Bridging veins on the tentorial surface of the cerebellum: a microsurgical anatomic study and operative considerations.

OBJECTIVE: When using the median infratentorial supracerebellar approach, all or numerous bridging veins over the cerebellar surface must be sacrificed. Such sacrifice potentially causes cerebellar venous infarction, especially when excessive cerebellar retraction is applied. To prevent such potential complications, neurosurgeons must have adequate knowledge of the anatomy of the bridging veins, particularly the hemispheric bridging veins.
METHODS: In 14 cadaveric specimens (26 sides), the number, locations, and tributaries of both the vermian and hemispheric bridging veins between the superior surface of the cerebellum and the tentorium were examined with the aid of an operating microscope. In addition, particular attention was given to the distribution patterns and collateral pathways of the hemispheric bridging veins.
RESULTS: The average number of vermian bridging veins per cerebellum was 3.24. The average number of hemispheric bridging veins per side was 1.69, and they were most frequently located in the intermediate third of the hemisphere (59.0%). The distribution patterns of the hemispheric bridging veins were classified into six groups according to the draining patterns of each cerebellar hemisphere. Each hemispheric bridging vein usually had several collateral pathways between other draining veins. The most prominent collateral pathways of the hemispheric bridging veins frequently connected with the vermian bridging veins.
CONCLUSION: Anatomic familiarity with the bridging veins can minimize their intraoperative sacrifice and avert subsequent postoperative complications. This knowledge also assists in planning the best approach to the pineal region.