Endoscopic endonasal approach to the mesial temporal lobe: anatomical study and clinical considerations for a selective amygdalohippocampectomy

Background Selective amygdalohippocampectomy (AH) is a surgical option for patients with medically intractable seizures from mesial temporal lobe pathology. The transcranial route is considered the best method to achieve this goal. However, the standard approach through the neocortex is still invasive. The risks can be minimized if the mesial temporal lobe is resected while preserving the lateral temporal lobe and the Meyer’s loop. This study explores the feasibility of selective AH by endoscopic endonasal approach (EEA) in cadaveric specimens. Methods The endoscopic anatomy of the mesial temporal lobe and the feasibility of a successful selective AH were studied in six hemispheres from three injected human cadavers. Quantitative analyses on the extent of resection and angles of exposure were performed based on CT and MRI studies of pre- and post-selective AH and measurements taken during dissections. Results The EEA V1-V2 corridor provided a direct and logical line of access to the mesial temporal lobe, following its natural trajectory with no brain retraction and minimal exposure of the pterygopalatine fossa. The components of the mesial temporal lobe were resected just as selectively and easily as the transcranial route, but without compromising the structures of the lateral temporal lobe or the Meyer’s loop. Conclusions The EEA V1-V2 corridor demonstrated its selective resectability and accessibility of the mesial temporal lobe in cadaveric specimens. The clinical value of this approach should be explored responsibly by a surgeon with both competent microsurgical skills and experiences in EEA.