Serotonin toxicity — structured clinical viva

Diagnosis. Serotonin toxicity from venlafaxine + linezolid (linezolid has MAOI activity). Hunter pathway: serotonergic exposure plus ocular clonus with agitation and/or inducible clonus with diaphoresis/agitation — criteria met. Tempo and drug history argue strongly against delayed NMS from an antipsychotic two months ago.^[1][3][4]

Differential. NMS, anticholinergic toxicity, sympathomimetic toxicity, sepsis/CNS infection, withdrawal states — use skin moisture, bowel sounds, reflex/clonus pattern, and drug timeline as discriminators.^[2][4]

Management. Stop venlafaxine and reassess need/alternative for linezolid with infectious diseases. Supportive care, IV fluids, continuous monitoring, benzodiazepines (e.g. lorazepam 1–2 mg IV titrated), active cooling, cyproheptadine 12 mg oral/NG then 2 mg q2h if needed, maintenance 8 mg q6h. ICU if progressive hyperthermia/rigidity; consider non-depolarising paralysis for refractory heat generation. Avoid bromocriptine.^[2][5]

Prevention counselling. Medication reconciliation before starting linezolid or methylene blue; warn about tramadol/pethidine/dextromethorphan with MAOIs; document high-risk combinations in the record; plan safer long-term antidepressant strategy after recovery.^[3][5]