Headache is one of the most common ills. Most adults have experienced a headache at some point. They range from mild and fleeting to severe and requiring hospital admission. In certain countries, headache accounts for around 10 percent of visits to a doctor. The causes of headache are numerous and varied. Headaches can be disorders themselves (such as migraine, tension headache, cluster or vascular headache) or they can be a secondary symptom of another problem. Secondary causes include problems within the brain itself (eg tumours, stoke, infection, injury); most headaches from secondary causes are from problems originating outside the brain but in the head (eg sinus infection; numerous problems in the eyes, ears or nose, etc.) or from systemic conditions. These can include everything from high blood pressure to a low blood count, from the flu to not getting enough sleep or to drinking too much alcohol or not enough caffeine. Side effects of medications also often cause headaches. Sometimes, no specific cause can be identified. Neither the intensity of the headache nor its location on the head denotes whether it is due to a serious intracranial disease or, as in 90 percent of cases, minor and superficial disorder.
Current thinking about headaches allows for there to be both vascular (migraine) and muscular (tension) headaches co-existing, and that one may cause the other. The major types of chronic headaches are:
An estimated 45 million Americans suffer from chronic, recurrent headaches. They make more than 50 million office visits a year to doctors and spend more than $400 million on over-the-counter pain relievers. Migraine alone is such a pervasive problem that 157 million work days are lost each year in the USA, at a cost of $17.2 billion. American children lost 1.3 million days of school in 1986 because of headaches.
The Chinese restaurant syndrome headache was widely reported in the 1970s and was named for the severe vise-grip headache reported after eating in Chinese restaurants. This was later attributed to the relatively large amount of monosodium glutamate (MSG) used to add flavor to the food.
In approximately 9 out of 10 patients afflicted with headache, the condition stems from readily reversible changes in cranial arteries or in skeletal muscles of the scalp and neck; these changes are usually physiological responses to adverse attitudes and stressful living situations. For example, a common cause of severe headaches is occipital neuralgia, a disease where the nerves to the back of the head are pinched either by muscles or neck bones. Manipulative therapies such as chiropractic, massage, or physical therapy can help and in stressed persons behavioral training to relax and control pain is useful.