To assess the effects of neonatal seizures on the hypothalamus and to
test clinical use of prolactin as a neonatal seizure marker, we studie
d postictal and recovery baseline serum prolactin levels in 19 neonate
s whose seizures were classified according to their clinical and EEG f
eatures. Postictal prolactin levels were obtained 30 min after the sei
zure, and recovery levels were ascertained 2-4 days later. The ratio o
f postictal prolactin level to recovery baseline level (prolactin rati
o) was used as an indicator of postictal prolactin increase. The speci
ficity and sensitivity of a prolactin ratio of >2 was compared with th
e current standard of diagnosis (seizure discharges recorded by ictal
EEG). Infants with electroclinical seizures had significantly higher p
rolactin ratios than control infants or infants with seizures without
EEG correlation. Marked prolactin increases were noted only in infants
with focal tonic seizures and temporal electrode involvement. A prola
ctin ratio of >2 had a specificity of 100% and a sensitivity of 40%. W
e conclude that neonatal seizures have variable effects on the hypotha
lamus and that the low sensitivity and the need to await recovery leve
ls limit the clinical value of prolactin ratio as a neonatal seizure m
arker.