Evaluating the IHS criteria for cluster headache--a comparison between patients meeting all criteria and patients failing one criterion.

Cluster headache (CH) is diagnosed according to criteria of the International Headache Society (IHS), but, in clinical practice, these criteria seem too restrictive. As part of a nation-wide study, we identified a group of patients who met all criteria minus one (IHS-CH-1), and assessed in which way they differed from CH patients meeting all criteria (IHS-CH). We performed a nation-wide questionnaire study for CH and CH-like syndromes, including questions based on the IHS criteria, and additional features such as restlessness during attacks, nocturnal onset of attacks, circadian rhythmicity of attacks and response to treatment. IHS-CH and IHS-CH-1 patients were compared. Of 1452 responders to two questionnaires, 1163 were IHS-CH and 289 were IHS-CH-1. The majority of the IHS-CH-1 patients were classified as such because their attacks exceeded 3 h (64%, median attack duration: 5 h), or came in a frequency of less than 1 per 2 days (16%). Age at onset was similar between the groups. The male to female ratio was 3.7 : 1 in the IHS-CH group and around 1.6 : 1 in the IHS-CH-1 groups (P < 0.005). Patients with attacks exceeding 3 h less often reported a circadian rhythmicity (IHS-CH-1: 49%, IHS-CH: 64%), episodic periodicity (IHS-CH-1: 65%, IHS-CH: 78%), nocturnal attacks (IHS-CH-1: 67%, IHS-CH: 78%), smoking (IHS-CH-1: 90%, IHS-CH: 80%) and restlessness during attacks (IHS-CH-1: 64%, IHS-CH: 76%) than IHS-CH patients (P < 0.005). Photo- or phono-phobia (IHS-CH-1: 67%, IHS-CH: 54%) and nausea (IHS-CH-1: 38%, IHS-CH: 27%) were more frequently reported by patients who reported to have attacks exceeding 3 h (P < 0.005). Similar proportions reported effect of verapamil on their attacks (IHS-CH-1: 54%, IHS-CH 61%). We conclude that average attack duration exceeding 3 h was frequently the reason for not fulfilling IHS CH criteria. Symptoms often accompanying CH such as restlessness, nocturnal attacks and an episodic attack pattern were relatively frequently present in IHS-CH-1 patients with longer attacks. These patients may therefore be diagnosed with CH. Attack frequency may not be a useful criterion for the diagnosis of CH. The upper limit of 3 h should be increased in future diagnostic criteria.

Features involved in the diagnostic delay of cluster headache.

BACKGROUND: Cluster headache (CH) is a comparatively rare, very severe primary headache. Although circumscript and recognisable criteria are available, the diagnosis is often missed or delayed. Besides, while adequate and evidence based treatment is available in diagnosed cases, CH seems to be poorly managed. The authors performed a nationwide survey among CH patients, and looked for factors involved in the diagnostic delay. METHODS: The authors performed a nationwide mailing to all Dutch general practitioners (about 5800), and neurologists (about 560) and invited them to refer patients in whom the diagnosis CH was made or considered. Patients could also apply via the Dutch Headache Patients Society. A variety of clinical characteristics were assessed by means of questionnaires. Specifically, patients were asked about the time between their first episode and the diagnosis. RESULTS: The IHS criteria for CH were met by 1429 of 2001 responders, and 1163 of these filled in an extended questionnaire. The male to female ratio was 3.7:1. Mean age at onset was 32 (SD 14) years. Seventy three per cent had episodic CH, 21% had chronic CH, and in 6% the periodicity was undetermined. The time between the first episode and the diagnosis ranged from 1 week to 48 years (median 3 years): 34% had consulted a dentist and 33% an ENT specialist before the diagnosis was established. Among factors that increased the diagnostic delay were the presence of photophobia or phonophobia, nausea, an episodic attack pattern and a low age at onset (p<0.01). Sex or presence of restlessness during episodes did not influence the diagnostic delay. CONCLUSION: CH remains unrecognised or misdiagnosed in many cases for many years. Photophobia or phonophobia and nausea were in part responsible for this delay, and should be recognised as part of the clinical spectrum of CH. Many patients were first seen by a dentist or ENT specialist for their CH episodes, so more attention should be paid to educate first line physicians to recognise CH, to improve the diagnostic process and so to expose patients to earlier and better treatment of CH.