Headache

A headache (medically known as cephalalgia) is a condition of pain in the head; sometimes neck or upper back pain may also be interpreted as a headache. It ranks amongst the most common local pain complaints.

Headaches have a wide variety of causes, ranging from eye strain, sinusitis and tension to life-threatening conditions such as encephalitis, meningitis, cerebral aneurysms and brain tumors. When the headache occurs in conjunction with a head injury the cause is usually quite evident; however, many causes are more unclear. The most common type of headache is a tension headache. Some experience headaches when dehydrated; caffeine withdrawal is another common cause.

Treatment of uncomplicated headache is usually symptomatic with over-the-counter painkillers such as aspirin, paracetamol (acetaminophen) or ibuprofen, although some specific forms of headaches (e.g. migraine) may demand other, more suitable treatment.

Pathophysiology
The brain itself is not sensitive to pain, because it lacks pain-sensitive nerve fibers. Several areas of the head can hurt, including a network of nerves which extends over the scalp and certain nerves in the face, mouth, and throat. The meninges and the blood vessels do have pain perception. Headache often results from traction to or irritation of the meninges and blood vessels. The muscles of the head may similarly be sensitive to pain.

Types
There are four types of headache: vascular, myogenic (muscle tension), traction, and inflammatory.
 * Vascular
 * The most common type of vascular headache is migraine. Migraine headaches are usually characterized by severe pain on one or both sides of the head, an upset stomach, and, at times, disturbed vision. It is more common in women. After migraine, the most common type of vascular headache is the "toxic" headache produced by fever.
 * Other kinds of vascular headaches include cluster headaches, which cause repeated episodes of intense pain, and headaches resulting from high blood pressure (rare).
 * Muscular/myogenic headaches appear to involve the tightening or tensing of facial and neck muscles; they may radiate to the forehead. Tension headache is the most common form of myogenic headache.
 * Traction and inflammatory headaches are symptoms of other disorders, ranging from stroke to sinus infection.

Specific types of headaches include:
 * Medication overuse headaches
 * Ictal headache
 * Ice cream headache
 * Thunderclap headache
 * Vascular headache
 * Toxic headache
 * Coital cephalgia (also known as: sex headache)
 * Sinus headache
 * Hemicrania Continua

Like other types of pain, headaches can serve as warning signals of more serious disorders. This is particularly true for headaches caused by inflammation, including those related to meningitis as well as those resulting from diseases of the sinuses, spine, neck, ears and teeth.

Diagnosis
While statistically headaches are most likely to be harmless and self-limiting, some specific headache syndromes may demand specific treatment or may be warning signals of more serious disorders. Some headache subtypes are characterized by a specific pattern of symptoms, and no further testing may be necessary, while others may prompt further diagnostic tests.

Headache associated with specific symptoms may warrant urgent medical attention, particularly sudden, severe headache or sudden headache associated with a stiff neck; headaches associated with fever, convulsions, or accompanied by confusion or loss of consciousness; headaches following a blow to the head, or associated with pain in the eye or ear; persistent headache in a person with no previous history of headaches; and recurring headache in children.

Computed tomography (CT/CAT) scans of the brain or sinuses are commonly performed, or magnetic resonance imaging (MRI) in specific settings. Blood tests may help narrow down the differential diagnosis, but are rarely confirmatory of specific headache forms.

Treatment
Not all headaches require medical attention, and respond with simple analgesia (painkillers) such as paracetamol/acetaminophen or members of the NSAID class (such as aspirin/acetylsalicylic acid or ibuprofen).

In recurrent unexplained headaches, healthcare professionals may recommend keeping a "headache diary" with entries on type of headache, associated symptoms, precipitating and aggravating factors. This may reveal specific patterns, such as an association with medication, menstruation and absenteeism.

Some forms of headache may be amenable to preventative treatment, such as migraine. On the whole, long-term use of painkillers is discouraged as this may lead to "rebound headaches" on withdrawal. Caffeine, a vasoconstrictor, is sometimes prescribed or recommended, as a remedy or supplement to pain killers in the case of extreme migraine. This has led to the development of Tylenol Ultra, a paracetamol/caffeine analgesic.