Effect of Thermal Stimulation on Cortical Excitability and Motor Function in Chronic Stroke Patients

Overview

Functional magnetic resonance imaging (fMRI) has confirmed that thermal stimulation (TS) may facilitate cortical excitability in healthy adults. However, it is unknown whether TS can increase cortical excitability in stroke patients. Compared to the fMRI, the transcranial magnetic stimulation (TMS) possesses more concise conditions in temporal resolution, and it can present the cerebrum activation situation more instantaneously. This study aimed to use TMS examining the effect on corticomotor excitability, reorganization and functional motor recovery after TS on affected upper limbs of chronic stroke patients.

The study was an assessor-blinded randomized controlled clinical trial. The participants (more than 3 months posts-stroke)were randomly assigned to experiment (EXP) and control (COT) groups. All participants received regular conventional rehabilitation programs. The EXP and COT received additional upper extremity TS protocol for 30 minutes a day for 20 days. The TS temperature of EXP for noxious stimulation was set at 46-47°C for heat and 7-8°C for cold stimulation; the temperature of COT for innoxious stimulation was set at 40°C for warm and 20°C for cold stimulation. The motor and sensory performance were evaluated at baseline and post-20th- TS by Brunnstrom's recovery stage, Modified Ashworth Scale (MAS), Barthel Index (BI), Upper Extremity Subscale of the Fugl-Meyer Motor Function Assessment (UE-FM) and Thermal Quantitative Sensory Testing (tQST). At pre-1st-TS, post-1st-TS, post-10th-TS and post-20th-TS, focal TMS was used to obtain measurement of motor threshold (MT), motor evoked potentials (MEPs), size of cortical motor output map and location of the amplitude-weighted centre of gravity of the motor output map (CoG) from abductor pollicis brevis (APB) in bilateral upper extremities.