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Metastatic Tumors of the Spinal Canal
Metastatic TUlllors
of the Spinal Canal From the Department of Neurosurgery, Palo Alto Medical Clinic, Palo Alto, California
JAMES B. GOLDEN, M.D., F.A.C.S.
A SURGICAL consideration of metastatic spinal tumors starts with the premise that these patients have elsewhere, perhaps undisclosed, a serious disease that seriously threatens life expectancy. As the results in treatment of primary lesions constantly improve, it becomes even more important to prevent disability from the effects of metastatic lesions. Delayed treatment of metastatic lesions in the spinal canal uniformly results in the severe consequences of the paraplegic state. The clinical characteristics and results of treatment in collected series have been well tabulated and discussed in several recent papers. I , 2,6 These reports illustrate that the clinical picture created by these tumors is remarkably similar from case to case, regardless of the primary site. When compared with the course of benign intraspinal tumors, malignant lesions cause a more rapidly developing paralysis. It appears that paraplegia of rapid onset from neoplastic compression is frequently not reversed by surgical decompression. Thus, early diagnosis and treatment are stressed. Malignant tumors in the spinal canal can be classified, according to origin, into three main groups: (1) malignant lymphomas, (2) malignant tumors of adjacent tissues, and (3) metastatic tumors of epithelial or connective tissue origin. While this classification is of little importance in terms of diagnosis and specific treatment of the spinal lesion, it can be related to prognosis. It appears that immediate surgical results are more satisfactory when the neoplasm is one of the forms of lymphoma or myeloma rather than carcinoma or sarcoma. The same may be said of the results of radiation treatment which is usually employed following surgical decompression. Other reports discuss specifically the special features of malignant lymphomas and myeloma.": 4,5 It is the purpose
1349
1350
JAMES
B.
GOLDEN
of this paper to discuss the principles that may lead to a higher incidence of prevention of paraplegia from malignant tumors of the spinal canal. SURGICAL PATHOLOGY
Metastatic tumors of the spinal canal are extradural in location. The much less frequent carcinomatous involvement of the subarachnoid space and rare metastasis within the substance of the spinal cord differ clinically and do not represent surgical problems. The extradural space of the spinal canal is normally occupied by a thin fascial layer containing large lobules of fat and a rich plexus of veins. This venous plexus, which anastomoses freely with branches of pelvic veins, lumbar and intercostal radicles and directly with the venous channels of vertebral bodies, is a major portal of entry for blood-borne metastases. This venous plexus is readily seen in venograms as a major collateral route if there is caval or iliac obstruction, such as may occur with pelvic or retroperitoneal neoplasm. If the extradural space is thought of as circular, the dura represents the inner limit, and this dense, fibrous tissue acts as a barrier to the invasion of the leptomeninges and spinal cord by malignant neoplasm. The outer limit may be regarded as the posterior longitudinal ligaments, the ligamenta flava, and the pedicles of the vertebral arches. Thus the outer limit is perforated regularly by intervertebral foramina, representing another major ingress route for malignant neoplasm involving paravertebral structures. A malignant lesion within a vertebral body will usually give rise to acute local symptoms resulting from pathological compression fracture, and, even though recognized and treated, may later erode through the posterior ligaments into the extradural space. The fact that a great majority of extradural metastatic tumors occur in the thoracic portion of the spinal canal and a preponderance of these in the upper thoracic portion must be related to the above factors, particularly the anatomical relationship of paravertebral lymphatic channels to the intervertebral foramina and extradural venous systems. In general, the major exceptions to the thoracic location of metastatic neoplasm are the greater variability in location of lymphomas and the direct extensions of vertebral body metastases at any level of the spine. If a cancer cell embolus lodges in the extradural venous plexus and thrives, it soon, through enlargement, begins to deform the dura and cord, thus giving rise to neurological symptoms of cord compression. Further tumor enlargement extends not only longitudinally but also in annular fashion and in so doing will compress nerve roots against the walls of their foramina and give rise to neuralgic pain. A metastasis of this type affects the cord and nerve roots in the same way as a benign tumor of the spinal canal and, if removed before the spinal cord has sustained permanent injury, will be followed by prompt recovery of function.
