A man is brought dead with a history of ingesting rat poison. At autopsy the body shows generalized rigid convulsive posture with opisthotonus, facial grimacing, and arched back, yet rigor mortis develops rapidly and decomposition sets in early. Consciousness was reportedly intact during the convulsions. Which toxin is responsible?

• A Strychnine ✓
• B Zinc phosphide
• C Thallium sulphate
• D Yellow oleander

Explanation

Strychnine competitively antagonizes the inhibitory neurotransmitter glycine at postsynaptic receptors on spinal motor neurons and Renshaw cells, producing reflex exaggeration into generalized tonic convulsions with risus sardonicus and opisthotonus while consciousness remains fully retained. Death occurs from respiratory failure or medullary spasm. Rapid onset of rigor mortis and early putrefaction are described postmortem findings. Zinc phosphide and oleander do not cause convulsions, killing those distractors.

Reference: Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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