Transpetrosal approach: an anatomical study of temporal bone.

Resection of the petrous temporal bone to various degrees provides different levels of access to lesions of the posterior fossa. However, regarding the numerous variations, precise distances of petrosal bone are not still clearly described. This may lead to serious complications during transpetrosal surgeries. Our objective was to evaluate different distances of temporal bone landmarks in order to assess their variations and the possible correlations between them. This anatomical study was performed on 60 temporal bones from 60 human cadavers in the years 2006 and 2007. All the bones contained an adequate portion of the petrous apex and attached fossa dura. Twelve landmarks were defined and 27 different distances were measured for each temporal bone using two-point caliper. Less variation was observed in the superoinferior diameter of horizontal carotid canal with the less coefficient of variation (CV) of 9.29; whereas, the most variation was detected in the inferior (axial) plane of posterior semicircular canal to superior plane of jugular bulb (CV = 57.65). There was a significant correlation between vertical intratemporal diameter of carotid in pyramidal direction, and superior-inferior diameter of horizontal carotid canal (r (Pearson) = 0.500, P < 0.001). Other significant correlations were also found between other distances. The variations of different distances and landmarks were evaluated and many significant correlations were demonstrated between them which could potentially aid ENT specialists and neurosurgeons in order to approach anatomical landmarks and cranial fossas more safely during otologic and neurotologic surgeries. It could also help the design of middle ear prosthesis.