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 brain in itself is not sensitive to pain, because it lacks nociceptors. Several areas of the head can hurt, including a network of nerves which extend over the scalp and certain nerves in the face, mouth, and throat. The meninges and the blood vessels do have pain perception. Headaches often result from traction to or irritation of the meninges and blood vessels. The membrane surrounding the brain and spinal cord, called the dura mater, is innervated with nociceptors. Stimulation of these dural nociceptors is thought to be involved in producing headaches. Similarly the muscles of the head may be sensitive to pain.
[edit] Types
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There are five types of headache: vascular, myogenic (muscle tension), cervicogenic, traction, and inflammatory.
[edit] Vascular
Main article: vascular headache
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.
Other kinds of vascular headaches include cluster headaches, which are very severe recurrent short lasting headaches, often located through or around either eye and often wake the sufferers up at the same time every night. Unlike migraines, these headaches are more common in men than in women.
[edit] Muscular/myogenic
Muscular (or 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.
[edit] Cervicogenic
Cervicogenic headaches originate from disorders of the neck, including the anatomical structures innervated by the cervical roots C1–C3. Cervical headache is often precipitated by neck movement and/or sustained awkward head positioning. It is often accompanied by restricted cervical range of motion, ipsilateral neck, shoulder, or arm pain of a rather vague non-radicular nature or, occasionally, arm pain of a radicular nature.
[edit] Traction/inflammatory
Positron emission tomography functional imaging shows activation of specific brain areas during a cluster headache.
Traction and inflammatory headaches are symptoms of other disorders, ranging from stroke to sinus infection. Specific types of headaches include:
* Tension headache
* Migraine
* Idiopathic intracranial hypertension (headache with visual symptoms due to raised intracranial pressure)
* Ictal headache
* Cluster headache
* "Brain freeze" (also known as: ice cream headache)
* Thunderclap headache
* Vascular headache
* Toxic headache
* Coital cephalalgia (also known as: sex headache)
* Hemicrania continua
* Rebound headache (also called medication overuse headache, abbreviated MOH)
* Red wine headache
* "Spinal headache" (or: post-dural puncture headaches) after lumbar puncture or related procedure that will lower the intracranial pressure
* Hangover (caused by heavy alcohol consumption)
A headache may also be a symptom of sinusitis.
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.
[edit] 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 an 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.
[edit] Treatment
Not all headaches require medical attention, and many 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 or absenteeism or with certain foods. It was reported in March 2007 by two separate teams of researchers that stimulating the brain with implanted electrodes appears to help ease the pain of cluster headaches.[2]
[edit] Prevention
Some forms of headache, such as migraine, may be amenable to preventative treatment. On the whole, long-term use of painkillers is discouraged as this may lead to drug induced headaches and "rebound headaches" on withdrawal.[3] 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 paracetamol/caffeine analgesic.
Petasites, magnesium, feverfew. riboflavin, CoQ10, and melatonin are "natural" supplements that have shown some efficacy for migraine prevention; a 2006 review tentatively ranked petasites and magnesium with the best evidence, and melatonin with by far the least. Adverse events included sore mouth and tongue (including ulcers) and abdominal pain for feverfew.[4]
[edit] Manual therapy
Headache sufferers often use manual therapy, such as spinal manipulation, soft tissue therapy, and myofascial trigger point treatment. A 2006 systematic review found no rigorous evidence supporting manual therapies for tension headache.[5] A 2005 structured review found that the evidence was weak for effectiveness of chiropractic manipulation for tension headache, and that it was probably more effective for tension headache than for migraine.[6] A 2004 Cochrane review found that spinal manipulation may be effective for migraine and tension headache, and that spinal manipulation and neck exercises may be effective for cervicogenic headache.[7] Two other systematic reviews published between 2000 and May 2005 did not find conclusive evidence in favor of spinal manipulation.[8]
Spinal manipulation is associated with frequent, mild and temporary adverse effects,[9] including new or worsening pain or stiffness in the affected region.[10] They have been estimated to occur in 34% to 55% of patients, with 80% of them disappearing within 24 hours.[11] Spinal manipulation, particularly on the upper spine, can also result in complications that can lead to permanent disability or death.[9] The incidence of these complications is unknown, due to high levels of underreporting and to the difficulty of linking manipulation to adverse effects such as stroke, a particular concern.[9] Weak to moderately strong evidence supports causation (as opposed to statistical association) between cervical manipulative therapy (whether chiropractic or not) and vertebrobasilar artery stroke.[12]
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