Frequency of neurologic disorders in the neonatal intensive care unit.

Neonatal intensive care unit survival rates have improved significantly over the past decade. This improvement primarily reflects declining mortality rates among preterm infants. Neurologic morbidity increases with prematurity and is the major predictor of long-term disability. Accordingly, concern has been expressed that the burden of neurologic dysfunction among contemporary neonatal intensive care unit survivors may be increasing. To define the trends of neurologic disorders in the contemporary neonatal intensive care unit, all 4164 admissions between 1986 and 1995 to a tertiary neonatal intensive care unit were examined. Neonatal intensive care unit admissions (413 +/- 49 per year), proportion of births at less than 37 weeks (70 +/- 3% per year), and referral patterns were stable between 1986 and 1995. Over the study period, 773 (18%) of 4164 neonatal intensive care unit infants had a total of 1062 neurologic disorders. The neonatal intensive care unit mortality rate declined from 12% in 1986 to 4.2% in 1995 (P < .01). Neurologic disorders declined, from 27% of infants born in 1986 to 12% in 1995 (P < .001): 356 had seizures (14% in 1986 to 4% in 1995; P < .001), 235 had hypoxic-ischemic encephalopathy (8% in 1986 to 4% in 1995, P < .01), and 167 had intraventricular hemorrhage (7% in 1986 to 1.4% in 1995, P < .005). Frequency of congenital or chromosomal aberration affecting the nervous system was relatively constant (4.5% per year). Despite a three-fold improvement in neonatal intensive care unit survival between 1986 and 1995, the frequency of perinatally acquired neurologic disorders declined by more than 50%.