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Diagnosis and preventive approaches in the management of migraine

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Ria Bhola, BSc (Hons), RN.

Headache Nurse Specialist, The National Hospital for Neurology and Neurosurgery, London

Headache is a common symptom that may be caused by a variety of conditions, or it may be the disorder itself. There are two distinct types of headache - primary and secondary - and it is important to differentiate between the two types.

Headache is a common symptom that may be caused by a variety of conditions, or it may be the disorder itself. There are two distinct types of headache - primary and secondary - and it is important to differentiate between the two types.

Primary headaches include migraine, cluster headache, tension-type headache and some other less common syndromes such as paroxysmal hemicrania and hemicrania continua. These headaches are not caused by other underlying medical conditions - the headache is the disorder itself. They are benign but can be very disabling.

Secondary headaches result from medical conditions such as infections, vascular disorders, tumour, metabolic or toxic disorders. Most headaches are primary and, as such, do not indicate the presence of a serious under- lying disease. But it is important to seek medical attention to rule this out and to find out how to manage the headache effectively.

Migraine is by far the most prevalent primary headache disorder and is the most common neurological condition. It affects up to 18% of women, 6% of men and 4% of children in the UK, and 10-15% of the world's population (Lipton, 2001). It is ranked 19th by the World Health Organization (2001) in the list of disabling diseases and is most prevalent in those aged between 25 and 55.

The pain, suffering and disability caused by migraine impose substantial burdens at both personal and economic levels. Personal costs are measured in terms of missed or reduced participation in family, social and recreational activities (Lipton, 2001), while economic costs are gauged in terms of the cost of treatment and reduced effectiveness at work, missed work or school as a result of acute attacks (Steiner et al, 2003).

Although migraine is common, it is under-diagnosed and under-treated worldwide. There is therefore huge potential to improve the quality of life of those who have migraines.

Clinical features
Migraine is an episodic headache disorder characterised by attacks that may be accompanied by neurological, gastrointestinal and autonomic symptoms (Goadsby et al, 2002). The International Headache Society (2004) classifies it further as 'migraine with aura' (MA) and 'migraine without aura' (MO).

About 15% of sufferers experience an 'aura', which may occur before a headache. The aura may present as visual abnormalities such as wavy or jagged lines, dots, flashing lights; or altered sensations of smell, sound or taste. These neurological symptoms will generally fade as the headache begins. It tends to be throbbing in nature and may be aggravated by movement. Nausea with or without vomiting, sensitivity to light, sound and possibly smell are common features.

A migraine attack can last between four and 72 hours and may occur once over several months or several times a week. Individuals often prefer to stay in a dark, quiet room and prefer to remain still. The headache often affects one side of the head, with pain severity ranging from moderate to incapacitating. Following an attack, the person may feel tired and irritable.

Pathophysiology
The causes of headaches and the mechanisms involved have been subject to extensive research. There is a strong familial component, suggesting a genetic link (Ferrari, 1998). Conventional tests - magnetic resonance imaging (MRI) and computerised tomography (CT) scans - generally reveal normal brain anatomy in those who get migraine, but newer technologies such as positron emission tomography (PET) and functional MRI have enabled further understanding of the mechanisms involved. These tests reveal areas of brain cell activation during migraine, thereby allowing researchers to visualise both the function and structure of the brain.

To date, the evidence suggests that migraines originate in the upper brain stem (Ashkenazi and Silberstein, 2004). It is believed that during an attack, trigeminal sensory neurones are activated, releasing substances that result in neurogenic inflammation, meningeal blood vessel dilation and plasma protein extravasation, and that some of these processes are mediated by serotonin. While the brain is insensitive to pain, it is surrounded by layers of protective membranes, the meninges, which are highly sensitive. These become inflamed during an attack, contributing to the pain.

The cells in the brain cortex of those who have migraine attacks are more sensitive to stimulation. This leads the brain to perceive sensory information at a heightened level so that during an attack, individuals are abnormally sensitive to stimulation that might not be unpleasant to others. During an attack, there appears to be some disruption in the way visual and auditory signals are processed in the relevant brain centres (Solomon, 2000). Nausea with or without vomiting is also common.

Triggers
'Triggers' are specific factors that may increase the risk of an attack. They do not cause a migraine but are thought to activate processes that may cause one in a headache-prone person. Recognising and avoiding or modifying these factors can help to reduce headache frequency and the need for medication. Some recognised migraine triggers are summarised in Table 1.

Management
The management of migraine begins with obtaining the right diagnosis. Brain scans and blood tests are necessary only if there is a suspicion of a secondary cause. A careful, thorough headache history is vital, and a typical clinical picture of migraine, together with a normal neurological examination, is a good indicator that there are no secondary causes. As the 'migrainous brain' does not appear to like change, it is important to aim for regularity in daily activities and to avoid known triggers.

