Conducted at 15 medical centers in the U.S., the study followed 157 participants who, on average, suffered from headache approximately 21 days per month. At 12 weeks, patients receiving PNS therapy reported an average of six fewer headache days a month.
Additional key findings at 12 weeks were as follows:
- 43 percent improvement in overall disability scores, as measured using the Migraine Disability
- Assessment questionnaire (MIDAS)
- 53 percent of the patients ranked their relief as excellent or good
- Patients reported a 42 percent improvement in pain relief
PNS therapy for this condition involves the delivery of mild electrical pulses to the occipital nerves that are located just beneath the skin at the back of the head. A small electrical lead or leads are placed under the skin and connected to a neurostimulator, which produces pulses of stimulation.
In this prospective, randomized, controlled study, participants were implanted with the St. Jude Medical Genesis™ neurostimulator and randomly assigned to an active or control group for 12 weeks. The active group received stimulation immediately upon implantation, while patients in the control group did not receive stimulation until after the first 12 weeks. Both the investigators and the patients were blinded to treatment.
Although statistical significance was demonstrated across most measures, it was not observed for the primary endpoint (defined as the difference in the percentage of patients in the active group versus control who achieved 50 percent or greater pain reduction at 12 weeks). However, patients in the active group were more likely than control patients to experience 30 percent or greater pain reduction, which is considered clinically meaningful.
"When this study was initially designed, the primary endpoint was based on a reduction in pain, which at the time was the standard measurement for neurostimulation studies," said, Dr. Mark Carlson, chief medical officer and senior vice president of research and clinical affairs for the St. Jude Medical Implantable Electronic Systems Division. "However during the course of the study, many neurologists began to recognize reduction in the number of headache days as a more significant improvement in patient quality of life than the measurement of pain reduction alone."
The most common adverse event was persistent pain and/or numbness at the implant site, followed by lead migration. The majority of adverse events were classified as mild or moderate in severity.
Preliminary data from this study was presented at the International Headache Congress (IHC) in 2011. The Genesis neurostimulation system used in this study is approved in Europe and Australia for the management of the pain and disability associated with intractable chronic migraine.
About Chronic Migraine
Chronic migraine is a disabling neurological disorder that can last for hours or days at a time. The World Health Organization (WHO) estimates that 1.7 to 4 percent of adults have headache on more than 15 days per month. Compared with people who periodically experience migraine headache, individuals with chronic migraine experience significantly greater disability, economic burden, and impairments in health-related quality of life. According to the European Journal of Neurology the total annual cost attributed to migraine amounts to €111 billion in the EU.
Source