Metastatic Tumors of the Spinal Canal
1351
A paravertebral metastasis in the abdomen or chest that has grown to sufficient size to invade the vertebral arches and intervertebral foramina and gain access to the spinal canal will already have encircled one or more spinal nerves and will have caused neuralgic pain. By the time it has attained sufficient size in the extradural space to cause neurological symptoms of cord compression, it may well have interfered sufficiently with the radicular blood supply to the cord that neurological symptoms of spinal cord disease will have developed for this reason alone, and removal of extradural neoplasm will not effect clinical improvement. Thus, one would expect to be able to correlate clinical course following surgical decompression with: (1) duration of symptoms of cord compression, and (2) an estimate from clinical and operative findings whether the metastasis was blood-borne and originated in the extradural space or rather entered by extension from the vertebral column or paravertebral region. SYMPTOMS
The sequence of symptoms is quite similar from one case to another and all too familiar to the neurosurgeon, who will often receive a firsthand account from earliest symptom to marked or complete disability. Therefore the known clinical features of a developing spinal extradural metastasis should be reviewed with an eye toward earlier diagnosis. Most of these patients will give a past history of known malignant neoplasm, but in a few the symptoms of spinal cord or nerve root compression will be the first symptom of disease. Pain in the back, often interscapular in location because of the predominately upper thoracic location of these tumors, is usually the earliest and a nearly constant symptom. Associated with this local pain there is frequently girdle pain about one or both sides. This pain, due to involvement of one or more nerve roots, is usually about the chest or upper abdomen because the tumor is so often in the thoracic portion of the spinal canal, but, of course, may occur elsewhere in the trunk or extremities depending upon the spinal level of the tumor. Local pain, with or without root pain, is often a complaint for weeks or months before there are definite signs of cord compression. In contrast to the long duration of local pain, symptoms of cord compression advance rapidly. Weakness in the legs or ataxia of the legs often is noticed first, to be followed in a very short time by paresthesias and numbness in one or both legs. As walking becomes more difficult and sensory loss more pronounced, bladder retention and then greater bladder and bowel impairment occur. This sequence of events will usually occur over a period of one or two weeks. As the paralysis becomes more pronounced, the rate of progression seems to increase, and changes in function can be seen from hour to hour.
1352
JAMES
B.
GOLDEN
DIAGNOSIS
X-ray Examination of the Spine
Once the diagnosis is suspected, x-ray films of the entire spine should be obtained. Because the early signs of cord compression, even in the upper spine, occur first in the feet or legs, and attention of both doctor and patient focuses on the lower extremities, there is a tendency to restrict radiographic examination to the lower spine rather than the more likely location of upper spine. More often than not, absence of or destruction of one or more pedicles can be seen and may be associated with visible destruction in transverse process or some other portion of the vertebra as well. This abnormality differs in appearance from the erosion of the medial aspect of the pedicle that may occur with primary intradural tumors. A paravertebral soft tissue mass may show by film and, if present, will occur adjacent to areas of vertebral destruction as described above. Lumbar Puncture and Myelography
Regardless of findings on x-ray examination, if there is suspicion of spinal neoplasm, myelography should be performed and spinal fluid studies can be done at the time. When the lumbar puncture is done for this purpose, the fluid may run slowly and manometric studies may show evidence of spinal block. In this event, the fluid may be tinged yellow, but usually not because of the relatively short duration of spinal block with malignant neoplasms. If there does appear to be a spinal block, only a small amount of contrast medium is introduced in the event that it will be impossible to remove it later by aspiration because of impeded flow. If at fluoroscopy a constant defect or complete obstruction to the flow of contrast medium is demonstrated with the patient in a steep degree of head-downward tilt, a small lead marker is placed on the skin at this exact level, and the skin is later marked at this point as a guide to accurate surgical exposure. If some question exists as to the exact level or degree of spinal block, the lumbar puncture needle may be removed, and the fluoroscopic examination done with the patient supine, thus overcoming the disadvantageous course of the normal thoracic kyphosis that exists in the prone position. In addition to the importance of determining with accuracy that a significant intraspinal defect does exist and precisely identifying its location, two other points in this part of the examination bear emphasis. The first is that a lumbar puncture not be done unless one is prepared to introduce contrast medium at that time and proceed with a complete myelographic study. The second is that one should be prepared to proceed immediately with surgical exploration of any intraspinal lesion that is causing a complete subarachnoid block. These principles are based
Metastatic Tumors of the Spinal Canal
1353
