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Headache Care

Headache Classification And The International Headache Society Criteria

Tuesday, Jan 27 2009


Before 1988, the taxonomy of headache was not uniform and diagnostic criteria were rarely based on operational rules. In 1988, the International Headache Society (IHS) instituted a classification system for headache that has become the standard for headache diagnosis and clinical research (Headache Classification Committee of the International Headache Society, 1988). The IHS classification of headache provides operational definitions for all headache types. It divides headaches into two broad categories: the primary headache disorders (categories 1-4), which include migraine, tension-type headache, and cluster headache, and the secondary headache disorders (categories 5-12). We have summarized the new classification in Table 2-1 and the rules for classification in Table 2-2. Tables 2-3, 2-4, 2-5, 2-6 describe migraine without aura, migraine with aura, tension-type headache, and cluster headache, respectively.

An attempt has been made throughout the book to use the IHS classification where it is applicable, although in some chapters the more traditional names for headache or both old and new names are used. In the chapter on chronic daily headache, new terminology is proposed.

How should the IHS classification be used? It is a formidable, 96-page document, albeit a useful one. The classification represents an enormous step forward in the codification of headache. The IHS criteria have been translated into many languages and have been the basis for clinical trials and epidemiologic research since 1990. The criteria are now being revised to make them more useful and inclusive. The IHS classification system diagnoses headache attacks, not disorders. If a patient has more than one type of headache, each type should be diagnosed separately. The IHS criteria were modeled after the DSM-III criteria of the American Psychiatric Association.

The IHS system uses both clinical features and laboratory tests to provide criteria of inclusion (features needed to establish a particular diagnosis) and exclusion (features that prevent assigning a particular diagnosis). For primary headaches, physical examination and laboratory investigations serve to exclude secondary disorders, or they may provide evidence to support the diagnosis of a secondary headache. Thus, the diagnosis of a primary headache disorder is based on the patient’s report of symptoms of previous attacks, and accurate diagnosis requires explicit rules about the required symptom features. Each major category of primary headache has sub-types, which are differentiated based on the symptom profile (migraine with aura vs. migraine without aura), the temporal profile, or the attack frequency (episodic vs. chronic tension-type headache, episodic vs. chronic cluster headache). Details about subtyping are presented in the chapters about each major headache category.

The older classification system divided migraine headaches into two varieties, classic and common migraine. The nomenclature has been changed to reflect the presence or absence of the aura.

Common migraine (Table 2-3) is now called “migraine without aura” and is defined in terms of the duration and quality of the attack. To diagnose migraine without aura, the requirements under each lettered heading in Table 2-3 must be met. Some headings (e.g., Table 2-3A and B) have a single mandatory feature. Other headings include several alternative characteristics. For example, in Table 2-3C, only two of four pain features are required. No single pain feature under heading C is absolutely required for diagnosis. The exclusion criteria are provided under category E. They eliminate other headache disorders based on at least one of the history, physical, and neurologic examinations (El) or laboratory tests (E2). Alternatively, a secondary headache disorder may be present if the onset of the primary and that of the secondary disorders are separated in time.

Migraine with aura (Table 2-4), formerly classic migraine, is also precisely defined, particularly with respect to the time of the onset and duration of the aura. Types of aura include (1) homonymous visual disturbance, (2) unilateral paresthesias and/or numbness, (3) unilateral weakness, and (4) aphasia or unclassifiable speech difficulty. Most common is the visual aura.

Table 2-1 International Headache Society classification system (Headache Classification Committee, 1988)

Tension-type headache (Table 2-5) is the term now used to describe what was previously called “tension headache,” “muscle contraction headache,” “stress headache,” or “ordinary headache.” In earlier editions of this book, it was called “muscle contraction headache. The new IHS criteria distinguish between patients with episodic tension-type headache and chronic tension-type headache. The major distinguishing feature is the frequency of the headache, i.e., fewer than 15 headache days per month for episodic tension-type headache or more than 15 headache days per month for chronic tension-type headache. A new chapter deals with the other varieties of chronic daily headache, with a proposed classification system for the following subtypes: chronic daily migraine, chronic tension-type headache, new daily persistent headache, and hemicrania continua.

Table 2-2 General rules for classification

Table 2-3 Migraine without aura

Cluster headache (Table 2-6) is a disorder that affects predominantly men. Attacks are briefer and more frequent than migraine, are strictly unilateral, and usually occur in clusters that last for weeks (episodic cluster). Attacks that occur for more than 1 year without remission or with remissions that last less than 14 days define chronic cluster.

Group 4 of the classification (Table 2-1) deals with a variety of headache disorders that are not associated with a structural lesion. Some, like idiopathic stabbing headache, cold stimulus headache, and benign exertional headache, may be part of the migraine syndrome. The remainder of the headache disorders are secondary to, and considered symptomatic of, an organic disorder, although the clinical symptomology may be identical to one of the primary headache disorders. These will be discussed in their individual sections.

Stephen D Silberstein
Richard B Lipton
Donald J Dalessio

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