There is ongoing discussion as to what is a good definition of chronic daily headache; this is a term that is not defined by the International Classification of Headache Disorders (ICHD)40 This is a potential impediment to research. It has been proposed that chronic daily headache can be subclassified into primary headache that includes transformed migraine (TM), chronic tension-type headache (CTTH), hemicrania continua (HC) and new daily persistent headache (NDPH)41 Secondary CDH has an identifiable underlying cause e.g. post traumatic, cervical spine disorders, vascular disorders, chronic meningitis, idiopathic intracranial hypertension, temporamandibular joint dysfunction and sinus disorders. Silberstein et al highlighted that not all chronic daily headaches can be classified according to the ICHD; however, in 1996 they managed to completely sub-classified a population of CDH sufferers into those with transformed migraine (TM) 78%, chronic tension-type headache (CTTH) 15.3% and "other" 6.7%.42 Silberstein defined chronic daily headache as headaches that last for more than 4 hours a day for more than 15 days a month and this definition is used in their later study of propofol and headache. This definition becomes perhaps less crucial when dealing with a population of patients who suffer intractable continuous headache; this tends to be the characteristic of patients who are already known to us at the University of Alberta Hospital Pain Centre.