This study examined 18 patients with video electroencephaolography (EEG) findings suggestive of temporal lobe epilepsy (TLE) who had unremarkable MRI and normal verbal and visual memory scores on neuropsychological tests. Interictal SEEG abnormalities were observed in the mesial temporal structures in 17 patients (94%) and in the temporal tip in 6 patients (33%). The majority of seizure onset was exclusively from the mesial structures (72%); the others were exclusively from the lateral temporal cortex or temporal tip structures (11%) and independently from mesial and neocortical foci (17%). The authors state 3 important findings from the study:
- Normal memory does not preclude mesial temporal seizure onset
- Onset of seizures exclusively from mesial temporal structures without early neocortical involvement is common, even in the absence of memory deficits
- Extratemporal seizure onset is rare when video EEG and semiology are consistent with focal TLE.
Suresh S, Sweet J, Fastenau PS, Lüders H, Landazuri P, Miller J. Temporal lobe epilepsy in patients with nonlesional MRI and normal memory: an SEEG study. J Neurosurg. 2015:1-7.