Transcranial Magnetic Stimulation: Device Comparison and Clinical Experiences
ORLANDO—Neurostimulation, particularly transcranial magnetic stimulation (TMS), offers a unique approach to treat mood disorders with an electrical rather than pharmacologic intervention, said Scott Aaronson, MD, Director of the Clinical Research Program in the Sheppard Pratt Health System.
TMS uses a moving magnetic field to create an electrical current perpendicular to the moving magnetic field in an area of the brain in which we find decreased activity in depression.
“The really simple explanation for repetitive TMS is increasing activity in an area of the brain that has decreased activity due to depression, the left dorsolateral prefrontal cortex,” explained Dr. Aaronson in a presentation at the 27th Annual U.S. Psychiatric and Mental Health Congress.
This stimulation of the dorsolateral prefrontal cortex alters activity in the anterior cingulate as well as deeper limbic regions.
TMS also results in chronic effects, alterations of monomine concentrations, serotonin receptor modulation, and increase in the plasticity of the brain and in neurogenesis. “Increasingly, BDNF is going to wind up being a marker for improvement,” said Dr. Aaronson.
A typical treatment session for TMS involves four seconds of 10 Hz (40 separate stimulations) with a 26-second rest time and another four seconds of stimulation. Slight discomfort occurs during the stimulation. “My patients have said it feels like a woodpecker pecking on the side of your head,” said Dr. Aaronson.
Two FDA-Approved Devices
There are two FDA-cleared devices for TMS—a Neuronetics device and a Brainsway device that claims a deeper and wider area of stimulation.
A randomized controlled trial supporting the Neuronetics device was published in Biological Psychiatry, but data for the Brainsway device, which was approved in 2013, are available on the FDA website but have not yet been formally published.
The Brainsway device uses an H coil design that supports deeper penetration of the magnetic field. It uses an 18 Hz frequency and train duration of 2 seconds, compared with the 10 Hz and 4 seconds of Neuronetics. The overall session duration of Neuronetics device is 37.5 minutes, while the Brainsway session duration is 20.2 minutes, explained Dr. Aaronson.
Business models of the two devices also differ. Neuronetics offers purchase or lease agreement for use of the chair, which Dr. Aaronson said is possibly close to cost.
The revenue comes from single use shields, but the reimbursement rates are low, making it hard for sites to be profitable.
Brainsway takes the approach of a lease-only agreement with a first-year lease of unlimited treatments for a single price. “The problem is that model prefers institutions with a larger patient base than private doctors. For the next year, the lease provides a certain number of treatments for a fixed price,” said Dr. Aaronson.
Although Medicare will pay for TMS in many parts of the country, they might not pay enough to make the investment worthwhile for clinicians considering purchasing one of the devices. However, Dr. Aaronson added that these business models are evolving.
Personal Experience With TMS
Dr. Aaronson has personally used TMS in clinical practice since April 2009. So far, he has treated about 175 patients, all of whom were cash or free care. The typical patient has failed two to six antidepressants in current episodes.
Nearly all patients, except as required by study, were on antidepressant medication, and about half of patients premedicated with an NSAID or acetaminophen. After 30 treatments over six weeks, patients experienced a 63% response rate and 33% remission rate by MADRS scores.
No patient was unable to complete a course of treatment due to intolerable adverse effects, and several maintenance patients have been in remission for two to four years.
Dr. Aaronson believes TMS may be ideal for multi-medication intolerant patients and could be especially helpful in avoiding the use of medications in pregnancy or postpartum.
He sees TMS as more of an alternative to polypharmacy than as an alternative to ECT. “The reason for that is I don’t think it’s as strong as ECT, and we really haven’t looked at the folks who have failed treatments.” Nonetheless, on a personal basis he would want to fail TMS before trying ECT.
In addition, Dr. Aaronson says TMS appears to be more helpful as an add-on treatment to medication than as monotherapy.
Little data exist on TMS for bipolar depression or about maintenance treatment. “I think those are the two things I would like someone to study,” said Dr. Aaronson.
“We are at the beginning of a revolution in the care of psychiatric illness,” Dr. Aaronson concluded.
1. Aaronson S. [Psych Congress conference presentation]. September 21, 2014. Neurostimulation in the Treatment of Mood Disorders 2014 .