The usefulness of stereo-electroencephalography (SEEG) in the surgical management of focal epilepsy associated with “hidden” temporal pole encephalocele: a case report and literature review

The authors report a case of 18-year-old woman with partial complex seizures compatible with temporal epilepsy by semiology. Due to medical refractoriness, she was referred to pre-surgical evaluation. Initially, MRI showed no significant structural abnormality and superficial scalp EEG demonstrated epileptiform activity in the frontotemporal areas. Due to the lack of clear MRI abnormalities and the potential involvement of dominant mesial temporal structures by seizure semiology and non-invasive data, extra-operative invasive evaluation using stereo-electroencephalography (SEEG) methodology was indicated. Invasive monitoring demonstrated seizure onset in the left temporal pole with early spread to ipsilateral amygdala. Surgical treatment resulted in resection of the temporal pole and amygdala, with preservation of the remaining mesial temporal lobe structures. Intraoperatively, it was observed that multiple dural defects in the anterior middle temporal fossa with invagination of adjacent temporal pole parenchyma are compatible with temporal encephalocele. Patient remains seizure-free since surgery (12 months follow-up period) with preservation of neuropsychological functions. Although temporal pole resection plus amygdalohippocampectomy has been described as an adequate surgical approach in temporal encephalocele cases, we demonstrated the usefulness of the SEEG methodology in minimizing the volume of temporal lobe resection without compromising seizure and neuropsychological outcomes. The optimal results in this case and the review of the literature may suggest that in medically refractory epilepsies caused by temporal pole encephaloceles, preservation of the temporal lobe mesial structures should be attempted.