Surface anatomy of the transverse sinus for the midline infratentorial supracerebellar approach.

AIM Knowing the location of the transverse sinus in the midline supracerebellar infratentorial approach is important to prevent its inadvertent injury. The external landmarks of the occipital bone have been studied in this anatomic study in order to reveal their relationship with the transverse sinus. MATERIAL AND METHODS Fifty-two dried skulls were used to study the relationship of the transverse sinus with various surface bone structures. The key bone surface structures identified in each specimen were the superior nuchal line, the inferior nuchal line, the inion, internal occipital protuberance, and the transverse sulcus. RESULTS The distance from the inion to the inferior nuchal line in specimens ranged from 12.7 mm to 37.7 mm. The distance from the inferior nuchal line to the midline foramen magnum in the specimens ranged from 19 mm to 34.75 mm. The width of the proximal transverse sulcus ranged from 2.6 mm to 10.16 mm with an average of 6.43 mm on the right side and 3.4 mm to 10.6 mm with an average of 6.15 mm on the left. CONCLUSION The first and most superior burr hole for midline supracerebellar infratentorial approach can be safely placed approximately 1 cm below the inferior nuchal line. A burr hole in this localization will avoid the transverse sinus.