Interictal responsiveness in therapy-resistant partial epilepsy

A polygraphic study of the somatic, autonomic and EEG components of the orienting reaction elicited by an auditory stimulus was performed in 66 epileptics with therapy-resistant partial seizures (TRPS) and in 135 matched subjects in two control groups. The study showed a significant interictal hyperresponsivity in epileptics with TRPS vs. the normal subjects of control group I, which consisted in a marked increase of the intensity of the orienting reaction components. This hyperresponsivity was also more marked than that noted in epileptics with therapy-controlled partial seizures of control group II. The correlational analysis of data showed that the severity of these responsiveness disturbances in epileptics with TRPS depended on the patients' age, type of electroclinical seizures, pretrial seizure frequency, type of resting EEG, administered treatment (no. of administered antiepileptic drugs/patient), daily dose, as well as on the serum level of these drugs. The multivariate regression analysis showed that the most significant predictive variables for the responsiveness disturbances were the pretrial seizure frequency, type of electroclinical seizures, daily dose of administered antiepileptic drugs and their serum level. The data also evidenced that the antiepileptic treatment improves the interictal responsiveness disturbances, the effect being the more marked as the treatment was more sustained. The above-mentioned responsiveness changes in epileptics with TRPS should be ascribed to some disturbances in nervous excitability.