Once a diagnosis of migraine has been established, a treatment plan should be developed. The issue of triggers should be addressed, and they should be corrected or avoided if possible. There is no evidence that foods such as chocolate, cheese and dairy products induce an attack. Part of the syndrome involves having a craving for certain foods before the pain begins (premonitory symptoms), so these foods may already have been consumed. However, the migrainous process will have already begun, so it is difficult to attribute the cause to the foods.

Treatment for an acute attack in the form of non-specific or specific migraine drugs aims to stop an attack and reverse the symptoms. A non-specific drug could be a non-steroidal anti-inflammatory analgesic, taken with or without an anti-emetic. Migraine-specific drugs are the serotonin agonists known collectively as the triptans: sumatriptan, zolmitriptan, almotriptan, eletriptan, naratriptan, rizatriptan and frova-triptan. Treatment for an acute attack is most effective if it is taken as soon as a headache starts. The dose should be adequate and the route of administration appropriate. Treatment should not be taken on more than two days a week to avoid medication-overuse headache.

Preventive treatment may also be necessary. If the migraine interferes significantly with daily life despite treatment by drugs, or if the attacks are frequent and do not respond to drugs, a preventive could be very useful. These medications are taken daily for six to 12 months to reduce the frequency, duration and severity of attacks. Patients should discuss these options with their GP or neurologist.

Patient outlook
Increased understanding of the disorder, along with the development of anti-migraine treatments, offers a positive outlook for patients. Those with migraine or frequent disabling headache need to seek help and advice. In the first instance, they may see their GP or contact a recognised headache charity, such as the Migraine Trust (www. migrainetrust.org), for advice.

A further referral may be obtained to a neurologist or a specialist headache clinic. To optimise the consultation, it is helpful if patients provide the following details:

- When the attacks first began, how often they occur and how long they last

- Location of the pain, what it is like and whether there are associated symptoms such as sensitivity to light, sound and smell, nausea or vomiting or warning symptoms before the pain occurs

- The frequency, duration and severity of the attacks, as recorded in a headache diary

- A list of the medications tried and the doses, including over-the-counter preparations

- Whether a family member has headaches.

Conclusion
Migraine is a chronic condition that is considered to be a primary brain disorder. Studies show that the brains of people with frequent migraine show areas of cell activation that make them susceptible to frequent or severe headaches. The aim of treatment is to manage the headaches so that attacks are fewer and less severe, and that those that occur are treated effectively. Lifestyle changes may also improve the quality of life of sufferers.

Latest policy
The 2004 International Headache Society classification system

Originally formulated in 1998, this has become the standard for headache diagnosis and clinical research. It divides headaches into three categories:

- Primary headache disorders, including migraine and cluster headaches

- Secondary headache disorders that are due to another organic disorder

- Cranial neuralgia, central and primary facial pain and other headaches

Source: International Headache Society, www.i-h-s.org

KEYPOINTS
- It is an episodic headache disorder

- It affects 10-15% of the world population, and is under-diagnosed and under-treated

- 15% of people experience an aura

- Evidence suggests that migraines originate in the upper brain stem

- The meninges become inflamed during an attack

- There are known triggers that increase the risk of a migraine

- Medication includes non-specific and specific anti-migraine drugs

- Acute treatment is most effective if taken as soon as the headache starts

- Treatment aims to manage the headaches so that attacks are fewer and less severe

Author's contact details
Ria Bhola, The National Hospital for Neurology and Neurosurgery, Queen's Square, London WC1 3BG. Email: r.bhola@ion.ucl.ac.uk

Ashkenazi, M.D., Silberstein, S.D. (2004) Headache management for the pain specialist. Regional Anaesthesia and Pain Medicine 29: 5, 462-475.

Ferrari, M. (1998)Migraine. Lancet 351: 1043-1051.

Goadsby, P.J., Lipton, R.B., Ferrari, M.D. (2002)Migraine: current understanding and treatment. New England Journal of Medicine 346: 257-270.

International Headache Society. (2004)The international classification of headache disorders (2nd edn). Cephalalgia 24: (supp 1), 1-60.

Lipton, R.B. (2001)Prevalence and burden of migraine in the United States: data from the American Migraine Study -2. Headache 41: 546-557.

Solomon, S. (2000)Advances in headache medicine. Headache, the Newsletter of the American Council for Headache Education 11: No 1.

Steiner, T., Scher, A.I., Stewart, W.F. et al. (2003)The prevalence and disability burden of adult migraine in England and their relationships to age, gender and ethnicity. Cephalalgia 23: 519-527.

World Health Organization. (2001)The World Health Report. Geneva: WHO.

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