Physiological significance of sharp wave transients on EEG recordings of healthy pre-term and full-term neonates.

One EEG sleep cycle was selected from each of ninety-four 3 h studies on 52 healthy neonates from 29 to 43 weeks post-conceptional ages (CA) (28 pre-term (PT)/24 full-term infants (FT); 51 are normal up to at least 18 months of age). Each record was reviewed to identify sharp wave transients (SWTs). No spike discharges were noted. 364 SWTs were tabulated in terms of amplitude, morphology, left:right predominance, anatomical site and EEG sleep state. Mean number of SWTs per hour for full-term, pre-term, and pre-term at post-conceptional term age (PTT) infants were 11.7 (+/- 12), 10.0 (+/- 7), and 13 (+/- 10). Mean amplitudes (microV) were 98.8 (+/- 23.2), 84.9 (+/- 38.3), and 99.4 (+/- 28.8) for FT, PT, and PTT infants respectively. FP1, FP2, T4 and C3 accounted for 94%, 83% and 84% of SWT sites for FT, PT and PTT groups, respectively. Biphasic waves were noted more frequently, and triphasic waves almost exclusively in PT infants (chi 2 = 130.8, P = 0.001). Spearman correlations were significant for amplitude of SWTs with CA (and r = 0.45, P = 0.0001). Significant differences (ANOVA) were found, for instance, between SWT frequency with the site and sleep state (R2 = 0.63, P = 0.0001) between SWT amplitude with sleep state and morphology (R2 = 0.59, P = 0.0001). Brain maturation alters the location and morphology of SWTs in healthy neonates. Descriptions of SWTs on EEG recordings of healthy neonates will improve the assessment of encephalopathic recordings of infants studied for clinical reasons.