A headache -What is it?

A headache (cephalalgia in medical terminology) 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 and may be frequent for many people.

The vast majority of headaches are benign and self-limiting. Common causes are tension, migraine, eye strain, dehydration, low blood sugar, hypermastication and sinusitis. Much rarer are headaches due to life-threatening conditions such as meningitis, encephalitis, cerebral aneurysms, extremely high blood pressure, and brain tumors. When the headache occurs in conjunction with a head injury the cause is usually quite evident. A large percentage of headaches among women are caused by ever-fluctuating estrogen during menstrual years. This can occur prior to, or even during midcycle menstruation.

Treatment of an 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., migraines) may demand other, more suitable treatment. It may be possible to relate the occurrence of a headache to other particular triggers (such as stress or particular foods), which can then be avoided.
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, for some people, disturbed vision. It is more common in women. While vascular changes are evident during a migraine, the cause of the headache is neurological, not vascular. After migraine, the most common type of vascular headache is the "toxic" headache produced by fever.
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.

The most important step in diagnosing a headache is for the physician to take a careful history and to examine the patient. In the majority of cases the diagnosis will be a "primary headache" which means that the headache, whilst unpleasant is not occurring as a manifestation of a more serious condition. The main types of primary headache are tension headache, migraine, and the trigeminal autonomic cephalalgias of which cluster headache is an example. As it is often difficult for patients to recall the precise details regarding each headache, it is often useful for the sufferer to fill-out a "headache diary" detailing the characteristics of the headache. When the headache does not clearly fit into one of the recognized primary headache syndromes or when atypical symptoms or signs are present then further investigations are justified.[1] 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.

In 2008 the American College of Emergency Physicians updated their guidelines on the evaluation and management of adult patients who have a nontraumatic headache of acute onset.