The value of the EEG as a predictor of outcome in term infants with hypoxic-ischemic encephalopathy (HIE) was determined in a study at Cork University Maternity Hospital and St Vincent’s University Hospital, Dublin, Ireland. Continuous video-EEG was recorded from <6 hours to 72 hours after delivery. One-hour EEG segments at 6, 12, 24, and 48 hours of age were analyzed visually, and neurologic outcome was assessed at 24 months. Of 44 infants who completed follow-up, 20 (45%) had abnormal neurodevelopmental outcomes. Clinical Sarnat scoring at 24 hours classified 18 infants with grade I HIE, 17 with grade II, and 9, grade III. EEG abnormalities were greatest on the earliest recordings of all cases and improved with time. Best predictive ability occurred at 6 hours of age. Normal/mildly abnormal EEG at 6, 12, or 24 hours had 100% positive predictive values for normal outcome, and negative predictive values of 67% to 76%. At 24 hours, the number of infants assigned to each EEG grade was 6 normal, 11 moderately abnormal, 9 severe, and 3 isoelectric. Background amplitude of <30 mcV, interburst interval of >30 sec, electrographic seizures, and absence of sleep-wake cycling at 48 hours were associated with abnormal outcome. Normal EEG within 6 hours after birth was associated with normal neurodevelopment at 24 months. [1]

COMMENT. Early EEG is a reliable predictor of neurodevelopmental outcome in term infants with HIE. EEG abnormalities evolving in the first 48 hours of life predict a poor outcome, and normal EEG at 6 hours of age is predictive of a normal outcome at 2 years. Early EEG study at 6 to 12 hours and repeat study at 48 hours should predict outcomes successfully in 95% of cases. EEG seizures detected by continuous monitoring correlate with poor outcome.

Neonatal EEG in periventricular leukomalacia (PVL). In a study at Anjo Kosei Hospital and other centers in Japan, EEG findings varied with the severity of PVL (noncystic, localized cystic, and extensive cystic) and the timing of recording. To detect PVL, >2 EEG recordings are recommended, 1 within 48 hours after birth for acute stage abnormalities, and 1 in the second week to detect chronic stage abnormalities. [2]

Dr Joseph J Volpe, in an editorial, comments that the report by Kidokoro and associates shows that the EEG may be important in diagnosis, timing, and severity of PVL [3], but the infants in this study were a severely affected subset of the premature population. In general, MRI in the neonatal period is the most effcctive method of identifying white-matter injury in premature infants. Ultrasonography is useful in detection of severe injury. The timing of the insult by EEG is useful in the decision to order potentially protective interventions such as antioxidants etc.