In 1988, the International Headache Society published a classification system for headache disorders. This extensive system is not convenient to apply in the clinical setting. However, it is diagnostically and therapeutically useful to consider headaches as being divided into two categories: primary and secondary. Primary headaches, which include migraine, tension-type headache and cluster headache, are benign; these headaches are usually recurrent and have no organic disease as their cause Secondary headaches are caused by under-lying organic diseases ranging from sinusitis to subarachnoid hemorrhage.