Anatomic Access to the Petrous Apex: Comparing Nasal and Lateral Approaches

Abstract

Objective: Compare the anatomic access to the petrous apex via the nasal and lateral approaches using CT reconstructions. Method: A total of 200 consecutive fine cut CT temporal bones performed at Royal Melbourne Hospital from July 27, 2007, to October 30, 2010, were reviewed. Easy lateral access allowed use of a 4mm burr past vital structures. Easy nasal access was when the sphenoid was pneumatized to back of sella/beyond and laterally beyond V2/vidian junction. Results: Easy surgical access via the lateral approach occurred in 74 sides (37%), with easy access via the supra-labyrinthine approach occurring in 4 sides (2%) and infra-labyrinthine approach in 72 sides (36%). Easy surgical access via the nasal approach occurred in 79 sides (39.5%). There was a poor correlation between easy nasal access and easy lateral access (r=0.1011 with P = .154). 125 (62.5%) had a pneumatized mastoid, and 126 (63%) had a large sphenoid sinus allowing easy surgical access. There was a significant correlation between mastoid and sphenoid pneumatization ( P < .001). Conclusion: Surgical access to the petrous apex via the lateral and nasal approaches are limited by tight anatomic confines. Ease of access via one or other approach does not correlate with ease via the other approach. However, pneumatization of the mastoid/ear does correspond to the anatomic size of the sphenoid.