Circumscribed midline EEG activity in neurologically normal neonates

Activity occurring predominantly at or circumscribed to the midline electrodes Fz, Cz and Pz was examined in 18 neurologically normal neonates of 27-42 weeks conceptional age (CA). Admixtures of delta and beta activity, which sometimes resembled delta brushes and rhythmical theta activity, of less than three seconds duration were seen during the suppressed portions of tracé alternant or discontinue quiet sleep in 27-32 week CA neonates. Single sharp midline waves, or entrained 4-8 Hz midline activity of 3 seconds or less duration, were found in preterm neonates (33-36.5 weeks CA) only in quiet sleep, whereas these phenomena were also present in active sleep in term (38.5-42 weeks CA) infants. Midline alpha activity with a duration less than or equal to 3 seconds was found initially in quiet sleep in the 33-36.5 week CA infants and then exclusively in active sleep in the term infants. These data consolidate and refine the existing literature on normal neonatal midline activity through the identification of the temporal and topographical characteristics of a spectrum of normal activity in infants of 32 weeks CA and older.