Abstract
Dear Sir International Classification of Headache Disorders, 2nd edn (ICHD-II) is primarily concerned with the classification of headaches. In the ICHD-II glossary, headache is defined as ‘pain located above the orbitomeatal line’. Neither ICHD-II in general nor Chapter 11 in particular deals with specific ear pain. Code 11.4 deals with the classification of headaches attributed to diseases of the ears. Using the diagnostic criterion 11.4A, the primary symptom is listed as ‘headache’ and not ‘ear pain’. Chapter 11.4 deals only with the classification of headaches that are attributed to diseases of the ears. Accordingly, the heading of this subgroup is ‘Headache attributed to disorder of ears’. Ear pain as a single symptom may not be coded under 11.4 under any circumstances. The headache classification is not intended for classifying specific pain unrelated to headaches that is solely limited to disorders of anatomical structures such as the cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cranial structures. It was not the intention of the authors to classify all types of pain in ICHD-II.
With Parts I and II, ICHD-II allows for extremely precise classification of headaches. Part III is used for the classification of headache and facial pain with a specific neural cause. The headaches listed in Part I (primary headache disorders) and Part II (secondary headache disorders) should not be merged with Part III, a separate section that includes cranial neuralgia and facial pain disorders. Although Chapter 11.4 is included in Part II of ICHD-II and describes headaches, disorders such as neuralgias, idiopathic facial pain and burning mouth syndrome are described in Part III (Chapter 13). Unlike Parts I and II of the classification, Part III contains disorders in which pain can occur below the orbitomeatal line. The pain disorders included here share a common cause in disorders of the peripheral and central nervous system. The chapter is not, however, intended for classification of pain caused by disorders of other anatomical structures. The classification of these types of pain is thereby left to other medical fields specializing in disorders of these anatomical structures.
The headache classification allows for independent and multiple classifications of specific headache disorders. Terms such as ‘mixed headache’ or ‘combination headache’ are not useful for specific headache diagnostics. For example, headache or facial pain attributed to temporomandibular joint disorder is coded under 11.7, whereas simultaneous chronic tension-type headaches can be classified under 2.3.
It is necessary to differentiate 11.5 ‘Headache attributed to rhinosinusitis’ from so-called ‘sinus headaches’, a common but non-specific diagnosis. Most such cases fulfil the criteria for 1.1 ‘Migraine without aura’, with headache either accompanied by prominent autonomic symptoms in the nose or triggered by nasal changes. The definition of trigger factors and peripheral stimulation is a subsequent increase in the probability of headache occurrence in the short term (usually < 48 h). However, they do not provide a basis for classification of primary headache disorders.
I am pleased by the increased interdisciplinary cooperation in the continued development of headache classification. A broad-ranging, interdisciplinary team of international experts was involved in the development of ICHD-I and -II. Our future task and challenge will be to gather more in-depth knowledge in all of the involved specialty fields for further development and improvement of headache classification.