MESIAL TEMPORAL VERSUS NEOCORTICAL TEMPORAL-LOBE SEIZURES - DEMONSTRATION OF DIFFERENT ELECTROENCEPHALOGRAPHIC SPREADING PATTERNS BY COMBINED USE OF SUBDURAL AND INTRACEREBRAL ELECTRODES

`We investigated differences between spatiotemporal intracranial EEG c haracteristics of temporal lobe seizures with mesiolimbic versus neoco rtical onset, using both subdural and intracerebral electrodes. In 37 patients we analyzed 128 seizures, assessing time intervals from initi al onset of a seizure in either mesial or neocortical temporal (NT) lo be structures to sequential ictal involvement of the contralateral mes iolimbic structures and the ipsi- and contralateral temporal and front al neocortical areas. We noted significantly more rapid seizure spread from mesiolimbic temporal (MT) structures ipsilateral to contralatera l in patients with NT versus MT seizure onset. Time values for total s eizure duration and time of spread from ipsilateral limbic to contrala teral limbic reliably discriminate between individual seizures of eith er type. Three different spreading patterns were noted in the MT group and two more were noted in the NT group. Theoretical considerations c oncerning routes of spread are presented. In neither the MT nor the NT group could a correlation be established between pattern of seizure s pread and outcome of surgery.