Cluster Headache Without Autonomic Symptoms: Why Is It different?

Background.—Some patients with otherwise typical cluster headache (CH) have persistent attacks free of cranial autonomic symptoms (CAS). The factors responsible for this atypical presentation are not known. Objectives.—To identify factors associated to the absence of CAS in patients with CH. Methods.—A prospective series of 157 patients with the diagnosis of CH was analyzed, comparing 148 typical CH patients with 9 CH patients without CAS. Results.—Patients without CAS reported significantly less intense attacks (P = .003) when compared to those with CAS. There was also a tendency (not reaching statistical significance) for a higher frequency of females and chronic CH among those without CAS. Otherwise, there were no differences between the two groups (in age, duration of illness, follow-up time, attack duration or frequency, nor side or site of pain). A logistic regression analysis showed that only pain intensity could explain the difference between the two groups, since the other explanatory variables were also associated with different intensity of attacks. Conclusions.—These results support the hypothesis that CH without cranial autonomic symptoms represents a milder form of CH. Ke yw ords: atypical cluster headache, cranial autonomic symptoms, trigemino-autonomic cephalalgia Abbreviations: CH cluster headache, CAS cranial autonomic symptoms (Headache 2005;45:190-195) There are patients with short lasting recurring unilateral headaches, in all identical to CH, with the exception that they never have autonomic symptoms during the attacks. They represent 3% to 7% of cases in large CH series 1-3 and some of them have been described in detail. 4 The International Classification of Headache Disorders (ICHD-II) 5 recently acknowledged that fact, by allowing patients to be included in this diagnostic category in the absence of any associated autonomic symptoms, if they reported agitation or restlessness during the attacks.