Interictal reactivity disturbances in temporal lobe epilepsy.

The electrographic study performed on 106 patients with temporal lobe epilepsy and 31 normal subjects showed marked interictal cerebral reactivity disturbances in this form of epilepsy. These disturbances, estimated by testing the orienting reflex and its habituation, were expressed, as a rule, by intensification of somatic, autonomic and electroencephalographic components of the reaction, increase in their resistance to habituation and change in the sequence in which they become habituated. The severity of reactivity disturbances depended on the localization of electroencephalographic focus, clinical form of seizures and characteristics of interictal electroencephalographic abnormalities. The most marked reactivity disturbances were noted in patients in whom the interictal foci were bitemporal, anterior or predominantly anterior (particularly left), accompanied specially by generalized or generalized + partial seizures or by interictal graphoelements of the irritative type. The reactivity disturbances were less severe in epileptics in whom the interictal foci were unitemporal (particularly right), middle, predominantly middle, posterior or associated to partial seizures. In a few patients in whom the interictal bioelectrical activity reflected a nervous hypoexcitability, the reactivity disturbances assumed the appearance of hyporeactivity. The different intensities of reactivity alterations in temporal lobe epilepsy should be related to the different capacity of the epileptogenic lesions to determine interictal changes in diffuse excitability. This capacity depends on he structures involved by the epileptic discharges, which by their morpho-functional particularities, can influence the cerebral excitability.