Quantitative EEG in ischemic stroke: correlation with functional status after 6 months

Objective: Stroke is a major cause of adult-onset disability and dependency. We investigated whether EEG parameters are of prognostic value for functional outcome 6 months after ischemic stroke.

Methods: One-hundred and ten patients presenting with acute ischemic stroke and persistent neurological deficits at EEG recording were incrementally included. Clinical characteristics, volume of ischemia and EEG parameters were correlated with functional outcome assessed with the modified Rankin Scale (mRS) score. Predictive values for disability, dependency and death were calculated using receiver operating characteristic (ROC) curves and logistic regression modeling.

Results: The EEG pairwise derived Brain Symmetry Index (pdBSI) and (delta+theta)/(alpha+beta) ratio (DTABR) were significantly correlated with the modified Rankin Scale (mRS) score at month 6 (Spearman ρ=0.46 and ρ=0.47, respectively, p<0.0005 for both). NIHSS (OR 1.15, 95% CI 1.04-1.27, p=0.005) and pdBSI (OR 4.07, 95% CI 1.32-12.58, p=0.015) were independently associated with disability 6 months after stroke. Dependency was independently indicated by NIHSS (OR 1.22, 95% CI 1.09-1.37, p<0.0005) and DTABR (OR 2.25, 95% CI 1.16-4.37, p=0.016). Six month mortality was independently indicated by age at stroke onset (OR 1.18, 95% CI 1.05-1.32, p=0.007), NIHSS (OR 1.11, 95% CI 1.03-1.21, p=0.009) and DTABR (OR 2.04, 95% CI 1.08-3.85, p=0.028).

Conclusions: EEG in the subacute setting of ischemic stroke may be of prognostic value for disability, dependency and death after 6 months.

Significance: Early prognostication of functional outcome after stroke is relevant to efficient rehabilitation management to enhance recovery and minimize long-term disability.