Transcranial magnetic stimulation (TMS) is a procedure that uses magnetic fields to stimulate nerve cells in the brain to improve symptoms of depression. Transcranial magnetic stimulation may be tried when other depression treatments haven't worked.
With TMS, a large electromagnetic coil is placed against your scalp near your forehead. The electromagnet used in TMS creates electric currents that stimulate nerve cells in the region of your brain involved in mood control and depression.
Depression is a treatable condition, but sometimes standard treatments aren't effective. Transcranial magnetic stimulation (TMS) may be used when standard treatments such as medications and talk therapy (psychotherapy) don't work.
How it works
How TMS helps relieve depression isn't completely understood. It's thought that magnetic pulses stimulate nerve cells in the region of your brain involved in mood control. This stimulation appears to affect how this part of the brain is working, which in turn seems to ease depression symptoms and improve mood.
Transcranial magnetic stimulation (TMS) is the least invasive of the brain-stimulation procedures used for depression. Unlike vagus nerve stimulation or deep brain stimulation, TMS doesn't require surgery or implantation of electrodes. And, unlike electroconvulsive therapy (ECT), it doesn't cause seizures or require complete sedation with anesthesia. However, TMS does have some risks and can cause some side effects.
Common side effects
TMS often causes minor short-term side effects. These side effects are generally mild and typically improve after the first week or two of treatment. They can include:
- Scalp discomfort at the site of stimulation
- Tingling, spasms or twitching of facial muscles
- Discomfort from noise during treatment
Uncommon side effects
Serious side effects are rare. They can include:
- Mania, particularly in people with bipolar disorder
- Hearing loss due to inadequate ear protection during treatment
More study is needed to determine whether TMS may have any long-term side effects.
Before having transcranial magnetic stimulation (TMS), you may need a medical exam to make sure it's safe and a good option for you. You may be asked a number of questions about your depression. Tell your doctor or mental health provider if:
- You're pregnant or thinking of becoming pregnant.
- You have any metal or implanted medical devices in your body. Due to the strong magnetic field produced during TMS, some people who have the following devices cannot have TMS:
- Aneurysm clips or coils
- Implanted stimulators
- Electrodes for monitoring brain activity
- Any magnetic implants
- Bullet fragments
- Any other metal device or object implanted in your body
- You're taking any medications, including over-the-counter medications, herbal supplements or vitamins. Bring a list of what you're taking to your doctor's appointment and include dosages and how often you take them.
- You have a history of seizures or mania, any past injuries or surgeries, or any other physical or mental health problems.
Little preparation is needed. TMS isn't invasive, doesn't require anesthesia and can be performed in a doctor's office. You don't need to arrange for someone to drive you home after treatment — unless, for the first treatment, you want someone to drive you so you get a sense of how you'll feel afterward. Before considering treatment, check with your health insurance company to see whether TMS is covered. Your policy may not cover it.
Transcranial magnetic stimulation is usually done on an outpatient basis in a doctor's office or clinic. It requires a series of treatment sessions to be effective. Generally, sessions are carried out daily, five times a week for four to six weeks.
Your first treatment
Before treatment begins, your doctor will need to identify the best place to put the magnets on your head and the best dose of magnetic energy for you.
Most likely, during your first appointment:
- You'll be taken to a treatment room. You'll be asked to sit in a reclining chair, and you'll be given earplugs to wear during the procedure.
- An electromagnetic coil will be placed against your head. The electromagnetic coil is switched off and on repeatedly to produce stimulating pulses. This results in a tapping or clicking sound that usually lasts for a few seconds, followed by a pause. You'll also feel a tapping sensation on your forehead. This part of the process is called mapping.
- The amount of magnetic energy needed will be determined. Your doctor will increase the magnetic dose until your fingers or hands twitch. Known as your motor threshold, this is used as a reference point in determining the right dose for you. During the course of treatment, the amount of stimulation can be changed depending on your symptoms and side effects.
Once the coil placement and dose are identified, you're ready to begin.
During transcranial magnetic stimulation
Here's what to expect during each treatment:
- You'll sit in a comfortable chair. The magnetic coil is placed against your head.
- The machine will be turned on. You'll hear clicking sounds and feel tapping on your forehead.
- The procedure will last about 40 minutes. You'll remain awake and alert. You may feel some scalp discomfort during the treatment and for a short time afterward. The entire appointment typically lasts about one to two hours.
After treatment, you can return to your normal daily activities.
There are different ways to perform the procedure. Techniques may change as experts learn more about the most effective ways to perform treatments.
If TMS works for you, your depression symptoms may improve or go away completely. Symptom relief may take a few weeks of treatment.
TMS may be less likely to work if:
- Your mental illness causes detachment from reality (psychosis)
- Your depression has lasted for several years
- Electroconvulsive therapy (ECT) hasn't worked to improve depression symptoms
It's not yet known if TMS can be used to treat depression for the long term, or whether you can have periodic maintenance treatments to prevent depression symptoms from returning. The effectiveness of TMS may improve as researchers learn more about techniques, the number of stimulations required and the best sites on the brain to stimulate.
Feb. 04, 2015
- Brain stimulation therapies. National Institute of Mental Health. http://www.nimh.nih.gov/health/topics/brain-stimulation-therapies/brain-stimulation-therapies.shtml. Accessed Oct. 18, 2012.
- Hales RE, et al. The American Psychiatric Publishing Textbook of Psychiatry. 5th ed. Washington, D.C.: American Psychiatric Publishing; 2008. http://www.psychiatryonline.com/resourceToc.aspx?resourceID=5. Accessed Oct. 22, 2012.
- Holtzheimer PE. Unipolar depression in adults: Treatment with transcranial magnetic stimulation (TMS). http://www.uptodate.com/index. Accessed Oct. 22, 2012.
- Rasmussen KG. Some considerations in choosing electroconvulsive therapy versus transcranial magnetic stimulation for depression. Journal of ECT. 2011;27:51.
- Cusin C, et al. Somatic therapies for treatment-resistant depression: ECT, TMS, VNS, DBS. Biology of Mood & Anxiety Disorders. 2012;2:14.
- Transcranial magnetic stimulation (TMS or rTMS). National Alliance on Mental Illness. http://www.nami.org/Content/ContentGroups/Helpline1/Transcranial_Magnetic_Stimulation_(rTMS).htm. Accessed Oct. 24, 2012.
- Kung S (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 1, 2012.