Abstract Body: Background:
Insights in motor cortex remodeling in stroke may allow for development of better rehabilitation strategies in acute phase. We aim to assess the affected and unaffected motor/premotor/somatosensory cortex resting state functional connectivity (RSFC) and reactivity with functional near-infrared spectroscopy(fNIRS) in patients with acute stroke compared to age, sex and comorbidity-matched subjects.

Methods:
Patients admitted with acute anterior circulation stroke syndrome with either right (RH) or left hemisphere (LH) were enrolled. Matched subjects or patients with recent transient ischemic attack (TIA) were enrolled as controls for the study. fNIRS was acquired with 8 optodes and 8 detectors arranged in motor cortex montage. Resting for 3 min and finger tapping (FT) signals were acquired. RSFC was assessed in both affected and unaffected hemispheres by group-level seed-based (Primary Motor cortex, PMC) correlation analysis was performed. FT-associated relative Oxyhemoglobin (ΔHbO) changes were analysed in affected and unaffected hemispheres with generalized linear model regression (Figure).

Results:
A total of 127 subjects (RH stroke, 51; LH stroke, 43; control, 33) with a median age of 67(58, 76) years, and 41% of females enrolled at a median of 21(15, 29)h after symptom onset. Compared to the control group the RSFC with the affected PMC (in LH stroke) was reduced over the affected somatosensory cortex (aSSC) in the minor ischemic stroke (IS) (r=-0.14(-0.3, -0.01)), minor intracerebral hemorrhage (ICH) (-0.48 (-0.78, -0.18)) and major ICH groups (-0.2(-0.4, -0.01). However, the RSFC with the unaffected PMC (LH in RH stroke) was reduced over the aSSC (-0.15(-0.3,-0.02)) in the minor IS, affected premotor cortex (-0.2 (-0.4, -0.01)), unaffected SSC (-0.3 (-0.5, -0.03)) in minor ICH and affected PMC (-0.25 (-0.4, -0.07) in major ICH. In the FT task compared to the control groups in LH stroke ΔHbO was increased over the affected SSC in minor IS (β11.2, (1.9, 20.5)) and major ICH group (β11.7 (1.4, 22.1)). In the FT task in RH stroke ΔHbO was increased over the unaffected PMC in minor IS(β12.1 (2.3, 21.8)), major IS(β14.9 (0.3, 29.5)), minor ICH(β25.7 (10.1, 41.2)) and major ICH(β13.4 (1.1, 25.6).

Conclusion:
Resting-state functional dysconnectivity may be worse over the LH stroke. In RH stroke there is early compensatory increased neuronal activity over the unaffected PMC. These results suggest differential remodeling in RH and LH stroke in acute phase.