Spinal Nerve Sheath Tumors Research Articles

Clinical Characteristics of Spinal Nerve Sheath Tumors: Analysis of 149 Cases

Spinal nerve sheath tumors arise from the spinal nerve root and grow along it. There are two sites at which the growth of a tumor is restricted: the dural aperture for the spinal nerve root and the intervertebral foramen. This article describes the growth pattern of a spinal nerve sheath tumor along the spinal nerve root at various spinal levels. We retrospectively reviewed the records for 149 patients with spinal nerve sheath tumors who were treated between 1980 and 2001. Of these, 176 resected tumors were classified into five groups according to the relationship to the dura mater and/or the intervertebral foramen. Strictly intradural tumors compose 8% of nerve sheath tumors of the first two cervical nerve roots. The percentage of these tumors increased gradually from the high cervical region to the thoracolumbar region, where it was more than 80%. In contrast, the percentage of strictly extradural tumors gradually decreased from the rostral portion to the caudal portion. Similarly, a percentage of tumors extending outside the spinal canal decreased from the rostral portion to the caudal portion. These changes of the growth pattern may be explained by the anatomic features of the spinal nerve roots, which have a longer intradural component at the more caudal portion of the spinal axis. The anatomic relationship of a nerve sheath tumor with the dura mater and the intervertebral foramen varies depending on the level of the tumor. This knowledge may help us to create a strategy for total resection of a nerve sheath tumor.

Treatment of Relevant Nerve Roots Involved in Nerve Sheath Tumors: Removal or Preservation?

Surgery for the treatment of patients with spinal nerve sheath tumors can require complete resection of the nerve roots involved in the tumor. The purpose of the present study is to analyze the risks of resection of eloquent roots as compared with the risks of incomplete tumor removal. The pertinent literature on spinal nerve sheath tumors was reviewed. A single-institution series of 26 patients who underwent operations for 27 spinal schwannomas or neurofibromas, which were removed together with functionally relevant nerve roots (C5-C8 or L3-S1), was studied. Worsening of preoperative radicular motor function was observed at follow-up in 4 (14.8%) of the 27 divided nerve roots, but the motor deficit was permanent and disabling in only 2 cases (7.4%). In the four patients who experienced worsened radicular motor function, the roots were cervical, and histological analysis revealed that the tumor was a schwannoma. Three of these patients were neurologically negative before surgery. Of the two patients with severe radicular weakness, the location of the tumor was extradural and extraradicular in one patient, who had normal preoperative root function, and the tumor was intraextradural in the other patient, who had a preoperative root deficit. After resection of a single eloquent nerve root involved in a nerve sheath tumor, the incidence of radicular dysfunction is low but severe weakness is possible. The main risk factors seem to be the pathological pattern (schwannoma versus neurofibroma) of tumor, the preoperative status (with versus without deficit) of the root, and, for extradural nerve sheath tumors, the location (cervical and extraradicular versus lumbosacral and intraradicular) of growth. Deafferentation pain does not occur. Unlike schwannomas with neurofibromatosis Type 2 and neurofibromas, the radicality of removal seems to be the main factor with regard to the recurrence of solitary schwannomas, although recurrent tumors often appear later in follow-up.

Thoracoscopic approaches to the thoracic spine.

Microsurgical approaches for the treatment of pathology located in the ventral thoracic spine using video-assisted thoracic surgery (VATS) allow neurosurgeons to access the disc spaces, vertebral bodies, paravertebral soft tissues, spinal cord, spinal nerves, and sympathetic chain with minimally invasive surgery. This has been associated with substantial clinical benefits including reduced postoperative pain, lower complication rates and shorter recovery times when compared with standard thoracotomy techniques. This article describes the experience at our institution with VATS for discectomy (20 cases), corpectomy and spinal reconstruction (8 cases), thoracic sympathectomy (3 cases), and nerve sheath tumor removal (1 case). The technique can be mastered but requires surgeons to learn the new psychomotor skills needed to perform endoscopic spine surgery. The learning curve is steep. Special training in instructional seminars, surgical skill laboratories, and clinical preceptorships is needed before this surgical approach can be used clinically to treat spinal pathology. VATS has significant advantages compared to standard thoracotomy, including reduced incisional pain and avoidance of the postthoracotomy pain syndrome. If intercostal neuralgia develops postoperatively, it is milder and usually transient compared to the pain associated with standard thoracotomy. Better cosmetic outcomes, earlier mobilization, and faster recovery are added benefits. The surgical techniques are relatively new for neurosurgeons and require dedicated practice to master them. Once the surgical skills are perfected, VATS is feasible for spinal pathology and can be performed safely and effectively.

Surgery of spinal nerve sheath tumors with special reference to neurofibromatosis.

