Anterior Clinoid Line: A Predictor for Operative Outcome of Medial Sphenoid Wing Meningiomas

Background Medial sphenoid wing meningiomas (MSWM) account for approximately 20% of all meningiomas. They are notoriously known for their complicated relation to adjacent structures including the optic nerve, internal carotid artery and its branches, cavernous sinus, or other critical structures. Therefore, gross total resection of the tumor is challenging and has a high mortality rate up to 8% as well as high morbidity in comparison to other locations. The purpose of this study is to establish an association between the maximum diameter of the MSWM medial to the anterior clinoidal line (AC line) and postoperative outcome.

Methods This is a retrospective cohort study investigating all surgically resected MSWM cases at the National Neurosciences Institute, Riyadh, Saudi Arabia, over the past 10 years. We have measured the MSWM maximum medial margin and maximum lateral margin in relation to a line crossing the tip of the anterior clinoid line (AC line) and parallel to a midline that extends between the most caudal edge of superior sagittal sinus and the most midline structure, such as the rostrum of the sphenoid sinus. A ratio was then generated between the medial extension of the MSWM to the maximum diameter of the tumor. These measurements were then correlated with patient demographics, preoperative symptoms, and postoperative assessment to look for any significant correlations.

Results One hundred and fifty patients with meningioma were identified and 51 patients had MSWM and fulfilled the inclusion criteria. Preliminary analysis was done (72.5%) in males with a median age of 48 years (SD: 47.75 ± 15.11). Most of the cases had (92.2%) MSWM of WHO Grade I and the remaining (7.8%) were WHO Grade II. The follow-up period ranged between 0.5 and 10 years. We have divided the patients based on the measurement of the medial extension of the tumor to the AC line ≤ 14 mm as Group 1, and a measurement more than 14 mm as Group 2. Group 1 was composed of 27 (52.9%) and Group 2 was composed of 24 (47.1%) patients. Forty-eight percent of Group 1 had total resection, whereas 78.3%% of Group 2 had total resection. The most common presentation in all patients was headache (66.6%, p = 0.017). In group 1, seizure was observed in 48.1% of the patients with 69.2% improvement, whereas in Group 2, only 4.2% had seizures with (100%) improvement. Almost 49% of the patients had medial extension greater than 37% (which is the average ratio of the tumor extension medial to the AC line). Sixty percent of these patients had gross total resection; however, it was found be higher (69%) in patients with extension of less than 37%. In both groups, there was no significance in developing major postoperative complications.

Conclusion The current study suggests that the size of MSWM medial to the AC line has no significant effect on major postoperative complications; however, it does have significant effect on improvement of preoperative seizures.