Headache and Migraine Causes, Symptoms, Diagnosis, Types and Drug Treatment.

Headache and migraine
Causes
The causes of most headaches fall into three categories:
1.   Tension: the most common cause of headache, thought to be due to pericranial muscle contraction. It is often psychogenic in origin and caused or made worse by tension, anxiety or fatigue.
2.   Vascular, caused by dilatation or constriction of blood vessels in the brain and cranium: headaches associated with febrile illnesses are caused by vasodilatation. Migraine is also believed to be vascular in origin, at least in part, although neurochemical pathology also appears to be involved.
3.  Traction: infl ammation or compression of the brain and associated structures is responsible for headache associated with meningitis, encephalitis, haematomas (including those resulting from head injury), tumours and cerebral abscesses. Sinusitis, often associated with upper respiratory tract infections and allergic rhinitis, also frequently causes headache from congestion in the frontal and maxillary sinuses exerting pressure on surrounding nerves.
Other causes include:
  spasm or fatigue of the ciliary and periorbital muscles of the eye, causing eye strain
glaucoma
  referred pain from the jaw; muscle strain and pulled ligaments in the neck or upper back
infl ammation of the temporal arteries in temporal arteritis
  neuropathic pain from shingles.
Epidemiology
Headache is the most commonly experienced of all symptoms: 96% of people are estimated to suffer a headache at least once in their life and 80–90% will experience one or more per year.
  Migraine is suffered by about 15% of the population overall, with a female:male ratio of incidence of 3:1. Migraine mainly affects younger people: 80% of sufferers have their fi rst attack before the age of 30, and incidence is rare after age 50.
Signs and symptoms
The clinical features of the main types of headache are outlined in Table
Differential diagnosis
Eye strainEye strain can be responsible for frontal headaches. There may be occupational pointers, e.g. people using computers for long periods. Refer to an optometrist. Headache may also be a symptom of glaucoma; if suspected, refer immediately to a doctor.
Meningitis
In meningitis there may be a severe generalised headache associated with fever, nausea, neck stiffness, pain behind knees when extended (Kernig’s sign) and a purpuric rash in later stages. Refer urgently any child with headache, high temperature and who is unable to bend head forward easily.
Cluster headache
This is a condition of unknown cause that predominantly affects men between the ages of 40 and 60. Typically, headaches occur at the same time each day and last for between 10 minutes and 3 hours. About half of sufferers have attacks at night. Pain is sudden in onset, intense and ‘boring’ and localised around one eye. The affected eye becomes red and watery and there may be nasal congestion. Attacks persist for between a few weeks and a few months, with periods of remission of months or years. Refer immediately to a doctor.
Subarachnoid haemorrhage
Subarachnoid haemorrhage is caused by bleeding between the meningeal layers covering the spinal cord. There is sudden intense severe occipital headache, often described as ‘the worst I’ve ever had’. It is often accompanied by nausea and vomiting. There may be transient loss of consciousness. Refer urgently to Accident & Emergency.
Temporal arteritis
Temporal arteritis is infl ammation of the temporal artery running down the side of the head just in front of the ear. It occurs almost exclusively in elderly people. There is severe unilateral pain, and the area of the temple is infl amed and tender to the touch. There may be associated jaw pain and generalised rheumatic pains. Refer immediately to a doctor.
Space-occupying lesions
These lesions may be caused by tumour, haematoma or abscess. The pain can be localised or diffuse. It may be initially mild and get progressively worse. It may be severe on waking in the morning and lessen after getting up. It is made worse by coughing, sneezing or lying down. Refer if suspected. Symptoms may sometimes be confused with sinusitis, but the latter is usually associated with symptoms of upper respiratory tract infection or allergic rhinitis.
Trigeminal neuralgia
Infl ammation of the trigeminal nerve occurs in people mainly over the age of 50 and is more common in women than men. The pain is intensely sharp, and cutting or searing in nature. Pain is experienced in either the forehead or the side of the head, around the eye, with redness and lacrimation, the cheek and upper jaw, or the lower jaw, depending on which branch of the trigeminal nerve is affected. Refer immediately to a doctor. 
Symptoms and circumstances for referral
su  dden onset and/or very severe headache
  headache after head injury
  headache of long duration
  recurring headaches (excluding diagnosed migraine)
  headaches worsening over time
  headache accompanied by nausea/vomiting (except as part of diagnosed migraine), drowsiness
vision affected
  pupils uneven or not reacting to light
  child under 12 (urgent if with neck stiffness, fever or rash)
  cluster headache symptoms.
Treatment
This section covers oral non-prescription medicines for most types of pain, including tension headache, migraine, sinusitis, dental pain and musculoskeletal pain. Non-prescription oral analgesics are based on three compounds:
1.  aspirin
2.  ibuprofen
3.  paracetamol.
