POSITIVE TEMPORAL SHARP WAVES IN ELECTROENCEPHALOGRAMS OF THE PREMATURE NEWBORN

Positive temporal sharp waves (PTS) were studied in electroencephalogr ams (EEG) of 92 premature infants born either at 31 and 32 weeks of ge stational age, recorded during the first week of life. The infants wer e assigned either to a reference group (asymptomatic) or to one of thr ee pathologic groups (neonatal asphyxia, hypoglycemia or hypocalcemia, or periventricular leukomalacia with rolandic positive sharp waves), Regardless of the group, no significant differences in PTS criteria (m orphology, frequency, amplitude, duration and lateralization) were Fou nd between 31- and 32-week infants. The PTS observed in 558 of the asy mptomatic infants were characterized by low frequency (0.13 +/- 0.12/m in), a mean amplitude of 109.8 +/- 25.8 mu V and a mean duration of 14 8.7 +/- 35.4 ms. For PTS recorded in 72 to 758 of pathologic infants, mean duration and amplitude were significantly greater in all groups t han in asymptomatic infants, whereas frequency was significantly great er only in the group presenting with asphyxia. Discriminant analysis b ased un the three PTS criteria frequency, amplitude and duration) allo wed correct classification for only 30 to 54% of infants in the four g roups. The frequency of PTS decreased rapidly during the second week o f life in asymptomatic infants, but persisted in a larger number of in fants in the pathologic groups. This study shows that PTS have no nega tive significant with they are few in number, short in duration, moder ate in amplitude and rapidly regressive, thus probably reflecting the vulnerability of the temporal lobe during the traumatic period of birt h. However, they require attention when they are abundant and/or slow, ample or tend to persist. They may thus constitute a nonspecific resp onse to injury to an immature brain.