Trautmann's Triangle and the Transpetrosal Approaches: An Anatomical Study

Introduction: Trautmann's triangle is defined as the area limited by the anterior border of the sigmoid sinus posteriorly, the petrous ridge superiorly, and a line connecting the jugular bulb to the petrous apex anteriorly. Its size is important for transpetrosal approaches and variants. We studied Trautmann's triangle anatomy and its area in transpetrosal approaches.

Methods: Five cadaveric heads (10 sides) were submitted to transpetrosal approaches and its variants: retrolabyrinthine, partial labyrinthectomy, translabyrinthine, transcochlear, and total petrosectomy. At each step the following measurements were taken: (1) area of the Trautmann's triangle; (2) sinodural angle to jugular bulb (SA-JB); (3) sinodural angle to otic capsule (SA-OC); and (4) otic capsule to jugular bulb (OC-JB).

Results: Progressive drilling of the otic capsule for each of the transpetrosal approaches increased the area of the triangle. The exposure of the structures of the posterior fossa was increased significantly after the partial labyrinthectomy, but not after the next steps. The average distances were: (1) SA-JB, 26.5mm (± 3.3 mm SD); (2) SA-OC, 18 mm (± 2.3 mm SD); and (3) OC-JB, 18.4 mm (± 1.7 mm SD).

Conclusion: Trautmann's triangle is of greatest importance in the performance of the lateral transtemporal approaches. Its size determines the working area and angle of attack to the posterior fossa.