Chvostek sign

Chvostek Sign

Demonstration of the Chvostek sign.

Chvostek Sign

The Chvostek sign, pronounced /ˈkvɒstɪk/, is a clinical indication of hypocalcemia, characterized by the twitching of muscles innervated by the facial nerve (CNVII). It reveals an abnormal reaction to facial nerve stimulation.

Overview

Chvostek sign is a notable diagnostic tool used to identify hypocalcemia, a condition characterized by low levels of calcium in the blood.

Pathophysiology

When the facial nerve is tapped near the tragus, the facial muscles on the same side of the face (ipsilateral) contract momentarily. This reaction, often seen as a twitch of the nose or lips, is due to the hyperexcitability of nerves caused by hypocalcemia. Conditions leading to hypocalcemia include hypoparathyroidism, pseudohypoparathyroidism, and hypovitaminosis D.

Clinical Significance

Hypocalcemia

Hypocalcemia is the primary condition associated with the Chvostek sign. This electrolyte imbalance leads to increased nerve excitability and muscular spasms.

Other Conditions

Though classically associated with hypocalcemia, the Chvostek sign can also manifest in respiratory alkalosis conditions like hyperventilation, which causes a decrease in serum calcium levels while maintaining normal overall calcium due to a shift of Ca2+ ions.

Diagnostic Application

The Chvostek sign is used in clinical settings to quickly assess the possibility of hypocalcemia. Its presence prompts further investigation and management of underlying conditions.