Dr. Lanocha: TMS is transcranial magnetic stimulation, and it is basically a clinical application of Faraday’s Law, which states that a moving magnetic field can cause an electrical current to flow. TMS may work by modulating activity in the brain default mode network, which is a set of brain regions that oscillate in a synchronous manner and are thought to be involved in affective processing and mood regulation.
TCPR: And how is this related to depression?
Dr. Lanocha: Functional imaging studies have shown decreased activity in the left prefrontal region in patients with depression, and TMS may stimulate those underactive neurons, restoring them to a normal level of function, which can then persist long after the direct stimulation.
TIPR: Is there any pre-TMS imaging workup required to determine where to place the magnet?
Dr. Lanocha: No, brain imaging is not necessary in order to determine the correct placement of the magnet—there are other methods for determining that. The most common approach is to determine the patient’s motor threshold, which is the magnetic field strength required to produce a visible muscle movement. That is usually done by positioning the magnet over the motor cortex and stimulating the area that controls movement of the thumb. Then the magnet can be moved anteriorly by a certain amount and placed over the left dorsolateral prefrontal cortex.
TCPR: Who is the ideal TMS candidate and who is maybe not such a good candidate?
Dr. Lanocha: Any patient who has failed to respond to initial antidepressant treatment is potentially a candidate for TMS. The FDA product labeling for both the NeuroStar and Brainsway devices states that these treatments are appropriate for patients who have failed any number of antidepressants in the current episode. However, it is likely effective in patients who have not responded to treatments in more than just one episode. The most recent systematic review of rTMS for treatment-resistant depression (defined as depression that has been resistant to at least two prior antidepressant attempts) found that those receiving TMS were three times more likely to respond as those receiving sham TMS (Gaynes BN et al, J Clin Psychiatry 20l4;75(5);477-489). As a general rule, TMS works best when it is given relatively early in the course of the illness before more severe treatment resistance develops. But in my experience it works remarkably well, even for patients with a high level of treatment resistance.
TIPR: So while the research shows that TMS works best in those who have failed antidepressants for a single episode of depression, it sounds like you will often treat people who have failed three or four trials for multiple episodes.
Dr. Lanocha: I have never treated a patient with TMS who has failed only one antidepressant. That just doesn’t happen. All of my patients have failed to respond to multiple medication trials, often over the course of many years. What is interesting is that the duration of illness, number of failed medications, and other factors, such as age, appear to be very weak predictors of response. So it is hard to say that there is an ideal candidate versus a patient who should not be considered for TMS. I don’t think that I or anyone would really advocate TMS as a first-line treatment, however. I think that medication and psychotherapy are still the preferred first line of treatment, and when a patient responds, it’s great.
TIPR: A lot of us understand TMS as sort of a noninvasive form of EIT, perhaps even targeting the same brain areas. Is there a relationship between responsiveness to E|T and responsiveness to TMS?
Dr. Lanocha: No. ECT is a convulsive therapy that produces its therapeutic effect by inducing a generalized seizure that involves the entire brain from cortex to brain stem. TMS is a nonconvulsive treatment that does depolarize neurons, but acts in very discrete areas of the brain. It is also very focal compared to ECT, which is very diffuse. Although the data show that ECT is in general more effective than TMS, I have successfully used TMS in patients who had failed to respond to ECT.
TCPR: Can you walk us through what a practice might need to offer TMS to patients?
Dr. Lanocha: You don’t need a lot of space, but you do need a dedicated treatment room that’s probably at least 10 x 12 feet. Of the two devices that are currently available, the Neuronetics NeuroStar System requires a little bit more space because it is an integrated system that includes a reclining chair. In addition to the equipment and the treatment room, most people are also going to want to have a TMS technician to assist them with administering the treatment. It is necessary to track personnel costs in addition to the capital investment of the device itself.
TCPR: What is that capital investment and then what are the recurrent costs?
Dr. Lanocha: The capital investment for the system itself is about $65,000, and the devices can be either purchased or leased. The Neuronetics System, which I use, requires a single-use disposable component for each treatment, but operating costs for both systems are determined by use and are roughly equivalent over the course of the year assuming similar use.