A patient on phenelzine (MAOI) was given tramadol for pain. Within 2 hours she develops agitation, tremor, myoclonus, hyperreflexia, diaphoresis, and temperature of 39.1°C. The finding that BEST distinguishes this from NMS is:
- A Clonus and hyperreflexia ✓
- B Elevated creatine kinase
- C Hyperthermia
- D Diaphoresis
Correct answer: A. Clonus and hyperreflexia
Explanation
Clonus (especially ocular clonus) and hyperreflexia are hallmark features of serotonin syndrome that are absent or minimal in NMS. NMS has lead-pipe rigidity with normal or reduced reflexes. Both conditions share hyperthermia, diaphoresis, and elevated CK. Tramadol inhibits serotonin reuptake and combined with an MAOI creates serotonin toxicity.
Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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