Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive therapy that uses a magnet to stimulate the brain using repeated low-intensity pulses. The magnetic field it creates is about the same strength as an MRI scan.
rTMS: Why it’s done
Several rTMS devices have been cleared to treat specific mental disorders. The FDA cleared the first rTMS device in 2008 for depression in people who did not respond to at least one antidepressant medication in the current depressive episode. Although ECT is still considered the “gold standard” for treatment-resistant depression, strong clinical evidence supports the effectiveness of rTMS in reducing depressive symptoms. rTMS is now used to treat moderate-to-severe depression in cases where medications have proven ineffective or intolerable.
Since 2008, rTMS has been cleared to treat several types of depression, including depression with comorbid anxiety and depression with suicidality. In 2018, the FDA also cleared rTMS for severe OCD .
More recently, the FDA cleared a rapid-acting form of rTMS for treatment-resistant depression . Accelerated protocols that act more quickly than standard rTMS show similar effectiveness while shortening treatment length. Thus, patients benefit from receiving an entire course of treatment in much less time and getting relief from their symptoms more rapidly.
Newer forms of rTMS involving magnetic pulses with other parameters are also being investigated to treat depression, OCD, and other mental disorders.
rTMS: How it works
Rather than electric currents, rTMS uses low-intensity magnetic pulses to stimulate the brain. Unlike ECT, in which stimulation is generalized, in rTMS, magnetic stimulation is targeted to a specific brain site. Also, in contrast to ECT, the procedure does not require anesthesia and can be performed in a clinical or office setting.
A typical rTMS session lasts 30–60 minutes. A typical course of rTMS treatment consists of daily sessions 5 days per week for 4–6 weeks.
Accelerated rTMS protocols work much faster (within seconds to minutes). In this case, multiple sessions are delivered on a single day, with short breaks in between.
During the procedure:
- An electromagnetic coil is held against the head near an area of the brain thought to be involved in mood regulation, cognitive control, or both. These brain areas include the left prefrontal cortex (for depression) and the dorsomedial prefrontal cortex or anterior cingulate cortex (for OCD). In deep TMS, two coils may be used to deliver more stimulation to the region and target larger structures deep in the brain
- .Short electromagnetic pulses are repeatedly administered through the coil or coils. The patient usually feels a slight knocking or tapping on the head as the pulses are administered.
- The magnetic pulses pass easily through the skull and cause small electric currents that stimulate nerve cells in the targeted brain region.n
There is no consensus on the best way to position the coil on the head or deliver the electromagnetic pulses. It has also yet to be determined if rTMS works best when delivered as a single treatment or when combined with psychotherapy, medication, or both. Research is underway to establish the safest and most effective uses of rTMS, the optimal brain sites to target, and the best follow-up approach to sustain clinical improvement.
rTMS: Side effects
Overall, rTMS is safe and well tolerated But, like all therapies described here, it can have side effects. These include:
- Discomfort at the site on the head where the magnet is placed
- Contraction or tingling of scalp, jaw, or face muscles during the procedure
- Mild headaches or brief lightheadedness
- Dizziness
Using magnetic pulses and targeting a specific brain site results in milder stimulation than in ECT, avoiding most seizure activity. Although it is possible for the procedure to cause seizures, a comprehensive review found that the risk is low. Most side effects appear to be mild and short-term when expert guidelines are followed.
Long-term side effects have not been determined, and more research is needed to establish the long-term safety of rTMS.
National Institute of Mental Health Last Reviewed: March 2024