Abstracts

This study evaluated whether ictal EEG yields new information with regards to seizure onset in patients with temporal lobe epilepsy (TLE) considered for epilepsy surgery, in whom interictal EEG showed purely unitemporal epileptiform discharges and MRI detected ipsilateral temporal pathology., We searched the data base of the University of Munich Epilepsy Monitoring Unit and identified 269 temporal lobe epilepsy patients. Patients were defined as right temporal (n=134), left temporal (n=104), bilateral (n=28) or not lateralized (n=3) based on the electroclinical and imaging results. MRI of the brain was performed in all patients., Interictal epileptiform discharges were recorded in 97% (231 of 238) of the unilateral TLE patients. Purely unitemporal spiking was present in 58% (136 of 231) of these patients. Ictal EEG showed ipsilateral seizure patterns in 97% (132 of 136) of these patients. One patient did not have a seizure recorded, two patients had non-lateralized EEG seizure patterns and another patient (resected temporal angioma) has had contralateral seizure patterns. Ipsitemporal MRI pathology was found in 79% (107 of 136) of these patients. Ictal EEG was consistent with the side of TLE in 98% of these 107 patients. One patient, in whom a left temporal angioma was resected prior to the monitoring, has had contralateral ictal EEG seizure patterns and in another patient with lateral temporal cavernoma ictal EEG showed seizure pattern arising form either temporal lobe. Both patients were seizure free after resection of the lesion and the surrounding cortex. In patients with 51-99% of spikes in one temporal region (78 of 231 patients; 34%), ictal EEG was consistent with this site in only 77% (60 of 78 patients). Non-epileptic pseudoseizures were not recorded in these patients., Most patients (98%) with purely unitemporal spiking and ipsitemporal MRI pathology will show ictal EEG seizure pattern consistent with these findings, but rare (2%) exception exist. However, lesion resection lead to seizure freedom in these rare patients. Our data support the view that it is not mandatory to record seizures in patients, in whom interictal EEG and MRI show consistent unitemporal pathology. If epileptiform discharges are not purely unitemporal, however, ictal EEG will show significantly more discrepant results. Further prospective studies should include the results of outpatient EEG prior to EEG-video monitoring.,