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The neurotechnology market for treating chronic migraine and other forms of headache pain has moved closer to commercial viability as several research institutions and manufacturers in the U.S. and Europe have made progress in occipital nerve stimulation (ONS). The market in many ways seems to mirror the advent of the market for spinal cord stimulation (SCS) systems to treat chronic back pain, and indeed, some SCS vendors are looking to use their same implantable pulse generators (IPGs) for ONS, albeit with leads directed to more anterior placements in the C1-C3 region at the top of the neck.
The potential market for chronic headache pain is at least as promising as the chronic back pain market. The National Headache Foundation estimates that 28 million Americans?70 percent of whom are women?suffer from migraine headaches caused by disorders such as occipital neuralgia and transferred migraine. The foundation says that sufferers lose about 157 million workdays each year. Many migraine sufferers progress to a chronic condition, experiencing headaches more than 15 days per month. The majority of chronic migraine sufferers can be helped with medical measures that prevent attacks or treat them when they occur. However, vendors estimate that approximately 40,000 people in the U.S. do not respond to existing treatments, and many may be candidates for an alternative therapy.
One of the first entrants in the ONS market is Medtronic, Inc. The Minneapolis, MN manufacturer of neurostimulation systems recently announced the first patient implant in a preliminary study to evaluate if an implanted device might help chronic migraine sufferers who have not responded to other treatments. Called Occipital Nerve Stimulation for the Treatment of Intractable Migraine, or ONSTIM, the study involves a Medtronic Synergy IPG, which was implanted in a 47-year old female who has suffered from chronic headache for eight years.
The neurostimulator delivers electrical impulses via insulated lead wires tunneled under the skin near the occipital nerves at the base of the head. According to Joel Saper, the ONSTIM study's principal investigator, and the founder and director of the Michigan Head Pain and Neurological Institute in Ann Arbor, MI, "It is time to take a hard look at stimulation for chronic migraines. If stimulation proves to be as effective as we hope, it could help the large numbers of people who have failed to respond to currently available treatments."
Medtronic launched a prospective, randomized, blinded feasibility study, which will enroll participants at seven medical centers in the U.S. and one medical center in Europe. The company received approval from the U.S. Food and Drug Administration (FDA) to conduct the study. Candidates for the study are adults who have had chronic migraines which have persisted at least 15 days per month over three months and have been refractory to other treatments. Study patients first will receive stimulation from an external device to determine patient response. If adequate response is achieved, the Medtronic Synergy or Synergy Versitrel neurostimulator system will be implanted.
Other SCS vendors who are exploring the occipital nerve stimulation market include Advanced Neuromodulation Systems, Inc., the Plano, TX manufacturer of neurostimulation systems, and Advanced Bionics Corp., the Valencia, CA subsidiary of Boston Scientific Corp. The latter firm has performed clinical trials in nine patients, each using the company's BION microstimulator injected in the subcutaneous space above the trapezius muscles. Advanced Bionics also plans to conduct trials using its rechargeable IPG system. Some researchers believe a leadless system like the BION offers an advantage over IPG systems, since it is immune from problems like lead migration and stress fracturing. Indeed, some patients receiving an occipital nerve stimulator are reportedly instructed to reduce their vigorous exercise and head movements that might dislodge the leads. IPG advocates stress the greater proximity of electrical energy to the target nerve possible with leads.
A team of researchers at the University of Missouri, Allegheny General Hospital in Pittsburgh, PA, and the Houston Pain Management Clinic published a paper in the journal Neuromodulation earlier this year that suggested that paddle-style stimulation leads had an advantage over traditional cylindrical leads in reducing migrations caused by cervical tension or anchor dislodgement. Another team at the Institute of Neurology in London reported in the journal Brain that eight chronic migraine patients with implanted ONS systems exhibited changes in regional cerebral blood flow, as measured by PET scans, that corresponded with stimulation-induced pain relief. The authors suggest that the dorsal rostral pons may be a locus of neuromodulation in this treatment.
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