Extent of Tumorigenic Brain Edema on Long-Term Patient Outcomes in Surgically Resected Large Vestibular Schwannomas

Background: Tumorigenic edema related to large skull base meningiomas is known to correlate with differences in intraoperative difficulty and outcomes. This association is not well described for surgically treated large (≥ 30 mm) vestibular schwannomas (VS). Recent studies, however, suggest a link between patient outcome and extent of VS tumorigenic edema and have proposed alternative tumor grading systems to account for this. Current literature does not offer a consensus on these findings, particularly the extent of tumorigenic edema related to the completeness of resection, postoperative facial nerve outcome and bulbar symptoms. This retrospective study of surgically treated large VS aims to add to this literature.

Methods: A single-center, retrospective cohort study of patients undergoing surgical resection of large VS between 2017 and 2021 was conducted. The primary outcome of the study was facial nerve function at 2 years postoperatively defined using House-Brackmann (HB) scoring. Patient demographics, radiology, clinical features, and surgical outcomes were collected. Patients with minimum two years of documented follow-up were included. The extent of radiographic edema was defined by three independent reviewers using two separate grading scales on MRI:

Edema < tumor volume, edema = tumor volume, edema > tumor volume.

Absence of edema, edema adjacent to tumor site, or edema remote from tumor site.

Results: A total of 28 patients underwent surgical resection of large VS during the study period. The average preoperative maximal tumor diameter was 36.7 ± 5.6 mm, and all patients were HB I preoperatively. Of these patients, 9 (32.1%) had no edema, while 19 (67.9%) had edema on MRI. Between these cohorts, no significant difference was found regarding tumor diameter (p = 0.161) or initial presenting symptoms ([Table 1]). Additionally, no significant difference was found regarding total operative time (p = 0.394), degree of intraoperative difficulty, extent of resection (p = 0.169), length of stay (p = 0.068), or postoperative complications ([Table 2]).

Notably, no significant difference was found between the two cohorts for facial nerve function at both two weeks (p = 0.253) and two years (p = 0.942) postoperatively. Similarly, postoperative trigeminal and bulbar symptoms showed no significant difference ([Table 3]). When stratified by the presence of postoperative facial nerve palsy, there remained no significant difference at both two weeks (p = 0.214) and two years (p = 1.00) postoperatively ([Table 4]). Furthermore, when those patients with postoperative facial nerve palsy were stratified by the extent of edema using scales 1 and 2, there remained no significant difference between the extent of edema and 2-week and 2-year facial nerve outcome postoperatively (Tables 5 and 6). Similarly, no significant difference in facial nerve function was observed when stratified by the extent of resection (Table 7).

Conclusion: In this retrospective study, large VS undergoing primary surgical resection, the presence and degree of tumorigenic edema does not impact facial nerve outcomes, even when subtotal and near-total resections are considered. The presence of edema does not add clinical value in the consideration of treatment selection and patient outcomes. Additionally, it does not significantly affect the degree of intraoperative difficulty or extent of resection, postoperative complications, and trigeminal and bulbar symptoms.

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Artikel online veröffentlicht:
07. Februar 2025