Transuncal Selective Amygdalohippocampectomy by an Inferolateral Preseptal Endoscopic Approach Through Inferior Eyelid Conjunctival Incision: An Anatomic Study

Abstract

BACKGROUND: Transorbital endoscopic approaches have been described for pathologies of anterior and middle fossae. Standard lateral orbitotomy gives access to mesial temporal lobe, but the axis of work is partially obscured by the temporal pole and working corridor is limited. OBJECTIVE: To evaluate the usefulness of an inferolateral orbitotomy to provide a more direct corridor to perform a transuncal selective amygdalohippocampectomy. METHODS: Three adult cadaveric specimens were used for a total of 6 dissections. A step-by-step description and illustration of the transuncal corridor for a selective amygdalohippocampectomy were performed using the inferolateral orbitotomy through an inferior eyelid conjunctival incision. The anatomic landmarks were demonstrated in detail. Orbitotomies and angles of work were measured from computed tomography scans, and the area of resection was illustrated by postdissection MRI. RESULTS: Inferior eyelid conjunctival incision was made for exposure of the inferior orbital rim. Inferolateral transorbital approach was performed to access the transuncal corridor. Endoscopic selective amygdalohippocampectomy was performed through the entorhinal cortex without damage to the temporal neocortex or Meyer's loop. The mean horizontal diameter of the osteotomy was 14.4 mm, and the vertical one was 13.6 mm. The mean angles of work were 65° and 35.5° in the axial and sagittal planes, respectively. Complete amygdalohippocampectomy was achieved in all 6 dissections. CONCLUSION: Transuncal selective amygdalohippocampectomy was feasible in cadaveric specimens using the inferolateral transorbital endoscopic approach avoiding damage to the temporal neocortex and Meyer's loop. The inferior eyelid conjunctival incision may result in an excellent cosmetic outcome.

Endoscopic transorbital resection of the temporal lobe: anatomic qualitative and quantitative study

“…Parallel to the development of this technique for the management of extra-axial lesions and considering the “easy-access pathway” given by the transorbital corridor to the temporal region, the possibility of managing intra-axial pathologies and performing resection of selective parenchymal has also been investigated (Chen et al, 2014 , 2015 ; Dallan et al, 2018a ; Kim E. H. et al, 2021 ; Câmara et al, 2023 ). In particular, Chen et al demonstrated with an anatomic investigation the feasibility of the transorbital approach in dissecting the mesial temporal lobe structures in a subpial manner and pointed out the advantages of early visualization of the medial structures, i.e., oculomotor and trochlear nerves, and the avoidance of exposure of the temporal stem by the transorbital approach, theoretically reducing the risk of postoperative complications when comparing to the standard craniotomy approach (Chen et al, 2014 ).…”

“…In particular, Chen et al demonstrated with an anatomic investigation the feasibility of the transorbital approach in dissecting the mesial temporal lobe structures in a subpial manner and pointed out the advantages of early visualization of the medial structures, i.e., oculomotor and trochlear nerves, and the avoidance of exposure of the temporal stem by the transorbital approach, theoretically reducing the risk of postoperative complications when comparing to the standard craniotomy approach (Chen et al, 2014 ). More recently, Camara et al have also proposed a modification of the standard superior eyelid approach in resecting selectively the mesial temporal lobe through an infero-lateral pre-septal approach without violating the neocortex or the roof of the temporal horn (Câmara et al, 2023 ).…”