Transcranial magnetic stimulation (TMS) is a noninvasive procedure to stimulate nerve cells in the brain. The US Food and Drug Administration (FDA) has approved the use of TMS for certain medical conditions, such as migraine with aura, depression, and obsessive compulsive disorder (OCD). There are ongoing studies on using transcranial magnetic stimulation to treat other conditions including stroke, spinal cord injury, spasticity, and psychological disorders like eating disorders and schizophrenia.

The principle of the transcranial magnetic stimulation system is stimulation of the brain through a treatment coil. Electromagnetic waves used are similar to those in a magnetic resonance imaging (MRI) machine—a mild electromagnetic current that stimulates the nerve cells without causing any pain and is generally safe.

Although the mechanism of how transcranial magnetic stimulation works is still being studied, researches have shown that repetitive magnetic pulses causes changes in the nerve circuits and reduces the function of the hypothalamic-pituitary-adrenocortical system, leading to changes in the neurotransmitters. In stroke patients, when brain cells are destroyed, brain function is compromised. Transcranial magnetic stimulation is used to stimulate the damaged part of the brain to improve function as well as stimulate important hormones, such as growth hormones and brain-derivated neurotopic factor, while reducing signals sent by the normal parts of the brain to the damaged parts.

Currently transcranial magnetic stimulation is frequently used to rehabilitate stroke patients who have weakness of the arms and legs, troubled speaking, and difficulty swallowing. It is considered a safe treatment option. It is highly effective when combined with physical therapy.