Effect of thermal stimulation on corticomotor excitability in patients with stroke.

OBJECTIVE: This study examined the immediate effects of noxious and innocuous thermal stimulation intervention on corticomotor excitability for the paretic arm in patients with stroke.

DESIGN: Sixteen patients with stroke for more than 3 mos were randomly assigned into the experimental and control groups. All participants received the thermal stimulation protocol on the affected arm for 30 mins. The experimental group received noxious heat (46°C-47°C) and cold (7°C-8°C) stimuli, and the control group received innocuous heat (40°C-41°C) and cold (20°C-21°C) stimuli. Corticomotor excitability was assessed to measure the motor threshold, size of cortical motor output map, and mean motor evoked potentials for the abductor pollicis brevis by focal transcranial magnetic stimulation before and after 30 mins of thermal stimulation intervention program.

RESULTS: The findings of transcranial magnetic stimulation revealed a significant increase in map size of the affected hemisphere and mean motor evoked potentials in the experimental group. Moreover, significant differences in the change values of map size (7.0 [7.9] for the experimental group vs. -1.7 [2.9] for the control group, P = 0.03) and mean (SD) motor evoked potentials (0.4 [8.9] mV for the experimental group vs. -0.1 [0.1] mV for the control group, P = 0.03) were found.

CONCLUSIONS: The preliminary results suggest that the noxious 30 mins of thermal stimulation intervention induced neurophysiologic changes in the motor cortex of the lesioned hemisphere.