Hypertonia, hyperreflexia, and excessive startle response in a neonate.

Following an uneventful gestation, a newborn girl presented with hypertonia, hyperreflexia, tremor, and excessive startle response. Nose tap elicited a dramatic head recoil. Her mother had similar symptoms beginning as a child that improved but persisted into adulthood. In addition, several members of mother's family died unexpectedly in infancy. Hypertonia in the newborn period indicates central nervous system dysfunction of several possible causes, most of which are associated with severe cognitive deficits and limited neurological development.