Chapter 39: Overview of Headache

INTRODUCTION

HEADACHE IS A COMMON PATIENT COMPLAINT, both in the United States and globally. If persistent or severe, headaches can create a significant level of functional impairment. Both the general and subspecialized physiatrist will undoubtedly encounter headache as a part of their clinical practice. The goal of the chapter is to provide a brief overview of the characterization and management of common headache conditions.

EPIDEMIOLOGY

Head pain by patient report was the fifth-leading cause of emergency department visits overall in the United States and accounted for 1.2% of outpatient visits, according to data from the National Hospital Ambulatory Medical Care Survey (2009) and National Ambulatory Medical Care Survey (2009), respectively.¹

Tension-type and migraine headaches are the most common causes of primary headache. Interestingly, systemic infection is the most common etiology of secondary headaches, with head injury being the second most common etiology (Table 39–1).

Headaches and migraines are more common in females than in males, as represented in several population-based studies. Additionally, migraines tend to be more common in the 25- to 55-year-old age group. The American Migraine Prevalence and Prevention study estimates a migraine prevalence of 11.7% in the United States using the International Classification of Headache Disorders (ICHD-2) criteria, with an additional 4.5% being classified as “probable migraine.” Severe headache and migraine combined prevalence ranges from 16.6% to 22.7% based on ongoing U.S. public health surveillance studies.¹ Data on tension-type headache prevalence is less readily available but is generally thought to be more prevalent than migraine. A review on the global burden of headache² reports that current adult prevalence for headache in general is 46%, 11% for migraines, and 42% for tension-type.

ANATOMY AND PATHOPHYSIOLOGY

There are complex mechanisms of pain generation and pain processing for headache disorders. The basic principles involved in the generation of headache will be reviewed and will serve as a foundation for the management of headache disorders. With respect to headache, pain may be generated when nociceptors and pain pathways, which involve either the peripheral or central nervous system, are activated. Major pain-producing structures include the scalp, dural sinuses, meningeal or pial arteries, and the falx cerebri. Of these, the large intracranial vessels, dura mater and trigeminal nerve/nucleus, seem to be most involved in the generation of primary headaches (Fig. 39–1).