Endoscopic Endonasal Transclival Approach versus Dual Transorbital Port Technique for Clip Application to the Posterior Circulation: A Cadaveric Anatomical and Cerebral Circulation Simulation Study

Abstract

Purpose Simulation training offers a useful opportunity to appreciate vascular anatomy and develop the technical expertise required to clip intracranial aneurysms of the posterior circulation. Materials and Methods In cadavers, a comparison was made between the endoscopic transclival approach (ETA) alone and a combined multiportal approach using the ETA and a transorbital precaruncular approach (TOPA) to evaluate degrees of freedom, angles of visualization, and ergonomics of aneurysm clip application to the posterior circulation depending on basilar apex position relative to the posterior clinoids. Results ETA alone provided improved access to the posterior circulation when the basilar apex was high riding compared with the posterior clinoids. ETA + TOPA provided a significantly improved functional working area for instruments and visualization of the posterior circulation for a midlevel basilar apex. A single-shaft clip applier provided improved visualization and space for instruments. Proximal and distal vascular control and feasibility of aneurysmal clipping were demonstrated. Conclusions TOPA is a medial orbital approach to the central skull base; a transorbital neuroendoscopic surgery approach. This anatomical simulation provides surgical teams an alternative to the ETA approach alone to address posterior circulation aneurysms, and a means to preoperatively prepare for intraoperative anatomical and surgical instrumentation challenges.

Keywords: endonasal transclival approach; endoscopic approach; posterior circulation aneurysms; simulation training; transorbital neuroendoscopic surgery.

Fig. 1

Endoscopic endonasal transclival approach to the posterior circulation for ( A ) high-riding basilar apex and ( B ) midlevel basilar apex.

Fig. 2

Right transorbital view of combined endoscopic multiportal transorbital and endonasal view and approach for posterior circulation clipping with a high-riding basilar apex. The dual approach is limited by transposition of the pituitary gland to achieve visualization of the posterior circulation.

Fig. 3

Endoscopic endonasal transclival approach demonstrating successful clip application for ( A ) posterior cerebral artery, ( B ) basilar artery, ( C ) anterior inferior cerebellar artery, and ( D ) superior cerebellar artery when there is a high-riding basilar apex.

Fig. 4

Right transorbital view of combined endoscopic multiportal transorbital and endonasal view and approach for posterior circulation clipping with a midlevel basilar apex. Sufficient clipping of ( A ) posterior cerebral artery, ( B ) Basilar, and ( C ) superior cerebellar artery is obtained with good visualization.

Fig. 5

Endoscopic endonasal transclival approach alone is limited by instrument “sword fighting” for posterior circulation clipping with a midlevel basilar apex.

Fig. 6

Schematics showing that the endoscopic endonasal transclival approach alone is limited by ( A ) coning down effect and ( B ) instrument sword fighting.

Fig. 7

Schematics showing that the right transorbital view of the combined endoscopic multiportal transorbital and endonasal approaches increases ( A ) visualization and ( B ) working area for instrumentation.