Transcranial magnetic stimulation (TMS) and repetitive TMS (rTMS) are indirect and non-invasive methods used to induce excitability changes in the motor cortex via a wire coil generating a magnetic field that passes through the scalp. Today, TMS has become a key method to investigate brain functioning in humans. Moreover, because rTMS can lead to long-lasting after-effects in the brain, it is thought to be able to induce plasticity. This tool appears to be a potential therapy for neurological and psychiatric diseases. However, the physiological mechanisms underlying the effects induced by TMS and rTMS have not yet been clearly identified. The purpose of the present review is to summarize the main knowledge available for TMS and rTMS to allow for understanding their mode of action and to specify the different parameters that influence their effects. This review takes an inventory of the most-used rTMS paradigms in clinical research and exhibits the hypotheses commonly assumed to explain rTMS after-effects.

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Stroke is a leading cause of adult motor disability. The number of stroke survivors is increasing in industrialized countries, and despite available treatments used in rehabilitation, the recovery of motor functions after stroke is often incomplete. Studies in the 1980s showed that non-invasive brain stimulation (mainly repetitive transcranial magnetic stimulation [rTMS] and transcranial direct current stimulation [tDCS]) could modulate cortical excitability and induce plasticity in healthy humans. These findings have opened the way to the therapeutic use of the 2 techniques for stroke. The mechanisms underlying the cortical effect of rTMS and tDCS differ. This paper summarizes data obtained in healthy subjects and gives a general review of the use of rTMS and tDCS in stroke patients with altered motor functions. From 1988 to 2012, approximately 1400 publications were devoted to the study of non-invasive brain stimulation in humans. However, for stroke patients with limb motor deficit, only 141 publications have been devoted to the effects of rTMS and 132 to those of tDCS. The Cochrane review devoted to the effects of rTMS found 19 randomized controlled trials involving 588 patients, and that devoted to tDCS found 18 randomized controlled trials involving 450 patients. Without doubt, rTMS and tDCS contribute to physiological and pathophysiological studies in motor control. However, despite the increasing number of studies devoted to the possible therapeutic use of non-invasive brain stimulation to improve motor recovery after stroke, further studies will be necessary to specify their use in rehabilitation.

Objective: Transcranial direct current stimulation (tDCS) has shown positive results in neurorehabilitation. However, there is limited evidence on its use in acute stroke, and unclear evidence regarding the best tDCS montage (anodal-, cathodal-, or dualtDCS) for stroke recovery. This study investigated the effects of these montages combined with physical therapy on haemodynamic response and motor performance.Methods: Eighty-two eligible acute stroke participants were allocated randomly into anodal, cathodal, dual, and sham groups. They received 5 consecutive sessions of tDCS combined with physical therapy for 5 days. Cerebral mean blood flow velocity (MFV) and motor outcomes were assessed pre- and post-intervention and at a 1-month follow-up.Results: None of the groups showed significant changes in the MFV in the lesioned or non-lesioned hemispheres immediately post- intervention or at a 1-month follow-up. For motor performance, all outcomes improved over time for all groups; between-group comparisons showed that the dual-tDCS group had significantly greater improvement than the other groups for most of the lower-limb performance measures. All 5-day tDCS montages were safe.Conclusion: MFV was not modulated following active or sham groups. However, dual-tDCS was more efficient in improving motor performance than other groups, especially for lower-limb performance, with after-effects lasting at least 1 month.