How Does TMS Therapy Work?

TMS is an innovative way to treat depression by stimulating the brain non-invasively through an electromagnetic field. During TMS Therapy, a magnetic field is administered in very short pulses (microseconds in length) to the patient’s left prefrontal cortex, an area of the brain that has been demonstrated to function abnormally in patients with depression. The magnetic field, about the same strength and power produced by an MRI scanner, passes through the skull and into the brain where they produce an electric field that stimulates the neurons in this region, causing them to release various neurotransmitters and hormones involved in mood regulation. TMS also results in changes in other brain regions which are also thought to be beneficial in the treatment of depression[1]. During a single session, 3,000 magnetic pulses are given over an interval of about 37 minutes. TMS Therapy requires four to six weeks of treatment.

TMS Therapy is based on knowledge of physical principles dating back nearly 175 years. In 1831, Michael Faraday discovered that a magnetic field could induce an electrical current in a coil of wire. That basic discovery has been applied to create a powerful and focused electromagnetic coil that can stimulate the brain.

  • Since the 1980s, TMS Therapy has been used in humans to study the nerve fibers that carry information about movements from the brain cortex to the spinal cord and the muscles.
  • In the late 1990s physicians began to explore the therapeutic potential of TMS Therapy for the treatment of a variety of diseases, with depression being the most thoroughly studied to date.
  • More than 30 randomized, controlled trials of TMS Therapy as a treatment for depression have been published by investigators around the world. [2,3]
  • Neuronetics conducted the largest controlled, multi-center TMS study ever conducted (n=301) in patients with major depression, demonstrating its safety and efficacy for this use.

TMS technology differs radically from the popular use of low intensity magnets that deliver weak and undirected static fields incapable of exciting brain cells. There are no controlled clinical trials that show proof of efficacy for these products.

Neither is TMS like electroconvulsive therapy (ECT) or “Shock therapy” that intentionally causes a seizure. Patients receiving ECT must be sedated with general anesthesia and paralyzed with muscle relaxants. In contrast, during the TMS Therapy procedure, the patient sits in a chair and is awake and alert throughout the entire 37-minute procedure. No sedation is used. Recovery from an ECT treatment session occurs slowly, and patients are usually closely monitored for minutes or a few hours after a treatment, compared to TMS Therapy in which the patient can walk out the door as soon as the treatment is over.

Like any treatment option, patients and clinicians should work together to find the most appropriate treatment option for each patient.


References:

  1. Richelson, E. Mechanisms of Action of Repetitive Transcranial Magnetic Stimulation (rTMS) and Vagus Nerve Stimulation (VNS). Psychiatric Annals, 2007: Vol 37-No. 3, 181-187
  2. Schutter, D. (2009). “Antidepressant efficacy of high-frequency transcranial magnetic stimulation over the left dorsolateral prefrontal cortex in double-blind sham-controlled designs: a meta-analysis.” Psychological Medicine 39: 65-75.
  3. Data on file.

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