Impact of target exposure via retrosigmoidal approach in surgical injury measured by virtual reality skill

Abstract

Objective To discuss the impact of target exposure via retrosigmoidal approach in surgical injury based on virtual reality anatomic models. Methods CT and MR imaging data of 15 adult cadaver heads were utilized to establish three-dimensional anatomy models of petrous bone. Surgical routes exposing different targets though retrosigmoidal approach were simulated by selecting osseous landmark points on the calvaria and skull base. Special form and sequence of anatomic structures in different routes were observed. Volumes of anatomic tissues were measured. Results All the surgical routes passed below the transverse sinus and lateral to the cerebellum. Route a exposed the lower cranial nerve and anterior inferior cerebellar artery; when reached the jugular tubercle, the route exposed inferior petrous sinus. Route b exposed the anterior inferior cerebellar artery, labyrinth and facial-acoustic nerve complex. Route c passed the medial to the superior petrous sinus and exposed the facial-acoustic nerve complex; when being arrived at petrous apex, the route exposed the trigeminal nerve, superior cerebellar artery and cavernous sinus. The volumes of the lower cranial nerve, osseous structures, cerebellum and artery were significantly different in models adopted different routes (P route a>route b, the volume of osseous structures was as follows: route c >route b>route a, the volume of cerebellum was as follows: route b >route a>route c, and the volume of artery was as follows: route a >route c>route b. Venous structure involved in route a ([68.91±1.91] mm3) was larger than that in route c ([248.92±11.26] mm3) with statistical significance (P<0.05), and route b did not involve venous structure. Conclusions Targets in skull base has significant impaction on the size of anatomic structures involved in the route of retrosigmoidal approach. Relationship between injury and exposure can be evaluated objectively by the volume measurement. Key words: Virtual reality; Three-dimensional anatomy; Retrosigmoidal approach; Petrous bone; Minimal invasion