Anterior Petrosectomy vs. Retrosigmoid Approach-Surgical Anatomy and Navigation-Augmented Morphometric Analysis: A...

Area of Science:

• Neurosurgery
• Surgical Anatomy
• Medical Imaging

Background:

• Petroclival region and mid-upper brain stem lesions present surgical challenges due to limited access and potential neurovascular damage.
• Conventional cranial approaches often require extensive bone removal, increasing surgical risks.
• Neuronavigational systems aid in preoperative planning and intraoperative guidance for optimizing surgical access.

Purpose of the Study:

• To evaluate the utility of an anterior petrosectomy (AP) approach for accessing petroclival region pathologies.
• To perform a navigation-augmented morphometric analysis comparing AP with the retrosigmoid (RS) approach.
• To quantify differences in surgical corridor volume and working distances.

Main Methods:

• Eight cadaveric heads underwent microsurgical dissection for 14 approaches (8 AP, 6 RS).
• Preoperative and post-dissection CT and MRI scans were obtained for all specimens.
• A neuronavigational system was utilized for measurements of distances, craniotomy size, and surgical corridor volumes.

Main Results:

• The anterior petrosectomy (AP) approach demonstrated a significantly shorter distance from the skull surface to the petrous apex (46.0 ± 1.9 mm) compared to the retrosigmoid (RS) approach (71.3 ± 1.8 mm).
• While craniotomy sizes were comparable, the AP approach yielded a significantly larger surgical corridor volume (21.31 ± 1.91 cm³) versus RS (13.39 ± 1.8 cm³).
• AP significantly increased the exposure length of the basilar artery (22.1 ± 1.7 mm) compared to a standard subtemporal approach (6.9 ± 1.5 mm).

Conclusions:

• The anterior petrosectomy (AP) approach offers a significantly wider surgical corridor and shorter working distances for petroclival region lesions, enhancing surgical freedom.
• Neuronavigation is essential for overcoming anatomical variations encountered during AP and RS approaches.
• This study supports AP as a valuable technique for managing petroclival region pathologies, aided by neuronavigation.