Electroencephalography improves the prediction of functional outcome in the acute stage of cerebral ischemia.

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Abstract
We studied the value of clinical and electroencephalographic assessment in patients with acute first-ever supratentorial ischemia in predicting functional outcome after 1 year. In 55 consecutive patients admitted after a median interval of less than 24 hours, the degree of handicap was dichotomized as moderate (Rankin grade 1, 2, or 3) or severe (Rankin grade 4 or 5). Clinical deficits were categorized according to signs of a lacunar or a cortical syndrome. Without knowledge of clinical data, electroencephalograms (EEGs) were classified according to findings predicting good or poor prognosis. The outcome after 1 year was assessed as good (Rankin grade 3 or less) or poor (Rankin grade 4 or 5 or death from stroke) and was correlated to clinical data and to EEG findings in the acute stage. Thirty patients with a moderate handicap on admission all had a good outcome (predictive value [PV] of the initial handicap, 1.00; 95% confidence interval [CI], 0.88 to 1.00). Of the 25 patients with severe handicap on admission a poor outcome occurred in 13 (PV, 0.52; 95% CI, 0.31 to 0.72). If these patients with severe handicap at baseline were subdivided according to clinical features, a lacunar syndrome predicted good outcome in 4 of 5 patients (PV, 0.80; 95% CI, 0.28 to 1.00), but a cortical syndrome predicted poor outcome in only 12 of 20 patients (PV, 0.60; 95% CI, 0.36 to 0.81). Of the 20 patients with severe handicap and a cortical syndrome at baseline, an EEG with features predicting a good prognosis correctly predicted good outcome in 6 of 7 patients (PV, 0.86; 95% CI, 0.42 to 1.00). An EEG with features predicting poor prognosis correctly predicted poor outcome in 11 of 13 patients (PV, 0.85; 95% CI, 0.55 to 0.98). Electroencephalography improves the prediction of functional outcome in patients with a severe neurological deficit in the acute stage of cerebral ischemia. This may have implications for the design of future intervention trials in acute stroke.