Occipital nerve stimulation for chronic migraine: already advised?

Chronic migraine is a relatively new concept in the headache world. Until recently, the biased view in many headache specialist centres was that chronic migraine was usually due to medication overuse and improved once patients were detoxified (1). Large population-based studies, however, identified patients with chronic migraine without medication overuse (2–5). With such a recent addition to the nomenclature of headaches (6), it is easily understood that only a handful of intervention studies have addressed drug therapy for the treatment of chronic migraine. Examples are the studies with topiramate (7,8) and onabotulinumtoxinA (9–11). These studies showed that active treatment was superior to placebo, that the treatment difference to placebo was small and that the placebo effect was very high. Neuro-modulation has experienced a renaissance in recent years for the treatment of pain conditions including chronic headache (12). Most of the studies have been conducted among patients with treatment refractory cluster headache (13–15). Failure to treatment was defined as a patient who did not respond to treatment of cluster attacks (by oxygen or triptans) and failing preventive drug therapy with verapamil, lithium, methysergide and topiramate. The study by Silberstein and colleagues published in this issue of Cephalalgia investigated occipital nerve stimulation (ONS) in patients with chronic migraine refractory to treatment of acute migraine attacks and having failed at least two different classes of prophylactic medication. One-hundred and fifty-seven patients received ONS device implants of whom 105 were randomised to active and 52 to sham stimulation. The study failed to show a significant benefit for the primary endpoint, defined as a 50% reduction in mean daily visual analogue scale score after 12 weeks. The study was positive for a number of secondary endpoints, including 30% reduction in mean daily visual analogue scale scores, number of headache days, and migrainerelated disability. Seventy-three patients in the active group (69%) and 34 in the sham group (65%) had adverse events. Common adverse events were lead migration (13% of all patients) and consistent implant site pain or numbness (15% of all patients). Should ONS be recommended for the treatment of patients with chronic migraine? I think at present there is not enough evidence to promote this procedure for patients with chronic treatment refractory migraine for the following reasons: