Predicting outcome in acute stroke: a comparison between QEEG and the Canadian Neurological Scale.

OBJECTIVE: To determine and compare the predictive value of quantitative EEG (QEEG) and the Canadian Neurological Scale (CaNS), in patients with an acute cerebral stroke. METHODOLOGY: Twenty-eight patients were studied with the diagnosis of acute ischemic middle cerebral artery stroke, within the first 72 hours of clinical evolution. Thirty-seven EEGs and clinical evaluations were collected: 13 during the first 24 hours after stroke onset, 9 between 24-48 hours and 15 between 48-72 hours. The QEEG studied variables were: the Z values (maximum, minimum and the Z medians from the 5 nearest points to each one) of absolute energies (AE) from the 4 classic frequencies bands. The clinical scale showed a smaller percent of correct prognosis than QEEG variables. CONCLUSIONS: QEEG was demonstrated to be a powerful tool to predict the degree of residual functional disabilities after an acute ischemic stroke and showed a higher prognostic value than CaNS when they are performed within the first 72 hours of brain infarct.

Source analysis of alpha rhythm reactivity using LORETA imaging with 64-channel EEG and individual MRI.

Conventional EEG and quantitative EEG visual stimuli (close-open eyes) reactivity analysis have shown their usefulness in clinical practice; however studies at the level of EEG generators are limited. The focus of the study was visual reactivity of cortical resources in healthy subjects and in a stroke patient. The 64 channel EEG and T1 magnetic resonance imaging (MRI) studies were obtained from 32 healthy subjects and a middle cerebral artery stroke patient. Low Resolution Electromagnetic Tomography (LORETA) was used to estimate EEG sources for both close eyes (CE) vs. open eyes (OE) conditions using individual MRI. The t-test was performed between source spectra of the two conditions. Thresholds for statistically significant t values were estimated by the local false discovery rate (lfdr) method. The Z transform was used to quantify the differences in cortical reactivity between the patient and healthy subjects. Closed-open eyes alpha reactivity sources were found mainly in posterior regions (occipito-parietal zones), extended in some cases to anterior and thalamic regions. Significant cortical reactivity sources were found in frequencies different from alpha (lower t-values). Significant changes at EEG reactivity sources were evident in the damaged brain hemisphere. Reactivity changes were also found in the "healthy" hemisphere when compared with the normal population. In conclusion, our study of brain sources of EEG alpha reactivity provides information that is not evident in the usual topographic analysis.

QEEG prognostic value in acute stroke.

The objective of our study is to determine the predictive value of QEEG in patients suffering from an acute ischemic cerebral stroke. Twenty-eight patients were studied within the first 72 hours of clinical evolution of middle cerebral artery territory ischemic stroke. Thirty-seven QEEG recordings were obtained: 13 in the first 24 hours after cerebral stroke onset, 9 between 24-48 hours and 15 between 48-72 hours. Absolute Energies (AE) were the QEEG selected variables for statistical analysis: first, AE Z values were calculated using the Cuban QEEG norms, then the maximum and minimum AE Z values were selected within each frequency band and total power. The medians of the five neighboring Z values were also chosen. Regression models were estimated using the RANKIN scores as dependent variables and the selected QEEG variables as independent, then outcome predictions at hospital discharge and 3 months later were calculated. Percentages of concordance and errors between the estimated and real outcome scores were obtained. Alpha and theta AE were the best predictor for short-term outcome and delta AE for long-term outcome. We conclude that QEEG performed within the first 72 hours of ischemic stroke might be a powerful tool predicting short- and long-term outcome.