Inhibition of the contralesional dorsal premotor cortex improves motor function of the affected hand following stroke.

Abstract

Numerous studies have shown that repetitive transcranial magnetic stimulation (rTMS) over the primary motor cortex (M1) may improve motor function of the affected hand after stroke. The effects of 1 Hz rTMS applied over the contralesional dorsal premotor cortex (PMd) on hand function and cortical neurophysiology in subacute stroke were examined. Ten subacute stroke patients with mild hand motor impairment were enrolled in a prospective, double-blind, randomized, placebo-controlled, crossover study with two intervention sessions. 1 Hz rTMS was applied over the contralesional PMd (real rTMS, 900 pulses at 110% of the motor threshold; sham rTMS, 900 pulses at 0% of the motor threshold). Tests of hand function (Jebsen-Taylor hand function test, box and block test) and neurophysiological evaluations (resting motor threshold, motor evoked potentials, cortical silent period, ipsilateral silent period) were obtained from both hands and hemispheres prior to (baseline) and after each treatment. Hand function tests revealed significant improvement of motor function of the affected but not of the unaffected hand after real rTMS only. Neither intervention changed the neurophysiological measures in comparison to baseline. One hertz rTMS over the contralesional PMd improves motor function of the affected hand in subacute stroke. The PMd may be a novel rTMS target to treat motor impairment after stroke.