Positive temporal sharp waves on EEG recordings of healthy neonates: a benign pattern of dysmaturity in pre-term infants at post-conceptional term ages.

One complete sleep cycle was selected in each of ninety-four 3 h EEG recordings on 52 healthy neonates from 29 to 43 weeks CA (28 pre-term (PT)/24 full-term (FT)); 51 who are neurodevelopmentally normal up to at least 18 months of age. Each recording was reviewed to identify positive temporal sharp waves (PTS). This wave form was compared to another commonly occurring wave form, temporal theta of prematurity (PT theta). 588 PTS and 626 PT theta observations were tabulated in terms of frequency, amplitude, morphology, left:right predominance, and sleep state at 6 post-conceptional age ranges up to term. Mean PTS for FT, PT and pre-term at post-conceptional term age (PTT) infants, respectively, were 1.5 +/- 0.85, 2.8 +/- 2.5, 2.0 +/- 1.6 per sleep cycle. PTS amplitudes (microV) were 59.7 +/- 23.5, 38.2 +/- 17.8, and 51.8 +/- 29.3. The peak incidence of PTS occurs at older post-conceptional ages than PT theta (r = 0.21, P = 0.0001). PTT infants had more PTS (chi 2 = 32.5, P = 0.001) than FT infants. Similar numbers and descriptions of PT theta were noted between neonatal groups at post-conceptional term ages. While pathological PTS waves have been described in FT neonates and infants (Chung and Clancy: Electroenceph. clin. Neurophysiol., 1991, 79: 256-263), benign PTS waves are also present on recordings of healthy pre-term and full-term neonates. PTS are electrographically similar to PT theta, but are more abundant at older post-conceptional ages in pre-term infants than full-term infants.(ABSTRACT TRUNCATED AT 250 WORDS)