Microsurgical Anatomical Study Of The Tentorial Venous Sinus, Cerebellar Bridging Vein And Superior Petrosal Vein

Objective To provide anatomical data for reducing postoperative complications in theposterior fossa craniotomy through anatomical study of the tentorial venous sinus, cerebellarbridging vein and superior petrosal vein.Methods The morphology and type of the tentorial venous sinus; the morphology,distribution and type of the cerebellar bridging vein; the morphology, course, entrancelocation and the surrounding tissue markers distance relationship of the superior petrosalvein(SPV) were anatimized and observed on10cases (20sides) adult headspecimens，whichwere fixed in10%formalin and irrigation colorful silicone. The clinical significance wasassessed according to the anatomical characteristics.Results In the20side specimens,1.the tentorial venous sinuses were found in14sides,the rate was70%, a total of21branches(13on the left side and8on the right). According tothe shape, size, location and drainage area, the patterns of the tentorial venous sinus wasclassified into three groups, Type I had6roots(29%), Type II had10roots(48%), Type III had5roots(23%).2.The cerebellar bridging veins were found in32roots.①The branch ofcerebellar bridging vein, according to injected tentorial venous sinuses, is divided into:single-stem21roots(65.63%), double-stem7roots(21.88%), three-stem4roots (12.50%). Inmost cases, the single-stem of bridging vein empty into tentorial venous sinus;②The numberof the cerebellar bridging vein per case was (4.98±2.49) branchs, and the outer diameter was(3.83±0.97)mm.③According to the location of the junction of the cerebellar bridging veinsin the tentorium,the patterns of drainage of the cerebellar bridging veins were classified intofour groups: the vermian group had11roots(34.37%), the medial group had8roots(25%),themiddle group had9roots(28.13%), the lateral group had4roots(12.5%)%.In most cases, thelocation of bridging veins located on the vermian, medial, middle side of the tentorium, but ina few cases, located on the lateral.3.The superior petrosal vein were found in19side, a totalof25branches.①Superior petrosal vein usually import2/3of the petrosal sinus along the petrous ridge. Superior petrosal vein was variation in the individual.②The length ofSuperior petrosal vein was (11.15±4.36)mm, and the outer diameter was (3.83±0.97)mm.③The stem of the SPV, according to injected petrosal sinus, was divided into:single-stem typehad12sides(63.16%), double-stem type had5sides(26.32％), triple-stem type1sides(5.26%)and lack of such as1side(5.26%). The branch of SPV is divided into: single-branch type2side (10.53%), double-branch type12side (63.16%), three-branch type4side (21.05%) andfour-branch type1side (5.26%).④According to SPV relationship with the Meckel’s caveand internal acoustic meatus(IAM)，the patterns of drainage of the SPV were classified intothree groups: Type I had4roots(16%), Type II had16roots(64%), Type III had5roots(20%).Conclusion1.A familiar understanding of microanatomic characteristics of thetentorial venous sinus and cerebellar bridging vein is helpful in revealing the pineal regionlesions from different directions using natural clearance under the tentorium, reducing theoperation complications and improving the resection rate.2.Although the site which the SPVemptied into the superior petrosal sinus was variation,was relationship closely with the MCand IAM,and located in between the two.Familiar with the SPV microsurgical anatomy anddrainage type, it has clinical significance that the cerebellopontine angle surgery involved inthe vein.3.The tentorial venous sinuses, cerebellar bridging veins and superior petrosal veintogether constitute the part of collateral circulationon of the posterior fossa, and play animportant role for venous blood backflow of the posterior fossa. So protection as much aspossible is still the best way to reduce the effects of postoperative complications.