The significance of excessive rhythmic alpha and/or theta frequency activity in the EEG of the neonate

Objective: The goal of this study was to determine the significance of excessive rhythmic alpha and/or theta frequency activity in neonatal EEGs. Methods: The EEGs of 963 neonates, 26–44 weeks conceptional age (CA), performed during the years 1992–1994 at the Texas Children’s Hospital, Houston, Texas, were reviewed for the presence of excessive rhythmic alpha and/or theta frequency activity. Cases in which such activity was identified were further characterized by the presence or absence of other EEG abnormalities. The medical records of these patients and a group of control infants with normal EEGs were reviewed to identify associated pathological conditions. Results: Forty patients were identified whose EEGs revealed such activity. The CA of these patients ranged from 37 to 44 weeks. A variety of pathological conditions were seen in these patients, most commonly congenital heart disease, congenital brain anomalies and hypoxia. These conditions were not seen in the control group of infants. Twenty patients had received CNS-active drugs. The EEGs of 32 patients revealed additional abnormalities, most commonly multifocal sharp waves and episodes of voltage attenuation during slow-wave sleep. Conclusions: The results indicate that excessive rhythmic alpha and/or theta frequency activity is an abnormal finding in the newborn’s EEG.