Headache is among the most common medical complaints. An overview of the approach to the patient with headache is presented here. The approach to adults presenting with headache in the emergency department is reviewed elsewhere. (See "Evaluation of the adult with headache in the emergency department".)
The clinical features and management of specific primary headache syndromes are discussed separately. (See "Pathophysiology, clinical manifestations, and diagnosis of migraine in adults" and "Tension-type headache in adults: Pathophysiology, clinical features, and diagnosis" and "Cluster headache: Epidemiology, clinical features, and diagnosis".)
EPIDEMIOLOGY AND CLASSIFICATION OF HEADACHE
Many controversies exist in the literature regarding the nomenclature and classification of headache. The International Headache Society (IHS) classification and diagnostic criteria for headache were revised in 2004 . This system gives operational diagnostic criteria for headaches, cranial neuralgias, and facial pain syndromes. The IHS classification also details which clinical features must be present and in what combination to establish a precise diagnosis. However, this classification system can be cumbersome for day to day use. The IHS criteria may be most useful for grouping patients for scientific purposes, such as clinical trials and epidemiologic studies .
As many as 90 percent of all benign headaches fall under a few categories, including migraine, tension-type, and cluster headache. While a population-based study found that the one-year prevalence of episodic tension-type headache was 38 percent , most of these people do not present to physicians for care. As an example, a study of two primary care units in Brazil found that migraine was the most prevalent primary headache disorder, accounting for 45 percent of patients reporting headache as a single symptom .
Cluster headache typically leads to significant disability and most of these patients will come to medical attention. However, cluster headache remains an uncommon diagnosis in primary care settings because of overall low prevalence in the general population (<1 percent). (See "Cluster headache: Epidemiology, clinical features, and diagnosis", section on 'Epidemiology'.)