Members of the panel expressed doubts that the machine, called NeuroStar, helps depressed patients or provides any advantage over placebo treatment.
The device looks much like a dentist’s chair with metal prongs attached to a nearby console.
It works on the same principle as electroconvulsive therapy (ECT) -- commonly called "electric shock treatment" -- a treatment usually reserved for severely depressed patients who do not respond to antidepressant drugs or therapy.
But instead of using electric shocks, NeuroStar stimulates the brain by sending a focused magnetic field into the brain from outside the skull -- a treatment called transcranial magnetic stimulation, or TMS.
In 2005, the FDA approved an implantable nerve stimulation device made by Cyberonics to treat depression.
The implantable device uses vagus nerve stimulation, or VNS, to stimulate the vagus nerve (which runs from the neck to the brain and relays messages to the brain) rather than the brain directly. VNS is already used to treat epilepsy.
Neuronetics, the company that manufactures NeuroStar, presented TMS as an advantage to implantable devices because it does not require invasive surgery.
The company sought to show that the device is equivalent to ECT but with fewer side effects and is more accessible to patients.
“Many patients cannot avail themselves of (ECT) ... cannot afford this treatment,” says Philip G. Janicak, MD, a researcher who conducted clinical trials of TMS for the company.
Also, “Only 8% of psychiatrists provide electroconvulsive treatment,” says Janicak, a professor of psychiatry at Rush Presbyterian Medical Center in Chicago.
But the advisory panel was generally unimpressed with the company’s studies, even though they showed a slight statistical advantage in treating depression symptoms vs. dummy therapy after six weeks of treatment.
Several panelists expressed dismay that patients showed no improvement on some depression scales and only minor improvement on the ones that did show a difference.
“Perhaps a reasonable person could question whether there has been an effect at all,” says Thomas G. Brott, a neurologist from Mayo Medical School in Jacksonville, Fla., and the advisory panel's chairman.
The panel did not formally recommend to the FDA whether or not the machine should be approved.
But FDA scientists suggested at a public hearing that they were also uneasy with the company’s results.
Ann Costello, PhD, an FDA medical official, questioned whether the mixed evidence of effectiveness in Neuronetics’ studies contained “any clinical relevant information.”
Patients who used TMS appeared to avoid the memory loss often seen in those who undergo ECT.
But Diana Zuckerman, PhD, president of the National Research Center for Women and Families, told the panel the company’s studies did not show the device could help patients.
“It’s not a statistically significant difference, and it’s not a meaningful difference," says Zuckerman, a clinical psychologist and epidemiologist. "Yes, it is safer than ECT, but it doesn’t appear to actually work.”
Steve Newman, executive director of the National Alliance for the Mentally Ill’s Washington, D.C., chapter, was one of a few patients from Neuronetics’ studies who told experts his deep depression eased after being treated with the machine.
“It was like a light switched on,” he says.