Headache disorders can exist without any obvious structural or metabolic cause.
It is also important to emphasize that recurrent episodic headaches are rarely due to structural lesions. Table 2 gives the universally accepted IHS criteria for diagnosis of migraine with aura and migraine without aura. Migraine is a syndrome with a wide variety of neurological and non-neurological manifestations. It is not simply a headache. Diagnosis of migraine is not obtained solely by exclusion of other disorders.