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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., (© 2010 American Headache Society.)

Certain migraines are labeled as refractory, but the entity lacks a well-accepted operational definition. This article summarizes the results of a survey sent to American Headache Society members to evaluate interest in a definition for RM and what were considered necessary criteria. Review of the literature, collaborative discussions and results of the survey contributed to the proposed definition for RM. We also comment on our considerations in formulating the criteria and any issues in making the criteria operational. For the proposed definition for RM and refractory chronic migraine, patients must meet the International Classification of Headache Disorders, Second Edition criteria for migraine or chronic migraine, respectively. Headaches need to cause significant interference with function or quality of life despite modification of triggers, lifestyle factors, and adequate trials of acute and preventive medicines with established efficacy. The definition requires that patients fail adequate trials of preventive medicines, alone or in combination, from at least 2 of 4 drug classes including: beta-blockers, anticonvulsants, tricyclics, and calcium channel blockers. Patients must also fail adequate trials of abortive medicines, including both a triptan and dihydroergotamine (DHE) intranasal or injectable formulation and either nonsteroidal anti-inflammatory drugs (NSAIDs) or combination analgesic, unless contraindicated. An adequate trial is defined as a period of time during which an appropriate dose of medication is administered, typically at least 2 months at optimal or maximum-tolerated dose, unless terminated early due to adverse effects. The definition also employs modifiers for the presence or absence of medication overuse, and with or without significant disability.

The proposed definitions for refractory migraine (RM) and refractory chronic migraine (R-CM) comprise 5 key components that must be operationalized for epidemiologic research. Persons with RM or R-CM must meet the second edition of the International Classification of Headache Disorders criteria for migraine or chronic migraine. They must experience significant interference with function or quality of life due to headaches. This interference must be present despite adequate treatment in 3 domains: modification of triggers and lifestyle factors, acute medication, and preventive medicines. The epidemiologic data which address these 5 components will be reviewed herein though specifically designed studies will be required to fully explore RM and R-CM. In addition, 2 "modifiers" of RM and R-CM have been proposed; one addresses medication overuse and the other considers disability based on a Migraine Disability Assessment score of 11 or greater. The epidemiology of these modifiers is discussed.

The study of migraine has yielded many benefits for headache patients. Little research, however, has been performed on refractory migraine (RM) headache, a term often used interchangeably with intractable migraine. This may be a consequence of a lack of a well-accepted definition. In a survey performed by the Refractory Headache Special Interest Section (RHSIS) on the American Headache Society (AHS) in 2006, 58% of the members agreed that a definition for refractory headache should be added to the International Classification of Headache Disorders-2. A PubMed search identified 21 articles that defined refractory or intractable headache/migraine. Sixteen (76%) defined the term "refractory" and 5 (24%) defined the term "intractable." Many of these definitions did not address the need for an adequate trial of a preventive medicine, disability, and medication overuse. An operational definition will allow us to better characterize the disorder, address unmet medical needs, and identify the most effective treatments. RHSIS of the AHS has proposed a definition of RM. It is our hope that this definition will spur interest in this entity and will lead to further research in the area.

There are a number of reasons to attempt to define and classify refractory headache disorders. Particularly important are the potential benefits in the areas of research, treatment, and medical cost reimbursement. There are challenges in attempting to classify refractory forms of headaches, including the lack of biological or other objective markers and a lack of consensus among practitioners as to what qualifies as refractoriness, or even if a separate category for refractory migraine and other refractory headaches needs to be established. A definition of refractory migraine has been proposed by Schulman et al in this issue ("Defining Refractory Migraine [RM] and Refractory Chronic Migraine [RCM]: Proposed Criteria for the Refractory Headache Special Interests Section of the American Headache Society"), which should be tested for validity and usefulness. It seems reasonable to consider adding this defined syndrome to the International Classification of Headache Disorders, second edition (ICHD-II). In this article, options for adding refractory headache syndromes to the ICHD are discussed with pros and cons for each. Two "best" options for adding the disorder "refractory migraine" to the ICHD are presented along with an illustrative case example.