SAN FRANCISCO – Sphenopalatine ganglion stimulation using an implanted miniature neuromodulation device shows the potential to be a breakthrough nonpharmacologic therapy for acute episodes of chronic cluster headache based upon the results of the sham-controlled Pathway CH-2 study.
Self-administered sphenopalatine ganglion (SPG) stimulation using a wireless hand-held controller not only resulted in a 2.6-fold greater likelihood of providing pain relief within 15 minutes without resort to acute medications, compared with sham stimulation, but the device therapy also led to a significant reduction in cluster headache frequency over time, presumably through its neuromodulatory effects,, said in presenting the study results at the annual meeting of the American Headache Society.
An additional benefit of SPG stimulation was less need for triptans, with their many side effects. Patients in the active treatment arm of the 28-week sham-controlled portion of the multicenter prospective study used triptans for abortive therapy an average of 3.7 times less per week during the final 4 weeks of that period than they did during the 4-week baseline period, compared with a 1.2-dose per week reduction in the control group, noted Dr. Dodick, principal investigator for theand professor of neurology at the Mayo Clinic in Scottsdale, Ariz.
Cluster headache pain has been described as one of the most severe forms of pain known to humans. It is extremely disabling. Treatment options leave much to be desired, as detailed in a patient survey presented elsewhere during the meeting.
The 93 participants in the Pathway CH-2 study had a mean 8-year history of chronic cluster headaches. During the 4-week baseline assessment period, they averaged roughly 11 cluster attacks per week. All patients underwent surgical insertion of the miniature through a small incision in the upper gum. The device was placed deep in the face adjacent to the SPG nerve bundle. Patients were taught to activate the neurostimulator by placing a hand-held controller on the side of the face near the implanted device when a cluster headache attack struck. Participants were randomized to active treatment or sham stimulation, which delivered a mild electric current to the side of the face.
The primary efficacy endpoint was pain relief within 15 minutes of starting SPG stimulation without resort to abortive medications. Sixty-three percent of the SPG neurostimulation group and 29% of sham-treated controls achieved that goal for at least 50% of their headache attacks. Forty-six percent of SPG stimulators were able to attain pain relief within 15 minutes for 75% or more of their attacks. Fifty-seven percent of the active treatment group maintained pain relief at 60 minutes, compared with just 5% of controls.
“We’re used to thinking in terms of responder rates. Roughly half of patients using SPG stimulation had at least a 75% reduction in weekly cluster attacks, 46% of them had at least a 75% reduction in the severity of attacks, and 71% were super-responders, so to speak, with at least a 75% reduction in either attack frequency or severity,” according to Dr. Dodick.
The mean reduction in cluster attack frequency from baseline through 28 weeks was 6.8 fewer attacks per week in the active treatment group, significantly better than the mean 2.6-attack reduction in controls. At 1 year post implantation, the SPG stimulation group averaged 9.4 fewer cluster attacks per week than at baseline.
The ATI SPG Microstimulator System was well tolerated overall. Common treatment-related adverse events limited to the first 30 days after device implantation included numbness, swelling, pain, bruising, and paresthesia secondary to the surgical procedure. Given the discomfort inherent to gum surgery, “I was actually surprised there weren’t more adverse events,” Dr. Dodick said.
Four serious adverse events related to the device or its implantation occurred among the 93 participants: a venous injury, an infection, aspiration during intubation, and an instance of nausea and vomiting. All resolved without sequelae.
The ATI SPG Microstimulator System is investigational in the United States. The system is approved by European authorities for acute treatment of cluster headaches and refractory disabling migraine.