4.0 Framing note: what "refractory chronic CH" means, and why it matters here

Every device and procedure in this chapter is aimed at a specific population, and it is worth being precise about the entry criteria, because response rates are quoted for people who have already failed everything else.

peer-reviewed The European Headache Federation consensus defines refractory chronic cluster headache (rCCH) as: “a situation that fulfills the criteria of ICHD-3 beta for CCH with at least three severe attacks per week despite at least three consecutive trials of adequate preventive treatments” (Mitsikostas DD, Edvinsson L, Jensen RH, Katsarava Z, Lampl C, Negro A, Osipova V, Paemeleire K, Siva A, Valade D, Martelletti P. J Headache Pain 2014;15(1):79. DOI 10.1186/1129-2377-15-79, PMID 25430992).

The formal criteria are (verbatim from that consensus):

• A. “Headache attacks fulfilling the ICHD-3 beta criteria for chronic cluster headache (CCH), or probable cluster headache (CH) and B-E criteria.”
• B. “At least three severe CH attacks per week that impact patients’ quality of life despite preventive or symptomatic treatment.”
• C. “Failed consecutive prophylactic treatment trials with at least three agents that showed efficacy over placebo in randomized controlled studies, used at the maximum tolerated dose over a sufficient period of time.”
• D. “Symptomatic CCH is ruled out by negative investigation with brain MRI and MRA, eventually supplemented with carotid CT angiograms or triplex carotid ultrasound.”
• E. “Not better accounted for by another ICHD-3 beta diagnosis.”

peer-reviewed The same consensus lists the preventives that count towards criterion C: “verapamil, lithium, oral or iv steroids, greater occipital nerve infiltration, topiramate, methysergide, ergots, civamide and long acting triptans. Among them verapamil has better documentation. Some agents may be not available across all European countries” (EHF consensus 2014). It also cautions that the indomethacin test should be used to exclude paroxysmal hemicrania, and that SUNA/SUNCT, cluster-tic syndrome and persistent idiopathic facial pain should be ruled out first.

peer-reviewed The consensus was cautious about this whole chapter’s subject matter: “The new frontier for the treatment of the subset of patients with rCCH could be neuromodulation, an interesting approach but still not sufficiently validated” (EHF consensus 2014). That was 2014; the picture in 2026 is somewhat better evidenced but commercially worse.

peer-reviewed A 2021 narrative review of all neurostimulation methods in chronic CH landed on a blunt summary: “Altogether, only nVNS and SPG stimulation are supported by at least one positive sham-controlled clinical trial for preventive and acute attack (only SPG stimulation) treatment… The evidence for these neurostimulation methods in the treatment of chronic cluster headache is poor and in part contradictive. However, except deep brain stimulation, tolerability and safety of these methods are good so that in refractory situations application might be justified in individual cases” (Neurostimulation Treatment in Chronic Cluster Headache — a Narrative Review, Neurol Ther / PMC8665918, 2021).

peer-reviewed An important methodological caveat from that same review, and one that is rarely stated aloud: “The real efficacy of the stimulation techniques remains also unknown since only refractory patients were treated (and included in trials). It might be that patients responding to oral drugs also respond to stimulation techniques” (PMC8665918, 2021). In other words: nobody knows what these devices would do in a less pre-selected population.