Defining the pharmacologically intractable headache for clinical trials and clinical practice.

The terms refractory headache and intractable headache have been used interchangeably to describe persistent headache that is difficult to treat or fails to respond to standard and/or aggressive treatment modalities. A variety of definitions of intractability have been published, but as yet, an accepted/established definition is not available. To advance clinical and basic research in this population of patients, a universal and graded classification scheme of intractability is needed, and must include a definition of failure, to which and how many treatments the patient has failed, the level of headache-related disability, and finally, the intended intervention (clinical or research) and intensity of the intervention. This paper addresses each of these variables with the intent of providing a graded classification scheme that can be used in defining intractability for clinical practice interventions and clinical research initiatives.