Stroke causes a transient imbalance of interhemispheric information flow in EEG during non-REM sleep

Publication date: July 2018
Source:Clinical Neurophysiology, Volume 129, Issue 7
Author(s): Frederic Zubler, Andrea Seiler, Thomas Horvath, Corinne Roth, Silvia Miano, Christian Rummel, Heidemarie Gast, Lino Nobili, Kaspar A. Schindler, Claudio L. Bassetti
ObjectiveLarge-scale connectivity, especially interhemispheric connections, plays a crucial role for recovery after stroke. Here we used methods from information theory to characterize interhemispheric information flow in wake- and sleep-EEG after cerebral ischemia.Methods34 patients with unilateral ischemic stroke were included. Symbolic Transfer Entropy (STE) was applied between bipolar EEG signals on the left and the right cerebral hemisphere during polysomnographic recordings in the acute phase and 3 months after stroke.ResultsIn the acute phase, we found a sleep stage-dependent preferred interhemispheric asymmetry: during non-REM sleep the information flow was predominantly directed from the contralesional toward the ipsilesional hemisphere. This effect was greatly reduced in a follow-up recording 3 months after stroke onset.ConclusionOur findings are consistent with functional imaging studies showing a transient hyperactivity of contralesional areas after stroke. We conclude that STE is a robust method for detecting post-stroke connectivity reorganizations, and that sleep stages have to be taken into account when assessing functional connectivity.SignificanceEEG is more widely available than functional MRI. Future studies will have to confirm whether EEG derived STE can be useful in a clinical setting during rehabilitation after stroke.



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