Chvostek sign

Lore & Background

František Chvostek was a Czech-born Austrian surgeon who devoted himself to the study of etiopathogenesis and the treatment of neurological disorders, including by means of electrotherapy. In 1876, he first described the sign that bears his name. Later, in 1883, the sign was independently described by another Austrian physician, Nathan Weiss.

The Chvostek sign is elicited by tapping a point approximately 2 cm in front of the ear lobe and about 1 cm below the zygomatic process, causing ipsilateral contraction of some or all muscles innervated by the facial nerve. A second type involves tapping between the middle and upper third of the line from the mouth angle to the zygomatic process, resulting in contraction of mouth and nose muscles only.

The sign is found in tetany but also in hypomagnesemia, which can cause hypocalcemia, and is frequently seen in alcoholics, persons with diarrhea, patients taking aminoglycosides or diuretics. It can also occur in respiratory alkalosis, measles, tetanus, and myxedema.

Reader's Guide

The Chvostek sign serves as a clinical indicator of hypocalcemia, though its utility is limited by poor sensitivity and specificity. It is not a very specific sign of tetany, as it may be seen in 10% to 25% of healthy adults. The sensitivity is lower than that of the Trousseau sign of latent tetany, which generally occurs earlier and is a more accurate predictor of hypocalcemia. The Chvostek sign is negative in 30% of patients with hypocalcemia, further reducing its clinical reliability. Despite these limitations, it remains a well-known bedside test for assessing neuromuscular irritability. The sign's association with conditions such as hypoparathyroidism, vitamin D deficiency, and respiratory alkalosis underscores its role in prompting further diagnostic evaluation of calcium metabolism disorders. Its historical significance lies in its naming after František Chvostek, who first described it in 1876, and its independent description by Nathan Weiss in 1883.

Did You Know?

• The Chvostek sign is named after František Chvostek, a Czech-born Austrian surgeon who first described it in 1876.
• The sign is elicited by tapping the facial nerve in front of the ear, causing ipsilateral facial muscle spasms.
• The Chvostek sign can be seen in 10% to 25% of healthy adults, reducing its specificity for tetany.
• The Trousseau sign of latent tetany is a more accurate and earlier predictor of hypocalcemia than the Chvostek sign.