Content area
Full Text
Figure 1. Distribution of epilepsy etiologies by age.
(Figure omitted. See article PDF.)
Epilepsy is a major neurological disorder, the symptoms of which are preventable and controllable to some extent and which has deep clinical, psycho-socio-demographic and economic implications that vary across different regions of the world [1-3] and are associated with varied incidence, prevalence and mortality [1-3]. Despite substantial advances in epileptology for identification of newer syndromes, for example, molecular and structural patterns and so on, a wide gap still exists that stems mainly from epilepsy's extremely heterogeneous and complex set of risk factors. Past subjective reviews in epileptology have concentrated mainly on single risk factors and on other aspects, such as isolated seizures. In this article, we have addressed epilepsy as a whole, defined as a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures. This predisposition or underlying mechanism can be the result of a variety of risk factors and their significance varies from population to population. The objective of this article is to systematically and comprehensively review epilepsy risk factors, excluding provoked seizure, in order to provide a glimpse into epidemiological and clinical differences within epilepsy, based upon these risk factors. We discuss major factors that may influence the risk of epilepsy in Figure 1.
Genetic epilepsy
Although several genes and their corresponding mutations have been identified, these represent only a small proportion of idiopathic epilepsy and other rarer epilepsy forms [4], and specific genetic influences remain to be identified in the majority of cases. In general, studies have shown a high concordance rate of epilepsy among monozygotic compared with dizygotic twins (62 vs 18%) [4], as well as a fivefold higher epilepsy risk in close relatives of epilepsy cases [5]. This concordance is significantly higher among monozygotic pairs for generalized (both idiopathic and symptomatic) than for partial epilepsy, which implies the existence of syndrome-specific genetic determinants. However, in contrast to this assumption, the genetic contribution, based on familial aggregation studies, varies for generalized and partial epilepsy, suggesting some common genetic mechanisms increase the risk for both epilepsy types. Genetic mechanisms that can be implicated in epilepsy syndromes are poorly understood and may involve development abnormalities, neuronal death, changes in neuronal excitability via modifications in voltage-...