Headache
Headache, pain in any part of the head. Although the condition is widespread, less than 1 percent of all headaches indicate serious physical problems. This small percentage includes headaches caused by, or occurring after, concussion or injury to the head (see Concussion of the Brain ), meningitis , encephalitis , stroke , or brain tumors. Headache may also accompany misalignment of the jaw or teeth. Short-lived headaches may occur after eating very cold foods or foods high in nitrites or monosodium glutamate. Caffeine withdrawal also may provoke headaches. The majority of headaches belong to one of three main groups: migraine , a recurrent, severe headache, usually with throbbing on one side, accompanied by nausea and sometimes impaired vision; cluster, similar to migraine, but of short duration, occurring daily in series over weeks or months and predominantly in the area of one eye; and tension, a headache without consistent location thought to result from contractions of the face, s