Occipital nerve stimulation may help safely prevent attacks of medically intractable chronic cluster headache, according to a new study.
Medically intractable chronic cluster headaches are unilateral headaches that cause excruciating pain during attacks, which may happen as frequently as eight times per day. They are refractory to, or intolerant of, preventive medications typically used in chronic cluster headaches.
“ONS was associated with a major, rapid, and sustained improvement of severe and long-lasting medically intractable chronic cluster headache, both at high and low intensity,”, of Leiden (the Netherlands) University Medical Centre, and coauthors wrote in their paper.
The findings were.
The multicenter, randomized, double-blind, phase 3 clinical trial was carried out at seven hospitals in the Netherlands, Belgium, Germany, and Hungary. A total of 150 patients with suspected medically intractable chronic cluster headache were enrolled between October 2010 and December 2017, and observed for 12 weeks at baseline. Of those initially enrolled, 131 patients with at least four medically intractable chronic cluster headache attacks per week and a history of nonresponsiveness to at least three standard preventive medications were randomly allocated to one of two groups: Sixty-five patients received 24 weeks of ONS at high intensity (100% intensity, or the intensity 10% below the threshold of discomfort as reported by the patient) while 66 received low-intensity (30%) ONS. At 25-48 weeks, the patients received open-label ONS.
Safe and well tolerated
“Because ONS causes paraesthesia, preventing masked comparison versus placebo, we compared high-intensity versus low-intensity ONS, which are hypothesised to cause similar paraesthesia, but with different efficacy,” wrote Dr. Wilbrink and colleagues.
From baseline to weeks 21-24, the median weekly mean attack frequencies decreased to 7.38 (95% confidence interval [CI]: 2.5-18.5, P < .0001). A median decrease in 5.21 attacks per week (–11.18 to –0.19, P < .0001) was observed.
The 100% ONS group saw a decrease in mean attack frequency from 17.58 at baseline (range, 9.83-29.33) to 9.5 (3-21.25) at 21-24 weeks with a median change of –4.08 (–11.92 to –0.25). In the 30% ONS group, the mean attack frequency decreased from 15 (9.25 to 22.33) to 6.75 (1.5-16.5) with a median change of –6.5 (–10.83 to –0.08).
At weeks 21-24, the difference in median weekly mean attack frequency between the groups was –2.42 (–5.17 to 3.33).
The authors stated that, in both groups, ONS was “safe and well tolerated.” A total of 129 adverse events were reported in the 100% ONS group and 95 in the 30% ONS group, of which 17 and 9 were considered serious, respectively. The serious adverse events required a short hospital stay to resolve minor hardware issues. The adverse events most frequently observed were local pain, impaired wound healing, neck stiffness, and hardware damage.
Low intensity stimulation may be best
“The main limitation of the study comes from the difficulty in defining the electrical dose, which was not constant across patients within each group, but individually adjusted depending on the perception of the ONS-induced paraesthesia,” Denys Fontaine, MD, and Michel Lanteri-Minet, MD, both from Université Cote D’Azur in France, wrote in an.
Given that the primary outcome did not differ significantly between the treatment groups, the editorialists stated that “the lowest stimulation intensity that induces paraesthesia is sufficient to obtain an effect in the patients who respond. Increasing the electrical dose or intensity does not seem to bring better efficacy and might even induce discomfort (painful paraesthesia or shock-like sensations) that might substantially reduce the tolerance of this approach.”
While the trial did not provide convincing evidence of high intensity ONS in medically intractable chronic cluster headache, the editorialists are otherwise optimistic about the findings: “… considering the significant difference between baseline and the end of the randomised stimulation phase in both groups (about half of the patients showed a 50% decrease in attack frequency), the findings of this study support the favourable results of previous real-world studies, and indicate that a substantial proportion of patients with intractable chronic cluster headache, although not all, could have their condition substantially improved by ONS.” Dr. Fontaine and Dr. Lanteri-Minet added that they hope that “these data will help health authorities to recognise the efficacy of ONS and consider its approval for use in patients with intractable chronic cluster headache.”
Priorities for future research in this area should “focus on optimising stimulation protocols and disentangling the underlying mechanism of action,” Dr. Wilbrink and colleagues wrote.
The study was funded by the Spinoza 2009 Lifetime Scientific Research Achievement Premium, the Netherlands Organisation for Scientific Research, the Dutch Ministry of Health (as part of a national provisional reimbursement program for promising new treatments), the NutsOhra Foundation from the Dutch Health Insurance Companies, and an unrestricted grant from Medtronic, all to Dr. Ferrari.