The crux of helix curvature: A potential surface landmark for the anterior border of the sigmoid sinus in minimally invasive presigmoid approaches

Background: Surgical landmarks are widely used across all surgical specialties to assist surgeons in accurately estimating the deep anatomical structures. We describe the crus of helix curvature as a potential indicator for the anterior border of the sigmoid sinus (SS) in the setting of minimally invasive presigmoid approaches. Methods: Anatomy investigations were performed on injected cadaveric heads to identify consistent surface surgical landmarks estimating the curse of the SS. Results: Presigmoid mastoid was noted in the center of the skin incision in 100% of the specimens. The crus of helix curvature was superimposed on the anterior border of the SS on 6 sides (60%). On the other four sides, the curvature lays within 5 mm of the anterior SS border (40%). Conclusion: For the minimally invasive presigmoid approaches, the “crus of helix curvature” can be used as a landmark for the anterior border of the SS, which can aid in the speed and safety of the procedure. The ease of use of this landmark makes it particularly convenient for physicians early in training.