Clinical observations on familial cluster headache.

Cluster headache (CH) has traditionally been considered a sporadic disease. Recently, an Italian study pointed out a risk of developing CH in the affected patients' firstdegree relatives that was increased 39-fold compared with the general population. The aims of this study were to investigate any possible differences in mean age at onset, clinical features and lifestyle between familial and non-familial CH cases. Among all CH patients referred to the Parma Headache Centre (n=691), we considered those who reported at least a first-degree relative with a probable diagnosis of CH in their family histories (n=30). CH diagnosis in the relatives was confirmed for 19 of the 30 patients. Each one of the 19 "familial cases" was matched by sex and age at the first visit (within 2 years) to two CH patients who did not report any family history for CH. The male:female ratio was 1.4:1 in the familial cases. Mean age at onset was significantly lower in women with familial CH than in those with non-familial CH. The study did not show any significant differences in symptoms between the two CH groups, such as pain location, accompanying symptoms, duration and frequency of attacks, and active periods. Our study seems to suggest that genetic factors play a role in the female gender, affecting age at onset of headache without modifying the clinical features.