The prognostic value of the electroencephalogram in premature infants.

A retrospective analysis of 184 EEGs performed during the neonatal period was accomplished on 81 premature infants (gestational age less than or equal to 36 weeks). The neurological outcome of the 64 surviving infants, considered as normal or abnormal with minor or major sequelae, was compared with the neonatal EEGs which were graded as normal, moderately or markedly abnormal. Infants whose serial EEGs were normal during the neonatal period were usually normal at follow up or suffered minor sequelae. All the children who had at least one markedly abnormal EEG suffered some type of neurological sequela or died. EEGs were classified as markedly abnormal if they contained at least one of the following patterns: isoelectric or paroxysmal backgrounds, positive rolandic sharp waves, electrographic seizures, marked interhemispheric voltage asymmetry or asynchrony or excessively slow background with a reduction or absence of the patterns expected at the particular conceptional age. A moderately abnormal EEG was of no significant prognostic value. This study also revealed the value of recording serial EEGs in the neonatal period. In many cases, markedly abnormal EEG patterns were transient and normal records were often obtained prior to the child's release from the nursery.