Inhibition of the contralesional premotor cortex enhances motor function of the affected hand following stroke

Inhibition of the contralesional premotor cortex enhances motor function of the affected hand following stroke

Abstract

Objective: Inhibitory (1Hz) rTMS applied over the contralesional M1 improves dexterity of the affected hand after stroke. To test if 1Hz rTMS over the contralesional premotor cortex results in a similar improvement of motor function of the affected hand after stroke. Methods: 14 right-handed patients with impaired dexterity after stroke and 14 right-handed healthy control subjects received a single session of 1Hz rTMS (15 minutes stimulation, 900 pulses, 110% of the resting motor threshold) over the contralesional or left dorsal premotor cortex, respectively. For behavioral testing, each participant performed the Jebsen Taylor Test of hand function with both hands. To test for changes in cortico-spinal excitability motor evoked potentials and the cortical silent period were obtained from the unaffected/right hand. The ipsilateral silent period was assessed from the affected hand to test for changes in interhemispheric inhibition. All tests were performed prior to and after the intervention. Results: 1Hz rTMS over the premotor cortex caused a significant reduction in cortico-spinal excitability as probed by motor evoked potential size and cortical silent period duration both in patients and healthy controls. The ipsilateral silent periods were not significantly changed after premotor rTMS in patients and healthy controls. 1Hz rTMS over the left premotor cortex enhanced motor function of both hands in healthy controls, but improved motor function of the affected hand only in stroke subjects. Conclusion: Inhibition of the contralesional premotor cortex reduces excitability of the motor cortex and at the same time improves motor function of the affected hand after stroke.