Abstract Body: Introduction: Neuroplasticity is highest during the first weeks after stroke and can be studied at the bedside using EEG. However, brain mapping studies during this time are uncommon and longitudinal data are spaced weeks or months apart, which is insufficient to capture neuroplasticity and respond therapeutically. Towards this goal, a longitudinal study of frequent EEG was performed in subacute stroke patients to deeply understand neuroplasticity during this time period.
Methods: Post-stroke patients were included 16 days after stroke onset and were seen four times every 2.1±0.3 days (n=2). They performed paretic hand grip contractions while 32-lead EEG and paretic flexor digitorum communis electromyography (EMG) were recorded. In the EEG beta frequency band, event-related desynchronization (ERD) was calculated as well as cortico-muscular coherence (CMC) with paretic flexor digitorum communis EMG. Cortical coherence (CC) was calculated between EEG electrodes. Longitudinal variation was quantified as % change between visits.
Results: The contralesional hemisphere showed maximum plasticity between days 16 and 18. A 24% increase in ERD amplitude and a 30% decrease in CMC were seen between day 16 and 18, compared with respective variations of 0% and 4% between subsequent visits. The ipsilesional hemisphere showed maximum plasticity between days 21 and 23. A 26% decrease in ERD amplitude and a 54% increase in inter-hemispheric connectivity were seen, compared with, respectively, 12% and 11% variation between the other visits.
Discussion: Findings suggest two-stage neuroplasticity, first involving the contralesional, and then the ipsilesional, hemisphere. Recruitment of the contralesional hemisphere increases, while its communication with the paretic flexor muscle decreases, suggesting its indirect involvement in motor control. Subsequently, ipsilesional hemisphere activity decreases, while its connectivity with the contralesional hemisphere increases, reinforcing the contralesional hemisphere role in movement programming early post-stroke. Frequent bedside EEG provides precise measures of sequential stages of neuroplasticity early post-stroke, finding that may ultimately inform sub-acute post-stroke rehabilitation.