The anterior incisural width as a preoperative indicator for intradural space evaluation: An anatomical investigation

BACKGROUND: The opticocarotid triangle (OCT) and the carotico-oculomotor triangle (COT) are two anatomical triangles used in accessing the interpeduncular region. Our objective is to evaluate if the anterior incisural width (AIW) is an indicator to predict the intraoperative exposure through both triangles. METHODS: Twenty sides of 10 cadaveric heads were dissected and analyzed. The heads were divided into the following: Group A – narrow anterior incisura and Group B – wide anterior incisura – using 26.6 mm as a cutoff distance of the AIW. Subsequently, the area of the COT and the OCT in the transsylvian approach was measured, along with the maximum widths through the two trajectories in modified superior transcavernous approach. RESULTS: The COT in the wide group was shown to have a significantly larger area compared with the COT in the narrow group (38.4 ± 12.64 vs. 58.3 ± 15.72 mm, P < 0.01). No difference between the two groups was reported in terms of the area of the OCT (50.9 ± 19.22 mm vs. 63.5 ± 15.53 mm, P = 0.20), the maximum width of the OCT (6.6 ± 1.89 vs. 6.5 ± 1.38 mm, P = 1.00), or the maximum width of the COT (11.7 ± 2.06 vs. 12.2 ± 2.32 mm, P = 0.50). Clinical cases were included. CONCLUSION: An AIW <26.6 mm is an unfavorable factor related to a limited COT area in a transsylvian approach for pathologies at the interpeduncular fossa. Preoperative identification and measurement of a narrow AIW can suggest the need to add a transcavernous approach.