P023 Motor cortical reorganization and clinical outcomes after stroke: A longitudinal TMS/EEG evaluation

Abstract

Introduction Since early days after stroke, the brain undergoes a complex reorganization to allow compensatory mechanisms that promote functional recovery. Characterizing specific neurophysiological markers of motor recovery after stroke could improve clinical decision making. Objectives: To track the time-course of motor cortical reorganization in a stroke patients group, and to individuate the neurophysiological markers associated to clinical outcome. Patients & methods Ten patients in the sub-acute phase of ischemic subcortical stroke were evaluated within 20 days and after 40, 60 and 180 days after stroke. For each time-point, cortical reactivity and cortical oscillations changes, evoked by 80 single TMS pulses, were assessed over the motor cortex of the affected and unaffected hemisphere, combining TMS-EEG. These measurements were paralleled with motor and clinical evaluations. Repeated measures ANOVA and Friedman test were used to evaluate changes over time of all measures. Results Our data showed specific cortical oscillatory activity changes in the alpha band, in a specific time point of the longitudinal evaluation only in the affected hemisphere. Stroke patients showed a significant increase in TMS-evoked alpha oscillations, as highlighted by spectral perturbation analysis. Notably, these changes occurred at 60 days after stroke, indicating that crucial mechanisms of cortical reorganization occur in this short-time window. Moreover, a cortical reactivity increase was observed at 40 days after stroke onset in affected hemisphere respect to other times and respect to unaffected hemisphere. These changes coincided with the clinical and behavioural amelioration. Conclusion For the first time, this study demonstrates the possibility to track longitudinally the motor cortical changes following stroke, by means a multimodal approach. These findings could allow, not only to identify neurophysiological markers of stroke pathophysiology, but also to provide new insight into how and when neuromodulatory interventions could drive neuroplasticity in a functional direction.