Repetitive transcranial magnetic stimulation (TMS) uses a magnet to activate the brain. First developed in 1985, TMS has been studied as a treatment for depression, psychoses, anxiety, and other disorders.

Unlike ECT, in which electrical stimulation is more generalized, TMS can be targeted to a specific site in the brain. Scientists believe that focusing on a specific site in the brain reduces that chance for the types of side effects associated with ECT. But opinions vary as to what site is best.

TMS: Why it’s done

In 2008, TMS was approved for use by the FDA as a treatment for major depression for patients who do not respond to at least one antidepressant medication in the current episode. It is also used in other countries as a treatment for depression in patients who have not responded to medications and who might otherwise be considered for ECT.

The evidence supporting TMS for depression was mixed until the first large clinical trial, funded by NIMH, was published in 2010. The trial found that 14% achieved remission with TMS compared to 5% with an inactive (sham) treatment. After the trial ended, patients could enter a second phase in which everyone, including those who previously received the sham treatment, was given TMS. Remission rates during the second phase climbed to nearly 30%. A sham treatment is like a placebo, but instead of being an inactive pill, it’s an inactive procedure that mimics real TMS.

TMS: Side Effects

Sometimes a person may have discomfort at the site on the head where the magnet is placed. The muscles of the scalp, jaw or face may contract or tingle during the procedure. Mild headaches or brief lightheadedness may result. It is possible that the procedure could cause a seizure, although documented incidences of this are uncommon. Two large-scale studies on the safety of TMS found that most side effects, such as headaches or scalp discomfort, were mild or moderate, and no seizures occurred. Because the treatment is relatively new, however, long-term side effects are unknown.

How does TMS Therapy Work?

During NeuroStar TMS Therapy, the treating clinician positions the treatment coil over the left prefrontal cortex, an area of the brain known to affect mood. Through the treatment coil, the NeuroStar System generates a highly focused, pulsed magnetic field, similar in type and strength to those produced by a magnetic resonance imaging (MRI) machine, to stimulate cortical neurons.

The TMS Process

1. Pulsed magnetic fields induce small electric currents in the prefrontal cortex of the brain

2. Local neurons depolarize and release neurotransmitters

3. Distant areas of the limbic system are activated via neuronal pathways

4. Blood flow and glucose metabolism rise in the stimulated regions, which is thought to result in
    improved mood.

Repeated activation of the left prefrontal cortex is shown to produce antidepressant effects in patients suffering from major depression. NeuroStar provides targeted stimulation of the brain regions involved in mood regulation without the burden of systemic side effects.

Demitrack MA, Thase ME. Clinical significance of transcranial magnetic stimulation (TMS) in the treatment of pharmacoresistant depression depression: synthesis of recent data.Psychopharm Bull.2009, 42(2(: 5-38).