Endoscopic endonasal approach for olfactory groove meningioma resection: Strategies and outcomes in a retrospective case series.

OBJECTIVE: Though the endoscopic endonasal approach (EEA) is a widely accepted treatment for skull base tumors, the specific use of EEA for olfactory groove meningiomas (OGMs) is debated, with variable outcomes reported in the literature. We review the surgical results of OGM resections for one surgeon including the operative approach, surgical nuances, and outcomes, with a focus on factors relating to patient selection which favor EEA over transcranial approaches.

METHODS: We retrospectively reviewed thirteen cases of endoscopic endonasal resection of olfactory groove meningiomas. Patient characteristics, clinical characteristics, surgical outcomes, and complications were analyzed. Extent of resection was determined based on volumetric analysis of pre- and postoperative MRI.

RESULTS: Anatomic characteristics that render a tumor difficult to access fully are lateral extension beyond the mid-orbit and anterior extension to the falx. Simpson Grade I resection was achieved in 11/13 (84.6 %) cases. Mean pre-operative tumor volume was 8.99 cm3 (range 2.19-16.79 cm3 ), and 92 % of tumors were WHO grade I. We demonstrate 2 cases of smell preservation, possible with small unilateral tumors and tumors that are confined to either the anterior or posterior portion of the cribriform plate. The post-operative CSF leak rate was 7.7 %, without prophylactic lumbar CSF drainage. The mortality rate was 7.7 % (n = 1) after infectious complications following CSF leak.

CONCLUSIONS: Endoscopic endonasal resection of olfactory groove meningiomas is an effective and safe operative method with outcomes and complication rates comparable to transcranial approaches. Key considerations include careful patient selection and familiarity with technical nuances of endoscopic endonasal approach for this specific tumor type.