Abstracts

Rationale: Temporal lobe encephaloceles (TEs) are increasingly identified in patients with epilepsy due to advances in neuro-imaging. Case series have established that select patients become seizure-free with lesionectomy. In practice, however, many of these patients will undergo standard anterior temporal lobectomy. We describe the first series of refractory temporal lobe epilepsy patients with encephalocele in which chronic or intra-operative electrocorticography (ECoG) is used to characterize the putative epileptogenic nature of these lesions and guide surgical planning.Methods: This retrospective study includes 9 adult patients with MRI/CT defined temporal encephalocele treated between 2007 and 2014 at UCSF. Clinical features, ECoG, imaging and surgical outcomes are reviewed.Results: Six of the nine patients underwent resective epilepsy surgery. Each of these cases demonstrated abnormal epileptiform discharges around the cortical area of the encephalocele. Two underwent tailored lesionectomy and four underwent lesionectomy plus anterior medial temporal resection (due to concerns for involvement of the mesial temporal structures in the epileptogenic network). Post-operatively, five of the patients, including those with lesionectomy only, had Engel Class Ia surgical outcome, and one had Class IIIa outcome at the time of publication.Conclusions: Although increasingly recognized, the role of TE in the pathogenesis of epilepsy has remained uncertain. Electrocortigraphic evidence in this series of patients supports the epileptogenic nature of TE’s. Further, these cases demonstrate that patients with TE’s can have excellent outcomes, even with selective surgical approaches when a broader network is not identified.