Morphometric comparison of Fisch type A and endoscopic endonasal far-medial supracondylar approaches to the jugular foramen.

Abstract

The jugular foramen (JF) is one of the most complex and challenging skull base regions to approach surgically. The extreme medial approach to access the JF provides the approach angle from an anterior direction and does not require dissection and sacrifice of the jugular bulb (JB) to reach the pars nervosa. The authors compared the Fisch type A approach to the extreme medial approach to access the JF and evaluated the usefulness of the extreme medial approach. This study was performed at the Anatomical Laboratory for Visuospatial Innovations in Otolaryngology and Neurosurgery of The Ohio State University. For the comparison of surgical maneuverability and visualization, two angles were measured: 1) the angle of attack (AoA), defined as the widest angle of movement achieved with a straight dissector; and 2) the angle of endoscopic exposure (AoEE), defined as the widest angle of movement in the nasal cavity. The differences in eustachian tube (ET) management, approach angle, surgical maneuverability, and surgical application of the Fisch type A approach to the extreme medial approach were compared. There was no difference between ET mobilization and transection regarding cranial-caudal (CC) or medial-lateral (ML) AoA (p = 0.646). The CC-AoA of the Fisch type A approach was significantly wider than the CC-AoA of the extreme medial approach (p = 0.001), and the CC-AoEE was significantly wider than the CC-AoA of the extreme medial approach (p < 0.001). There was no significant difference between the CC-AoA of the Fisch type A approach and the CC-AoEE. The ML-AoA of the Fisch type A approach was significantly wider than the ML-AoA of the extreme medial approach (p = 0.033), and the ML-AoEE was significantly wider than ML-AoA in the extreme medial approach (p < 0.001). The ML-AoEE was significantly wider than the ML-AoA in the Fisch type A approach (p = 0.033). The surgical maneuverability of the extreme medial approach was not inferior to that of the Fisch type A approach. The extreme medial approach can provide excellent surgical field visualization, while preserving the JB. Select cases of chordomas, chondrosarcomas, and JF schwannomas should be considered for an extreme medial approach. These two approaches are complementary, and a case-by-case detailed analysis should be conducted to decide the best approach.