A surgical technique for lesions involving the ultra-high-riding carotid sheath based on the anatomical principles of the prevertebral fascia: cadaveric dissection and case illustrations.

Background: The classic extreme lateral approach (ELA) requires posterior retraction of the sternocleidomastoid muscle (SCM) to expose the ultra-high-riding carotid sheath (UHRCS), which is precisely defined as the segment of the carotid sheath (CS) extending from the site where the sigmoid sinus transitions into the jugular bulb (JB) and exits the skull base to the transverse process of the C2 vertebra. Doing so easily injures the parotid gland (PG) and carotid sheath (CS) and causes significant traction on the internal jugular vein (IJV) and accessory nerve. Thus, this study aimed to describe a novel surgical technique based on the anatomical principle of the prevertebral fascia (PVF) for treating UHRCS-involving lesions. Methods: Five cadaveric head specimens (10 sides) were used for anatomical research. A standardized ELA position was established, and soft-tissue dissection was modified. The SCM was retracted anteriorly via the natural space of the PVF to expose the UHRCS through the posterior surgical corridor. Based on this, 11 UHRCS-involving lesions were safely resected. Results: This technique effectively avoided IJV obstruction and reduced traction on the IJV and accessory nerve during UHRCS exposure. Standardized positioning better utilizes PVF anatomical characteristics and the triangular corridor formed by the mastoid tip, C1 transverse process, and occipital condyle, significantly improving exposure efficiency and surgical safety. No PG/CS injuries or new neurological dysfunctions occurred in the 11 surgeries. Conclusion: The PVF anatomy-based ELA, via standardized positioning, optimized SCM retraction, and key anatomical landmark-guided corridor construction, avoids classic ELA risks and reduces the learning curve. Thus, it provides a safer and more efficient surgical option for UHRCS-involving lesions.