Causes
Epilepsy can have both genetic and acquired causes, with the interaction of these factors in many cases. Established acquired causes include serious brain trauma, stroke, tumours, and brain problems resulting from a previous infection. In about 60% of cases, the cause is unknown. Epilepsies caused by genetic, congenital, or developmental conditions are more common among younger people, while brain tumors and strokes are more likely in older people.Seizures may also occur as a consequence of other health problems; if they occur right around a specific cause, such as a stroke, head injury, toxic ingestion, or metabolic problem, they are known as acute symptomatic seizures and are in the broader classification of seizure-related disorders rather than epilepsy itself. Genetics
Genetics is believed to be involved in the majority of cases, either directly or indirectly. Some epilepsies are due to a single gene defect (1–2%); most are due to the interaction of multiple genes and environmental factors. Each of the single gene defects is rare, with more than 200 in all described. Most genes involved affect ion channels, either directly or indirectly. These include genes for ion channels themselves, enzymes, GABA, and G protein-coupled receptors.In identical twins, if one is affected, there is a 50–60% chance that the other will also be affected. In non-identical twins, the risk is 15%. These risks are greater in those with generalized rather than focal seizures. If both twins are affected, most of the time they have the same epileptic syndrome (70–90%).
The essential changes in terminology are that "partial" is called "focal" with awareness used as a classifier for focal seizures -based on description focal seizures are  now defined as behavioral arrest, automatisms, cognitive, autonomic, emotional or hyperkinetic variants while atonic, myoclonic, clonic, infantile spasms, and tonic seizures may be either focal or generalized based on their onset. Several terms that were not clear or consistent  in description were removed such as dyscognitive, psychic, simple and complex partial, while "secondarily generalized" is replaced by a clearer term "focal to bilateral tonic clonic seizure". New seizure types now believed to be generalized are eyelid myoclonia, myoclonic atonic, myoclonic absence, and myoclonic tonic clonic. Sometimes it is possible to classify seizures as focal or generalized based on presenting features even though onset in not known. This system is based on the 1981 seizure classification modified in 2010 and principally is the same with an effort to improve the flexibility and clarity of use to understand seizures types  better in keeping with current knowledge. Syndromes
Cases of epilepsy may be organized into epilepsy syndromes by the specific features that are present. These features include the age that seizure begin, the seizure types, EEG findings, among others. Identifying an epilepsy syndrome is useful as it helps determine the underlying causes as well as what anti-seizure medication should be tried.The ability to categorize a case of epilepsy into a specific syndrome occurs more often with children since the onset of seizures is commonly early.