Abstracts

Rationale: Hypothermia can alter eeg patterns and terminate seizures. How this will affect seizures in the neonate is unknown. We characterize seizures and rhythmic activity during whole body hypothermia. Methods: Therapeutic whole-body hypothermia was performed in 56 infants ? 36 wks gestation transported to our hospital within 6 hrs of life with either severe acidosis or perinatal complications at birth, and who had moderate or severe encephalopathy [Shankaran et al 2005]. Infants were cooled to an esophageal temperature of 33.5 C for 72 hours, then rewarmed at 0.5 C/hr to 36.5 C. Continuous video-EEG monitoring was initiated within 24hrs of life and continued throughout cooling and rewarming. 53 patients had EEGs available for review MA & TW & TT. Medical records were reviewed for administration of anticonvulsants. Results: 15 of 53 patients had electrographic seizures. 4/15 had received Phenobarbital prior to start of video EEG monitoring. Seizures were detected on EEG within 37 hrs of life (5-37hr). 8/15 had seizures within 24 hours of life. 13/15 had seizures within 30 hours of life. Median seizure duration was 220 seconds with range 30-845 sec. No de novo seizure occurred during rewarming. In some recordings, rhythmic delta activity were noted in the same channels that subsequently would have electrographic seizures. This rhythmic activity could also have some features of a seizure such as buried spikes, sharp morphology or slight changes in morphology and frequency without the full evolution of a typical seizure. This activity was not seen when seizures were controlled for at least 24 hours. Conclusions: Characteristics of seizures during hypothermia are similar to what has been described previously in neonates. Certain rhythmic patterns can be seen in association with seizures. Further research is needed to determine whether treatment of particular types of rhythmic activity improves clinical outcome.