Differences in neural pathways are related to the short- or long-term benefits of constraint-induced movement therapy in patients with chronic stroke and hemiparesis: a pilot cohort study

Background: No previous studies have determined how the post-stroke integrity of non-corticospinal neural pathways relates to the efficacy of constraint-induced movement therapy (CIMT). Objectives: We aimed to clarify the relationship between several non-corticospinal neural pathway integrities and the short- and long-term benefits of CIMT. Methods: This was a pilot cohort study (UMIN registration number: R00027136UMIN000023566), for which we enrolled 13 patients with chronic stroke and hemiparesis who had undergone CIMT. We assessed patients' motor function improvement by comparing the Fugl-Meyer Assessment (FMA) scores, as well as the Amount of Use (AOU) and Quality of Movement (QOM) scales of the Motor Activity Log before, immediately after (short-term), and 6 months after (long-term) CIMT. We assessed neural pathway integrity by calculating fractional anisotropy (FA) in diffusion tensor images acquired before CIMT. We then assessed correlations between FA and short- and long-term post-CIMT motor function improvements. Results: The patients showed significant improvements in all functional assessments at both short- and long-term follow-ups. Immediate FMA score improvements were significantly correlated with FA of the affected anterior limb of the internal capsule (ALIC), body of the corpus callosum, column and body of the fornix (CBF), cingulate cortex (CgC), cerebral peduncle (CP), and posterior limb of the internal capsule. Six-month FMA score improvements were significantly correlated with FA of the affected ALIC, CgC, CBF, CP, and superior frontooccipital fasciculus. Conclusions: The integrity of the affected corticospinal and non-corticospinal motor pathways was associated with CIMT-induced motor learning at least 6 months after CIMT.