Hypervascular vestibular schwannomas

Abstract

BACKGROUND Vestibular schwannoma (VS) is usually hypovascular and can be resected totally without major morbidity. Resection of the more uncommon hypervascular VS is complicated by excessive tumor bleeding. We have attempted to clarify the clinical characteristics and management of hypervascular VS. METHODS Surgical reports and videos of 78 patients with unilateral VS (5 hypervascular, 73 nonhypervascular) were retrospectively reviewed and clinical characteristics, radiological findings, and case management were compared. RESULTS Hypervascular VS presented at a younger age than nonhypervascular VS (29 ± 12 vs. 52 ± 16 years old) ( p < 0.01). Magnetic resonance imaging (MRI) showed that hypervascular VS was solid, without tumor cyst, and significantly larger than nonhypervascular VS ( p < 0.05). The surface of hypervascular VS consistently showed multiple flow voids representing large draining veins. The characteristic angiographical findings of hypervascular VS were extensive tumor vessels, tumor stains, and early filling of draining veins; vertebrobasilar arteries supplied hypervascular VS. A multi-stage surgical approach was used since torrential tumor bleeding in the first surgery interfered with resection, resulting in partial tumor removal. Angiography before the second surgery showed much reduced tumor vascularity, bleeding was much reduced, and tumor was resected with less difficulty. In this approach, all 5 hypervascular VS were resected totally (1 case) or near-totally (4 cases) without major morbidity. CONCLUSIONS Hypervascular VS, a solid and large tumor, presents at an earlier age. Although angiography provides characteristic findings, MRI can confirm the diagnosis of a hypervascular VS by showing multiple flow-voids on the tumor surface. Since partial tumor removal (first surgery) extensively reduces tumor vascularity and intraoperative tumor bleeding considerably, hypervascular VS should be managed by a multi-staged surgical approach.