SPECIAL REVIEWS

Abstract

THE subject of hypocalcemic states is one on which a great deal of work has been done but one in which there is as yet much disagreement concerning some points and a recognized lack of knowledge of others. In general it may be stated that hypocalcemic states are manifested clinically by signs and symptoms of tetany. The symptom complex of tetany is now less common than in former times when rachitic tetany was the most frequent cause of convulsions in infancy. It was well described in the older literature. The manifestations consist of central and peripheral nervous system symptoms, irritability often alternating with lethargy, nystagmus and strabismus, contractions and pain in the muscles of the face with "half moon eyes," "carp mouth," trismus and convulsions Edema, most marked in the hands, feet and around the eyes is often observed. Confirmatory signs of tetany may be elicited by special methods of examination. Chvostek's sign, jerking of the facial muscles when the facial nerve is tapped, is a sign of tetany in children from one month to two years of age. It is unreliable in newborn infants, in older children and adults since in them it may be present normally. When the facial muscles are in spasm with manifest tetany it can seldom be elicited. The peroneal sign consists of dorsiflexion and abduction of the foot on tapping the peroneal nerve on the lateral surface of the fibula just before the knee. Trousseau's sign is carpopedal spasm induced by pressure applied for some time over the upper arm or leg. Erb's sign, or increased electrical excitability of the peripheral nerves to the galvanic current, was the most reliable proof of tetany in the days before blood chemical analyses were available. The procurement of electrical reactions is such a time consuming procedure that they are seldom sought for now.