Comparison of Clinical Characteristics and Surgical Outcomes of Cystic and Solid Vestibular Schwannomas.

Abstract

The aim of this study was to compare the clinical characteristics of cystic vestibular schwannomas (CVSs) and solid vestibular schwannomas (SVSs). Retrospective review. Tertiary care center. A total of 220 patients who underwent microsurgery for vestibular schwannomas between 2007 and 2016. CVSs were defined as cystic components ≥1/3 of total tumor volume based on automated volume measurement. Tumors larger than 5 cm were defined as large tumors. Clinical characteristics and surgical outcomes, including preoperative symptoms, hearing threshold, vestibular function, tumor volume, extent of resection, facial nerve outcomes, and nonfacial complications were evaluated. Tumor volume was significantly larger in CVSs (20.44 ± 13.85 cm in CVSs; 4.75 ± 6.48 cm in SVSs, p < 0.001) and the proportion of larger tumors was also greater in CVSs (66.0% in CVSs; 11.4% in SVSs, p < 0.001). Preoperative dizziness was highly prevalent in CVSs (32.1% in CVSs; 18.6% in SVSs, p = 0.038) and postoperative facial nerve outcomes were significantly worse in CVSs (67.9% favorable rate in CVSs; 87.4% favorable rate in SVSs, p = 0.001). When the comparison was limited to large tumors, no clinical characteristics or surgical outcomes were significantly different. Tumor volume had a greater effect than tumor type on the surgical outcomes. The odds ratios for subtotal resection and unfavorable facial nerve function with a large tumor were 5.77 (confidence interval [CI]: 1.52-21.95, p = 0.010) and 5.34 (CI: 1.41-20.22, p = 0.014), respectively. CVSs tend to be larger than SVSs. Tumor volume, not cystic component, is thought to be a major determinant of surgical outcomes.