Purely Endoscopic Resection of Malignant Skull Base Tumors: An 8-Year Experience with Postoperative Outcomes and Indications

Introduction: Resection of malignant skull base tumors pose complex pathological and treatment related morbidities. The recent advancement of newer endoscopic technology offers the ability to reexamine traditional treatment paradigms. The goal of complete oncological resection continues to be the area of concern for endoscopic procedures as open surgical approaches are still considered the standard of care. The utility of endoscopic procedures was quantitatively examined in a longitudinal series with attention to associated with morbidities and postoperative complications.

Methods: A retrospective review was performed of malignant sinonasal tumors from 2010 to 2018 at our institution. Patients with purely endoscopic endonasal surgery (EES) were selected for analysis. Demographics as well as neurological presentation, resection extent, surgical factors, postoperative complications, and time to adjunctive treatment were assessed. Preoperative indicators, surgical results, and postoperative findings were quantitatively assessed.

Results: Fifty-five patients (54.5% female, 45.5% male) with an average age of 59.4 years were identified. The most common tumor types in this cohort were adenocarcinoma (16.3%), squamous cell carcinoma (10.9%), and esthesioneuroblastoma (10.9%). The most common regions of tumor location in the skull base were the sphenoid (69.1%), ethmoid (65.4%), and maxillary (54.5%) sinuses. The most common presenting clinical features were epistaxis, nasal congestion, and headache. Vision impairment, anosmia, and facial pain were the most frequently reported neurological presentations. Cranial nerves VI, II, and III were most commonly affected in patients presenting with cranial neuropathies. Less than 10% of patients had extensive systemic disease at the time of surgery.

The most common surgical approaches were transsphenoidal (72.7%) and ethmoidal (23.6%). Gross total resection was achieved in 84.6% of cases, subtotal resection was achieved in 10.2%, and 5.4% of cases were biopsies. In cases where gross total resection could not be achieved, the most common reasons were extensive dural involvement or proximity to the optic apparatus and other cranial nerves.

Significant pain (9.1%), infection (meningitis) (5.5%), and CSF leak (1.8%) were the most common postoperative complications. The average length of postoperative hospital stay was 3.1 days. 61.8% of the patients in this study have underwent or begun adjunctive treatment, including conventional radiation (38.2%), fractionated radiation (11.8%), proton beam radiation (23.5%), chemotherapy (38.2%), immunotherapy (5.9%), and Cyberknife radiation (2.9%). The average time between surgery and initiation of adjunctive surgery was 48.3 days. One patient in this study experienced cranial neuropathy as a result of surgery.

Conclusion: In our 8-year experience, we found that entirely endoscopic resection of skull base tumors is oncologically feasible and can be accomplished with high gross total resection rates and with few complications. The population in this study had a low incidence of extensive systemic disease, and an overall high survival outcome. There may be a role for EES to reduce operative morbidity and attenuate the period of time in between surgery and adjunctive treatment. More work is needed to expand this analysis and systematically compare the outcomes in this study with similar variables for open surgical approaches.