Positive rolandic sharp waves in neonatal EEG; types and significance.

We describe two types of electropositive rolandic sharp waves (PRS) in EEGs of premature infants with markedly different prognostic implications. Type A occurs singly and is clearly distinguished from the background activity; type B appears in bursts and blends somewhat with the background. Among neonates recorded at less than 35 weeks' conceptional age, 21% of those with type A only had normal neurological examinations or only minor sequelae at age 2 years. When type B appeared in the same tracing as type A, the percentage with normal examinations or minor sequelae at 2 years rose to 86%. Only 42% of those without type A or B had favourable 2 year evaluations. For those recorded at 35 weeks or later, normal or minor sequelae were found at 2 years as follows: type A only - 57%; type B only - 75%; types A and B - 92%; no positive rolandic sharp waves - 53%. We conclude that in both age groups type B PRS confer a relatively favourable prognosis and are more prognostically influential than type A. Patients with either type A or no PRS have less favourable outcomes than those with type B. Finally, although the majority of patients with intraventricular haemorrhage have type A PRS, IVH occurred in only 50% of patients with type A PRS when recorded before 35 weeks' conceptional age.