upon clinical observations of cerebrospinal fluid distribution under abnormal conditions. One common observation is that if a lumbar puncture is attempted within 24 or 48 hours following a previous one, there may be difficulty placing the needle entirely within the subarachnoid space. Following the first tap, fluid may continue to leak through the arachnoid perforation into the subdural space, collapsing the normally distended arachnoid. Under this condition a subarachnoid tap cannot be done, but a subdural tap results. Pressure readings and cerebrospinal fluid flow are then greatly reduced, and contrast medium injected into this compartment will not flow readily for more than a few segments. Thus a definite hazard is created by a necessary delay in diagnosis. Another observation is the well-known fact that if an intraspinal tumor is creating a subarachnoid block, and fluid pressure in the thecal sac below this lesion is sharply reduced by lumbar puncture, acute cord compression may result at the site of the tumor. For the above reasons it is always preferable, in cases of suspected intraspinal neoplasm, that lumbar puncture and myelography be done within the schedule of the neurosurgeon. Once a subarachnoid block or a major defect is identified by myelography, the patient should be prepared for operation as soon as possible. In the course of impending paraplegia, if no defect is demonstrated by myelography, the cord lesion can be assumed to be due to vascular insufficiency of the spinal cord, and laminectomy is not indicated. Vascular insufficiency will occur in association with metastatic lesions of the paravertebral region and intervertebral foramina from mechanical compression of segmental vessels that accompany the nerve roots and contribute significantly to the total blood supply of the spinal cord. Thrombosis of the anterior spinal artery as a primary phenomenon, other than occurring as a painless condition, may bear a close resemblance to the clinical picture of malignant extradural tumor, but is readily differentiated at myelography by absence of any defect. Dissecting aneurysm of the aorta may at first produce symptoms resembling those of cord compression and, if not diagnosed on physical examination alone, will be attended with normal findings on myelographic study. SURGICAL DECOMPRESSION
When the clinical and roentgenographic evidence indicates that the cord compression does exist, surgical decompression should be done as an emergency operation. The proper conduct of this procedure, which is done with the patient prone, includes the availability of blood for transfusion, adequate support of chest and abdomen on bolsters to assure unimpeded respiratory movement, and general endotracheal anesthesia. The skin scratch made at the level of block during the
1354
JAMES
B.
GOLDEN
myelogram is used as a guide in making the skin incision. Exposure is planned so that laminectomy is begun one segment caudad to the level of block in order that removal of bone can be started over normal dura. Laminal arches and pedicles may be fragile from tumor invasion and heavy downward pressure with instruments should be avoided to prevent plunging through and damaging the spinal cord. Because of this possibility, it is preferable to separate the muscles from the spines and laminae by sharp dissection. Evidence of malignant tumor may be seen grossly in the laminae, facets, ligaments or paraspinal musculature. Laminectomy is then done, proceeding upward over the tumor and continuing cephalad until normal dura again comes into view. The bony decompression is then extended laterally on both sides. The malignant tumor that occupies the extradural space is easily removed piecemeal with grasping instruments. Tumor should be removed from the dorsal and lateral aspects of the dura, but the dura should not be retracted to remove all the tumor that may lie ventrally, since the spinal cord is unable to withstand such additional compression. It must be kept in mind that the object of surgical intervention is merely to relieve acute spinal cord compression and that it may not be possible by surgical means to accomplish complete eradication of tumor. Removal of tumor results in opening numerous extradural veins and is always accompanied by brisk bleeding. When bleeding has been controlled the deep layers are closed with wire to minimize later reaction, particularly if radiation treatment is to be given. Postoperative Management
Postoperative care is essentially the same as paraplegic care until the needs of a given case can be determined. Cardinal in this management are the prevention of skin injury and bladder distention and adequate relief of pain to permit proper respiratory expansion. The neurological status of the lower extremities must be determined frequently. If there is further progressive loss of function, one must consider the probability of postoperative blood clot and be prepared to reopen the wound. If the biopsy specimens indicate the neoplasm to be even possibly radiosensitive, radiation therapy should be started within a few days, as soon as postoperative edema has subsided. Again it must be kept in mind that surgical treatment is the safest means of alleviating cord compression, but any long-term control of a malignant neoplasm must be accomplished by adequate radiation therapy. The one exception to primary surgical intervention is the alternative course, in cases of known lymphoma, when the myelographic defect is small and neurological signs minimal, that radiation treatment be used without exploration and biopsy. In such cases it is necessary to watch for evidence of neurological progression during the course of therapy.
