Quantitative EEG in ischemic stroke: correlation with infarct volume and functional status in posterior circulation and lacunar syndromes

Objective: The significant impact of stroke on health care results in an unmet need for efficient stroke care in resources limited environments. Practical, inexpensive and easy to obtain predictive EEG parameters have been suggested in anterior circulation syndromes. We investigated whether EEG parameters are of additional predictive value with regard to lesion volume and short-term functional outcome in lacunar (LACS) and posterior circulation (POCS) syndromes of presumed ischemic origin.

Methods: Sixty (60) patients presenting with LACS or POCS were incrementally included. EEG parameters were correlated with volume of ischemia and functional status. Predictive values for definite stroke and unfavourable outcome were calculated using receiver operating characteristic (ROC) curves and logistic regression modelling.

Results: The pairwise derived brain symmetry index (pdBSI) emerged as independent predictor for definite stroke in patients presenting with LACS and POCS (odds ratio (OR) 2.69, 95% confidence interval (CI) 1.24-5.82, p=0.012) and in patients with a National Institutes of Health Stroke Scale (NIHSS) score of 0 at EEG recording (OR 7.67, 95% CI 1.24-47.32, p=0.026). In ROC analysis, the (delta+theta)/(alpha+beta) ratio (DTABR) predicted unfavourable outcome at day 7 with an accuracy of 83% in LACS but not in POCS. In logistic regression, unfavourable outcome in LACS was predicted by nominal NIHSS with marginal significance (OR 1.84, 95% CI 1.00-3.37, p=0.05), while in categorical modelling, DTABR>2.4 displayed a statistically significant ominous odd ratio of 13.00 (95% CI 1.11-152.35, p=0.041) with identical predicted and observed values.

Conclusions: EEG may be of additional value by confirming or excluding definite stroke after resolution of symptoms in lacunar and posterior circulation syndromes of presumed ischemic origin and prognosticating short-term functional status in lacunar syndrome.

Significance: These findings may have an impact on stroke care.