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Migraine: management aetiology and diagnosis

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VOL: 98, ISSUE: 36, PAGE NO: 22

Manuela Fontebasso, MB ChB, is a GP and clinical assistant in neurology, Headache Clinic, York District Hospital, York

Migraine can affect people of any age, sex, ethnicity or social class, but 90% of people will have experienced their first attack by the age of 40. It is a common condition, affecting 15-18% of women and 6% of men in the UK (Lipton and Stewart, 1994; Rasmussen et al, 1991). It is more common than asthma, diabetes and epilepsy combined.

Migraine can affect people of any age, sex, ethnicity or social class, but 90% of people will have experienced their first attack by the age of 40. It is a common condition, affecting 15-18% of women and 6% of men in the UK (Lipton and Stewart, 1994; Rasmussen et al, 1991). It is more common than asthma, diabetes and epilepsy combined.

What is migraine?
Migraine, as defined by the International Headache Society (IHS) (Headache Classification Committee, 1988; International Headache Classification Committee, 1997), is an episodic condition. Daily headache is not migraine, and both tension type headache (TTH) and chronic daily headache may co-exist with migraine. The condition is divided into two major categories, primarily on the basis of presence or absence of aura.

Migraine without aura
The majority (70%) of people who have migraine experience it without aura. For up to 24 hours before the onset of headache they may experience a prodrome, symptoms of which include yawning, tiredness, food cravings, excess energy and mood swings.

The headache, which can last between four and 72 hours, is unilateral, moderate or severe and throbbing or pounding. It is aggravated by normal activity and is associated with nausea (with or without vomiting) and photophobia (with or without phonophobia). The headache is followed by a postdrome, in which the sufferer often feels tired and lethargic, although some people feel full of energy and revitalised during this period (IHS, 1988; IHCC, 1997; Steiner et al, 1998).

Migraine with aura
Of the remaining 30% of people who get migraines, 10% experience migraine with aura, while the remaining 20% experience both types of attack (IHS, 1988; IHCC, 1997). The aura may be visual, sensory or both, and generally lasts 10-30 minutes. Auras lasting more than 60 minutes need investigation to exclude vascular or other pathology.

A typical visual aura is described as a 'spreading scintillating scotoma', flashing or zigzag lights or a fortification pattern. There may be a transient visual field loss, or hemianopia (reduced field of vision). Sensory symptoms range from pins and needles affecting the limbs or extremities to a temporary paresis. As these symptoms subside the headache develops. Some sufferers also describe a speech disturbance, ranging from slurring words to a true expressive dysphasia, which may extend into the headache phase of the attack but should subside before the headache. The final phase of the attack is the postdrome.

Diagnosing migraine
It is essential to obtain a good headache history to exclude other types of headache. The most common type of headache is TTH, but this does not affect the person's ability to function. The headache is mild to moderate, lasts for hours or days, is described as a band, tightness or pressure and is not associated with any of the more typical migraine symptoms.

Chronic daily headache has a variety of subgroups. It is typically a dull nagging ache that is present for at least four hours on more days than not. The most important subgroup is medication misuse headache (MMH). Up to 65% of people who get MMH started with episodic migraine and 27% with TTH. The condition is associated with the inappropriate and/or overuse of analgesic agents to treat headache symptoms (Antonacci, 1998), and the only treatment is to stop all analgesia.

The best way of preventing MMH it is to ensure that headaches are treated with the right treatment at the right dose at the right time. Since 70% of people who get migraine use over-the-counter medication to treat their symptoms it is easy for them to increase their intake of drugs when treatment is ineffective, thus escalating the risk of getting MMH.

The hardest part of treating people with headache is counselling those who get MMH. They must stop all painkillers in the knowledge that their headaches will get worse before they get better (Antonacci, 1998).

Cause and impact of migraine
Current theory suggests that migraine is caused by the activation of the trigeminal nucleus (a structure in the brain stem), leading to dilation of cranial blood vessels. This releases vasoactive neurotransmitter peptides that cause neurogenic inflammation of the cranial blood vessels (Goadsby and Oleson, 1996). Modern imaging techniques demonstrate increased cerebral blood volume and reduced blood flow during an attack. Serotonin levels fall in the brain during a migraine and this may cause the observed vessel dilatation that results in pain.

Migraine has a significant impact on quality of life, and this has direct and indirect cost implications (Cull et al, 1992). In the UK, 187,000 migraine attacks are experienced each day, with 140,000 people reporting disability and 90,000 being absent from work or school as a result. However, only 30% of them seek medical help or advice. When they do, they need someone to listen to their problems, understand the impact the attacks have on their lives and find the most effective acute treatment for their symptoms. They need to feel that they are in control of their lives rather being controlled by their migraine.

