Epilepsy is a neurological disorderthat affects people in every country throughout the world. Epilepsy is also oneof the oldest conditions known to mankind. It is characterized by a tendency torecurrent seizures and it defined by two or more unprovoked seizures.
The belief widely held in many countries is that a personwith epilepsy is seized by a supernatural force or power. This ancient belief isreflected in the name of the disorder -- the word "epilepsy" beingderived from the Greek word "epilambanein" which means "to seizeor attack". We now know, however, that seizures are the result of sudden,usually brief, excessive electrical discharges in a group of brain cells (neurones)and that different parts of the brain can be the site of such discharges. Theclinical manifestations of seizures will therefore vary and depend on where inthe brain the disturbance first starts and how far it spreads. Transientsymptoms can occur, such as loss of awareness or consciousness and disturbancesof movement, sensation (including vision, hearing and taste), mood or mentalfunction.
Seizures may vary from the briefest lapses of attention ormuscle jerks to severe and prolonged convulsions. They may alsovary in frequency, from less than one a yearto several per day. Seizures are classified according to where in the brain theyarise, for instance:
These seizures arise from an electric discharge of one ormore localised areas of the brain regardless of whether the seizure issecondarily generalized. Depending on their type, they may or may not impairconsciousness. Whether seizures are partial or focal, they begin in a localizedarea of the brain, but then may spread to the whole brain causing a generalizedseizure.
The electrical discharge which leads to these seizuresinvolves the whole brain and may cause loss of consciousness and/or musclecontractions or stiffness. They include what used to be known as "grandmal" convulsion and also the brief "petit mal" absence ofconsciousness.
This is a state in which a person has frequent seizureswithout recovery of consciousness between each episode. It is a dangerous stateand if not treated may lead to brain damage or death.
It is unclear why particular seizures occur at a particularage or time and not at other ages or times. Provocative factors, however, arerecognized in some patients. For example, certain flashing lights (discos,television, video games etc.), over-breathing, over-hydration, loss of sleep,and/or emotional and physical stress, may stimulate seizures. Although these arenot causes of epilepsy, they may influence the timing and frequency of seizures.
Different epileptic syndromes are based on the age of onset,the type of seizure, the presence or absence of detectable brain disease andgenetic background. However, medical science is only at an early stage inunderstanding these different types.
Epilepsy knows no geographical, racial or social boundaries.It occurs in men and women and can begin at any age, but is most frequentlydiagnosed in infancy, childhood, adolescence and old age. Anyone can be affectedby seizures. In fact, up to 5% of the world's population may have a singleseizure at some time in their lives, but a diagnosis of epilepsy is reserved forthose who have recurring seizures, at least two unprovoked ones.
The prevalence of a disorder is the proportion of apopulation with that disorder at a given point in time. From many studies aroundthe world it hasbeen estimated that the mean prevalence of active epilepsy (i.e. continuingseizures or the need for treatment) is approximately 8.2 per 1,000 of thegeneral population. However, this may be an underestimate as some studies indeveloping countries (such as Colombia, Ecuador, India, Liberia, Nigeria,Panama, United Republic of Tanzania and Venezuela) suggest a prevalence of morethan 10 per 1,000.
The incidence of a disorder is the number of new cases at agiven time. Studies in developed countries suggest an annual incidence ofepilepsy of approximately 50 per 100,000 of the general population. However,studies in developing countries suggest that this figure is nearly double thatat 100 per 100,000.
One of the main reasons for the higher incidence of epilepsyin developing countries is the higher risk of experiencing a condition which canlead to permanent brain damage. These conditions include 1neurocysticercosis,meningitis, malaria, pre and perinatal complications and malnutrition.
Epilepsy is associated with an increased risk of mortality.Death may be related to:
Whilst studies on this subject are sparse, epilepsy-relateddeaths in young adults in the UK, for example, are 3 times higher than standardage-related mortality rates.
Epilepsy is often, but not always, the result of anunderlying brain disease. Any type of brain disease can cause epilepsy, but notall people with the same brain disease will have epilepsy. In view of the factthat only a proportion of people who have abrain disease experience seizures as asymptom of that disease, it is suspected that those who do have such symptomaticseizures are more vulnerable due to biochemical/neurotransmitter reasons.
Recent studies in both developed and developing countrieshave shown that up to 70% of newly diagnosed children and adults with epilepsycan be successfully treated (i.e, their seizures can be completely controlledfor several years) with anti-epileptic drugs. After 2-5 years of successfultreatment, drugs can be withdrawn in about 70% of children and 60% of adultswithout relapses.