[Familial occurrence of chronic tension headache].

Chronic tension-type headache occurs in 3% of the Danish population. the aetiology remains an enigma, even though it is one of the most frequent illnesses with chronic pain. A family study indicates the importance of genetic factors. Compared with the general population, first degree relatives (parents, siblings and children) of probands with chronic tension-type headache have a three-fold significantly increased risk of chronic tension-type headache, while spouses had no increased risk. Complex segregation analysis indicates multifactorial inheritance. Thus, a combination of genetic and environmental factors causes chronic tension-type headache.