Pain that occurs over various parts of the head is called a headache. It is one of humankind's most common afflictions. In
the United States alone, up to 50 million persons seek medical help for this problem every year, and about half a billion dollars is spent on headache remedies annually.
Physicians have treated headache in various ways throughout history. As long ago as 5000 ©, the Chinese used acupuncture to relieve head pain. The Greek physician Galen (c.130Ðc.200) wrote about headache in his treatise Maintaining Good Health. Following his lead, Roman and medieval physicians used cathartics and bloodletting to treat headache. The pre-Columbian Inca of Peru drilled holes in the skull to release the evil spirits that they believed to be at the root of the problem. Today headache is mostly treated with a wide variety of drugs and behavior modification techniques.
Brain tissue itself is insensitive to pain, as is the bony covering of the brain (the cranium). Headache pain results from the stimulation of such pain-sensitive structures as the membranous linings of the brain (the meninges) and the nerves of the cranium and upper neck. This stimulation can be produced by inflammation, by the dilation of blood vessels of the head, or by sustained muscle contractions in the neck and head.
Headaches brought on by muscle spasms are classified as tension-type headaches; those caused by the dilation of blood vessels are called vascular headaches. A more specialized classification, by the International Headache Society, further divides headaches into 14 categories for research purposes.
Most headaches are not caused by organic disease. Only about 2% of all headaches result from organic disorders, including diseases of the eye, ear, nose, throat, and sinuses; brain tumors; and aneurysms (the ballooning of an artery, brought about by a weakness in the arterial wall). The most common form of headache is the tension-type headache, which can be divided into two categoriesÑepisodic and chronic. People rarely visit physicians because of tension headaches. Vascular headaches are probably the most severe form and are the most frequent reason cited for patients visiting a physician with the primary complaint of headache. Vascular headaches include migraine, cluster, and hypertensive headaches. Chronic sinus problems rarely cause headaches, although these are frequently cited in the media as a major headache trigger. Acute sinusitis, with an accompanying fever, can precipitate headache, and the underlying infection must be treated to relieve the symptoms.