Headaches

---Almost everyone has had a headache at some time. Yet you might think it strange that headaches ever happen, when you remember that the brain which largely occupies the head is quite incapable of feeling pain. In fact, headaches stem not from the brain itself but from vessels, nerves or muscles connected with the brain or scalp.

---Headaches are often due to veins or arteries in or near the brain dilating, narrowing or being pulled out of position. Thus raised blood pressure can cause headache by dilating branches of the external carotid artery. This dilation sets off reactions by pain-sensitive nerve-endings in the affected blood vessels. The outcome is a throbbing headaches perhaps accompanied by dizziness and vertigo. High-blood-pressure headaches have a similar immediate origin to migraines, usually a one-sided affliction with a name that comes from hemicrania ("half the cranium"). Migraines tends to run in families. Sufferers endure periodic attacks , often heralded by coloured lights or blurred vision produced as blood vessels that supply the brain go into spasm. Then the vessels dilate and the attack shifts into top gear with throbbing headache, nausea and photophobia (intolerance of light). Discovery that animal facts, chocolate, alcohol and other foods precipitate attacks in many individuals suggests their headaches may be due at least partly to a specific biochemical disturbance. So-called migrainous neuralgia involves spasms of severe pain in the front of the head.

---Psychogenic headaches often mimic migraine. But sufferers frequently describe a "tight band" around the head due to nothing more that persistent contraction of scalp and other muscles caused by nervous stress. Brain infections, tumours, scalp injuries and internal bleeding in the cranium can all cause headaches by affecting the pain sensors in the sheaths wrapped around the brain. Tumours probably provoke headaches less by pressing on other structures than by pulling on cerebral vessels. Infections involving ears, teeth and sinuses - hollows in the front of the skill connecting the nostrils - any of these may unleash pain in head or face. (incidentally, few headaches are so unendurable as the facial pain meted out by trigeminal neuralgia, a pain caused by malfunctions of the fifth cranial nerve.)

---Fortunately, most headaches simply goo away or can be treated. Painkilling drugs like aspirin relieve the "stress headaches" from which so many people suffer, and migraine often responds to ergotamine, a drug that relieves painful blood vessels. Rarely, surgery may be required, if the headache is produced by something serious like a brain tumour, or bleeding beneath the skill.

---Different types of headache have individual features that aid identification. Differences are in type of pain, time of outset, duration, frequency, and area of head affected, as well as associated symptoms such as nausea, vertigo and visual disturbance.

Sinus Pain

---Most headaches originate in tissues that are outside the skill (extracranial). Pain is often referred from these sources, such as the sinuses to other regions of the head. Respiratory diseases, or allergies such as asthma which affect the pain sensitive tissue of the nasal sinuses are commonly accompanied by severe headache. The pain is usually worst around the affected area, such as just over the eyes, but is often felt round the forehead and temple as well.

External Sources

---Pain may be referred to the head from damaged or infected tissues in the ears, eyes, nose, teeth and mouth, or even as in arthritis, areas as distant as the spinal vertebrae. Painful prolonged contractions of the muscles of the neck, scalp and face can be caused by tension of fatigue, or may be the result of pre-existing headache affecting the muscles around the head. Dilation of the arteries, particularly the temporal artery, tends to cause the throbbing nauseous pain associated with migraine.

Internal Sources

---Pain-sensitive tissues in contact with the brain include the great veins on the surface of the brain, the cerebral arteries and parts of the dura, particularly at the base of the skill. Headache results if these are pulled or distorted as by a tumour or haemorrhage, or if the areas around them become inflamed as with infections like meningitis. Pain may also result from irritation or pressure on nerves such as trigeminal that have their roots in the brain.

Migraine

---Many people experience similar sensations of bright lights at the onset of a migraine attack. The lights typically form characteristic patterns (fortification patterns) of which the c-shaped grouping of bars of light is the most common. The sensation is due to groups of neurons in the visual cortex firing together. This, in turn, is thought to be caused by the contraction of cerebral arteries which cuts off the supply of oxygen to some areas of the brain.

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