2025 Proffered Presentations
S203: SURGICAL ANATOMY OF THE FAR LATERAL APPROACH WITH SUPRACONDYLAR AND TRANSCONDYLAR VARIATIONS: ANALYSIS OF ACCESS TO THE CRANIOCERVICAL JUNCTION
Alessandro De Bonis, MD; Megan M.J. Bauman, MS; Luciano César P.C. Leonel, PhD; Michael Link, MD; Maria Peris-Celda, MD, PhD; Mayo Clinic
Objective: The Far Lateral Approach (FLA) is a neurosurgical approach widely employed to access lesions located in the craniocervical junction (CCJ). Within this approach, variations such as the Supracondylar (SC-FLA) and Occipital Transcondylar (TC-FLA) have been developed to reduce brainstem retraction and maximize access to the region. This study aims to investigate the extent of access to the CCJ provided by these two FLA variations and to identify their appropriate indications.
Methods: Ten sides of five formalin-fixed, latex-injected anatomical specimens were examined using microsurgical techniques to elucidate the anatomical differences between the SC-FLA and TC-FLA. The access to the CCJ in the two variations was demonstrated through sequential osseous drilling. A morphometric study was conducted to assess and compare the surgical routes. Illustrative cases were described.
Results: The access to the CCJ in the two variations was categorized into medial, inferior, and superior routes. The TC-FLA provides medial access from 19% to 58% of the foramen magnum's anterior circumference, determined by sequential occipital condyle (OC) removal. The TC-FLA offers maneuverability ranging from 7 mm to 9 mm in the inferior route and 7 mm to 12 mm in the superior route. Conversely, the SC-FLA achieves medial access from 23% to 41% of the lower clivus's anterior circumference, determined by jugular tubercle (JT) removal. Maneuverability in the SC-FLA ranges from 9 mm to 11 mm in the inferior route and 10 mm to 17 mm in the superior route.
Conclusions: In the access to the craniocervical junction, the decision between Supracondylar and Transcondylar variations of the Far Lateral Approach should be individualized based on the specific patient's anatomy and pathology. The TC-FLA is suitable for lesions extending medially up to 60% of the foramen magnum's anterior circumference, reaching the hypoglossal canal superiorly and staying within 1cm below the OC. The SC-FLA is recommended for lesions not extending more than 40% medially from the lower clivus's anterior circumference, reaching the hypoglossal canal inferiorly, and staying within 1.5cm above the JT.
