# Case Report: Electro-cortical network effects of an acute stroke revealed by high-density electroencephalography

## TL;DR

This case study shows how high-density EEG can reveal both local and distant brain network effects caused by a stroke.

## Contribution

The study demonstrates the feasibility of using HD-EEG to detect network-level effects of acute stroke.

## Key findings

- HD-EEG detected delta-range slowing beyond the stroke site, including perilesional and distant regions.
- Delta connectivity was observed in the stroke hemisphere, suggesting network-level diaschisis.
- The findings suggest HD-EEG could be useful for personalized stroke-network mapping in acute cases.

## Abstract

Focal lesions such as a stroke can cause not only local effects but also distant effects in anatomically intact regions. The impact of stroke lesions on brain networks has been mapped using neuroimaging techniques such as functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). In the present study, we established the feasibility of detecting network dysfunction at the electrocortical level using high-density electroencephalography (HD-EEG).

We studied brain function using HD-EEG in a patient with an acute left middle cerebral artery stroke. Slowing in the delta range was present beyond the ischemic focus, extending to the perilesional regions as well as distant regions. There was also delta connectivity in the stroke hemisphere with slowing affecting mainly distant regions that were interconnected with the site of the ischemic region (i.e., network-level diaschisis), although this was not statistically significant.

This case study illustrates the feasibility of using HD-EEG to map local and distant electrical activity consequences of an acute stroke on cortical functions. Such a technique could be clinically useful to improve personalized stroke-network mapping in patients with acute cortical lesions.