History of headache research in Denmark.

Headache research in Denmark started with the description in 1949 by Dalsgaard-Nielsen of the percutaneous nitroglycerin test. In 1976 Jes Olesen started The Copenhagen Acute Headache Clinic and from that time modern headache research began in Denmark. Specific changes in regional cerebral blood flow during attacks of migraine with aura, spreading oligaemia, were described for the first time in 1980. The first headache classification with operational diagnostic criteria was published in 1988 and used in a Danish population study from 1989. The lifetime prevalence of migraine was 8% in men and 25% in women. An intravenous nitroglycerin test was introduced in 1989 and has been developed as an experimental headache model. In 1993 it was suggested by Jes Olesen et al. that NO supersensitivity could be a possible molecular mechanism of migraine pain. Recent genetic studies have supported the distinction between migraine with aura and migraine without aura. From the middle of the 1980s the pathophysiology of tension-type headache has been investigated and recent results indicate central sensitization in patients with chronic tension-type headache.