Tetany is divided into: manifest, latent and alkalosic.
Symptoms of manifest tetany include muscle aches and cramps, opisthotonos, paresthesias or stiffness in the hands and feet. Convulsions, laryngospasms, and carpo-podal spasms may occur.
Symptoms of latent tetany are: carpo- podalic spasms, contraction of the orbicularis orbicularis muscle of the mouth, dorsal flexion of the foot, elongated QT, diffuse slow activity.
Alkalotic tetany is very rare in infants and young children.
Tetany is often due to magnesium or calcium deficiency, characterized by the association between the signs and symptoms of neuromuscular excitability and psychosomatic manifestations of neurosis. Magnesium deficiency is generally due to loss of the mineral through the gastrointestinal tract and kidney. The most common causes of deficiency are gastrointestinal disorders, renal disorders, endocrine and metabolic disorders, and drugs magnesium regulates the excitability of nerve and muscle membranes, so the clinical manifestations from hypomagnesemia are characterized by neuromuscular hyperexcitability in the form of latent tetany or spontaneous carpo-podal spasms.
Source: Mediserve‘s Medical Emergencies in Pediatrics.