Why does rTMS work?
rTMS has been shown to produce changes in neuronal activity in regions of the brain implicated in mood regulation, such as the prefrontal cortex. As each magnetic pulse passes through the skull and into the brain, this induces brief activity of brain cells underlying the treatment coil.
The frequency of pulse delivery also influences whether brain activity is increased or decreased by a session of rTMS. Recent studies also suggest that stimulation over the left and right sides of the brain can have opposite effects on mood regulation.
What happens during an rTMS procedure?
Because rTMS uses magnetic pulses, before beginning a treatment, patients are asked to remove any magnetic-sensitive objects (such as jewelry, credit cards). Patients are required to wear earplugs during treatment for their comfort and hearing protection, as rTMS produces a loud clicking sound with each pulse, much like an MRI machine. Patients are seated during each session of rTMS.
During the first rTMS session, several measurements are made to ensure that the TMS coil will be properly positioned over the patient’s head. Once this is done, the TMS coil is suspended over the patient’s scalp. The TMS physician then measures the patient’s motor threshold, by administering several brief pulses. The motor threshold is the minimum amount of power necessary to make the patient’s thumb twitch, and varies from individual to individual. Measuring the motor threshold helps the physician personalize the treatment settings and determine the amount of energy required to stimulate brain cells.
Once the motor threshold is determined, the coil is then brought forward so that it rests above the front region of the patient’s brain. Treatment is then commenced. During the treatment, patients will hear a series of clicking sounds and will feel a tapping sensation under the treatment coil.
Motor threshold is not checked at every treatment but may be reassessed if there is concern it may have changed, for example, because of a change in medication.
How long is an rTMS procedure?
rTMS therapy involves a series of treatment sessions. Treatment sessions vary in length depending on the TMS coil used and the number of pulses delivered but typically last around 30 – 40 minutes. Patients receive TMS 5 days a week. A typical course of rTMS is 4 to 6 weeks. However, this can vary depending on an individual’s response to treatment.
Do I need to be hospitalized for a course of rTMS?
Unlike ECT, rTMS does not require any sedation or general anesthesia, so patients are fully awake and aware during the treatment. There is no “recovery time”, so patients can drive home afterwards and return to their usual activities.
What are the side-effects of rTMS?
rTMS is well-tolerated and associated with few side-effects and only a small percentage of patients discontinue treatment because of these. The most common side-effect, which is reported in about half of patients treated with rTMS, is headaches. These are mild and generally diminish over the course of the treatment. Over-the-counter pain medication can be used to treat these headaches.
About one third of patients may experience painful scalp sensations or facial twitching with rTMS pulses. These too tend to diminish over the course of treatment although adjustments can be made immediately in coil positioning and stimulation settings to reduce discomfort.
The rTMS machine produces a loud noise and because of this earplugs are given to the patient to use during the treatment. However, some patients may still complain of hearing problems immediately following treatment. No evidence suggests these effects are permanent if earplugs are worn during the treatment.
rTMS has not been associated with many of the side-effects caused by antidepressant medications, such as gastrointestinal upset, dry mouth, sexual dysfunction, weight gain, or sedation.
The most serious risk of rTMS is seizures. However, the risk of a seizure is exceedingly low. At Johns Hopkins, we follow up-to-date safety guidelines that are designed to minimize the risk of seizures. While rTMS is a safe procedure, it is important to point out that because it is a new treatment, there may be unforeseeable risks that are not currently recognized.
Who cannot get rTMS therapy?
Patients with any type of non-removable metal in their heads (with the exception of braces or dental fillings), should not receive rTMS. Failure to follow this rule could cause the object to heat up, move, or malfunction, and result in serious injury or death. The following is a list of metal implants that can prevent a patient from receiving rTMS:
· Aneurysm clips or coils
· Stents in the neck or brain
· Deep brain stimulators
· Electrodes to monitor brain activity
· Metallic implants in your ears and eyes
· Shrapnel or bullet fragments in or near the head
· Facial tattoos with metallic or magnetic-sensitive ink
· Other metal devices or object implanted in or near the head