Transcranial magnetic stimulation (TMS) is a non-invasive tool used to study aspects of human brain physiology, includingmotor function and the pathophysiology of various brain disorders. A brief electric current passed through a magnetic coilproduces a high-intensity magnetic field, which can excite or inhibit the cerebral cortex. Although various brain regions canbe evaluated by TMS, most studies have focused on the motor cortex where motor evoked potentials (MEPs) are produced.Single-pulse and paired-pulse TMS can be used to measure the excitability of the motor cortex via various parameters, whilerepetitive TMS induces cortical plasticity via long-term potentiation or long-term depression-like mechanisms. Therefore,TMS is useful in the evaluation of physiological mechanisms of various neurological diseases, including movement disordersand epilepsy. In addition, it has diagnostic utility in spinal cord diseases, amyotrophic lateral sclerosis and demyelinatingdiseases. The therapeutic effects of repetitive TMS on stroke, Parkinson disease and focal hand dystonia are limited sincethe duration and clinical benefits seem to be temporary. New TMS techniques, which may improve clinical utility, are beingdeveloped to enhance clinical utilities in various neurological diseases.
