Around 50 million people in the world have epilepsy. It is the most common serious neurological condition, with an annual incidence in developed countries of 50 cases per 100,000 of population (in developing countries, the figure is higher due to less advanced maternal and child care conditions, and consequently the greater likelihood of cerebral infection and head trauma).
An epileptic seizure is a clinical event characterised by the manifestation of transient signs and/or symptoms which stem from abnormally excessive or synchronous activity of neurons in the brain. Depending on the location and distribution of the abnormal electrical activity in the central nervous system, the person with epilepsy can have various motor, psychic, sensory and autonomic clinical manifestations. The intensity of the clinical manifestations is variable because a seizure can have a generalised tonic-clonic presentation ('intense convulsive activity') which carries a high emotional burden, or sometimes a presentation characterised by subjective phenomena (only perceived by the patient).
Adapted from Fisher RS, et al. Instruction manual for the ILAE 2017 operational classification of seizure types. Epilepsia. 2017 Apr; 58(4):531-542.
Overall, nearly 60% of seizures are focal onset and the remaining 40% are generalised onset. In infancy/early childhood, a higher proportion of patients have generalised onset seizures. The proportion of focal and generalised onset seizures becomes equal by mid-childhood to early adulthood. With increasing age, the proportion progressively shifts toward focal onset seizure predominance.
Seizures are the manifestation of neurological disorder that can be attributed to several different neurological diseases. As such, the qualified physician must be able to frame all the clinical manifestations present in a given patient (such as the type and semiology of seizures, age at onset, family history, etc.) as well as the results of diagnostic tests (EEG, NMR, among others) and whenever possible define the specific epileptic syndrome.
The majority of people with epilepsy have a good prognosis. Prognosis is strongly influenced by the underlying cause. In some people, particularly children, the condition will remit, although a substantial proportion will have epilepsy all their lives. Overall, 60-70% of patients become seizure free after treatment with anti-epileptic drugs (figure 1), and some patients can remain in remission after subsequent drug withdrawal. The other 30-40% continue to have seizures with varying degrees of frequency and severity (refractory epilepsy).
Figure 1 Seizure free patients in response to antiepileptic drug treatment.
Source: adapted from Brodie MJ, Kwan P, Schachter SC. Fast Facts: Epilepsy. 3rd edition. Oxford (UK): Health Press Limited; 2005
1. Epilepsy: Key Facts. Available at: https://www.who.int/news-room/fact-sheets/detail/epilepsy [accessed 2019.11.21]
2. Pimentel, José, and Carla Bentes. Epilepsia : conceitos, diagnóstico e tratamento. Lisbon: Lidel, 2016. Print.
3. Fisher RS, et al. ILAE official report: a practical clinical definition of epilepsy. Epilepsia. 2014 Apr;55(4):475-82.
4. Fisher RS, et al. Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE). Epilepsia. 2005 Apr;46(4):470-2.
5. Fisher RS, et al. ILAE official report: a practical clinical definition of epilepsy. Epilepsia. 2014 Apr;55(4):475-82.
6. Fisher RS, et al. Instruction manual for the ILAE 2017 operational classification of seizure types. Epilepsia. 2017 Apr;58(4):531-542.
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