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

Abstract

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.

The auricula as a new surgical landmark for the transverse-sigmoid-sinus-transition

“…To our knowledge, there is no study exploring the anatomical relationship between the MPPA and the TSST/posterior border of the SS by means of MRI examinations. Posterolateral skull base approaches around the SS are frequently used for middle and posterior fossa pathologies, such as the retrosigmoid approach for lesions in the cerebellopontine angle ( Hoz et al, 2022 ; Raso et al, 2011 ). Accurately localizing the anterosuperior and inferomedial points of the TSST, as well as the course of the SS, on the external surface of the cranium is important in lateral skull base craniotomies ( Li et al, 2020 ; Day et al, 1996 ).…”

“…An abberant course of the SS forms a risk factor for unexpected bleeding during surgery ( Tsutsumi et al, 2020 ). Anatomical landmarks help improve patient safety and outcome during surgery, while minimizing extensive bony defects ( Hoz et al, 2022 ; Li et al, 2020 ; Day et al, 1996 ). Although navigation is routinely used, the consequences of errors or navigation failure can not be underestimated ( Hoz et al, 2022 ).…”

“…Anatomical landmarks help improve patient safety and outcome during surgery, while minimizing extensive bony defects ( Hoz et al, 2022 ; Li et al, 2020 ; Day et al, 1996 ). Although navigation is routinely used, the consequences of errors or navigation failure can not be underestimated ( Hoz et al, 2022 ). However, the use of navigated mixed-reality can help in the peroperative visualization of intraosseous structures (such as venous sinuses) through the neurosurgeon's oculars.…”

“…However, the use of navigated mixed-reality can help in the peroperative visualization of intraosseous structures (such as venous sinuses) through the neurosurgeon's oculars. Therefore, anatomical landmarks should always be used as an adjunct to neuronavigation rather than a replacement, since interindividual anatomical variability is common ( Hoz et al, 2022 ).…”

“…Although the localization of the anterior border of the SS is extensively studied in current literature, there is a paucity of superficial anatomical landmarks for localization of the posterior border of the SS ( Hoz et al, 2022 ). These reference points can be grossly devided into landmarks for the upper limit and lower limit of the SS ( Raso et al, 2011 ).…”