Modular headache theory

Many people experience headaches that do not fulfil the International Heada che Society's criteria for a specific headache disorder yet behave biologic ally like that disorder. Others fulfil criteria for one headache disorder a nd yet have features of another disorder. To explain these observations, we propose that groups of neurones called modules become activated to produce each symptom of a primary headache disorder, and that each module is linke d to other modules that together produce an individual's headache. This the ory has implications for the classification, research and treatment of prim ary and secondary headache patients.