A seizure is a transient brain dysfunction caused by an excessive synchronous discharge of neurons in the brain, usually referred to as a single seizure process.
In contrast, epilepsy refers to a group of disorders or syndromes that are chronic recurrent brain dysfunctions characterised by recurrent seizures. A history of seizures is often required to diagnose epilepsy, and the presence of seizures is not sufficient to diagnose epilepsy and often needs to be combined with other clinical information about the patient.
Epilepsy is often divided into three categories, depending on the cause.
Idiopathic (primary) epilepsy: epilepsy of unknown etiology, mostly associated with genetic factors, often starting at a particular age, with characteristic clinical symptoms and EEG manifestations, and with more definite diagnostic criteria.
Symptomatic (secondary epilepsy): epilepsy is caused by various definite or possible brain lesions, such as congenital malformations of the skull, traumatic brain injury, intracranial infections, poisoning, brain tumours, cerebrovascular disease, etc.
Cryptogenic epilepsy: clinical manifestations suggestive of symptomatic epilepsy without a definite cause being found, which may start at a particular age but without specific clinical and electroencephalographic features.