"With a little luck, it'll be on the market by the end of the year," says Fischell, who also started a company, called Neuralieve, to produce it.
Fischell, a former Johns Hopkins physics professor who lives in Howard County, has invented dozens of medical devices over the past 40 years -- including the rechargeable pacemaker, implantable insulin pump and a variety of stents to help unclog coronary arteries.
He says that in most cases his new invention can relieve a migraine with just two magnetic pulses delivered over a few seconds. "It says, `Neurons, whatever you're doing, stop it,'" Fischell says.
In November, a nationwide trial sponsored by Neuronetics found that TMS improved depression in a significant number of subjects. (Zatuchni was part of this research.)
In the study, chronically depressed subjects received TMS for 35 minutes a day, five days a week, for four to six weeks. Depression improved significantly in a quarter of the volunteers -- double the rate of a control group that had a sham TMS treatment (subjects were hooked up to the TMS device but didn't receive magnetic waves).
Dr. John O'Reardon, an associate professor of psychiatry at the University of Pennsylvania and lead researcher in the study, says the 1-in-4 success rate is actually quite good, given that the subjects suffered from "treatment-resistant depression," i.e. they had tried many medicines and therapies without success.
"These are the toughest patients to treat," he said. "This was a significant improvement." He notes that once the control group was also given TMS, the success rate shot up to almost half of all subjects.
TMS was developed in the mid-1980s as a research tool to help scientists understand how the brain works. It uses magnets to generate a powerful field, creating an electric current that alters brain waves. Scientists soon realized that many patients in TMS studies seemed to improve, and increasingly researchers have focused on its therapeutic potential.
It is not entirely clear how TMS works, in depression or any other ailment. Researchers know the treatment can change electrical activity in targeted brain regions; low-frequency magnetic waves decrease neuronal firing, while high-frequency waves increase it.
In depression, researchers have focused on the left prefrontal cortex, a part of the brain that plays a large role in regulating emotion and memory. Treatment involves sending high-frequency waves into this area, on the upper left forehead.
