Abstracts

Rationale: Hypothermia has been recognized as standard treatment after cardiac arrest. There are few data about the significance of findings in continuous EEG monitoring during therapeutic hypothermia. Methods: We performed a retrospective analysis on all patients that underwent therapeutic hypothermia after cardiac arrest. We reviewed data from January 2008 to December 2009. Every patient underwent continuous EEG monitoring. Board certified neurophysiologists interpreted EEG. Initial pattern of EEG background activity, latency of first epileptiform activity, latency of electrographic seizure and the prognosis were analyzed. Prognosis, at the time of discharge, was classified by utilizing Glasgow-Pittsburgh cerebral performance categories (CPC), dividing performance into five categories (1: conscious and alert with a normal function or slight disabilities, 2: conscious and alert with the moderate disabilities, 3: conscious with the severe disabilities, 4: comatose or persistent vegetative state, 5: brain death or death from other causes). Multiple comparison statistical analysis was performed using Tukey-Kramer Procedure. Results: A total of 26 patients (14 men and 12 women) were involved. All of patients were treated with standard protocol of therapeutic hypothermia, in which target body temperature of 32 degrees Celsius for initial 24 hours followed by gradual warming for next 24 hours. The mean age was 60.3 years, ranging from 32 to 87 with standard deviation (SD) of 17.5. Mean duration of monitoring was 86.8 hours, ranging from 4.9 to 381.1 hours with SD of 70.0. Initial EEG background was the severe diffuse suppression in 10 patients, suppression-burst pattern in 4 patients, alpha or theta coma pattern in 3 patients, generalized slow wave in 5 patients and generalized periodic epileptiform discharges (GPEDs) in 4 patients. Epileptiform activity was found in 12 patients (46.2%). Generalized spike or sharp wave in suppression-burst pattern was found in 9 patients, GPEDs were found in 7 patients. Tri- or diphasic sharp wave transients were found in 2 patients. Focal spike or sharp wave activity was found in 1 patient. Mean latency of 1st epileptiform activity onset was 17 hours 47 minutes (ranging from 0 to 87 hours 50 minutes). Electrographic seizures were recorded in 2 patients (7.7%). Both were generalized seizure arising from the background of suppression-burst pattern. Mean latency of 1st seizure onset was 11 hours 58 minutes (ranging from 2 hours 30 minutes to 21 hours 26 minutes). 21 patients had a CPC score of 5, 1 patient had 4, 2 patients had 3, none had 2 and 2 patients had 1. An initial background with the generalized slow wave was correlated with better prognosis compared with other types of background activity (p=0.017). The presence of epileptiform activity did not correlate with the prognosis. Conclusions: The majority of patients (21 of 26) failed to survive despite hypothermia. Continuous EEG background with generalized slow wave activity, but not epileptiform activity, correlated with survival in this study.