Metastatic Tumors of the Spinal Canal
1355
COMMENT
In treating metastatic tumors of the spinal canal, one can expect a rela tively high percentage of failures because of the irreversible vascular insufficiency of the spinal cord that will often result from extensive paraspinal neoplastic destruction. However, in those cases in which paralysis is mainly due to spinal cord compression, early surgical decompression followed by radiation treatment will often produce improvement and prevent paraplegia. The factors that determine results are so unpredictable that all cases with clinical and radiographic evidence of spinal block should be treated surgically. Even though overall prognosis may be poor for long life expectancy, an ambulatory patient with cancer is preferable to a paraplegic one. At the present time results of treatment can be improved only by earlier recognition and treatment. As our methods for the treatment and control of cancer improve, it becomes even more important to prevent severe incapacitating side effects of malignant disease. REFERENCES 1. Alexander, E., Davis, C. H. and Field, C. H.: Metastatic lesions of the vertebral
column causing cord compression. Neurology 6: 103-107, 1956. 2. Botterell, E. H. and Fitzgerald, G. W.: Spinal cord compression produced by extradural malignant tumors. Canad. M.A.J. 80: 791-796, 1959. 3. Bucy, P. C. and Jerva, M. J.: Primary epidural spinal lymphosarcoma. J. Neurosurge 19: 142-152, 1962. 4. Hayes, D. W., Bennett, W. A. and Heck, F. J.: Extramedullary lesions in multiple myeloma. Review of literature and pathologic studies. Arch. Path. 53: 262272, 1952. 5. Love, J. G., Miller, R. H. and Kernohan, J. W.: Lymphomas of spinal epidural space. Arch. Surge 69:66-75,1954. 6. Mullan, J. and Evans, J. P.: Neoplastic disease of the spinal extradural space. Arch. Surge 74: 900-907, 1957. 7. Perese, D. M. and Fracasso, J. E.: Anatomical considerations in surgery of the spinal cord. J. Neurosurg. 16: 314-325, 1959.
of the Spinal Canal From the Department of Neurosurgery, Palo Alto Medical Clinic, Palo Alto, California
JAMES B. GOLDEN, M.D., F.A.C.S.
A SURGICAL consideration of metastatic spinal tumors starts with the premise that these patients have elsewhere, perhaps undisclosed, a serious disease that seriously threatens life expectancy. As the results in treatment of primary lesions constantly improve, it becomes even more important to prevent disability from the effects of metastatic lesions. Delayed treatment of metastatic lesions in the spinal canal uniformly results in the severe consequences of the paraplegic state. The clinical characteristics and results of treatment in collected series have been well tabulated and discussed in several recent papers. I , 2,6 These reports illustrate that the clinical picture created by these tumors is remarkably similar from case to case, regardless of the primary site. When compared with the course of benign intraspinal tumors, malignant lesions cause a more rapidly developing paralysis. It appears that paraplegia of rapid onset from neoplastic compression is frequently not reversed by surgical decompression. Thus, early diagnosis and treatment are stressed. Malignant tumors in the spinal canal can be classified, according to origin, into three main groups: (1) malignant lymphomas, (2) malignant tumors of adjacent tissues, and (3) metastatic tumors of epithelial or connective tissue origin. While this classification is of little importance in terms of diagnosis and specific treatment of the spinal lesion, it can be related to prognosis. It appears that immediate surgical results are more satisfactory when the neoplasm is one of the forms of lymphoma or myeloma rather than carcinoma or sarcoma. The same may be said of the results of radiation treatment which is usually employed following surgical decompression. Other reports discuss specifically the special features of malignant lymphomas and myeloma.": 4,5 It is the purpose
1349
1350
JAMES
B.
GOLDEN
of this paper to discuss the principles that may lead to a higher incidence of prevention of paraplegia from malignant tumors of the spinal canal. SURGICAL PATHOLOGY
Metastatic tumors of the spinal canal are extradural in location. The much less frequent carcinomatous involvement of the subarachnoid space and rare metastasis within the substance of the spinal cord differ clinically and do not represent surgical problems. The extradural space of the spinal canal is normally occupied by a thin fascial layer containing large lobules of fat and a rich plexus of veins. This venous plexus, which anastomoses freely with branches of pelvic veins, lumbar and intercostal radicles and directly with the venous channels of vertebral bodies, is a major portal of entry for blood-borne metastases. This venous plexus is readily seen in venograms as a major collateral route if there is caval or iliac obstruction, such as may occur with pelvic or retroperitoneal neoplasm. If the extradural space is thought of as circular, the dura represents the inner limit, and this dense, fibrous tissue acts as a barrier to the invasion of the leptomeninges and spinal cord by malignant neoplasm. The outer limit may be regarded as the posterior longitudinal ligaments, the ligamenta flava, and the pedicles of the vertebral arches. Thus the outer limit is perforated regularly by intervertebral foramina, representing another major ingress route for malignant neoplasm involving paravertebral structures. A malignant lesion within a vertebral body will usually give rise to acute local symptoms resulting from pathological compression fracture, and, even though recognized and treated, may later erode through the posterior ligaments into the extradural space. The fact that a great majority of extradural metastatic tumors occur in the thoracic portion of the spinal canal and a preponderance of these in the upper thoracic portion must be related to the above factors, particularly the anatomical relationship of paravertebral lymphatic channels to the intervertebral foramina and extradural venous systems. In general, the major exceptions to the thoracic location of metastatic neoplasm are the greater variability in location of lymphomas and the direct extensions of vertebral body metastases at any level of the spine. If a cancer cell embolus lodges in the extradural venous plexus and thrives, it soon, through enlargement, begins to deform the dura and cord, thus giving rise to neurological symptoms of cord compression. Further tumor enlargement extends not only longitudinally but also in annular fashion and in so doing will compress nerve roots against the walls of their foramina and give rise to neuralgic pain. A metastasis of this type affects the cord and nerve roots in the same way as a benign tumor of the spinal canal and, if removed before the spinal cord has sustained permanent injury, will be followed by prompt recovery of function.
