Surgical and Neuropsychological Outcomes of Extended Bifrontal Transbasal Approach for Resection of Giant Midline Anterior Fossa Meningiomas

Background: Anterior skull base meningiomas comprise up to 40% of intracranial meningiomas and can grow to significant sizes. They often present with changes in mental status and executive function, in addition to causing visual and olfactory loss. These tumors can be approached with a variety of techniques including endoscopic, subfrontal, pterional. In the extended bifrontal approach, the orbital bar is removed which increases access and diminishes frontal lobe retraction. Decreased frontal lobe manipulation may decrease postoperative morbidity and improve neuropsychological outcomes.

Methods: Charts were reviewed for patients who underwent extended bifrontal craniotomies for meningiomas at our institution between 2016 and 2018. Brain edema was quantified by the maximum diameter of FLAIR/T2 abnormalities in preoperative, postoperative, and follow-up MRI scans. Cognitive function, including verbal memory and visuospatial reasoning, was evaluated with formal neuropsychological testing before and/or after surgery.

Results: Fourteen patients met inclusion criteria. All patients had tumors with a diameter greater than 3 cm, with the average tumor size being 5.9 cm (range: 3.5 cm–6.9 cm). Simpson grade 1 or 2 resection was achieved in 86% of patients, and mean operative time was 9 hours 35 minutes. Mean postoperative edema was not significantly different from preoperative edema as measured by FLAIR MRI (2.91 vs. 2.89 cm; p = 0.7). In 3 to 6 months, edema decreased by an average of 40% compared with preoperative edema (1.88 vs. 3.1 cm; p = 0.027). There were no postoperative infections and three cases of cerebrospinal leak—all of which were repaired by an endoscopic endonasal approach. The most common neuropsychological test parameters to improve were visuospatial reasoning and verbal memory, with scores improving in general from low-average to average. No patient had a decline in postoperative neuropsychological test scores compared with preoperative scores.

Conclusion: The extended bifrontal craniotomy is a safe and effective approach for the resection of giant anterior midline meningiomas. Postoperative edema significantly decreased in all patients and neuropsychological outcomes were either unchanged or improved in all patients. Future comparison of these results to those obtained after traditional cranial approaches and endonasal approaches will help clarify whether a particular approach is superior in the management of these tumors.