EEG investigation of temporal lobe epilepsy

We report the results of the study assessing the role of electroencephalogram (EEG) in the evaluation of patients with temporal lobe epilepsy (TLE). A prospective interictal EEG study was performed in 80 patients with TLE, and the results were compared with those of neuroimaging magnetic resonance imaging (MRI) and computed tomography (CT). All patients had interictal scalp-recorded electroencephalographic monitoring with a full array of electrodes placed according to the International 10-20 Placement System, CT and MRI. Scalp EEG had a success rate of 70% in TLE patients, this rate was 50% for MRI and 15% for CT. Epileptiform EEG abnormalities were unilateral in 25 (31%) and bilateral in 31 (39%) patients. In 56% of patients with unilateral interictal activity and 97% of patients with bilateral interictal activity, epileptiform activity was localized at the temporal electrodes. The wave morphology which we most frequently saw in our study was the sharp, sharp-slow wave or spike, or spike-wave. A correlation was observed between the focal MRI-CT abnormalities and the EEG findings. We found abnormal imaging incidence in patients with unilateral EEG findings to be significantly greater than in patients with bilateral EEG findings (chi 2 = 4.62, p = .032). EEG showed abnormality in 28 (70%) of 40 patients whose neuroimaging (NI) tests were found abnormal and also did in 70% of 40 patients whose NI tests were normal. In our study EEG has remained as the most efficient test in the localization of an epileptogenic focus.