A 28-year-old woman presents with perioral paresthesias and tetany after thyroid surgery. Tapping over the preauricular region reproduces twitching of the ipsilateral facial muscles. Which nerve is being stimulated to produce this sign?

• A Trigeminal nerve
• B Hypoglossal nerve
• C Glossopharyngeal nerve
• D Facial nerve ✓

Explanation

Chvostek's sign is elicited by tapping over the facial nerve as it exits the stylomastoid foramen anterior to the ear, causing contraction of the ipsilateral facial muscles in hypocalcemic states. It reflects neuromuscular irritability from reduced threshold potential of nerves. The trigeminal nerve is tapped in the jaw jerk reflex, and neither glossopharyngeal nor hypoglossal stimulation produces facial muscle twitching.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.