Reptitive transcranial magnetic stimulation (rTMS) utilizes an electromagnet placed on the scalp that generates magnetic field pulses roughly the strength of an MRI scan. The magnetic pulses pass readily through the skull and stimulate the underlying cerebral cortex. Low frequency (once per second) TMS has been shown to induce sustained reductions in cortical activation in multiple studies.
In use for the treatment of depression, rTMS is generally used with high frequencies, stimulating the left dorsolateral prefrontal cortex of the brain. This gives positive results with significant decrease of scores on depressive scales applied to resistant and non resistant depressions.
rTMS given to the front of the brain is generally not painful, but can be uncomfortable insofar as a tingling or knocking sensation is produced against the scalp. Scalp and facial muscle contractions sometimes occur during TMS. There is a very small risk of seizure associated with TMS, but for the frequency of stimulation used in this study (one stimulation per second), the risk is significant only for patients who have a prior history of seizures.
NeuroStar TMS Therapy® is specifically indicated for the treatment of Major Depressive Disorder in adult patients who have failed to achieve satisfactory improvement from one prior antidepressant medication at or above the minimal effective dose and duration in the current episode. In clinical trials with NeuroStar TMS Therapy, these patients had been treated with a median of 4 medication treatment attempts, one of which achieved criteria for adequate dose and duration. It is a 40-minute outpatient procedure that is prescribed by a psychiatrist and performed in a psychiatrist’s office. The treatment is typically administered daily for 4-6 weeks.
The benefits of TMS observed in its clinical trials include:
No systemic side effects, such as weight gain, sexual dysfunction, sedation, nausea, or dry mouth
No adverse effects on concentration or memory
No device-drug interactions
The most common adverse event related to treatment was scalp pain or discomfort at the treatment area during active treatments, which was transient and mild to moderate in severity. The incidence of this side effect declined markedly after the first week of treatment.
There was a less than 5% discontinuation rate due to adverse events.
During a 6-month follow-up period, there were no new safety observations compared to those seen during acute treatment.