Abstract 148: Cortical Connectivity is a Powerful Predictor of Motor Recovery in Chronic Stroke

Abstract

Introduction: Refinement of biomarkers and predictors of treatment response could greatly benefit restorative stroke therapeutics. The current study examined the performance of established biomarker/predictor measures in patients undergoing 4 weeks of therapy, and also examined performance of dense array EEG (d-EEG) measures of cortical connectivity. Methods: Twelve adults (mean age=54.0 ± 16.6 years) with chronic stroke and hemiparesis (Fugl-Meyer (FM) score=39 ± 12, range 23-56, max 66) underwent a baseline 3 minute resting dEEG recording (256 leads) as well as a 3T MRI scan, then received 4 weeks of telerehabilitation therapy. For dEEG measurement of cortical connectivity, mean coherence was derived for the high beta (20-30 Hz) frequency band, then partial least squares (PLS) regression was used to relate resting-state mean beta coherence to: (1) baseline impairment (FM score), and (2) improvement (change in FM across 4 weeks of therapy). Infarct volume and % corticospinal tract (CST) injury, measured on MRI scans, were also analyzed. Results: Arm motor status improved across the 4 weeks of therapy (FM change=4.5 ± 2.6, p=0.0001). Regarding biomarkers, CST injury correlated with baseline FM (R2=0.52, p=0.008), but infarct volume and age did not (p>0.05). Resting-state dEEG beta coherence correlated with baseline FM (R2=0.95); adding infarct volume and CST injury to the dEEG findings did not improve predictive strength. Regarding predictors, infarct volume, CST injury, age, and baseline FM each did not predict change in FM across the 4 wk of therapy (p>0.05). However, resting-state beta coherence, using a leave-one-out and predict validation procedure on the pre-therapy dEEG, predicted change in FM score with R2=0.74; adding infarct volume, CST injury, and baseline FM to the dEEG findings again did not improve prediction. Conclusions: The dEEG measures of cortical connectivity were strong correlates of baseline status and excellent predictors of behavioral improvement across 4 weeks of therapy. These dEEG measures compared favorably with established behavioral, demographic, and radiological measures. Resting state dEEG is a rapid, simple, safe method for studying brain function that performs excellently as a biomarker and as a predictor.