Seizures in the neonatal intensive care unit of the 1980s. Types, Etiologies, Timing.

A retrospective review was taken of 150 newborns with seizures evaluated at the same medical center and by the same investigator(s) from 1982 to 1987. The aims of the study were to determine in this current population the distribution of clinical seizure types, the distribution of causative etiologies, and the relation of etiology to the timing of onset of the seizures. Seizures were classified as subtle, multifocal clonic, generalized tonic, focal clonic, and myoclonic. Subtle (65% of total) and multifocal clonic seizures (54% of total) were the most common seizure types. Subtle seizures usually occurred in combination with other seizure types. Only one seizure type was related to gestational age, i.e., focal clonic seizures in the term infant. Hypoxic-ischemic encephalopathy (65% of total) was by far the most common etiology in both preterm and term infants. Seizures with hypoxic-ischemic encephalopathy occurred characteristically early in the neonatal period, i.e., 90 percent in the first 2 days of life. Moreover, 80 percent of all seizures in the first 2 days of life were related to hypoxic-ischemic encephalopathy.