Occipital nerve stimulation, which already is being used selectively for migraine, may be effective in reducing the incidence as well as the severity of chronic cluster headaches, according to a recent case report.
Results of the study were presented at the annual meeting of the American Society of Regional Anesthesia (ASRA) and Pain Medicine in San Antonio (abstract ID 22).
Although neurostimulation for chronic pain conditions has been used since the 1960s, the mechanism of action still is not entirely clear. Despite this, the range of conditions treated by neurostimulation has grown significantly over the past decade.
“Over the past [several] years, the neurostimulation world, at first slowly and then more rapidly, has gotten their arms around the technology and now they’ve begun placing electrodes everywhere, for all kinds of indications,” said Richard Weiner, MD, clinical associate professor of neurosurgery at the University of Texas Southwestern Medical Center in Dallas and vice-chair of neurosurgery at Texas Health Presbyterian Hospital of Dallas.
Dr. Weiner was the first to observe the effect of activating a lead in the subcutaneous tissue and subsequently developed the technique of nerve stimulation for occipital neuralgia.
Nearly 17 years ago, Dr. Weiner was placing a peripheral nerve stimulator for intractable nerve pain in a morbidly obese patient. As he dissected down toward the target nerve—the only way to place an electrode at the time—Dr. Weiner said he “basically got lost in the fat and couldn’t find the nerve.”
He attempted several times to locate the nerve by using a needle introducer and a wire electrode, which he would stimulate and check for the prerequisite tingling sensation. “Every time we turned on that wire electrode, she [the patient] felt stimulation. And every time I dissected down to the tip of the electrode, there was no nerve,” Dr. Weiner recalled. “It took a little while to understand what that meant, and the discovery was that placing an electrode into the subcutaneous tissue produced tingling sensations in the region of whatever nerves were in that area.”
Later, Dr. Weiner would place an electrode in the subcutaneous tissue behind the head in patients with occipital neuralgia. “Lo and behold, it helped the headaches. And that’s how it all got started,” he said.
Today, it is hypothesized that peripheral stimulation of the occipital nerve may improve pain syndromes by central neuromodulating effects that are distinct from the previously described peripheral mechanisms, thought by many to be responsible for pain improvement with peripheral stimulation, said Natalie Strand, MD, an anesthesiologist at Mayo Clinic in Scottsdale, Ariz., and the author of the ASRA study.
“Stimulation of the C1, C2 and C3 nerve roots may alter the way the brain responds to pain by decreasing the perception of pain and decreasing the amount of pain signaling that is actually transmitted,” she said.
In her study, Dr. Strand presented the case of a 57-year-old male with an eight-year history of severe and disabling chronic cluster headache. Typical of cluster headache, the patient’s pain was generally at 9 on a 10-point numeric pain scale and occurred five to seven times per day with duration of one to two hours per episode. Previous treatments, including multiple pharmacologic agents, dihydroergotamine mesylate injections, oxygen by nasal cannula and occipital nerve blockade, all failed to control the pain.
The patient underwent a trial of left occipital nerve stimulation using an octrode lead, which was adjusted intraoperatively to achieve an acceptable electrode and amperage combination.
Using the stimulator 24 hours a day over the course of five days, the patient reported 80% relief of his cluster headache pain and a decrease in frequency to two to three times per day.
Although the mechanism behind occipital nerve stimulation is not entirely clear, in many ways it has significant benefits over existing standards of treatment for severe headache. Chief among those is getting chronic headache patients off opioids or other pharmacologic treatments, said Dr. Strand.
“Successful occipital nerve stimulation often decreases the amount of medication that a patient needs and in doing so it decreases both side effects of pain medications and possible interactions with and intolerance to other medications,” she explained.
Furthermore, if occipital nerve stimulation is successful, patients have complete control over how often to use the treatment. And perhaps most importantly, like other peripheral neuromodulation, occipital nerve stimulation is completely reversible, should a trial period end unsuccessfully or a patient no longer wishes to continue treatment.
Although there is a small risk for infection when initially placing the lead, the most common complication is lead migration. Because the lead is placed at the back of the head and neck, migration can be more of a problem with occipital nerve stimulation than other placements.
“The reason for this is that these electrodes have to traverse a moveable area,” said Dr. Weiner. “We anchor them very well, but even in the best of hands, sometimes the lead will pull back.”
But when this does happen, leads are re-placed under light sedation, typically using fluoroscopy as guidance.
Although neurostimulation for occipital headache remains an uninsured, off-label use, for patients with the most painful, untreatable headache conditions, the technique can be life-changing.
“I think it should be considered by physicians for patients with chronic cluster headache who have failed traditional therapies,” said Dr. Strand. “It’s a new use for stimulation, but in the appropriate patients, it can be a lifesaver.”