Occipital Nerve Stimulation Effective For Some Headaches

BY ALICIA AULT
Elsevier Global Medical News

CHICAGO (EGMN) - Occipital nerve stimulation appears to be effective and safe for the treatment of some headaches, but even when it is effective, the durability of the effect is not clear, said Dr. David W. Dodick on June 10 at the annual meeting of the American Headache Society.

Dr. Dodick, of the department of neurology at the Mayo Clinic in Scottsdale, Ariz., reviewed results from two recently published studies as well as his clinic's experience.

The therapy involves implanting a pulse generator under the clavicle, in the buttock, or in the abdomen and snaking a stimulating lead up the neck to the occipital region. Pulses are delivered to the occipital nerve; the stimulator can be turned off or on by remote control. Several manufacturers, including Medtronic, are developing occipital nerve stimulators. None is currently approved by the Food and Drug Administration.

In one study, Dr. Delphine Magis and colleagues at Liege University (Belgium) implanted a Medtronic occipital nerve stimulator in eight patients with intractable cluster headache (Lancet Neurol. 2007;6:314-21). After a follow-up of 6 and 22 months, two of the eight patients were pain free. Three patients had a 90% reduction in frequency of attacks, and two patients had a 40% reduction. One patient dropped out of the study after 4 months and had the device explanted. No serious adverse events occurred; however, headaches returned quickly after interruption of stimulation.

Researchers at the National Hospital for Neurology and Neurosurgery in London also recently reported on an eight-patient study that involved implanting the Medtronic device in the suboccipital region (Lancet 2007;369:1099-106). All patients received bilateral stimulation. Although two patients reported no change in their headaches, two reported a substantial reduction in attacks, three had a moderate improvement, and one a mild improvement.

"When you think about the kind of patients that we're talking about, that's pretty doggone good," said Dr. Dodick.

There was a lead migration in one patient and battery depletion leading to replacement in four patients.

Lead migration has been a nagging issue with implantation of devices in patients at the Mayo Clinic, said Dr. Dodick. In initial results reported by Dr. Dodick and his colleagues, lead migration occurred in 60% of the cases (Cephalalgia 2007;27:153-7).

With 50 cases now done at Mayo, the lead migration and revision rates are still steep, at around 40%, he said. Without significant change to the technology, lead migration is likely to remain a problem, because "you're tracking a wire down the neck," he said.

Initially, he and his colleagues expected impressive results, but they learned to temper their expectations, Dr. Dodick said. "When you stick a $20,000 piece of hardware in someone and charge them $60,000 for the procedure and the operating room and nurses and surgeons, you generally want that to work and work really well," he said. "I was expecting a home run, and you don't get a home run with all these patients."

But, he added, there is a reduction in headache frequency and "that is huge for these patients given how long they've been suffering."

In the first 50 patients, they found significant differences in the frequency and severity of headaches, and in disability. Two patients with hemicrania continua had the strongest response with a reduction in frequency from about 90 headaches a month to 10 and 12, respectively.

Three posttraumatic headache patients also responded very well, he said.

One case of infection occurred in their published case series, and four more have occurred since that time. Four of the five patients required explantation. They were not perioperative infections; some occurred as long as a year after the implantation, said Dr. Dodick. "The whole system becomes infected, they become septic," he said, adding, "It's something we have to be on the lookout for and a good reason why the technology has to improve, and a lot smaller device is needed."

The durability of the response is another issue. The first patient implanted, in 1999, is currently hospitalized with intractable pain, he said. A patient with hemicrania who did well for 3 years is also back in the hospital for intractable pain.

The open-label studies have been informative, but more answers are likely to come from three randomized, controlled trials currently being conducted in the United States, he said.

Most importantly, "I don't think we know what the long-term outcome is in these patients," he said.

Dr. Dodick disclosed that he has consulted for Advanced Bionics, Advanced Neurostimulation Systems, and Medtronic, and has received honoraria from Allergan, Ortho-McNeil, Medtronic, GlaxoSmihKline, Valeant, Neuralieve, Merck, and Eli Lilly.

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