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Epidemiology of epilepsy in developed and developing countries

Around 50 million people in the world have epilepsy. It is the commonest serious neurological condition. The heterogeneiety of the clinical features of seizures is one reason for the problems in unterpretting and assesing epidemiological data on epilepsy. Some patients with seizures may never seek medical attention because they ignore or misinterpret the symptoms, or are unaware of them. Epidemiological studies of epilepsy often miss patients unless sensitive screening techniques are included. The overall incidence of epilepsy is generally taken to be around 50 per 100000/year (range 40-70 per 100 000/year) in industrialized countries and people socio-economically deprived are at higher risk, a range of 100-190 cases per 100 000/year is generally quoted. In developing countries incidence is higher due to more primitive obstetric services and the greater likelihood of cerebral infection and head trauma. For example, in Latin Amarica is neurocystircercosis on the brain caused ny tapeworn infection, in Africa, malaria ad meningitis are common causes, and in India neurocystircecosis and tuberculosis often lead to epilepsy. The lack of medical facilities in many resurce-poor countries may result in missclasification of some cases, particularly of acute symptomatic seizures. In industrialized countries there is evidence of a decrease in the incidence in children and a simultaneous increase in the elderly over the last three decades. This is partly because of demographic changes in the population (with an increasing proportion of the population in the elderly age range) also due to an increasing incidence of degenerative cerebrovascular disease. In western countries the incidence of epilepsy is now higher in people older than age 70 than in people younger than age 10. The prevalence of epilepsy is around 1%. Aethiological differences have only a small effect on prevalence rates, perahaps the majority of cases of epilepsy are criptogenic, but higher incidence rates in part of the tropical belt may reflect a high local prevalence of neurocysticercosis. Advances in neuroimaging by MRI have, however, increased the number of patients in whom putative positive aethiological diagnoses is possible. Experience in clinic-based populations suggest that at least half of patients would demonstrate evidence of hippocampal sclerosis , cortical dygenesis or small foreign tissue lesions. No consistent racial differences have been found, although several studies have shown higher incidence and prevalence figures in Afro-Americans than in white Americans- this may reflect a poorer standard of perinatal and other health care. In all comprehensive surveys, partial seizures account for most cases, complex partial and secondarily generalised seizures comprise 60% of prevalent cases, primary generalized tonic-clonic seizures about 30%, and generalised absence and myoclonus less than 5%. Other seizure types are rare. Of new cases of epilepsy, approximately 50% have seizures of partial origin and 50% of generalized origin before age 40. After age 40, the proportion of partial epilepsy cases rises to 75% by age 75. Most of the advances in developed economies are of little or no relevance to the 80% of people with epilepsy who live in developing countries. For most of these people the older supernatural views, social stigma and discrimination still prevail. Even in the developed world, the disorder is still shrouded in secrecy, and people prefer not to reveal or discuss their illness. Of the estemated 50 million people in the world with epilepsy, 32 million have no access to teratment at all-either because services are not existent or, just as importantly, because epilepsy is not viewed as a medical problem or a treatable brain disorder. Choice of drug Phenobarbitone has become WHO s front line antiepileptic drug in developing countries, where it is the most commonly prescribed antiepileptic drug. This may in part be because phenytoin, carbamazepine and valproate are up to 5, 15 and 20 times as expensive, respectively. Ideally the choice of antiepileptic drug for each patient should be based on seizure type and/or syndrome as well as the individual persons needs. Unfortunately in most developing countries both the choice and supply of drugs are limited. It should be noted that while four fifths of the potential market for antiepileptic drugs in the developing world, up to 90% of people with epilepsy in developing countries receive no treatment at all. The profitability of antiepileptic drugs for pharmaceutical companies and distributors can be an additional factor in their supply and use. The overall prognosis for seizure control is very good. With correct, early and uninterrupted therapy, up to approximately 75% of patients with epilepsy eventually become seizure free, many of them within five years after diagnosis. Up to approximately 25% of the patients may not respond to any kind of therapy. Seizures seem harder to control where there is a longer history of epilepsy or an underlying brain desease. Epilepsy is associated with increased risk of mortality . It is estimated that mortality in people with epilepsy is 2-3 times greater than that of the general population. The incidence of Sudden unexpected death in epilepsy (SUDEP) may account up to 1-5 per patients years . Conclusion Epilepsy, one of the most important noncommunicable neurological disease, is particularly underresourced and undertreated in the developing world. Epidemiological studies have made it clear that the magnitude of the problem makes it a public health priority. Large numbers of people are at risk of morbidity and mortality, mainly because of difficulties with treatment infrastructure and availability of suitable drugs. However, people with epilepsy need more than drug treatment because their local cultural context adds a social and economic burden to the psychical burden of their seizures. The education of health workers, patients and the wider community in therefore essential. A top down commitment to resources and political patronage should be adopted in order to ensure that epilepsy remains on the agenda and that drug supplies can be assured. There should also be a commitment to dealing with the many preventable causes of epilepsy in developing countries, such as neurocysticercosis. Epilepsy should therefore be integrated into wider public health programmes, such as those concerned with sanitation, safe water, nutrition, and mother and child health. Such commitments are not only required, however, from public health practicioners but also from people directly involved in epilepsy treatment so that prevention becomes part of their activities as well.

Epilepsy ; epidemiology ; developed countries ; developing countries

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