What can the patient expect during the transcranial magnetic stimulation (TMS) procedure?
The procedure is usually performed by a doctor while the patient is awake and seated in a chair. A device with an electromagnetic coil is placed near the patient’s left prefrontal cortex, or the front side of the scalp, an area where a lack of functional and metabolic activity is found in the depressed patient.
The device is held in place for about 40 minutes. A steady electric current is passed through this part of the brain causing neurons, or nerve cells, in the brain to send electrical impulses. These impulses will then trigger a chemical reaction that, over time, will help lift the patient’s mood.
Doctors typically recommend 30 sessions of TMS therapy, usually given five times per week for four to six weeks.
Because this type of pulse generally does not reach further than 2 inches into the brain, the doctor can specifically target the portion of the brain to treat. This precision also lessens the chance for side effects that may occur with other procedures.
What different types of transcranial magnetic stimulation (TMS) treatment are available?
Repetitive transcranial magnetic stimulation (rTMS) uses more intense electric pulses.
- rTMS is used to treat patients with unipolar depression.
- In rTMS an electromagnetic coil is held against the patient’s left side of the scalp while short electromagnetic pulses are administered through the coil. The magnetic and repeating pulses cause small electrical currents that stimulate nerve cells in the targeted region of the brain. Each rTMS session usually lasts 30 to 60 minutes and does not require sedation or anesthesia.
- The strength of these currents is about the same as a magnetic resonance imaging (MRI) scan.
- Research is still being conducted on the best treatment options for rTMS, such as whether the procedure works best as a single treatment or when the procedure is combined with medication and/or psychotherapy.
- Side effects of rTMS, such as headaches, scalp discomfort, or brief lightheadedness, are mild or moderate. Some patients may feel a tingle of the muscles of the scalp, jaw or face during the procedure. Although rare, it is possible that the procedure could cause a seizure.
Deep transcranial magnetic stimulation (dTMS) is a relatively new method of stimulating larger, deeper brain regions.
- The procedure uses specialized coils, called H coils, which reach about 2 inches beneath the surface of the skull and are designed to target different brain areas.
- During a dTMS session, a person wears a cushioned helmet, which generates brief magnetic fields, similar to those in MRI scans. This is an outpatient procedure that does not require anesthesia.
- The procedure takes place daily with 20-minute sessions over four to six weeks. The patient can resume normal activities immediately after the procedure. The dTMS procedure has few side effects and does not result in seizures or memory loss.