Low-frequency repetitive transcranial magnetic stimulation can alleviate spasticity and induce functional recovery in patients with severe chronic stroke: A prospective, non-controlled, pilot study.

Objective: Developing new therapies to improve motor function in patients with severe chronic stroke remains a major focus of neurorehabilitation. In this prospective, non-controlled, pilot study, we aimed to investigate the effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) combined with occupational therapy (OT) on the motor function recovery of the affected upper limb in chronic stroke patients with severe upper limb hemiparesis. Methods: Consecutive patients (n = 40) diagnosed with chronic stroke (time since stroke, ≥1 year) and upper limb hemiparesis were enrolled in this study. Patients were classified according to the Brunnstrom recovery stage (BRS) for fingers. The severity of upper limb hemiparesis was categorized as mild (BRS IV-VI) or severe (BRS I-III). Patients received low-frequency rTMS to the contralesional primary motor area (M1) followed by OT for 12 consecutive days. The primary outcome was upper limb motor recovery, as measured with the Fugl-Meyer assessment (FMA). Secondary outcomes included manual dexterity, upper limb use, spasticity of the fingers and wrist, and motor evoked potential (MEP). Results: Patients with severe hemiparesis showed a significant increase in upper limb use, significantly improved quality of movement, and significantly reduced spasticity. Those with mild hemiparesis showed significant improvements in the FMA scores and manual dexterity, a significant increase in upper limb use and MEP, and significantly reduced spasticity. Conclusions: Low-frequency rTMS applied to the contralesional M1 combined with OT was effective in the rehabilitation of chronic stroke patients with severe upper limb hemiparesis by reducing the spasticity of the fingers.

Effects of transcranial static magnetic stimulation over the primary motor cortex on local and network spontaneous electroencephalogram oscillations.

Transcranial static magnetic stimulation (tSMS) is a novel non-invasive brain stimulation technique that reduces cortical excitability at the stimulation site. We investigated the effects of tSMS over the left primary motor cortex (M1) for 20 min on the local electroencephalogram (EEG) power spectrum and interregional EEG coupling. Twelve right-handed healthy subjects participated in this crossover, double-blind, sham-controlled study. Resting-state EEG data were recorded for 3 min before the intervention and 17 min after the beginning of the intervention. The power spectrum at the left central electrode (C3) and the weighted phase lag index (wPLI) between C3 and the other electrodes was calculated for theta (4-8 Hz), alpha (8-12 Hz), and beta (12-30 Hz) frequencies. The tSMS significantly increased theta power at C3 and the functional coupling in the theta band between C3 and the parietal midline electrodes. The tSMS over the left M1 for 20 min exhibited modulatory effects on local cortical activity and interregional functional coupling in the theta band. The neural oscillations in the theta band may have an important role in the neurophysiological effects induced by tSMS over the frontal cortex.

Transcranial static magnetic stimulation over the motor cortex can facilitate the contralateral cortical excitability in human.

Transcranial static magnetic stimulation (tSMS) has been focused as a new non-invasive brain stimulation, which can suppress the human cortical excitability just below the magnet. However, the non-regional effects of tSMS via brain network have been rarely studied so far. We investigated whether tSMS over the left primary motor cortex (M1) can facilitate the right M1 in healthy subjects, based on the hypothesis that the functional suppression of M1 can cause the paradoxical functional facilitation of the contralateral M1 via the reduction of interhemispheric inhibition (IHI) between the bilateral M1. This study was double-blind crossover trial. We measured the corticospinal excitability in both M1 and IHI from the left to right M1 by recording motor evoked potentials from first dorsal interosseous muscles using single-pulse and paired-pulse transcranial magnetic stimulation before and after the tSMS intervention for 30 min. We found that the corticospinal excitability of the left M1 decreased, while that of the right M1 increased after tSMS. Moreover, the evaluation of IHI revealed the reduced inhibition from the left to the right M1. Our findings provide new insights on the mechanistic understanding of neuromodulatory effects of tSMS in human.

Effect of transcranial static magnetic stimulation on intracortical excitability in the contralateral primary motor cortex.

Transcranial static magnetic stimulation (tSMS) is a new technique of non-invasive brain stimulation using a small, high-powered neodymium magnet placed on the scalp. It can reduce cortical excitability below the magnet. The aim of this study was to investigate the effect of tSMS on the intracortical excitability of the primary motor cortex (M1) contralateral to the M1 where the magnet was placed. Fourteen right-handed healthy subjects participated in this experiment. TSMS was applied over the left M1 for 20 min. Single-pulse and paired-pulse transcranial magnetic stimulation (TMS) was applied over the right M1 to assess corticospinal excitability, short-latency intracortical inhibition (SICI), and intracortical facilitation (ICF) before and immediately after the intervention. ICF decreased significantly after tSMS, whereas corticospinal excitability and SICI did not change. This study suggests that tSMS applied over the M1 for 20 min has a remote modulatory effect on the interneuronal facilitatory circuit in the contralateral M1. The ability of tSMS to modulate neuronal activities in the remote cortex could expand the possibility of its clinical use.