A novel quantitative EEG injury measure of global cerebral ischemia

Objective: To develop a novel quantitative EEG (qEEG) based analysis method , cepstral distance (CD) and compare it to spectral distance (SD) in detect ing EEG changes related to global ischemia in rats. Methods: Adult Wistar rats were subjected to asphyxic-cardiac arrest for sh am, 1, 3, 5 and 7 min (n = 5 per group). The EEG signal was processed and f itted into an autoregressive (AR) model. A pre-injury baseline EEG was comp ared to selected data segments during asphyxia and recovery. The dissimilar ities in the EEG segments were measured using CD and SD. A segment measured was considered abnormal when it exceeded 30% of baseline and its duration was used as the index of injury. A comprehensive Neurodeficit Score (NDS) a t 24 h was used to assess outcome and was correlated with CD and SD measure s. Results: A higher correlation was found with CD and asphyxia time (r = 0.81 , P < 0.001) compared to SD and asphyxia time (r = 0.69, P < 0.001). Correl ation with cardiac arrest time (MAP < 10 mmHg) showed that CD was superior (r = 0.71, P < 0.001) to SD (r = 0.52, P = 0.002). CD obtained during globa l ischemia and 90 min into recovery correlated significantly with NDS at 24 h after injury (Spearman coefficient = -0.83, P < 0.005), and was more rob ust than the traditional SD (Spearman coefficient = -0.63, P <: 0.005). Conclusion: The novel qEEG-based injury index from CD was superior to SD in quantifying early cerebral dysfunction after cardiac arrest and in providi ng neurological prognosis at 24 h after global ischemia in adult rats. Stud ying early qEEG changes after asphyxic-cardiac arrest may provide new insig hts into the injury and recovery process, and present opportunities for the rapy. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.