Abstract WMP40: Premovement Sensorimotor Oscillations Are Associated With Motor Status In Chronic Stroke

Abstract

Introduction: Oscillations in the beta frequency range within sensorimotor cortex play a key role in normal motor control. Beta band activity decreases after stroke in association with motor impairment. Changes in sensorimotor beta band electrical activity in the time period preceding movement onset have received limited study in patients with stroke, although these events are critical to genesis of movement. Here we test the hypothesis that premovement beta band sensorimotor activity is associated with level of motor impairment. Methods: 27 subjects with stroke (age 60±14 yr, 46±57 mo post-stroke) and 23 healthy subjects (age 59±12 yr) performed a cued shoulder rotation movement during EEG (256 channels). EEG was analyzed in the window -1500ms to +500ms relative to the movement onset. Event-related desynchronization (ERD) in the beta (15 - 30 Hz) frequency range was computed in a cluster surrounding lead C1. Results: Subjects with stroke showed significantly decreased beta ERD amplitude in the -350 ms to -130 ms premovement time window compared to controls (gray box in Fig A, p<0.01). Fig B shows the topographic distribution of beta ERD during this time window, which is smaller in area among subjects with stroke. Beta ERD amplitude correlated with the proximal Fugl-Meyer motor score during the time window -300 ms to +100 ms relative to movement onset (Fig C), maximally correlating at 200ms before movement (r=-0.56, p < 0.01). Conclusion: Premovement beta ERD is reduced in amplitude and spatial distribution after stroke. This decrease in premovement beta oscillatory activity is associated with greater motor impairment. Measures of premovement electrical activity provide useful insights into motor system dysfunction after stroke and are attractive biomarker candidates given their ease of collection at the bedside.