The neonatal EEG: Statistical studies and prognostic value in full-term and pre-term babies

Abstract

This study is based on 691 neonatal EEGs of 270 children whose clinical course was followed from 3 to 14 years: 110 were born at 36–38 weeks of gestational age (pre-term) and 160 were born at or after 39 weeks (full-term). Statistical study of various EEG patterns, factors relating to normality or abnormality, was accomplished by comparing the children with favourable outcome (normal and those with minor sequelae) with the children with unfavourable outcome (major sequelae and early death). The favourable prognostic significance of a normal neonatal EEG is clear ( P < 0.001), in pre-term and full-term babies, but criteria of normality are different in the two groups. Some specific EEG patterns recorded during the first days of life (such as inactive or paroxysmal EEGs) or some associations of specific EEG patterns (such as low voltage with theta rhythms) are of grave prognosis in pre-term and full-term babies. Absence of lability of the tracing and persistent absence of occipital activity are also prognostically unfavourable in both pre-term and full-term babies. Persistence of some abnormal EEG patterns (such as slowness or low voltage) or of abnormal superimposed activity (such as abnormal anterior activity, fast spikes) after the second week, are prognostically unfavourable in full-term babies only and not in pre-term ones. The presence of paroxysmal electrical discharges in neonatal EEGs is of grave significance, but prognosis depends upon inter-ictal EEGs. Very few EEG patterns raise the probability of minor sequelac, and only in full-term babies.