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.

Because TMS is a relatively new depression treatment — approved by the Food and Drug administration in 2008 — more studies can help determine how effective it is, which treatment techniques work best and whether it has any long-term side effects.

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:

  • Headache
  • Scalp discomfort at the site of stimulation
  • Tingling, spasms or twitching of facial muscles
  • Lightheadedness
  • Discomfort from noise during treatment

Uncommon side effects

Serious side effects are rare. They can include:

  • Seizures
  • 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 the procedure, 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. Transcranial magnetic stimulation (TMS) usually isn't recommended if this is the case.
  • 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.

Nov. 20, 2012