ABSTRACT
We define epilepsy in general and mesial temporal lobe epilepsy in particular. Epilepsy, or really the epilepsies, involves a whole constellation of syndromes. The syndromes are characterized by recurrent unprovoked seizures, except for the reflex epilepsies, which are distinguished by seizures that are triggered by external stimuli such as familiar musical tunes. A seizure is the explosive activation of networks of hyperexcitable neurons, which then recruit neighboring neurons in a hypersynchronous manner. Mesial temporal lobe epilepsy is commonly associated with either of two kinds of partial (or focal) seizures:
simple, in which there is no impairment of consciousness;
complex, which begin with simple partial seizures that evolve into impairment of consciousness.
Epilepsies characterized by partial seizures that can be traced to well-circumscribed lesions of particular regions of the brain such as scar tissue or tumors are called “symptomatic localization-related epilepsies. Mesial temporal lobe epilepsy belongs to this group of epilepsies, with a significant number of cases associated with hippocampal sclerosis (i.e., scarring). The hippocampus plays a key role in memory and learning, and so a damaged hippocampus leads to impaired memory and cognition.
