Abstracts

Patients with temporal lobe epilepsy (TLE) and unilateral severe hippocampal sclerosis (HS) may have contralateral temporal scalp ictal onset. This has recently been called [ldquo]burned-out hippocampus[rdquo], which is believed to be a rare entity ¹. In this study we report four patients with unilateral hippocampal sclerosis and contralateral ictal onset registered by scalp-sphenoidal electrodes. We discuss the importance of such cases in pre-surgical evaluation of patients with TLE, as well as possible strategies used for evaluation of these particular cases. We reviewed charts from all patients with TLE submitted to pre-surgical evaluation, which included high resolution MRI and prolonged video-EEG monitoring, during a two-year period (2003-2004). We searched for patients who only had seizures that were clearly contralateral in location to the atrophic hippocampus. Four patients fulfilled the criteria above. All four had unilateral HS with severely atrophic hippocampus, confirmed by volumetric measures. Two of these patients went through semi-invasive video-EEG monitoring with foramen ovale (FO) electrodes, which revealed seizures originating from the atrophic hippocampus, hence confirming false lateralization in the scalp EEG. These patients were submitted to surgical treatment [ndash] anterior temporal lobectomy [ndash] and had favorable prognosis after surgery. The other two patients are still going through pre-surgical evaluation. Burned-out hippocampus syndrome may not be as rare as it was previously believed. Further studies will be necessary before one can affirm that patients with unilateral HS and scalp ictal EEG showing contralateral ictal onset may be operated without confirmation of the epileptogenic zone by invasive monitoring. In these patients, semi-invasive monitoring with FO electrodes might be an interesting alternative.
REFERENCES:
1. Mintzer S, Cendes F, Soss J, Andermann F, Engel J Jr., Dubeau F, Olivier A, Fried I. Unilateral hippocampal sclerosis with contralateral temporal scalp ictal onset. Epilepsia 2004; 45: 792-802. (Supported by FAPESP (Funda[ccedil][atilde]o de Amparo [agrave] Pesquisa do Estado de S[atilde]o Paulo) and CAPES (Coordena[ccedil][atilde]o de Aperfei[ccedil]oamento de Pessoal de N[iacute]vel Superior)/CNPq (Conselho Nacional de Desenvolvimento Cient[iacute]fico e Tecnol[oacute]gico).)