F72. Contralesional brain activity in acute ischemic stroke

Abstract

The non-injured, contralateral hemisphere is increasingly acknowledged in recovery from acute ischemic stroke. We estimate the value of conventional EEG recordings for identification of contralateral hemisphere involvement in relation to functional recovery. We analyzed two-minute epochs from 21 electrode EEG registrations from 18 patients with acute hemispheric ischemic stroke and compared with 18 age-matched controls. Outcome was dichotomized as good (mRS 0–2) or poor (mRS 3–5 or death) at three months. Effects of the infarct on the ipsi- and contralateral hemispheres were analyzed by the delta/alpha ratio (DAR) and two measures of functional connectivity (magnitude squared coherence (MSC) and weighted phase lag index (WPLI)). DAR was higher in patients than in controls, both in the ipsilateral and in the contralateral hemisphere (median 4.5 ± 6.7 ipsilateral and 2.4 ± 2.0 contralateral vs. 0.5 ± 0.5 in the control group, P < 0.001), indicating robust EEG changes in both lesioned and non-lesioned hemisphere. MSC and WPLI in the alpha and beta frequency bands were lower in patients than in controls in both hemispheres, indicating clear disturbances of functional connectivity (P < 0.05). In the poor outcome group, contralateral MSC and WPLI were lower than in the good outcome group, although these differences did not reach statistical significance. Short conventional EEG measurements show robust changes of brain activity and functional connectivity in both ipsilateral and contralateral hemisphere of patients with acute ischemic stroke. Changes of remote functional connectivity tend to interact with functional recovery. Associations between contralateral functional connectivity measures and incidence of apathy and depression are currently analyzed and will be presented.