We conducted a retrospective study of 87 patients with spinal nerve sheath tumors to determine the overall clinical outcome and specific features in 20 patients affected with neurofibromatosis Types 1 and 2 (NF-1 and NF-2, respectively). Case records, operation notes, outpatient files, and radiological examinations were analyzed for all patients treated between September 1977 and August 1994. Additional follow-up data were obtained using outpatient examinations, questionnaires, and telephone calls. During the study period, 128 spinal neuromas (i.e., schwannomas) and 6 neurofibromas in 87 patients were treated. Fifty-seven neuromas were associated with NF-2 in 17 patients and six neurofibromas with NF-1 in 3 patients. Patients with NF-2 and symptomatic neuromas presented with more severe neurological deficits compared to patients without NF-2. Eighty-six percent of the neuromas were removed completely. On average, most preoperative deficits or symptoms improved in patients without NF-2, whereas neurological symptoms remained unchanged in patients with NF-2. Multiple regression analysis revealed that partial removal, surgery of a recurrent tumor, NF-2, and old age predisposed for tumor recurrence. No increased risk of recurrence was observed for patients with NF-1. For patients without NF-2, we observed overall recurrence rates of 10.7% after 5 years and 28.2% after 10 and 15 years, respectively, as determined by Kaplan-Meier analysis. For NF-2, the recurrence rate at 5 years was 39.2%, and all tumors had recurred by 9 years. Spinal nerve sheath tumors carry an excellent prognosis in patients with NF-1 and in patients without neurofibromatosis. Symptomatic neuromas occurring in association with NF-2 present with more severe neurological deficits, demonstrate little postoperative improvement, and have a very high recurrence rate.

Surgery of Spinal Nerve Sheath Tumors with Special Reference to Neurofibromatosis

Surgery of Spinal Nerve Sheath Tumors with Special Reference to Neurofibromatosis

Surgery of Spinal Nerve Sheath Tumors with Special Reference to Neurofibromatosis

Surgery of Spinal Nerve Sheath Tumors with Special Reference to Neurofibromatosis

Surgery of Spinal Nerve Sheath Tumors with Special Reference to Neurofibromatosis

Surgery of Spinal Nerve Sheath Tumors with Special Reference to Neurofibromatosis

Proliferative potential of sporadic and neurofibromatosis 2-associated schwannomas as studied by MIB-1 (Ki-67) and PCNA labeling.

Neurofibromatosis 2 (NF2), a dominantly inherited disorder, is typically manifested as bilateral vestibular Schwannomas and predisposes to other nervous system tumors. Vestibular Schwannomas also occur sporadically but the onset is usually at an older age. Surgical and histological studies have shown that vestibular Schwannomas of NF2 patients are more invasive than sporadic Schwannomas and that the two groups also have morphological differences. We compared the proliferation activity of 26 vestibular Schwannomas (19 NF2 patients) to that of 27 sporadic cases using the Ki-67 (MIB-1) and PCNA (19A2) monoclonal antibodies. In addition, proliferation was assessed in 20 spinal benign Schwannomas, 4 spinal cellular Schwannomas and 3 spinal malignant peripheral nerve sheath tumors (MPNST). We found a significant difference in the proliferation potential between NF2 and sporadic vestibular Schwannomas (MIB-1-LI: 1.72 +/- 0.93 vs 0.95 +/- 0.57, p = 0.001; and PCNA-LI: 1.40 +/- 0.75 vs 0.81 +/- 0.52, p = 0.001). Age does not explain the detected difference in proliferation, since NF2 vestibular Schwannomas also had higher MIB-1 indices than 34 age-matched sporadic tumors. In spinal tumors, MPNST had higher MIB-1 indices than cellular Schwannomas, and therefore MIB-1 staining may be useful in distinguishing between them. Although the defective NF2 gene is important in the tumorigenesis of both NF2 and sporadic Schwannomas, our results suggest that there are differences in the molecular biology of these tumors.

Neurofibromatosis

The neurofibromatoses are defined by the presence of café-au-lait macules and neurofibromas and are associated with central and peripheral nervous system tumors. Individuals with neurofibromatosis 1 are at risk for optic nerve gliomas, nerve root and plexi neurofibromas and schwannomas, spinal cord tumors, benign and malignant peripheral nerve sheath tumors, and pheochromocytomas. Individuals with neurofibromatosis 2 are at risk for presenile cataracts, vestibular schwannomas, intracranial and intra-spinal meningiomas, and intramedullary spinal cord ependymomas.

Benign spinal nerve sheath tumors: their occurrence sporadically and in neurofibromatosis types 1 and 2

Benign spinal nerve sheath tumors (neurofibromas and schwannomas) often occur on dorsal nerve roots sporadically or in neurofibromatosis types 1 and 2. These are histologically benign tumors, and distinction between them is frequently not made by clinicians. To determine if there is a correlation between the histological pattern of benign spinal nerve sheath tumors and the type of neurofibromatosis, the clinical and pathological features of these tumors (86 surgical specimens and five autopsies) in 68 patients were reviewed. The patients were classified into one of four categories: neurofibromatosis type 1, neurofibromatosis type 2, uncertain, or sporadic. The diagnostic criteria used for neurofibromatosis types 1 and 2 were established by the National Institutes of Health. Patients who did not fulfill criteria for either neurofibromatosis type 1 or 2 but who had multiple nervous system tumors or other stigmata of neurofibromatosis were designated "uncertain." Spinal nerve sheath tumors were considered sporadic in 42 cases (40 schwannomas and two neurofibromas). In the 14 patients with neurofibromatosis type 1, all spinal nerve sheath tumors were neurofibromas. In six of the seven patients with neurofibromatosis type 2, all spinal nerve sheath tumors were schwannomas. One patient with neurofibromatosis type 2 had a spinal nerve sheath schwannoma and a tumor with features of both tumor types. The authors conclude that spinal nerve sheath tumors in patients with neurofibromatosis type 1 are neurofibromas. In contrast, spinal nerve sheath tumors occurring in neurofibromatosis type 2 or sporadically are most frequently schwannomas. The distinct histological features of these tumors may reflect different pathogenetic mechanisms even though they arise at identical sites in neurofibromatosis types 1 and 2.