Effect of baseline brain activity on response to low-frequency rTMS/intensive occupational therapy in poststroke patients with upper limb hemiparesis: a near-infrared spectroscopy study

Abstract

Background: The beneficial effects of the combination therapy of low-frequency repetitive transcranial magnetic stimulation of nonlesional hemisphere and intensive occupational therapy (LF-rTMS/OT) on upper limb hemiparesis have been well established in poststroke patients. However, there is no information on the effect of brain activity on LF-rTMS/OT treatment outcome.Method: A total of 59 poststroke patients with upper limb hemiparesis received 15-day LF-rTMS/OT. Motor function of the affected upper limb was evaluated before and after the treatment. We also conducted functional near-infrared spectroscopy (fNIRS) before the treatment and calculated the laterality index (LI) based on the change in oxy-hemoglobin in the primary sensorimotor cortex and supplementary motor cortex. The correlation between LI before LF-rTMS/OT and observed improvement in upper limb motor function was analyzed.Results: Motor recovery was significantly more pronounced in patients with unaffected hemisphere dominance in both hemispheres (LI of −1 to 0) than in those with affected hemisphere dominance in the lesional hemisphere (LI of 0 to 1). There was a significant negative correlation between LI and improvement in upper limb motor function.Discussion: The results demonstrated that patients with a shift in brain activity to the noninjured cerebral cortex exhibited better motor recovery following LF-rTMS/OT. The findings suggest that evaluation of brain asymmetry before LF-rTMS/OT with fNIRS can help predict the response to LF-rTMS/OT.