Transcranial Magnetic Stimulation (TMS)

TMS has garnered much attention in recent years as a noninvasive research tool and a way to diagnose and treat mental disorders.

People with depression may have a new reason to cheer: In October [2008], the U.S. Food and Drug Administration cleared the first transcranial magnetic stimulation (TMS) device for treating severe cases of the disorder. Like TMS systems for other disorders, Neurostar, manufactured by Malvern, Pa.–based Neuronetics, involves rapidly sending magnetic pulses into the skull. This triggers electrical activity in the prefrontal cortex, which is believed in turn to affect areas of the brain tied to mood. TMS has garnered much attention in recent years as a noninvasive way to diagnose and treat mental disorders, including stroke, multiple sclerosis and motor neuron diseases. It can be done on an outpatient basis with no need for anesthesia. In the case of depression, for example, TMS offers a milder alternative to controversial techniques such as electroconvulsive therapy (ECT). It also does not require surgery, as does deep brain stimulation, another experimental treatment that has generated promising results. “This approval was long coming, and it’s a great thing that it’s happening,” says Alvaro Pascual-Leone, a professor of neurology at Harvard Medical School who has treated hundreds of patients with TMS on an “off-label” basis (a purpose outside the scope of the FDA’s approval). But the FDA decision is not a complete vindication for TMS. Only the Neurostar device was certified for depression, and only for a very specific group of patients: those who have failed one round of conventional drug therapy, but not more. Misstep on path to approval Neurostar has had a somewhat rocky road on its way to clearance. The device failed its first FDA review, when Neuronetics tried to prove “substantial equivalence” to ECT, according to Siobhan DeLancey, an FDA spokeswoman. Substantial equivalence means that because a new treatment has benefits similar to an existing treatment with an established history of safe use, it also is safe and effective. “It turned out to be a very bad choice to compare TMS and ECT,” says Philip Janicak, a professor of psychiatry at Rush University Medical School and one of the researchers overseeing Neurostar’s six-week, 30-session clinical trial. Electroconvulsive therapy is most often used in people who have failed four or more rounds of medication—cases that are probably too severe to respond to TMS, he points out. The FDA reviewers were convinced, however, by the data from the 164 patients who had previously taken only one course of treatment. There were “very robust and clinically significant” improvements—nearly three times that of the placebo—Janicak says. “We saw some patients with dramatic benefits.” The safety of the treatment also was less controversial than that of ECT. TMS caused few side effects other than headaches. Electroconvulsive therapy, in contrast, can result in memory problems and seizures. More data on the way But not everyone is completely convinced—yet. “There are some question marks about the data,” says TMS pioneer Mark George, a professor of psychiatry, radiology and neuroscience at the Medical University of South Carolina. In particular, the study was not double-blind in the strictest sense, says George, who serves as an unpaid consultant to a number of TMS companies, including Neuronetics. Efforts to disguise the sham treatment were not very convincing, so even though patients and rates remained unaware of who got the real treatment and who got the placebo, “it was pretty easy” for the TMS treater to tell As leader of a National Institutes of Health study looking at TMS and depression, George is using more-convincing sham treatments to answer those questions. Results from the study, which involves about 250 people, should start appearing around April of next year, he says. It’s also not clear yet if insurance companies will pay for TMS treatment. At up to $10,000 per patient, TMS is far cheaper than ECT or hospitalization but still much more costly than depression medications. Even so, "I’m delighted to see TMS come so far,” says George. “I think this is just the tip of the iceberg when it comes to brain stimulation techniques."