Changes of the brain functional connectivity in post-stroke spasticity: A pilot study

Abstract

Resting-state functional magnetic resonance imaging (rs-MRI) has been used to examine cerebral correlates of post-stroke spasticity (PSS). The purpose of the study was to describe resting-state networks of chronic stroke patients with PSS and to explore the relationship between functional connectivity (FC) and spasticity, with particular emphasis on botulinum toxin type A (BoNT-A)-related changes. Ten chronic stroke patients (2 females, mean age 61 years, SD 9.7) with clinically relevant PSS of the upper limbs were investigated. fMRI examinations and clinical (spasticity) evaluation were performed just before BoNT-A injection (W0), then 4 weeks (W4) and 11 weeks (W11) thereafter. The change of PSS was assessed with the modified Ashworth scale (MAS). The rs-MRI scans were obtained using a 1.5-Tesla Siemens MRI scanner. Following standard preprocessing, changes in FC were evaluated using an independent component analysis in MELODIC and DualRegression tools (FSL v. 5.0.9). Results were thresholded at the corrected p < 0.05. Rs-MRI did not reveal any significant changes of FC attributable to the specific BoNT-A effect (W0-W4 or W4-W0), despite alleviation of PSS after BoNT-A treatment. Significant changes of FC were shown in the contralesional sensorimotor and bilateral parietal cortex (W0-W11) and in the default mode network (W4-W11). The absence of BoNT-A-related effects in our pilot study might be attributed to the relatively small sample size, which reduced the overall statistical power to detect smaller treatment effects.