Utility of EEG measures of brain function in patients with acute stroke

Abstract

EEG has been used to study acute stroke for decades; however, because of several limitations EEG-based measures rarely inform clinical decision-making in this setting. Recent advances in EEG hardware, recording electrodes, and EEG software could overcome these limitations. The present study examined how well dense-array (256 electrodes) EEG, acquired with a saline-lead net and analyzed with whole brain partial least squares (PLS) modeling, captured extent of acute stroke behavioral deficits and varied in relation to acute brain injury. In 24 patients admitted for acute ischemic stroke, 3 min of resting-state EEG was acquired at bedside, including in the ER and ICU. Traditional quantitative EEG measures (power in a specific lead, in any frequency band) showed a modest association with behavioral deficits [NIH Stroke Scale (NIHSS) score] in bivariate models. However, PLS models of delta or beta power across whole brain correlated strongly with NIHSS score (R(2) = 0.85-0.90) and remained robust when further analyzed with cross-validation models (R(2) = 0.72-0.73). Larger infarct volume was associated with higher delta power, bilaterally; the contralesional findings were not attributable to mass effect, indicating that EEG captures significant information about acute stroke effects not available from MRI. We conclude that 1) dense-array EEG data are feasible as a bedside measure of brain function in patients with acute stroke; 2) high-dimension EEG data are strongly correlated with acute stroke behavioral deficits and are superior to traditional single-lead metrics in this regard; and 3) EEG captures significant information about acute stroke injury not available from structural brain imaging.

Commentary: Utility of EEG measures of brain function in patients with acute stroke

“…Furthermore, restoration of cerebral blood flow following administration of a tissue plasminogen activator was associated with normalization of delta power within minutes (Finnigan et al, 2006). Wu et al (2016) report a positive correlation between ipsilesional delta power and infarct volume which appears to support previous findings indicating a relationship between delta power and cerebral blood flow following ischemic stroke. However, the relationship between beta power and impairment may reflect the importance of beta oscillations to motor function.…”

“…Recently, Wu et al (2016) investigated the capacity of EEG to capture behavioral impairment shortly following stroke. Resting state EEG recordings were performed in 25 patients between 3 and 12 days post-stroke in complex acute clinical settings.…”

“…Wu et al (2016) reported several interesting findings which provide unique insight to acute stroke neurophysiology. Here, we highlight those key findings and discuss their significance in advancing the field.…”

Early Rehabilitation After Stroke: a Narrative Review

“…In many cases, these plastic changes did not translate into functional gains. Nonetheless, research using tMS, fMRI, positron emission tomography (PET), or other novel tools such as high-density array EEG [90, 91] to understand how rehabilitation changes brain function after stroke is of great value in advancing the scientific underpinnings of the field and may aid in designing successful trials.…”

Contralesional Brain Activity in Acute Ischemic Stroke

“…Advances in digital EEG analysis have overcome limitations of specificity and provided techniques with additional diagnostic value in patients with brain infarcts. For example, interhemispheric spectral asymmetry in the 0.5–25 Hz range estimated with the Brain Symmetry Index predicted that outcome and treatment effect [7, 8], whole brain partial least square models for delta power correlated with the severity of neurological deficit [9], and ipsilateral motor cortex connectivity were associated with effects of physical therapy [10]. In studies with high density arrays, various measures of functional connectivity revealed changes in both ipsi- and contralateral hemisphere that were related to functional recovery [11, 12].…”