[Neuropsychology in epilepsy]

Abstract

In order to understand cognitive impairment associated with epilepsy, it is essential to appreciate that independent static and dynamic factors affect brain function in this disease. Whereas morphological lesions or structural changes are associated with more or less irreversible deficits, epileptic activity, seizures, and the treatment of epilepsy can cause dynamic and principally reversible impairment. The relative contribution of these factors differs depending on the type of epilepsy, the age at lesion/epilepsy onset, the localization and lateralization of epilepsy and individual demographic patient characteristics. Altered brain structure and function can result in epilepsy, but epilepsy can also alter the functional cerebral organization of the brain. Thus epilepsy-related cognitive impairment must be integrated within a developmental neuropsychological framework. The aetiology of epilepsy is strongly related to the age of onset. From a neuropsychological point of view, it makes a big difference for cognitive outcome as to whether epilepsy hits the maturing versus mature or aging brain. Dependent on this, epilepsy can result in retardation, loss of acquired functions, or accelerated mental decline. It will be demonstrated that cognitive impairments in epilepsy mostly exist from the beginning of epilepsy, that early onset lesions/epilepsy interfere with mental development, and that a progressive aetiology, severe seizures, and lesions secondary to epilepsy may accelerate mental decline. It will furthermore be discussed that uncontrolled epilepsy and epileptic activity may reversibly and irreversibly contribute to cognitive impairment. The same is demonstrated with regard to the pharmacological treatment of epilepsy. Finally, the cognitive risks and benefits of epilepsy surgery and the advantages of selective surgery will be addressed. The consequences for the neuropsychological assessment are discussed in part two of this review.