Relevant anatomy studies of subtemporal transtentorial and transpetrosal presigmoid approaches to petroclival region

Abstract

Objective To study the microscopic anatomy of the petroclival region through simulated subtemporal transtentorial and transpetrosal presigmoid approaches, and discuss their respective scope for clinical application and provide reference to petroclival region surgical approaches. Methods Ten wet adult head specimens (20 sides) were studied by subtemporal transtentorial and transpetrosal presigmoid approach under microscope, respectively; the features of vessels and nerves of the petroclival area, microanatomic relations of vessels and nerves with their surrounding structures were researched; the exposure scope of these two operative approaches to petroclival region was described. Results The trochlear nerve entered the edge of tentorium in post-lateral posterior clinoid process with a mean distance of (15.72±3.81) mm, and it sneaked (6.82±1.81) mm in the tentorium into the external wall of the cavernous sinus. When the tentorium was cut off, it could expose the posterior clinoid process and posterior communicating artery at upper bound, and petrous ridge at lower bound. The distance from petrous sigmoid sinus junction to the posterior semicircular canal was about (10.48± 0.42) mm, Trautman's triangle could be exposed about (243.5±26.1) mm2. The rear of the cavernous sinus, Meckel's cavity and saddle back at upper bound, the contralateral slopes at the inside, and the bridge of groove and ventral medulla oblongata at lower bound could be reached via transpetrosal presigmoid approach. Conclusions Subtemporal transtentorial approach mainly applys to the upper, middle parts of slopes and petrous apex lesions; the temporal lobe needs to be lifted in the operation, which may damage Labbe vein. Transpetrosal presigmoid approach can be applied to superior, middle and inferior slope and petrous apex lesions, it has advantage of light pulling brain tissues and wide exposure than subtemporal transtentorial approach; however, intraoperative trauma and long operation time may cause hearing impairment and cerebrospinal fluid leakage. Key words: Subtemporal transtentorial approach; Transpetrosal presigmoid approach; Petroclival region; Microscopic anatomy