Quantitative EEG indices of sub-acute ischaemic stroke correlate with clinical outcomes

OBJECTIVE We investigated the ability of quantitative electroencephalography (QEEG) measures in sub-acute stroke to assist monitoring or prognostication of stroke evolution. QEEG indices and National Institutes of Health Stroke Scale (NIHSS) scores were compared. METHODS Ischaemic cortical stroke patients were studied. Resting, 62-channel EEG and NIHSS score were acquired at 49+/-3h post-symptom onset, and NIHSS administered at 30+/-2 days post-stroke. Mean power was calculated for delta (1-4 Hz), theta (4.1-8 Hz), alpha (8.1-12.5 Hz) and beta (12.6-30 Hz) frequency bands, using a 62-channel electrode array and a 19-channel subset. RESULTS Thirteen patients (6 male, median age 66, range 54-86 years) were studied. Sub-acute delta:alpha power ratio (DAR; r=0.91, P<0.001), relative alpha power (r=-0.82, P<0.01), and NIHSS score (r=0.92, P<0.001) each were significantly correlated with 30-day NIHSS score. The former two significant correlations were upheld in 19-channel EEG data. QEEG measures involving theta or beta power were not significantly correlated with NIHSS scores. CONCLUSIONS QEEG measures such as DAR demonstrate potential to augment bedside assessment of cerebral pathophysiology and prognostication of stroke evolution. A standard, 19-channel array seems adequate for these purposes. Future studies in larger samples should investigate the potential effects on these measures of sleep state and possible causes of artefacts. SIGNIFICANCE QEEG measures from a standard number of electrodes, if available rapidly and robust to potential artefacts, may inform future management of stroke patients.

[1]  L. Murri,et al.  Evaluation of acute ischemic stroke using quantitative EEG: A comparison with conventional EEG and CT scan , 1998, Neurophysiologie Clinique/Clinical Neurophysiology.

[2]  Michel J A M van Putten,et al.  Continuous Quantitative EEG Monitoring in Hemispheric Stroke Patients Using the Brain Symmetry Index , 2004, Stroke.

[3]  K. Nagata,et al.  Topographic Electroencephalographic Study of Cerebral Infarction Using Computed Mapping of the EEG , 1982, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[4]  Don M. Tucker,et al.  Localizing Acute Stroke-related EEG Changes:: Assessing the Effects of Spatial Undersampling , 2001, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[5]  James N. Davis,et al.  Interrater reliability of the NIH stroke scale. , 1989, Archives of neurology.

[6]  H. Semlitsch,et al.  A solution for reliable and valid reduction of ocular artifacts, applied to the P300 ERP. , 1986, Psychophysiology.

[7]  M R Nuwer,et al.  Early detection of vasospasm after acute subarachnoid hemorrhage using continuous EEG ICU monitoring. , 1997, Electroencephalography and clinical neurophysiology.

[8]  H. Jasper,et al.  The ten-twenty electrode system of the International Federation. The International Federation of Clinical Neurophysiology. , 1999, Electroencephalography and clinical neurophysiology. Supplement.

[9]  Correlation of EEG activities between slow-wave sleep and wakefulness in patients with supra-tentorial stroke , 2005, Brain Topography.

[10]  P D Lyden,et al.  A Modified National Institutes of Health Stroke Scale for Use in Stroke Clinical Trials: Preliminary Reliability and Validity , 2001, Stroke.

[11]  B. Cohen,et al.  Quantification of computer analyzed serial EEGs from stroke patients. , 1976, Electroencephalography and clinical neurophysiology.

[12]  I Kanno,et al.  Regional correlations between the EEG and oxygen metabolism in dementia of Alzheimer's type. , 1997, Electroencephalography and clinical neurophysiology.

[13]  Stephen E. Rose,et al.  Rapid EEG changes indicate reperfusion after tissue plasminogen activator injection in acute ischaemic stroke , 2006, Clinical Neurophysiology.

[14]  E. Bravo-Fernandez,et al.  Automated electroencephalographic analysis as a prognostic indicator in stroke , 1977, Medical and Biological Engineering and Computing.

[15]  M R Nuwer,et al.  Evaluation of stroke using EEG frequency analysis and topographic mapping , 1987, Neurology.

[16]  K. Jordan,et al.  Emergency EEG and Continuous EEG Monitoring in Acute Ischemic Stroke , 2004, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[17]  J R Ives,et al.  Clinical applications of spectral analysis and extraction of features from electroencephalograms with slow waves in adult patients. , 1973, Electroencephalography and clinical neurophysiology.

[18]  M. Kaste,et al.  Visual and spectral EEG analysis in the evaluation of the outcome in patients with ischemic brain infarction. , 1983, Electroencephalography and clinical neurophysiology.

[19]  Ernst Fernando Lopes Da Silva Niedermeyer,et al.  Electroencephalography, basic principles, clinical applications, and related fields , 1982 .

[20]  U. Tolonen.  Parametric relationships between four different quantitative EEG methods in cerebral infarction. , 1984, Progress in brain research.

[21]  K. Nagata,et al.  Topographic electroencephalographic study with power ratio index mapping in patients with malignant brain tumors. , 1985, Neurosurgery.

[22]  Andrew L. Janke,et al.  Correlation of Quantitative EEG in Acute Ischemic Stroke With 30-Day NIHSS Score: Comparison With Diffusion and Perfusion MRI , 2004, Stroke.

[23]  E. Aubert,et al.  Predicting Outcome in Acute Stroke: A Comparison between QEEG and the Canadian Neurological Scale , 2003, Clinical EEG.

[24]  A. Janke,et al.  Improved Prediction of Final Infarct Volume Using Bolus Delay–Corrected Perfusion-Weighted MRI: Implications for the Ischemic Penumbra , 2004, Stroke.

[25]  P D Lyden,et al.  Does the National Institutes of Health Stroke Scale favor left hemisphere strokes? NINDS t-PA Stroke Study Group. , 1999, Stroke.

[26]  Eduardo Aubert,et al.  Sources of Abnormal EEG Activity in Spontaneous Intracerebral Hemorrhage , 2002, Clinical EEG.

[27]  Jan Claassen,et al.  Quantitative continuous EEG for detecting delayed cerebral ischemia in patients with poor-grade subarachnoid hemorrhage , 2004, Clinical Neurophysiology.

[28]  D. C. Howell.  Statistical Methods for Psychology , 1987 .

[29]  L. Hirsch.  Brain monitoring: the next frontier of ICU monitoring. , 2004, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[30]  Eduardo Aubert,et al.  Assessing Acute Middle Cerebral Artery Ischemic Stroke by Quantitative Electric Tomography , 2004, Clinical EEG and neuroscience.

[31]  C. Rosenberg,et al.  Electroencephalography: Basic Principles, Clinical Applications, and Related Fields, 3rd Ed. , 1994 .

[32]  R. J. Morgan,et al.  Use of a spectral ratio in lateralization of CNS lesions. , 1974, Electroencephalography and clinical neurophysiology.

[33]  T. Fernández,et al.  Sources of Abnormal EEG Activity in the Presence of Brain Lesions , 1999, Clinical EEG.