SEROTONIN AND ITS ROLE IN HEADACHE PATHOGENESIS AND TREATMENT

Objective: This review tries to consolidate the literature on changes in serotonin and the importance of these changes for understanding hea dache pathogenesis and determining treatment. A model is presented tha t integrates previous serotonin studies and offers an explanation for apparent contradictions in the literature. Data Sources: Fifty-four jo urnal articles that described a relationship between serotonin and hea dache in animal and human models were identified through Medline searc h and bibliography and reviewed. Alterations in serotonin, headache, a nd clinical situations influencing headache activity were examined. Da ta Synthesis: Abnormalities in blood vessels have traditionally been i mplicated in the pathogenesis of migraine headaches, and excessive mus cle contraction in tension-type headaches. Interestingly, both vascula r and muscular changes occur in both migraine and tension-type headach e. Recently, biochemical changes have been demonstrated in both types of headaches. These biochemical changes are postulated to precede and possibly cause the subsequent changes in blood vessels and muscle tone , known to occur in chronic headaches. Serotonin has been the most wid ely studied neurochemical in relation to headaches. Apparently contrad ictory results have been shown, such as increasing serotonin levels bo th increasing and decreasing headaches. Conclusions: Serotonin plays a n important role in the pathogenesis of headaches. Changes in serotoni n may precede the vascular and muscular changes of migraine and tensio n-type headaches. The influence of serotonin on headaches explains a n umber of clinical situations that affect headache activity and the var iety of classes of effective headache medications.