George Jallo, MD
Division of Pediatric Neurosurgery, John Hopkins Hospital, Baltimore, USA. E-mail: gjallo1@jhmi.edu
Published: 14 May 2007;
BACKGROUND
Spinal cord tumors are rare diseases of the central nervous system. Victor Horsley is credited with the first successful resection of an intradural tumor, which was performed in 1887. (Gowers) With the advent of microsurgical instruments and techniques, the development of complex spinal instrumentation techniques, and the refinement of nonsurgical adjuvant therapies, the ability to treat these tumors continues to improve.
Spinal cord tumors comprise approximately 15% of central nervous system tumors. These neoplasms can be categorized based on the relation of the tumor to the spinal cord. Intramedullary tumors are tumors within the spinal cord. Intradural extramedullary tumors are located within the dura and outside of the spinal cord. Extramedullary tumors are located outside of the dura and include tumors involving the osseous spine.
INTRAMEDULLARY TUMORS
Approximately one-third of spinal cord tumors are intramedullary in location. Primary glial tumors are the most common intramedullary spinal cord tumor. In the pediatric population, astrocytomas are the most common glial tumors. (Jallo) Ependymomas are the most common glial tumor in the adult population. (Lee) Gangliogiomas, subependymomas, and oligodendrogliomas are less common glial tumors. Other intramedullary tumors include hemangioblastomas (Lonser), metastases (Costigan), and lipomas.
INTRADURAL, EXTRAMEDULLARY TUMORS
The most common intradural, extramedullary spinal cord tumors are meningiomas and nerve sheath tumors, which include schwanommas and neurofibromas. Filum ependymomas, drop metastases from primary intracranial tumors, and paragangliomas are less common. These tumors may compress, but rarely invade, the spinal cord. These tumors are often amenable to complete surgical resection.
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EXTRADURAL TUMORS
Extradural tumors include tumors of the osseous spine. Tumors involving the bone of the spinal column can be benign or malignant in nature. Benign tumors include hemangiomas, osteoid osteomas, osteochondromas, and giant cell tumors. Malignant tumors are most commonly metastases from tumors located outside of the spine. Lung, breast, thyroid, prostate, and kidney tumors can often lead to metastatic spine lesions. Primary malignant tumors include chordomas, lymphomas, and sarcomas.
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DIAGNOSIS
MRI is the imaging modality of choice for spinal cord tumors (Li). Many tumors often have characteristic MRI signal properties that can help aid with diagnosis and formulation of a treatment plan. It can be used to plan the surgical approach to tumor resection. If conservative treatment is chosen, serial MRI studies can be used to track tumor growth or gauge response to adjuvant therapy (i.e. radiation and chemotherapy).
A CT scan is especially useful for tumors of the osseous spine. This study is useful in situations when the tumor leads to bone fractures, instability, and disruption of bony elements into the spinal canal. A CT scan can also help determine whether spinal instrumentation is necessary and feasible if a surgical resection is pursued. A CT myelogram can be used in situations where an MRI is contraindicated. CT myelograms can be used to localize the tumor and provide information about the degree of spinal cord compression.
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TREATMENT
Surgery is an option for many spinal cord tumors. For intradural, extramedullary spinal cord tumors, gross total resection of tumor is usually possible unless there is tumor invasion in or around nerve roots and/or vascular structures. Many types of intramedullary tumors are also amenable to total resection as long as a well demarcated plane exists between tumor and normal spinal cord tissue. However, glial tumors often invade normal spinal cord tissue, and aggressive resection can lead to severe neurological deficit. In these situations, a conservative resection of grossly abnormal tissue is pursued. For extradural tumors, specifically tumors invovling the osseous spine, surgical resection can lead to improvement in pain and neurological deficit (Patchell). Resection of osseous spine tumors may lead to spinal instability and may necessitate complex reconstruction using a variety of metallic and non-metallic devices.
Nonsurgical treatments for spinal cord tumors include radiation (Rodriques) and chemotherapy (Lowis). The choice of adjuvant therapy depends on the location and pathology of the tumor in addition to the clinical symptoms of the patient. The role for radiation and chemotherapy as an initial treatment or post-surgical therapy continues to be investigated.
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REFERENCES
Costigan DA, Winkelman MD: Intramedullary spinal cord metastases: A clinicopathological study of 13 cases. J Neurosurg 62:227-233, 1985.
Gowers WR, Horsley V (1888) A case of tumour of the spinal cord. Removal and recovery. Med Chir Trans 53:377–428
Jallo GI, Freed D, Epstein F. Intramedullary spinal cord tumors in children. Child Nerv Syst. 2003 Sep 19(9):641-9.
Lee J, Parsa AT, Ames CP, McCormick PC. Clinical management of intramedullary spinal ependymomas in adults. Neurosurg Clin N Am 2006:21-27.
Li MH, Holtas S: MR imaging of spinal intramedullary tumors. Acta Radiol 1991;32:505-513.
Lonser RR, Oldfield EH. Spinal cord hemangioblastomas. Neurosurg Clin N Am. 2006 Jan;17(1):37-44.
Patchell RA, Tibbs PA, Regine WF, Payne R, Saris S, Kryscio RJ, Mohiuddin M, Young B. Direct decompressive surgical resection in the treatment of spinal cord compression caused by metastatic cancer: a randomised trial. Lancet 2005;20:643-648.
Rodrigues GB, Waldron JN, Wong CS, Laperrier NJ. A retrospective analysis of 52 cases of spinal cord glioma managed with radiation therapy. Int J Rad Onc Biol Phys 2000;48:837-842.
Lowis SP, Pizer BL, Coakham H, et al. Chemotherapy for spinal cord astroctyoma: can natural history be modified? Child Nerv Syst 1998;14:317-321.
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