EEG Power Spectrum to Predict Prognosis after Hemicraniectomy for Space-Occupying Middle Cerebral Artery Infarction

Abstract

Background: Early prediction of outcome after decompressive surgery for space-occupying middle cerebral artery (MCA) infarction is needed to guide further therapy. Here we applied spectral EEG analysis to determine the prognosis early after hemicraniectomy, while the patient is still treated in the intensive care unit. Methods: Continuous EEG monitoring following hemicraniectomy was performed in 10 patients with space-occupying MCA infarction. All patients were analgosedated and mechanically ventilated. The first 6 h of monitoring after surgery were evaluated by spectral analysis. Outcome measures included Glasgow Outcome Scale (GOS), Level of Consciousness Scale (LOC) and National Institute of Health Stroke Scale (NIHSS) at discharge. Outcome after 3 months was assessed by modified Rankin Scale. Results: Six patients displayed a peak at 5–10 Hz in the EEG power spectrum. All these patients had a GOS score of 3 and an LOC score ≧7 at discharge. In contrast, the 4 patients without faster EEG activity had a GOS of 2 and LOC ≤6. GOS (r = 1, p < 0.001), LOC (r = 0.89, p = 0.001) and NIHSS (r = –0.8; p < 0.01) at discharge significantly correlated with the presence of 5- to 10-Hz activity, but not with age, time to hemicraniectomy, duration of hospital stay or baseline NIHSS scores. Outcome after 3 months significantly correlated with age (r = 0.67; p < 0.05) and the presence of faster EEG activity (r = –0.76; p < 0.01). Conclusions: Spectral analysis in the subacute phase following hemicraniectomy may represent a parameter to predict early regain of consciousness and thus the capability and potential for further rehabilitation and favorable outcome.