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1. A chronic disorder characterized by paroxysmal brain dysfunction due to excessive neuronal discharge, and usually associated with some alteration of consciousness. The clinical manifestations of the attack may vary from complex abnormalities of behavior including generalized or focal convulsions to momentary spells of impaired consciousness. These clinical states have been subjected to a variety of classifications, none has been universally accepted to date and, accordingly, the terminologies used to describe the different types of attacks remain purely descriptive and nonstandardized; they are variously based on: the clinical manifestations of the seizure (motor, sensory, reflex, psychic or vegetative); the pathologic substrate (hereditary, inflammatory, degenerative, neoplastic, traumatic, or cryptogenic); the location of the epileptogenic lesion (rolandic, temporal, diencephalic regions); and the time of day at which the attacks occur (nocturnal, diurnal, menstrual).