Holistic migraine management
At the headache clinic in York we ask detailed questions about diet and lifestyle. This includes the time when meal breaks are taken, the type of food eaten, snacks consumed, liquid drunk, as well as the person's sleep pattern, hobbies and causes of stress or anxiety. A social history can be as revealing as a headache history.

The specialist nurse and GP advise all patients about simple steps which will help them to take control of their migraine rather than letting it control them (Box 1). We reassure them that if they make changes things will get better, but emphasise that if they do not their condition is unlikely to improve - drugs are only part of the solution.

Acute treatment
Migraine is an inflammatory process associated with gastric stasis. Effective treatment therefore involves taking the right drug at the right dose at the right time. It is essential to have realistic goals and expectations of both acute and prophylactic treatment for them to be successful. Setting realistic goals involves taking time to explore the patient's concerns and ensure that the goals are achievable and that the patient understands them.

Simple analgesia and anti-emetics

Up to 50% of patients find that taking a high-dose non-steroidal anti-inflammatory drug (NSAID) with an anti-emetic as soon as possible after they start experiencing an aura or prodrome can abort their migraine attack (Steiner et al, 1998). However, timing is crucial: the earlier in the attack the medication is taken the more effective it is likely to be. Responses to different drugs can be idiosyncratic, and the patient may need to try a different NSAID for three consecutive attacks to assess which provides the best symptom control.

Triptans

Triptans are used to treat all migraine symptoms. They should be taken as soon as the headache starts. A second dose can only be taken if the headache clears completely but then returns. Triptan choice, which is available in various forms (Box 2), may depend on coexisting drug treatment and disease (Table 1).

Choosing which triptan to use as a first-line treatment may mean trading speed of onset against reduced need for multi-dosing, reduced side-effect profile against tablet-only availability and delivery system against cost. Sufferers are best placed to decide which works for them (Dahlof et al, 2002; Oldman et al, 2002). Triptans are not licensed for use in children aged under 12, and cannot be used if the patient has a history of cardiovascular disease or in the presence of uncontrolled hypertension.

All triptans are capable of producing the same range of side-effects, although the newer drugs are less likely to do so. The side-effects include nausea, dizziness, asthenia (weakness), dry mouth, myalgia or muscle weakness, and a heaviness or pressure in the chest, throat, neck or limbs.

Naratriptan and almotriptan have a side-effect profile similar to placebo. The higher the dose the more likely the person is to experience side-effects, and this may mean difficult choices have to be made. A higher dose may bring faster headache relief with a good sustained pain-free response but there may be more side-effects. Giving patients a range of options will enable them to choose the approach that best meets their needs.

Prophylaxis
Patients are often reluctant to take prophylactic tablets on a daily basis, as they can cause unacceptable side-effects and only halve the frequency of attacks in up to 50% of patients. Since prophylaxis will not stop all attacks, the patient will still require an effective acute treatment option.

Current guidelines suggest that prophylactics are prescribed after patients have experienced four or more attacks per month, unless they cannot find an effective acute treatment or attacks continue to have a significant impact on their life.

Licensed and unlicensed drugs are available (Steiner et al, 1998) (Box 3). They should be introduced singly at the lowest recommended dose and reviewed every three months with an assessment of attack frequency. The dose can be increased if there has been no effect on frequency, and the process repeated, while reinforcing diet and lifestyle advice, up to the maximum dose for that drug. Each drug can be tried in turn until an effective one is found.

Conclusion
Migraine is characterised by its effect on a person's quality of life. A survey undertaken in 1999 by the Migraine Action Association revealed that patients often found it difficult to communicate the problem when they consult a doctor or nurse about their condition. Respondents had required up to five consultations before the clinician had a good understanding of the condition's impact on their lives.

It is important to find the most effective acute treatment that will give the person flexibility and control. Prophylaxis may be indicated, but this should be at the threshold relevant to the patient and does not preclude effective acute treatment. All clinicians have the skills and expertise that may help patients to manage their migraine. Treating the condition is not just about taking tablets, it is about making choices and decisions that give control back to the patient.

Further information
- British Association for the Study of Headache, www.bash.org.uk

- Migraine Action Association (patient support, leaflets), www.migraine.org.uk

- Migraine Trust (research-based patient organisation), www.migrainetrust.org

- OUCH UK (patient organisation for cluster headaches), www.clusterheadaches.org.uk

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