The Study On Microsurgical Anatomy And Related Operative Approachs Of The Petroclival Region

Objective:1. To study the relationship of vessels and nerves of the petroclival region and its distribution and vessels perforating branches characteristics, provide microscopic anatomical basis for clinical surgical approaches.2. Through simulated subtemporal transtentorial approach,transpetrosal presigmoid approach and clinical application, observe two surgical approaches reveal difference range to the petroclival region, and discusses their respective scope for clinical application, provide the references to the choice of petroclival region surgical approachs.Methods:10 (20 sides) dry adult cadaveric head specimens which perfused with colored silicone were studied by subtemporal transtentorial approach and transpetrosal presigmoid approach under the microscope respectively, research the features about vessels and nerves of the petroclival area, the microanatomic relationship about vessels, nerves and its surrounding structures and described the exposure scope of two operative approaches to the petroclival region.Results:the petroclival region is divided into three parts:the superior petroclival region, the middle petroclival region and the inferior petroclival region.1. the superior petroclival region:the distance from the point that trochlear nerve enters into the edge of tentorium cerebelli to oculomotor nerve is 5.36(4.16-6.86) mm. the proximal of SCA near the bottom of the oculomotor nerve,they contact with each other.the length of from the beginning part of the SCA to the contact point about 4.20 (1.00～7.52) mm. the length of trochlear nerve form beginning to the contact point approximately 17.01(4.25～30.60) mm, the piont about 24.00 (13.20～38.00) mm to the proximal SCA.2. the middle petroclival region:the course of basilar artery (BA) has great variation and the higher apex of BA is 26.30%. BA gives off perforating arteries to supply lateral or vent ral pons in each segment. the starting point of BA about 6.48 (3.94～10.68) mm to vertebral artery,the diameters about 1.48 (0.70～2.02) mm.3. the inferior petroclival region:PICA(12 sides) originated from the vertebral artery, 8 sides origin from the basilar artery. the starting point of PICA from the front of the basilar artery about 13.46 mm in front of the medulla oblongata, diameter of about 1.08 mm, along the post-lateral to the inferior olive.4. subtemporal transtentorial approach:we found that the trochlear nerve entered the edge of tentorium in post-lateral PCP. the mean distance was 15.72±3.81mm. the distance about 6.82±1.81mm in the tentorium.5. transpetrosal presigmoid approach:(20 sides) the distance from petrous sigmoid sinus junction (PS point) to the posterior semicircular canal about 10.48±0.42 mm, the shortest distance from the lateral of posterior semicircular canal to outer surface of mastoid is 13.86±1.98 mm, it is safe to remove the lateral of petrous in this cope; trautman's triangle can be exposed average 243.5±26.1mm.Conclusion:1.because of the existence of the high apex of BA and the outer part of PICA,we must make clear the relationship of the apex of BA and dorsum sellae, PICA and VA before operation.2.the most lateral posterior semicircular canal to the mastoid from the outer surface to guide a more secure ground than the outer wall of petrous bone, posterior semicircular canal to the sigmoid sinus last ditch department of anterior and posterior wall of petrous bone from the ground to guide a more secure In addition to bone following the rock wall.3.subtemporal transtentorial approach mainly applied to the upper, middle parts of slopes and petrous apex lesions; require elevation of temporal lobe surgery may damage Labbe vein and the trigeminal nerve.4.transpetrosal presigmoid approach can be applied to superior, middle and inferior slope and petrous apex lesions, it has advantage of pulling light to brain, shallow surgical field and wide exposure than the subtemporal transtentorial approach.but because of long time intraoperatie, may cause the facial paralysis, hearing impairment.5.about lesions of the petroclival region, it need according the preoperative imaging studies to determine the origin of the tumor and appropriate surgical approach.