STOWE, VERMONT—Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (TDCS) are gaining attention as potential noninvasive therapies for migraine, according to research reported at the Headache Cooperative of New England's 23rd Annual Headache Symposium. Recent studies have suggested that the techniques may be beneficial, but their efficacy remains to be proven, said Daniel Press, MD, the Clinical Director for the Berenson-Allen Center for Noninvasive Brain Stimulation at Beth Israel Deaconess Medical Center in Boston.

TMS devices have been approved for treating medication-resistant depression, but not for migraine. TDCS is used during neurologic rehabilitation for patients with stroke and traumatic brain injury, and the technique may help alleviate neuropathic pain, said Dr. Press. Neurologists are also investigating whether TMS may improve mood and cognition in patients with Parkinson's disease and whether it could become an antiepileptic therapy for patients with non–temporal-lobe epilepsy.

Current use of TMS and TDCS is limited, because neurologists are uncertain about which part of the brain to stimulate and when. "We need a better handle on what part of the pathophysiology we want to intervene on, but these techniques can be used to directly modulate brain regions," said Dr. Press.

TMS May Reduce Pain for Migraineurs With Aura
In TMS therapy, neurologists turn a coil on and off quickly to create a 2-T magnetic field that passes through the skull and depolarizes neurons in the brain. Neurologists can deliver single pulses to inhibit a brain region or high-frequency pulses to stimulate it. A portable device that patients can use at home has also been developed, but has not yet been approved by the FDA.

Richard Lipton, MD, Vice Chair of Neurology at Albert Einstein College of Medicine in the Bronx, New York, and colleagues were the first to test whether TMS could block the spreading depression observed in migraine with aura, said Dr. Press. The researchers randomized 164 people to TMS (ie, two single pulses, approximately 30 seconds apart, at an intensity of

On the other hand, the researchers saw no difference between the two groups for total headache response on a global assessment of relief, said Dr. Press. Approximately 41% of patients in the sham group reported good to excellent relief, compared with 42% of patients in the active group. In addition, the total disability time was shorter in the sham group than in the TMS group, although the result was not statistically significant. "That study is in need of replication," said Dr. Press. Several of the researchers had a stake in the company that manufactured the TMS device, he added.

Tests of TMS as a prophylactic therapy for headache have yielded mixed results. One study indicated that daily treatments of low-frequency TMS over the visual cortex were no better than placebo at reducing headache frequency. In another trial, high-frequency TMS over the dorsolateral prefrontal cortex modestly decreased headache frequency in patients with chronic migraine, compared with placebo.

TDCS Not Superior to Placebo for Migraine In TDCS, the neurologist applies two pads, which are soaked in salt water and attached to a 9-V battery, to the patient's scalp. Rather than causing depolarization or cell firing, TDCS is neuromodulatory because it changes the likelihood of an action potential. The technique affects a much wider region of the brain than TMS does.

The method's low rate of complications is one of its advantages. "The only significant side effects are a slight scalp tingle and the small risk of a burn to the skin," said Dr. Press. Because of its simplicity, patients may find the portable TDCS unit less intimidating than the portable TMS device for home administration. "It's a nice technique if we can figure out the right settings," said Dr. Press.

With growing evidence that it can be helpful for neuropathic pain, TDCS is starting to be investigated for migraine prophylaxis. In a study with a crossover design, researchers randomized patients to three weeks of cathodal TDCS over the visual cortex or sham. Treatments lasted 15 minutes per day. The duration of migraine attacks decreased significantly in the active group, but the decrease was not significantly different from the decrease that the sham group experienced. TDCS had no effect on the frequency of migraine attacks.

In a separate trial, during which cathodal TDCS was given over the visual cortex for six weeks, the technique reduced pain intensity, but not the duration or number of attacks, compared with placebo. It is possible that anodal TDCS over the visual cortex would be more effective, said Dr. Press.

—Erik Greb
Senior Associate Editor

To view a video interview with Daniel Press, MD, click here.

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