Abstracts

Rationale: The analysis of spike voltage topography revealed two distinct patterns of temporal spikes of type I and type II. The application of source modeling techniques revealed that the orientation of current-dipole sources (O-CDS) of type I spikes was vertical or oblique, while that of type II spikes was horizontal. The correlation of the types with clinical data and intracranial EEGs suggest that type I spikes were more associated with medial temporal lobe epilepsy (m-TLE) than type II spikes. The purpose of this study is to identify the effects of O-CDS of anterior temporal spikes on the clinical factors including intractability, semiology etc. Methods: We examined the scalp EEGs of 25 epilepsy patients who had anterior temporal spikes. The patients included 13 females, with a mean age of 38.72 14.96 years (mean SD). We recorded the EEGs using a 32-channel digital EEG machine, and 21 or 25 electrodes placed on the scalp according to the international 10-20 system. We averaged 10-20 typical spikes in each patient to get an averaged-spike in each patient. We applied a spatiotemporal dipole model to determine O-CDS of the averaged spikes. We divide the patients into two subgroups oblique group and horizontal group according to the O-CDS of single or primary dipole. The current-dipole sources which have the polar angle over 30 degree were considered as oblique dipoles, and those with polar angle below 30 degree were as horizontal dipoles. Definition of drug resistance was the failure of two appropriate antiepileptic drugs and no more than one-year seizure-free hiatus at last follow-up. Clinical factors including age, onset age, disease duration, febrile convulsion, image finding, number of AED, drug response, extra-temporal or neocortical-temporal semiology, secondary generalization, and number of current-dipole sources were compared between two groups. Results: The current-dipole sources of the averaged spikes were explained by a single dipole in the 17 patients and two dipoles in 8 patients. Sixteen patients are in oblique group and 9 patients are in horizontal group. The extra-temporal or neocortical-temporal semiology were significantly more in horizontal group than oblique group, but no other factors are significantly different between two groups. The 1 of 16 patients of oblique group and 5 of 9 patients of horizontal group had extra-temporal or neocortical-temporal semiology. The tendencies of drug-resistance and polytherapy of AEDs were observed more in oblique group than horizontal group. Conclusions: The O-CDS of anterior temporal spikes may be associate with the semiology of epileptic patient. The horizontal O-CDS may be more associated with the extra-temporal or neocortical-temporal semiology than the oblique O-CDS. In addition, the oblique O-CDS have tendency to be associated with drug resistance and polytherapy AEDs of the epileptic patients with anterior temporal spikes. Our study suggests that the oblique O-CDS of anterior temporal spikes may be an electrophysiologic marker of intractable mesial-temporal lobe epilepsy.