Chvostek's sign

Described by Czech-Austrian Professor František Chvostek, the Chvostek's sign refers to the twitching of ipsilateral facial muscles upon mechanical stimulation of the facial nerve. This clinical sign is associated with hypocalcemia. This could be evaluated by carefully tapping on the patient's cheek approximately 2 cm in front of the ear.

Clinical findings
A positive Chvostek's sign could be due to the following related conditions as shown below:


 * Parathyroid diseases and relation between calcium and PTH.jpgLow parathyroid hormone (PTH) levels: PTH regulates the body Ca2+ levels in the body and is released by the parathyroid glands when the Ca2+ levels are low. Hypoparathyroidism could occur for instance, as a result of resection of the parathyroid glands, or less frequently, as a consequence of autoimmune disorders (like autoimmune polyendocrine syndrome type 1).
 * Kidney failure
 * Acute pancreatitis
 * Electrolyte imbalances: Ca2+ is one important electrolyte in the body, hence, its imbalance along with other disturbances such as Mg2+ and vitamin D could increase the excitability of the facial nerves, producing muscle contraction.
 * Respiratory alkalosis: Often due to hyperventilation.
 * Certain medications: Examples are bisphosphonates and proton pump inhibitors.

A negative Chvostek's sign is obtained when there is no facial muscle contraction following stimulation. However, this does not necessarily exclude the presence of hypocalcemia.