Clinical evidence shows that all three compounds are effective analgesics and antipyretics, and that ibuprofen is generally the most effective.
Aspirin and ibuprofen
Action and uses
Aspirin and ibuprofen are non-steroidal anti-infl ammatory drugs (NSAIDs).
  NSAIDs exert their therapeutic action by blocking the enzyme cyclo-oxygenase, which prevents the formation of prostaglandins from arachidonic acid, produced when tissue is damaged; prostaglandins are major contributors to infl  ammation and pain. The action of NSAIDs is local at the site of infl ammation.
  NSAIDs also inhibit production of cytoprotective prostaglandins in the gastric mucosa, accounting for their tendency to cause gastrointestinal irritation, although the incidence is much lower with ibuprofen than aspirin.
  Aspirin and ibuprofen are licensed for treatment of mild and moderate pain from a wide variety of causes, including dental and musculoskeletal pain and dysmenorrhoea, where their anti-infl ammatory activity is particularly useful. They also have antipyretic action and are used in cold and fl u medicines.
Adverse reactions, cautions and contraindications
  Aspirin and ibuprofen have similar side-effects, although side-effects are generally less pronounced with ibuprofen.
  The most common side-effects are gastric irritation and bleeding. Both drugs should be avoided by patients with ulcers or a history of gastric problems. Minor gastric side-effects can be reduced by taking the drugs with or after food.
  Hypersensitivity reactions to aspirin are much more likely to occur in patients with asthma or allergic problems than in the normal population. One in 10 patients with asthma may be hypersensitive and suffer severe bronchospasm. Other reactions are urticaria, angioedema and rhinitis. The incidence of hypersensitivity to ibuprofen is much lower than with aspirin, but the drug should be avoided by patients with asthma and individuals who are sensitive to aspirin, unless they have taken ibuprofen before without problems.
  Aspirin and ibuprofen should not be recommended to patients with renal, cardiac or hepatic disease: both medications may impair both liver and kidney function.
  Aspirin and ibuprofen should be used with caution in elderly patients, as renal function tends to decline with age and also because the elderly tend to be particularly vulnerable to gastric side-effects.
Aspirin and ibuprofen should be avoided during pregnancy.
  Aspirin has been associated with Reye’s syndrome, a rare but potentially fatal brain condition in infants and children. Aspirin is not licensed for use in children under16 years and it should also be avoided by breastfeeding women. However, there is no evidence of an association between ibuprofen and Reye’s syndrome and it is licensed for sale for use in children and babies from the age of 3 months.
Interactions
  Aspirin potentiates the anticoagulant effect of warfarin and other coumarins because of its inhibitory effect on platelet aggregation and inhibition of vitamin K synthesis. Ibuprofen may also enhance the effect of anticoagulants. Patients on anticoagulant therapy should avoid over-the-counter (OTC) aspirin and ibuprofen.
  Aspirin and, to a lesser extent, ibuprofen reduce excretion of methotrexate, and can cause life-threatening rises in serum levels. Concurrent administration should therefore be avoided.
  Ibuprofen reduces the excretion of lithium and can raise plasma concentrations to toxic levels. It may also antagonise the diuretic and antihypertensive effects of diuretics, and should not be recommended to patients taking these drugs.
Paracetamol
Action and uses
The mechanism of action of paracetamol is not well understood. It has little anti-infl ammatory activity but is an effective analgesic and antipyretic. It may selectively inhibit cyclo-oxygenase in the central nervous system rather than in peripheral tissues. It also appears to act peripherally at pain chemoreceptors. Toxicity
  Paracetamol is very safe at normal therapeutic dosages; its only major drawback
is hepatotoxicity in overdose.
  Paracetamol is metabolised in the liver, where it is converted to a highly toxic intermediate that is normally detoxifi ed by conjugation with glutathione. In overdose, this detoxifi cation mechanism is overwhelmed and the free toxic metabolite causes hepatitis and necrosis, which can prove fatal.
  Paracetamol poisoning is particularly dangerous as the toxic level may not be greatly above the therapeutic level. Also, symptoms of overdose may not appear for 2 days or more, allowing unwitting overdosage to continue.
  Fatalities have occurred in patients who were taking large doses, or two or more preparations containing paracetamol, for a minor ailment such as a cold. It is therefore extremely important to ensure that patients do not exceed the recommended dosage and do not use more than one paracetamol-containing product at a time.
  OTC pack sizes of products containing aspirin and paracetamol and the total amounts that can be supplied are restricted to reduce the incidence of poisoning (see  Medicines Ethics and Practice for details).
