Transcranial Magnetic Stimulation (TMS) Treatment for Depression

This week the focus is on mental health.

Currently I'm taking part in a training to learn how to use transcranial magnetic stimulation (TMS) for patients with major depressive disorder. My training and source of information is provided by Neurostar (the company whose machine we use in the outpatient practice I'm working in this year), and I've also supplemented Neurostar's information with information from Up to Date. This week, I will briefly share what TMS is, who might be a good candidate, and some of the research findings about the effectiveness of the treatment.

TMS is non-invasive (i.e. outside of the body) and non-systemic (localized effect). Simply stated, it involves placing a metal coil (seen in the picture above) against the scalp. This metal coil generates rapidly alternating magnetic fields, which penetrate approx 2-3 centimeters into the head. There are several steps the physician must take to find the effective target area which is located in the dorsolateral prefrontal cortex.  Once identified, the magnetic fields generated leads the neurons in this area to depolarize. While the exact mechanism of action is unknown, it is likely that this discrete cortical area is connected to a network of other areas in the brain that are involved in mood regulation. The magnetic fields change pathological activity within the network.

Who might be a good candidate for TMS? First, a person should have the diagnosis of major depressive disorder. They also should have failed to receive satisfactory improvement from prior antidepressant medication in the current episode of depression. Of note, the American Psychiatric Association Practice Guidelines recommend considering the use of TMS after evidence of failure of an adequate initial antidepressant medication attempt. In practice, this means that TMS can be considered before SSRI augmentation with other antidepressants or antipsychotic medications after just one antidepressant has been tried.

And who is not a good candidate? People who have conductive, ferromagnetic, or other magnetic-sensitive metals implanted in their head or which are non-removable and are located within 30 cm of the treatment coil cannot receive TMS.   Other medical conditions also need to be assessed, including a person's risk of seizures (risk of seizure is the most serious possible adverse effect of TMS).

Multiple studies have found that patients with treatment resistant depression do benefit from TMS. Compared to placebo, TMS alone showed a 14% remission rate in depression, compared to 5% in the placebo group, and TMS combined with antidepressant medication saw a reduction of symptoms in 47% of patients, compared to 22% in the placebo group. However, TMS is less effective that electroconvulsive therapy (ECT).

This post just scratches the surface of information about TMS. If you're interested in learning more, here is a link to assist you in finding a NeuroStar doctor: click here.