Sources of abnormal EEG activity in brain infarctions

Area of Science:

• Neuroscience
• Medical Imaging
• Neurology

Background:

• Stroke is a leading cause of long-term disability, necessitating advanced diagnostic tools.
• Electroencephalography (EEG) provides insights into brain electrical activity, but source localization is crucial for precise localization of abnormalities.
• Understanding EEG patterns in different stroke evolution stages can improve diagnosis and prognosis.

Purpose of the Study:

• To investigate EEG source localization in patients with stroke at various stages of evolution.
• To correlate EEG abnormalities with stroke pathology, including edema and ischemic penumbra.
• To identify specific EEG frequency bands associated with different stroke phases.

Main Methods:

• Recorded EEG from 16 stroke patients across acute, subacute, and chronic stages.
• Utilized frequency domain VARETA (Variable Electric Response Imaging) to calculate EEG sources at 0.39 Hz intervals.
• Analyzed EEG power and source locations in relation to lesion site, edema, and ischemic penumbra.

Main Results:

• The delta band was the main source of abnormal activity in 67% of acute/subacute stroke patients with edema.
• All patients exhibited abnormal theta band activity, with sources coinciding with edema and/or ischemic penumbra.
• Cortical and corticosubcortical infarcts showed abnormal EEG sources in the cortex surrounding the lesion, with decreased EEG power at the infarct site.

Conclusions:

• EEG source analysis, particularly in the delta and theta bands, can help identify and localize brain dysfunction in stroke.
• Abnormal delta band activity is characteristic of acute/subacute stroke with edema.
• Theta band abnormalities are consistently observed in stroke and are linked to edema and ischemic penumbra, offering potential biomarkers.