NEUROPHYSIOLOGICAL ASSESSMENT OF BRAIN-FUNCTION AND MATURATION .1. A MEASURE OF BRAIN ADAPTATION IN HIGH-RISK INFANTS

Neurophysiologic assessments using EEG/polysomnographic studies permit the clinician to recognize expected patterns of brain maturation in t he healthy neonate. By comparison, one can detect encephalopathic beha viors of newborns who are medically at risk. Severe physiologic expres sions of encephalopathy are associated with neuropathologic lesions on postmortem examinations, brain lesions documented on neuroimaging stu dies, and major neurodevelopmental sequelae of survivors. However, suc h patterns are observed for only a minority of high risk neonates; les s severe encephalopathies occur more frequently in neonates without ev idence of brain lesions on imaging studies who either recover from med ical illness or who manifest no findings of neurological dysfunction. These subtle and persistent brain disorders are obviously more difficu lt to detect and grade. This is specifically relevant for preterm infa nts in whom various degrees of encephalopathy may exist, but whose phy siologic behaviors must be distinguished from expected behavioral and neurophysiologic patterns of prematurity. Neonates may express brain d ysfunction as altered rates of brain maturation, as compared with expe cted patterns for a given conceptional age. Neurophysiologic expressio ns of brain dysmaturity, either from prenatal and/or postnatal stresse s, may actually occur in a substantially larger segment of the high ri sk neonatal population than has been anticipated. EEG-sleep studies ca n serve as a noninvasive neurophysiologic probe of brain organization and maturation to extend clinical observations to assess the severity and persistence of brain dysfunction in a neonate who may be at risk f or later neurodevelopmental compromise. (C) 1997 by Elsevier Science I nc.