Nose tapping test inducing a generalized flexor spasm: a hallmark of hyperexplexia.

The present report describes a benign disorder of neonates or young infants presenting with generalized hypertonicity accompanied by brisk muscle stretch reflexes, intermittent clonus, and exaggerated startle response. This condition is termed hyperexplexia, and may be either familial or sporadic. Two affected families are reported: Two sisters and their mother are involved in the first family; in the second family, where the parents are asymptomatic first degree cousins, all three siblings suffer from hyperexplexia of various severity. Nose tapping in infants of affected families induced a uniform reaction of facial twitching accompanied by head extension, and a generalized flexor spasm, all of which may be a hallmark of hyperexplexia. Severely hypertonic infants were treated with small doses of benzodiazepines and improved markedly, all becoming asymptomatic by two years of age. Unnecessary investigation and treatment may be avoided by sufficient awareness of possible hyperexplexia.