EEG Characteristics of Full-Term Neonatal Seizures Confirmed by Electrical Seizure

Hwang, Hee; Lim, Byung Chan; Choi, Ji Eun; Choi, Chang Won; Kim, Beyong Il; Chae, Jong Hee; Kim, Ki Joong; Hwang, Yong Seung

Abstract

PURPOSE
Neonatal seizure is the most significant parameter of neurological insult, however its pathophysiology and diagnostic consensus is still controversial. We performed this study to investigate the characteristics of electroencephalogram (EEG) in neonatal seizures, to validate the efficacy of radiological studies, and to estimate the occurrence of further subsequent epileptic seizures.
METHODS
Seventeen patients with full-term neonatal seizure confirmed by electrical seizure were enrolled. Mean birth weight is 3.29 kg, and mean duration of follow-up is 22.7 months. Medical records and EEG were retrospectively reviewed.
RESULTS
Subtle seizure is the most common seizure type: subtle seizure in 6 (35%), subtle seizure with focal clonic seizure in 2(12%). In 12 patients (71%), abnormal background activities were observed, and trace discontinua is the most common abnormal finding. Ictal EEGs were mostly localized into unilateral posterior quadrant in 11 (64%), however, the remained were localized into the frontal area. Brain USG did not reveal any abnormal finding in 9 patients (53%), whereas brain MRI didn't in 4 patients (25%). Brain MRI found abnormal findings in 5 out of 9 patients with negative brain USG result. Subsequent epileptic seizures followed in 7 patients (44%).
Conclusion
Background activity is still useful as an indirect marker of neonatal seizure. Different generation or propagation mechanism can be suggested in that ictal EEGs were often localized into the frontal area in minor portion. Brain MRI is more sensitive than brain USG, especially in case of cerebral infarct or hypoxic-ischemic encephalopathy.