Giant invasive spinal schwannomas: definition and surgical management

Object. 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 classificatio n system for spinal schwannomas as a means to define these giant lesions. T he classification is confined to tumors that are essentially intraspinal, w ith or without extraspinal components. Lesions that erode the vertebral bod ies (VBs) and extend posteriorly and laterally into the myofascial planes a re classified as giant "invasive" spinal schwannomas. Methods. The records of patients with giant invasive spinal schwannoma were analyzed. The radiological features, operative approaches, and intraoperat ive findings were noted. Ten patients with giant invasive tumors were surgically treated over the la st 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 preope rative planning. Radical excision of the tumors in multiple stages was poss ible in eight of the 10 patients. Dural reconstruction was required in four patients. All patients required fusion, and an additional stabilization pr ocedure was undertaken in three patients. Conclusions. The authors conclude that giant invasive schwannomas are uncom mon lesions and propose a new classification system. Because of their local ly "invasive" nature and extension in all directions, careful preoperative planning of the surgical approach is very important. Although radical excis ion is possible and promises good results, recurrences may occur and multip le surgical procedures may be required.