The Microsurgical Anatomy of the Modified Presigmoid Trans-Partial Bony Labyrinth Approach

Area of Science:

• Neurosurgery
• Surgical Anatomy
• Skull Base Surgery

Background:

• The petroclival region presents surgical challenges due to its complex anatomy and proximity to critical neurovascular structures.
• Traditional surgical approaches may offer limited exposure, potentially compromising lesion resection and increasing risks.

Purpose of the Study:

• To evaluate the modified presigmoid trans-partial bony labyrinth approach for surgical access to the petroclival region.
• To assess the advantages of this technique in exposing and treating lesions within the petroclival area.

Main Methods:

• A modified presigmoid trans-partial bony labyrinth approach was developed and tested on 15 cadaveric heads.
• Partial resection of semicircular canals and petrous apex was performed to enhance exposure.
• Measurements of surgical space and visualization angles were recorded.

Main Results:

• The modified approach yielded a large operational space, extending to the posterior cavernous sinus.
• Significant exposure ranges (horizontal and vertical) and angles were achieved.
• Key structures including the vertebral-basilar artery, cranial nerves III-X, and Meckel cave were well visualized.

Conclusions:

• The modified presigmoid trans-partial bony labyrinth approach provides excellent exposure of the petroclival region and posterior cavernous sinus.
• Advantages include extensive visualization, preservation of hearing and facial nerve function, and potential for early tumor devascularization.