Timing of EEG for predicting the outcome in patients with massive cerebral hemispheric infarction

Objective To determine the optimal timing of electroencephalogram (EEG) in predicting the outcome in patients with massive cerebral hemispheric infarction (MCHI) by evaluating and comparing the EEG changes during different acute stages after onset. Methods A total of 72 MCHI patients were selected to be monitored by bedside EEG at two stages: 1-3 and 4-7 d after onset, respectively. The outcome after 3 months was assessed as good [Glasgow Outcome Scale (GOS) score 3-5] or poor (GOS score 1-2). Then the predictive accuracy of EEG patterns and gradings (the Synek scale) were calculated and compared between two stages to confirm the optimal timing of prediction. Results In 72 cases, 62.50% (45/72) had good and 37.50% (27/72) had poor outcome 3 months after onset. Benign EEG patterns were protective factors for the outcome of MCHI (1-3 d: RR = 0.357, 95%CI: 0.153-0.834, Mantel-Haenszel χ2 = 6.147, P = 0.013; 4-7 d: RR = 0.240, 95%CI: 0.102-0.564, Mantel-Haenszel χ2 = 13.601, P = 0.000) and they could predict good outcome with incidence rate of 82.14% (23/28)-85.71% (30/35) and the accuracy of 62.50%-72.22% . Malignant EEG patterns at 4-7 d were risk factors for the outcome of MCHI (RR = 2.909, 95%CI: 1.611-5.253, Mantel-Haenszel χ2 = 11.110, P = 0.001), and they could predict poor outcome with incidence rate of 66.67% (16/24) and the accuracy of 73.63%. There was a significant negative correlation between the Synek scale and GOS score both during 1-3 d (rs = - 0.354, P = 0.002) and 4-7 d (rs = - 0.417, P = 0.000) after onset, indicating the higher the Synek scale was, the worse the outcome would be. The accuracy (83.33% vs 70.78%; χ2 = 4.000, P = 0.039), consistency (Kappa test: κ = 0.639, 95%CI: 0.522-0.746 vs κ = 0.406, 95%CI: 0.353-0.459; P = 0.001) and area under curves (0.86 ± 0.05, 95%CI: 0.761-0.958 vs 0.69 ± 0.07, 95%CI: 0.554-0.822; P = 0.002) of the Synek scale for prediction of long-term outcome during 4-7 d after onset were significantly higher than those during 1-3 d after onset. Conclusions EEG patterns and the Synek scale during 1-3 d after MCHI onset could be used to evaluate the severity of brain injury and to further guide medical treatment, while the Synek scale during 4-7 d after onset could be used to evaluate the long-term outcome and treatment with a high accuracy. DOI: 10.3969/j.issn.1672-6731.2015.12.005