Chvostek sign is described as which of the following?

• A. Twitch of the corner of the mouth on tapping CN VII at the zygoma
• B. Carpal spasm when blood pressure cuff is inflated above systolic BP
• C. Numbness around the mouth
• D. Fasciculations of the tongue

Answer: (A)

Chvostek sign reflects neuromuscular hyperexcitability from low calcium. It’s tested by tapping the facial nerve just anterior to the ear over the zygomatic arch. A positive sign is a twitch of the ipsilateral facial muscles, often at the corner of the mouth, when the nerve is stimulated. This occurs because hypocalcemia makes nerves more irritable, so a light tap triggers involuntary contraction of nearby muscles. It’s a useful clue to hypocalcemia, but not a definitive diagnosis on its own—serum calcium should be checked. This sign is distinct from Trousseau sign, which is carpal spasm produced by inflating a blood pressure cuff; numbness around the mouth can accompany hypocalcemia but is not produced by tapping, and tongue fasciculations are not characteristic of Chvostek.