Oct. 8, 2008 -- The FDA has cleared the NeuroStar TMS brain-stimulating device for treating depressed adults for whom one antidepressant has failed to work.

It's the first transcranial magnetic stimulation (TMS) device to pass FDA muster. An FDA spokesperson tells WebMD that because the NeuroStar device is not implanted and carries only "moderate" risk, the FDA needed to only "clear" the device and not formally "approve" it.

The clearance comes nearly two years after a January 2007 FDA advisory panel said clinical trials failed to establish that the device was clinically effective. Although TMS-treated patients were twice as likely as sham-treated patients to show clinical benefit, some panel members said this effect was "small," "borderline," "marginal," and "of questionable clinical significance."

Because of these questions about effectiveness, the panel said NeuroStar device's risk/benefit profile was not comparable to the risk/benefit profile of electroconvulsive therapy (ECT). Nevertheless, FDA today cleared the NeuroStar device based on "equivalence" to ECT.

This doesn't mean TMS is the same as ECT, says psychiatry professor Michael Thase, MD, chief of the mood and anxiety disorders program at the University of Pennsylvania. Thase has served as a consultant to NeuroStar maker Neuronetics Inc. On the company's behalf, he presented NeuroStar clinical trial data to the 2007 FDA advisory committee.

"TMS is in no way equivalent to ECT in terms of efficacy nor in terms of safety. TMS is less effective but substantially safer than ECT," Thase tells WebMD.

There are important differences between the two treatments:

• ECT, also known as electroshock therapy, uses an electric shock to induce seizure. TMS uses a magnetic field to induce a much smaller electric current in a specific part of the brain without causing seizure or loss of consciousness.
  
  
• ECT is extremely effective in treating severe depression. TMS is not so powerful. It is used to treat milder depression, and it works best in patients who have failed to benefit from one, but not two or more, antidepressant treatments.
  
  
• TMS is much safer than ECT. Unlike ECT, TMS does not require sedation and is administered on an outpatient basis.

How well does TMS work? Thase says he's seen meaningful benefit in patients he's treated -- a benefit also seen in clinical trials.

"The track record for TMS in depression is not 100% successful, but studies document a pattern of evidence that this has a significant treatment benefit," he says.

When, if ever, should a patient give TMS a try?

The FDA clearance is for the same patients who did best in clinical studies: people who did not benefit from one antidepressant medication, but who had not yet tried a second antidepressant.

"It fits in between first- and second-choice therapies and ECT," Thase says. "You would not use it in a patient for whom the depression was so disabling that hospitalization was required. And you certainly would not use it for someone who had tried antidepressant treatment of appropriate dosage and duration."

Patients undergoing TMS must be treated four or five times a week for four weeks. Thase says that during this time, his team starts patients on a new antidepressant and weans them from TMS treatment.

SOURCES: News release, Neuronetics Inc. Michael Thase, MD, professor of psychiatry and chief, mood and anxiety disorders treatment & research program, University of Pennsylvania. Karen Riley, FDA spokesperson. FDA, meeting transcript, Medical Devices Advisory Committee, Neurological Devices Panel, Jan. 26, 2007. FDA, "Brief Summary from the Neurological Devices Panel Meeting -- January 26, 2007. Neuronetics Panel Presentation, FDA Neurological Devices Panel Meeting, January 26, 2007. WebMd Medical News: "Device for Depression Criticized."

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