clinical features and laboratory findings can assist in distinguishing between these two syndromes.