Correlation of Quantitative EEG in Acute Ischemic Stroke With 30-Day NIHSS Score

Abstract

Background and Purpose-Magnetic resonance imaging (MRI) methods such as diffusion-(DWI) and perfusion-weighted (PWI) imaging have been widely studied as surrogate markers to monitor stroke evolution and predict clinical outcome. The utility of quantitative electroencephalography (qEEG) as such a marker in acute stroke has not been intensively studied. The aim of the present study was to correlate ischemic cortical stroke patients' clinical outcomes with acute qEEG, DWI, and PWI data. Materials and Methods-DWI and PWI data were acquired from 11 patients within 7 and 16 hours after onset of symptoms. Sixty-four channel EEG data were obtained within 2 hours after the initial MRI scan and 1 hour before the second MRI scan. The acute delta change index (aDCI), a measure of the rate of change of average scalp delta power, was compared with the National Institutes of Health Stroke Scale scores (NIHSSS) at 30 days, as were MRI lesion volumes. Results-The aDCI was significantly correlated with the 30-day NIHSSS, as was the initial mean transit time (MTT)abnormality volume (ϭ0.80, PϽ0.01 and ϭ0.79, PϽ0.01, respectively). Modest correlations were obtained between the 15-hour DWI lesion volume and both the aDCI and 30-day NIHSSS (ϭ0.62, PϽ0.05 and ϭ0.73, PϽ0.05, respectively). Conclusions-In this small sample the significant correlation between 30-day NIHSSS and acute qEEG data (aDCI) was equivalent to that between the former and MTT abnormality volume. Both were greater than the modest correlation between acute DWI lesion volume and 30-day NIHSSS. These preliminary results indicate that acute qEEG data might be used to monitor and predict stroke evolution.

Quantitative EEG for the Detection of Brain Ischemia

“…Th e addition of EEG data improved the predictive value to 85% (for both raw and quantitative EEG) [24]. Th e acute delta change index correlates with 30-day NIHSS as accurately as initial mean transit time on MRI and actually better than initial DWI volume (emphasizing the link between qEEG parameters and blood fl ow) [35]; other parameters such as the delta/alpha ratio and the relative alpha percentage also correlate with the 30-day NIHSS [34]. As early as 6 hours after stroke, the pdBSI correlates with the 1-week NIHSS.…”

“…Several parameters correlate with initial stroke severity as measured by the National Institutes of Health Stroke Scale (NIHSS) in both the acute (brain symmetry index [BSI]) [19,31] and subacute periods (relative alpha percen tage, relative alpha-beta percentage, relative delta-theta percentage, delta/alpha ratio, delta-theta/alpha-beta ratio, and global pairwise derived BSI [pdBSI]) [32][33][34]. qEEG parameters correlate with the volume of infarc tion on MRI, such as the acute delta change index [35], global pdBSI [32], relative alpha percentage, relative alpha-beta percentage, relative delta-theta percentage, delta/alpha ratio, and delta-theta/alpha-beta ratio [36]. In the case of subcorti cal infarcts, both the delta-theta/alpha-beta ratio and the pdBSI correlate surprisingly well with infarct volumes, possibly related to the consequences of diaschisis on CBF in lacunar brainstem infarcts [33,36].…”

The Utility of EEG, SSEP, and Other Neurophysiologic Tools to Guide Neurocritical Care

“…Measuring the rate of change in average delta power yields a modest correlation with volume of initial mean transit time (r00.79; p<0.01), follow-up diffusion-weighted imaging volume (0.62; p< 0.05), and 30-day National Institutes of Health Stroke Scale (NIHSS) score (r 00.80; p < 0.01) [112]. Subsequent quantitative EEG measures (subacute delta-alpha power ratio and relative alpha power) strongly correlated with 30-day NIHSS (r00.91; p<0.001 and r00.82; p<0.01, respectively) [113].…”

Can Quantitative EEG Reliably Predict Deterioration from Delayed Cerebral Ischemia Secondary to Vasospasm?

“…Prior studies have demonstrated that EEG changes can be seen with brain that is underperfused [13][14][15]. Actually, with decreasing perfusion sequential EEG changes are observed while brain tissue initially is in a state of reversible and then later irreversible brain injury [16].…”