Chvostek sign
Encyclopedia
The Chvostek sign is one of the signs of tetany
seen in hypocalcemia. It refers to an abnormal reaction to the stimulation of the facial nerve
. When the facial nerve
is tapped at the angle of the jaw (i.e. masseter muscle
), the facial muscles on the same side of the face will contract momentarily (typically a twitch of the nose or lips) because of hypocalcemia (i.e. from hypoparathyroidism, pseudohypoparathyroidism, hypovitaminosis D) with resultant hyperexcitability of nerves. Though classically described in hypocalcemia, this sign may also be encountered in respiratory alkalosis
, such as that seen in hyperventilation
, which actually causes decreased serum Ca2+ with a normal calcium level due to a shift of Ca2+ from the blood to albumin
which has become more negative in the alkalotic state.
It was first described by František Chvostek
, a Czecho-Austrian
physician in 1876, and later independently by Nathan Weiss
in 1883.
The Trousseau sign of latent tetany
is also often used to detect early tetany.
Chvostek's sign may also be present in hypomagnesemia, frequently seen in alcoholics, persons with diarrhea, patients taking aminoglycosides or diuretics, because hypomagnesemia can cause hypocalcemia. Magnesium is a cofactor for Adenylate Cyclase. The reaction that Adenylate Cyclase catalyzes is the conversion of ATP to 3',5'-cyclic AMP. The 3',5'-cyclic AMP (cAMP) is required for Parathyroid hormone activation.
Tetany (medical sign)
Tetany is a medical sign consisting of the involuntary contraction of muscles, which may be caused by disease or other conditions that increase the action potential frequency...
seen in hypocalcemia. It refers to an abnormal reaction to the stimulation of the facial nerve
Facial nerve
The facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...
. When the facial nerve
Facial nerve
The facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...
is tapped at the angle of the jaw (i.e. masseter muscle
Masseter muscle
In human anatomy, the masseter is one of the muscles of mastication.In the animal kingdom, it is particularly powerful in herbivores to facilitate chewing of plant matter.-Origin and insertion of the two heads:...
), the facial muscles on the same side of the face will contract momentarily (typically a twitch of the nose or lips) because of hypocalcemia (i.e. from hypoparathyroidism, pseudohypoparathyroidism, hypovitaminosis D) with resultant hyperexcitability of nerves. Though classically described in hypocalcemia, this sign may also be encountered in respiratory alkalosis
Respiratory alkalosis
Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH...
, such as that seen in hyperventilation
Hyperventilation
Hyperventilation or overbreathing is the state of breathing faster or deeper than normal, causing excessive expulsion of circulating carbon dioxide. It can result from a psychological state such as a panic attack, from a physiological condition such as metabolic acidosis, can be brought about by...
, which actually causes decreased serum Ca2+ with a normal calcium level due to a shift of Ca2+ from the blood to albumin
Albumin
Albumin refers generally to any protein that is water soluble, which is moderately soluble in concentrated salt solutions, and experiences heat denaturation. They are commonly found in blood plasma, and are unique to other blood proteins in that they are not glycosylated...
which has become more negative in the alkalotic state.
It was first described by František Chvostek
František Chvostek
František Chvostek was an Czecho-Austrian military physician. He is most notable for having described Chvostek's sign....
, a Czecho-Austrian
Austrian Empire
The Austrian Empire was a modern era successor empire, which was centered on what is today's Austria and which officially lasted from 1804 to 1867. It was followed by the Empire of Austria-Hungary, whose proclamation was a diplomatic move that elevated Hungary's status within the Austrian Empire...
physician in 1876, and later independently by Nathan Weiss
Nathan Weiss
Nathan Weiss was an Austrian physician and neurologist born in Gross-Meseritsch .He studied medicine in Vienna, earning his doctorate in 1874...
in 1883.
The Trousseau sign of latent tetany
Trousseau sign of latent tetany
Trousseau sign of latent tetany is a medical sign observed in patients with low calcium. This sign may become positive before other gross manifestations of hypocalcemia such as hyperreflexia and tetany, but is generally believed to be more sensitive than the Chvostek sign for hypocalcemia.To...
is also often used to detect early tetany.
Chvostek's sign may also be present in hypomagnesemia, frequently seen in alcoholics, persons with diarrhea, patients taking aminoglycosides or diuretics, because hypomagnesemia can cause hypocalcemia. Magnesium is a cofactor for Adenylate Cyclase. The reaction that Adenylate Cyclase catalyzes is the conversion of ATP to 3',5'-cyclic AMP. The 3',5'-cyclic AMP (cAMP) is required for Parathyroid hormone activation.