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Transcranial Magnetic Stimulation Stops Pain, Study Shows
By Kathleen Doheny
WebMD Medical News
Reviewed By Louise Chang, MD
on Thursday, June 22, 2006
Yousef Mohammad, MD, MSc, hopes he is studying the next best thing: a hand-held device about the size of a hair dryer that transmits magnetic pulses and aims to "short-circuit" the migraine by interrupting the brain activity believed to cause it.
Mohammad, an assistant professor of neurology at Ohio State University Medical Center in Columbus, found that 74% of migraine sufferers who received two magnetic pulses to the back of the head reported no pain or mild pain two hours later, compared with just 45% of those who got "placebo" pulses from an identical-looking device. He presented his findings at the 48th Annual Scientific Meeting of the American Headache Society in Los Angeles.
The study was small -- just 43 patients; larger, additional studies are crucial, he says. Still, "the results are encouraging."
Its use in headache is based on an emerging new theory of the cause of migraine, which affects an estimated 28 million Americans.
New Migraine Theory
"Migraine starts with a 'hyperexcitability' in an area in the brain," Mohammad says. "This hyperexcitability is manifested by the patients seeing flickering lights and bright spots in the vision. This is followed by exhaustion of the neurons -- usually blurred vision." This is the so-called aura -- changes in vision and light sensitivity, for instance -- that about one in five migraine patients have. Then the pain usually follows.
The TMS device, which is used as soon as the patient notices the onset of either the aura or the pain, aims to short-circuit this process, which scientists call "cortical spreading depression." As the depression spreads throughout the brain, the brain activates pain nerve endings on blood vessels surrounding the brain, resulting in the severe pounding and throbbing pain of the headache.
"The device has a coil in it," Mohammad explains. "The coil creates an electrical current that creates a magnetic field. The magnetic field will create an electric current in the brain and deactivate [the process]." The current model is electrical, but the developers plan to create a battery-operated version.
TMS Device Well-Tolerated
In his study, the TMS device greatly reduced noise and light sensitivity, both problems for migraine sufferers, says Mohammad, who serves on the medical advisory board of Neuralieve, the makers of the device. While 84% of the 23 patients who used the TMS device had no noise sensitivity two hours later, only 17% of the placebo group reported no noise sensitivity. While 70% of the TMS users had no light sensitivity two hours later, only 22% of the placebo group had no light sensitivity problems.
Ability to get back to work was better in the TMS group, with 86% of the TMS users saying they had "normal cognition" or "mild impairment" two hours later, compared with 56% of the placebo-treated group.
A new study of the device will begin in July at nine centers, with a goal of enrolling 200 patients, Mohammad says.
Ting Lu, the chief financial officer of Neuralieve in Sunnyvale, Calif., says the unit weighs just less than 3 pounds. The user charges the unit for about 15 seconds, picks it up by its two handles, holds it to the back of the head and presses a button to administer the two magnetic pulses. They will hear a clicking noise and vibration.
The hope is to create a version patients can use at home; the cost is not yet known, Lu says. It could be available by mid-2007.
SOURCES: Youssef Mohammad, MD, assistant professor of neurology, Ohio State University Medical Center, Columbus. Carol Murphy, accountant, Fairborn, Ohio. Ting Lu, chief financial officer, Neuralieve, Sunnyvale, Calif. Nick Nelson, product manager, Neuralieve, Sunnyvale, Calif.
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