Spinal Tumors (Continued)

The two most common intramedullary tumors are astrocytomas and ependymomas. Astrocytomas are infiltrative, and total excision is not possible; however, there is frequently a well-demarcated plane around ependymomas, permitting their excision. Intramedullary metastatic deposits also occur, and improved imaging has resulted in their being recognized with increasing frequency. Surgery on the spinal cord demands the most meticulous technique. If the tumor is not completely excised, radiation therapy may be indicated.

Intradural tumors of the lumbar spine involve the conus medullaris, filum terminale, and cauda equina. Both ependymomas and astrocytomas may arise from the conus medullaris. These tumors produce early deficits of sphincter and sexual function, and are difficult to remove without incurring significant neurologic deficit. Ependymomas of the filum terminale (see Plate 2-22) cause pain, often without significant neurologic findings, and can be cured by surgical excision.

The diffuse myxopapillary ependymoma, which involves the roots of the cauda equina, is difficult to excise and should receive postoperative radiation therapy. A neurilemmoma or a meningioma can be successfully removed. Lipoma of the cauda equina arises from fetal rests and is associated with spina bifida occulta. Excision of this tumor is difficult, but meticulous microsurgery can reduce the tumor and preserve neurologic function.

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