Giant invasive spinal schwannomas: definition and surgical management.

Abstract

Confusion exists regarding the term giant spinal schwannoma. There are a variety of nerve sheath tumors that, because of their size and extent, justify the label "giant schwannoma." The authors propose a classification system for spinal schwannomas as a means to define these giant lesions. The classification is confined to tumors that are essentially intraspinal, with or without extraspinal components. Lesions that erode the vertebral bodies (VBs) and extend posteriorly and laterally into the myofascial planes are classified as giant "invasive" spinal schwannomas. The records of patients with giant invasive spinal schwannoma were analyzed. The radiological features, operative approaches, and intraoperative findings were noted. Ten patients with giant invasive tumors were surgically treated over the last 8 years. Six patients were male. Erosion of the posterior surface of the VBs was the diagnostic finding demonstrated on plain x-ray films. Magnetic resonance imaging delineated the extent of the tumors and helped in preoperative planning. Radical excision of the tumors in multiple stages was possible in eight of the 10 patients. Dural reconstruction was required in four patients. All patients required fusion, and an additional stabilization procedure was undertaken in three patients. The authors conclude that giant invasive schwannomas are uncommon lesions and propose a new classification system. Because of their locally "invasive" nature and extension in all directions, careful preoperative planning of the surgical approach is very important. Although radical excision is possible and promises good results, recurrences may occur and multiple surgical procedures may be required.