A comatose man is brought to the emergency department smelling strongly of alcohol. To differentiate deep alcoholic coma from coma due to narcotic poisoning, the resident applies firm pinching pressure to the skin of the neck. Bilateral dilatation of the previously constricted pupils is observed. This sign is known as:
- A Chvostek's sign
- B McEwan's sign ✓
- C Kernig's sign
- D Marcus Gunn pupil
Correct answer: B. McEwan's sign
Explanation
McEwan's sign refers to dilatation of the pupils produced by pinching the skin of the neck or applying painful stimuli, classically described in alcoholic coma. Its persistence helps distinguish stuporous alcohol intoxication from deep narcotic or barbiturate coma, where the pupils remain fixed even to strong pain. Chvostek's sign tests facial nerve hyperexcitability in hypocalcaemia and Kernig's sign tests meningeal irritation.
Reference: Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.