[Headache diagnosis and vascular pathophysiology].

A new international headache classification has improved possibilities for uniformity of diagnosis throughout the world, because it gives operational diagnostic criteria for all headache disorders. The classification was an initiative of the International Headache Society, but has been supported by the Research Group on Headache and Migraine of the World Federation of Neurology and the main diagnosis entities have been used in the new International Classification of Diseases (ICD 10) by the WHO. Vascular mechanism of headache is only known in migraine. During attacks of migraine with aura pathognomonic changes in regional cerebral blood flow (rCBF) have gradually been characterized. The attack begins with occipito-parietal rCBF decrease which slowly spreads to involve a greater or smaller parts of one cerebral hemisphere. In the area of hypoperfusion the normal functional activation is abolished and response to altered PaCO2 is diminished. The autoregulation, however, seems to be preserved. Whether the area of hypoperfusion is actually ischemic is still uncertain. Later in the attack rCBF normalizes and then changes to become increased in the previously hypoperfused focus. Hyperperfusion persists for one to several hours. Headache begins during hypoperfusion and does not change with the later occurrence of hyperperfusion which may even outlast the headache. There is a strong correlation between the site of rCBF changes, the site of origin of aura symptoms and the laterality of headache. It is proposed that liberation of neurotransmitters sensitizes local nociceptors and thereby induces headache.