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TMS (Transcranial magnetic stimulation) 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 TMS. Recent studies also suggest that stimulation over the left and right sides of the brain can have opposite effects on mood regulation.
Antidepressant medications and psychotherapy are the first line treatments for major depression. These treatments, however, do not work for all patients. In these instances, TMS might be used as an alternative treatment, or to augment antidepressant medications or psychotherapy. Patients who have failed to achieve an adequate response from antidepressants, or who are unable to tolerate medications, might consider TMS therapy.
During the first TMS 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.
Because TMS 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 TMS produces a loud clicking sound with each pulse, much like an MRI machine. Patients are seated during each session of TMS.
During the first TMS 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.
TMS 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 18 – 25 minutes. Patients receive TMS 5 days a week. A typical course of TMS is 4 to 6 weeks.
TMS 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 TMS, 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 TMS 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.
TMS 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 TMS 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 TMS 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.
Patients with any type of non-removable metal in their heads (with the exception of braces or dental fillings), should not receive TMS. 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 TMS:
Existing evidence to date suggests that patients who are less treatment-resistant respond better to TMS than those who are highly treatment-resistant. However, there is much yet to be learned about particular variables that may impact response to TMS. Researchers are presently conducting clinical studies to evaluate who will benefit most from TMS therapy. For example, there is a lot of interest in evaluating whether TMS with antidepressant medications is more effective than TMS alone.
Indication
Positive Change TMS® Advanced Therapy is indicated for the treatment of Major Depressive Disorder in adult patients who have failed to receive satisfactory improvement from prior antidepressant medication in the current episode.
Important Safety Information
The most common side effect is pain or discomfort at or near the treatment site. These events are transient; they occur during the TMS treatment course and do not occur for most patients after the first week of treatment.
Positive Change TMS® should not be used with patients who have non-removable conductive metal in or near the head. Positive Change TMS® has not been studied in patients who have not received prior antidepressant treatment.
Complete information is available at positivechangetms.com