Transcranial magnetic stimulation (TMS) is a noninvasive procedure that uses magnetic fields to stimulate nerve cells in the brain to improve symptoms of depression. TMS is typically used when other depression treatments haven't been effective.

This treatment for depression involves delivering repetitive magnetic pulses, so it's called repetitive TMS or rTMS.

How it works

During an rTMS session, an electromagnetic coil is placed against your scalp near your forehead. The electromagnet painlessly delivers a magnetic pulse that stimulates nerve cells in the region of your brain involved in mood control and depression. It's thought to activate regions of the brain that have decreased activity in depression.

Though the biology of why rTMS works isn't completely understood, the stimulation appears to impact how the brain is working, which in turn seems to ease depression symptoms and improve mood.

There are different ways to perform the procedure, and techniques may change as experts learn more about the most effective ways to perform treatments.

Depression is a treatable condition, but for some people, standard treatments aren't effective. Repetitive TMS is typically used when standard treatments such as medications and talk therapy (psychotherapy) don't work.

Repetitive TMS is a noninvasive form of brain stimulation used for depression. Unlike vagus nerve stimulation or deep brain stimulation, rTMS does not require surgery or implantation of electrodes. And, unlike electroconvulsive therapy (ECT), rTMS doesn't cause seizures or require sedation with anesthesia.

Generally, rTMS is considered safe and well-tolerated. However, it can cause some side effects.

Common side effects

Side effects are generally mild to moderate and improve shortly after an individual session and decrease over time with additional sessions. They may include:

• Headache
• Scalp discomfort at the site of stimulation
• Tingling, spasms or twitching of facial muscles
• Lightheadedness

Your doctor can adjust the level of stimulation to reduce symptoms or may recommend that you take an over-the-counter pain medication before the procedure.

Uncommon side effects

Serious side effects are rare. They may include:

• Seizures
• Mania, particularly in people with bipolar disorder
• Hearing loss if there is inadequate ear protection during treatment

More study is needed to determine whether rTMS may have any long-term side effects.

Before having rTMS, you may need a:

• Physical exam and possibly lab tests or other tests
• Psychiatric evaluation to discuss your depression

These evaluations help make sure that rTMS is safe and a good option for you.

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. In some cases, people with metal implants or devices can have rTMS. However, due to the strong magnetic field produced during rTMS, the procedure is not recommended for some people who have the following devices:
  • Aneurysm clips or coils
  • Stents
  • Implanted stimulators
  • Implanted vagus nerve or deep brain stimulators
  • Implanted electrical devices, such as pacemakers or medication pumps
  • Electrodes for monitoring brain activity
  • Cochlear implants for hearing
  • Any magnetic implants
  • Bullet fragments
  • Any other metal device or object implanted in your body
• You're taking any medications, including prescription or over-the-counter medications, herbal supplements, vitamins or other supplements, and the dosages.
• You have a history of seizures or a family history of epilepsy.
• You have other mental health disorders, such as substance misuse, bipolar disorder or psychosis.
• You have brain damage from illness or injury, such as a brain tumor, a stroke or a traumatic brain injury.
• You have frequent or severe headaches.
• You have any other medical conditions.
• You've had prior treatment with rTMS, and whether it was helpful in treating your depression.

Before your first appointment

Repetitive TMS isn't invasive, doesn't require anesthesia and can be performed on an outpatient basis. You don't need to arrange for someone to drive you home after treatment — unless, for the first treatment, you prefer a driver until you get a sense of how you'll feel afterward.

Before considering treatment, check with your health insurance company to see whether rTMS is covered. Your policy may not cover it.

Repetitive TMS is usually done 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. Your first appointment typically lasts about 60 minutes.

Most likely, during your first appointment:

• You'll be taken to a treatment room, asked to sit in a reclining chair and given earplugs to wear during the procedure.
• An electromagnetic coil will be placed against your head and 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.
• Your doctor will determine the amount of magnetic energy needed by increasing 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.

During each treatment

Once the coil placement and dose are identified, you're ready to begin. Here's what to expect during each treatment:

• You'll sit in a comfortable chair, wearing ear plugs, with the magnetic coil placed against your head.
• When the machine is turned on, you'll hear clicking sounds and feel tapping on your forehead.
• The procedure will last about 40 minutes, and you'll remain awake and alert. You may feel some scalp discomfort during the treatment and for a short time afterward.

After each treatment

You can return to your normal daily activities after your treatment. Typically, between treatments, you can expect to work and drive.

If rTMS works for you, your depression symptoms may improve or go away completely. Symptom relief may take a few weeks of treatment.

The effectiveness of rTMS may improve as researchers learn more about techniques, the number of stimulations required and the best sites on the brain to stimulate.

Ongoing treatment

After completion of an rTMS treatment series, standard care for depression ― such as medication and psychotherapy ― may be recommended as ongoing treatment.

It's not yet known if maintenance rTMS sessions will benefit your depression. This involves continuing treatment when you are symptom-free with the hope that it will prevent the return of symptoms.

However, if your depression improves with rTMS, and then later you have another episode of symptoms, your rTMS treatment can be repeated. This is called re-induction. Some insurance companies will cover re-induction.

If your symptoms improve with rTMS, discuss ongoing or maintenance treatment options for your depression with your doctor.