Headaches, Migraine, and Cluster Headache

Abstract

Headache is the leading reason for medical consultation and particularly for neurological consultation. A tremendous range of disorders can present with headaches. A systemic approach to headache classification and diagnosis is therefore essential both for clinical management and research. Epidemiology is the study of diseases, their risk factors, causes, natural history, and burden in the population. While epidemiologic studies are often population based, this is particularly important for headache because the disorder is often under-ascertained in the health care system. Most patients with headache can be diagnosed simply from a good history and general and neuralgic examinations. In some cases, however, diagnostic testing is necessary to distinguish primary causes from secondary ones, which may share similar features. The differential diagnosis of headache is one of the longest in all of medicine with more than 300 different types and causes. We offer an algorithmic approach to primary headache diagnosis based on attack frequency and duration, using the second edition of ICHD-2 classification (Headache Classification Committee of the International Headache Society 2004) highlighting the primary headache disorders and their diagnostic criteria. Recurrent headache disorders impose a substantial burden on individual headache sufferers, on their families, and on societies. Headache disorders are divided into secondary disorders, attributed to an underlying condition, and primary disorders, such as migraine, trigeminal autonomic cephalalgias, and tension-type headaches, where there is no underlying cause. The epidemiology of secondary headache is largely determined by the epidemiology of the underlying cause. Therefore in this chapter we focus on the epidemiology of primary headache disorders.