[The central or peripheral nature of pain in essential headaches]

As an alternative to the conventional peripheral (vascular or chemical) thesis, the possibility of the central origin of pain in essential headaches is illustrated. In fact, observations carried out on animal and man reveal that, central pain, besides being organic, may be of a functional nature. It may be correlated to the lack of those biochemical mechanisms, which take place in the assimilation of those painful inputs at a cerebral level. Particularly pain may be caused by a lack of the 5HT turn-over. As a result of experiments carried out on animals, this takes the role of mediating pain inhibition, being present in the modulation stage of those multi-integrated processes which permit the central perception of pain. Some biochemical and pharmacological clinical observations suggest a serotonin lack in patients affected by essential headaches. A special interest is established by the reciprocal involvement of ancestral functions in essential headaches, such as: emotion, sleep, appetite, vomit, thermoregulation and sex, which are functions directly or undirectly controlled by serotonin. In the therapeutic field, the apparent contradiction between the benefit achieved by anti-serotonin drugs (such as: ergotamine, methisergide, org. G.C. 94 and LSD-25 at non-hallucinogen doses) and the substances with pro-serotonin activity (L-triptophane and L-5 hydroxy-triptophane) supports the hypothesis of a central lack of 5HT, due to the fact that the recent experiments on animal and man have shown a serotonin compatibility by "antiserotonin" drugs, when they are administered at therapeutic doses. If this initial thesis finds further confirmations, we could define essential headaches as a peculiar "pain disease", thus allowing them a well defined nosologic classification.