Case-control study on the epidemiology of cluster headache. I: Etiological factors and associated conditions. Italian Cooperative Study Group on the Epidemiology of Cluster Headache (ICECH).

The etiological and physiopathological mechanisms of cluster headache (CH) are still largely unknown. The majority of the studies published on the possible risk factors and conditions associated with CH rely on either anecdotal observations or generalizations and have not been supported by serious epidemiological investigations. The aim of this case-control study was to evaluate the real association of life habits and general risk factors with CH. CH was associated only with cigarette smoking, head trauma and a positive family history for headache. Further epidemiologic studies are probably necessary in order to find clues to CH etiology.