The Value of Radiation Therapy in the Management of Intrinsic Tumors of the Spinal Cord

Abstract

Intrinisic tumors of the spinal cord arise from neuronal tissue, glial cells, vascular structures, and occasionally from other cellular components of the spinal medulla. Tumors which arise from the meninges and nerve root sheaths or which result from the developmental inclusion of foreign dermal, fibrous or adipose tissue within the substance of the spinal cord are not truly intrinsic tumors. As in the brain, the majority of primary intrinsic spinal cord tumors are gliomas, but the growth characteristics and effects upon the host are not the same. It is the purpose of this paper to analyze the case histories of a relatively large number of patients with primary spinal cord tumor and to evaluate the effect of radiation therapy upon the course of the disease. Incidence and Pathology It is difficult to establish definitely the relative incidence of intraspinal tumors, either in comparison with intracranial tumors or with other neurologic diseases, since necropsy material, even in large metropolitan hospitals, is meager and unrepresentative. Gliomas of the spinal cord, however, are encountered much less frequently than their intracranial counterparts. In an attempt to establish a ratio, 500 consecutive surgically verified central nervous system glial tumors encountered at the Neurological Institute of New York in recent years were analyzed, with the result that 7 per cent were found to originate within the spinal cord. The incidence is higher than that reported earlier by Wolf (16), Elsberg (6), and others. A possible explanation of the current high incidence is the refinement of neurologic and radiologic diagnosis, and the use of myelography, in particular, to differentiate expanding spinal lesions from degenerative diseases (Figs. 2 and 3). An indication of the relative frequency of intrinsic new growths in relation to all spinal cord tumors is gained from an analysis of the large series of 979 intraspinal neoplasms studied by Woltman, Kernohan, Adson and Craig (17). These investigators found that 22.5 per cent of this group of almost a thousand spinal tumors were gliomas. Approximately 56 per cent were schwannomas and meningiomas; the remainder, aside from the glial tumors, comprised extradural sarcoma, hemangioma, chordoma, dermoid, and neoplasms of miscellaneous tissue types. Regardless of the histologic nature of spinal cord glioma, the gross pathologic change is an enlargement of the spinal cord within its pial covering and derangement of normal topography. Since the tumors infiltrate and expand the medullary substance (but generally are retained by the pia mater), their longitudinal extent may involve several spinal segments, with the result that externally the appearance often is a fusiform enlargement of the spinal cord (Fig.1). Usually the involved cord is pale or purplish; if tumor presents at the cord surface, it may appear grayish white, reddish gray, or reddish blue.