Additional constituents
  Most proprietary OTC oral analgesics are not simple formulations of aspirin, ibuprofen or paracetamol, but combination products containing other analgesics and sometimes other constituents.
  The theory behind combination products is that they will be more effective than one drug used alone and that the dose of each analgesic can be reduced, lessening the possibility of adverse effects. Further additional components are sometimes included to treat symptoms associated with pain.
  Leading medical opinion (e.g. as represented in the British National Formulary) does not generally favour combined analgesics, claiming that low doses of additional ingredients may reduce the severity but increase the range of side-effects without producing signifi cant extra pain relief. Clinical evidence indicates that additional constituents add little to analgesic effi  cacy.
Codeine and dihydrocodeine
  Codeine is combined with aspirin, paracetamol and ibuprofen in many OTC analgesic products, and also in the formulary preparations co-codamol (with paracetamol) and co-codaprin (with aspirin). Dihydrocodeine is included with paracetamol in one OTC product, and at a higher dose in co-dydramol tablets, which are prescription-only medicines (POM).
  Codeine and dihydocodeine are opioid analgesics that act directly on opiate receptors in the brain, producing analgesia, respiratory depression, euphoria and sedation. They are weak narcotic analgesics, useful for the treatment of mild to moderate pain. Their major side-effect at non-prescription dosages is constipation.
Caffeine
  Many OTC analgesics contain caffeine, the rationale being that, as a central nervous system stimulant, it will alleviate the depression often associated with pain.
  Most preparations contain low doses, although they may be suffi  cient to add to gastrointestinal adverse effects. Caffeine is also habit-forming and may itself induce headache in large doses or on withdrawal.
Antihistamines
Tension in muscles at the back of the neck is thought to be a contributory factor to tension headache. Sedating antihistamines are included in some products for their claimed muscle-relaxant effect.
Migraine treatments
Migraine can often be treated with paracetamol, ibuprofen or aspirin alone, or with combination products containing them. There are also some non-prescription medicines specifi cally licensed for the treatment of migraine. One such is a co-formulation of paracetamol, codeine and the antihistamine buclizine, included for its antiemetic action. Other specifi  c migraine treatments are reviewed below.
Sumatriptan
  Sumatriptan is one of a group of compounds known as triptans. Triptans are 5HT1D-receptor agonists; they cause constriction of the cerebral arteries and counteract the cranial vasodilatation thought to be responsible for migraine attacks. Triptans are now established as a fi rst-line treatment for migraine.
  Sumatriptan is licensed for pharmacy sale for acute relief of migraine attacks, with or without aura, in adults aged 18–65 years. Treatment may not be supplied for prophylaxis or for patients who:
–  are pregnant or breastfeeding
–  have existing medical conditions, including cardiovascular conditions, hypertension, peripheral vascular disease, liver or kidney disorders 
–  have any neurological condition or symptoms, including epilepsy
–  are allergic to the drug
–  are taking concurrent medication for migraine
–  are assessed as having a high cardiovascular risk, using the factors in the
cardiovascular risk prediction charts in the British National Formulary.
  The dose is one 50 mg tablet, taken as soon as possible after the onset of an attack. A second dose may be taken after 2 hours if migraine recurs. If there is no response to the fi rst tablet, a second tablet should not be taken for the same attack. Maximum dosage is two tablets in 24 hours.
  Referral to a doctor should be made if:
–  attacks last longer than 24 hours, become more frequent or symptoms change
–  the patient generally has four or more attacks per month
–  the patient does not completely recover between attacks
–  the patient is over 50 years of age and is suffering a migraine attack for the fi rst time.
Side-effects are usually mild and transient.
  Sumatriptan should be avoided by patients taking selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, moclobemide, St John’s wort and other vasoconstrictor migraine treatments, especially ergotamine and methysergide.
Isometheptene mucate
  Isometheptene is a sympathomimetic, used in the treatment of migraine and throbbing headache for its vasoconstrictor effect. It is combined with paracetamol in one proprietary product.
The British National Formulary has classifi ed this product as ‘less suitable for prescribing’ and states that other more effective treatments are available.
Prochlorperazine
  Prochlorperazine is a phenothiazine derivative.
It is widely used on prescription for the treatment of vertigo and the prevention of nausea and vomiting.
  Prochlorperazine maleate buccal tablets are licensed for the non-prescription treatment of nausea and vomiting associated with migraine.
The licensing conditions only permit supply if migraine has already been diagnosed by a doctor, to adults of 18 years and over. It is contraindicated in pregnant and breastfeeding women, and also in patients with impaired hepatic function, narrow-angle glaucoma, prostatic hypertrophy, epilepsy or Parkinson’s disease.