Metastatic Tumors of the Spinal Canal
1351
A paravertebral metastasis in the abdomen or chest that has grown to sufficient size to invade the vertebral arches and intervertebral foramina and gain access to the spinal canal will already have encircled one or more spinal nerves and will have caused neuralgic pain. By the time it has attained sufficient size in the extradural space to cause neurological symptoms of cord compression, it may well have interfered sufficiently with the radicular blood supply to the cord that neurological symptoms of spinal cord disease will have developed for this reason alone, and removal of extradural neoplasm will not effect clinical improvement. Thus, one would expect to be able to correlate clinical course following surgical decompression with: (1) duration of symptoms of cord compression, and (2) an estimate from clinical and operative findings whether the metastasis was blood-borne and originated in the extradural space or rather entered by extension from the vertebral column or paravertebral region. SYMPTOMS
The sequence of symptoms is quite similar from one case to another and all too familiar to the neurosurgeon, who will often receive a firsthand account from earliest symptom to marked or complete disability. Therefore the known clinical features of a developing spinal extradural metastasis should be reviewed with an eye toward earlier diagnosis. Most of these patients will give a past history of known malignant neoplasm, but in a few the symptoms of spinal cord or nerve root compression will be the first symptom of disease. Pain in the back, often interscapular in location because of the predominately upper thoracic location of these tumors, is usually the earliest and a nearly constant symptom. Associated with this local pain there is frequently girdle pain about one or both sides. This pain, due to involvement of one or more nerve roots, is usually about the chest or upper abdomen because the tumor is so often in the thoracic portion of the spinal canal, but, of course, may occur elsewhere in the trunk or extremities depending upon the spinal level of the tumor. Local pain, with or without root pain, is often a complaint for weeks or months before there are definite signs of cord compression. In contrast to the long duration of local pain, symptoms of cord compression advance rapidly. Weakness in the legs or ataxia of the legs often is noticed first, to be followed in a very short time by paresthesias and numbness in one or both legs. As walking becomes more difficult and sensory loss more pronounced, bladder retention and then greater bladder and bowel impairment occur. This sequence of events will usually occur over a period of one or two weeks. As the paralysis becomes more pronounced, the rate of progression seems to increase, and changes in function can be seen from hour to hour.
1352
JAMES
B.
GOLDEN
DIAGNOSIS
X-ray Examination of the Spine
Once the diagnosis is suspected, x-ray films of the entire spine should be obtained. Because the early signs of cord compression, even in the upper spine, occur first in the feet or legs, and attention of both doctor and patient focuses on the lower extremities, there is a tendency to restrict radiographic examination to the lower spine rather than the more likely location of upper spine. More often than not, absence of or destruction of one or more pedicles can be seen and may be associated with visible destruction in transverse process or some other portion of the vertebra as well. This abnormality differs in appearance from the erosion of the medial aspect of the pedicle that may occur with primary intradural tumors. A paravertebral soft tissue mass may show by film and, if present, will occur adjacent to areas of vertebral destruction as described above. Lumbar Puncture and Myelography
Regardless of findings on x-ray examination, if there is suspicion of spinal neoplasm, myelography should be performed and spinal fluid studies can be done at the time. When the lumbar puncture is done for this purpose, the fluid may run slowly and manometric studies may show evidence of spinal block. In this event, the fluid may be tinged yellow, but usually not because of the relatively short duration of spinal block with malignant neoplasms. If there does appear to be a spinal block, only a small amount of contrast medium is introduced in the event that it will be impossible to remove it later by aspiration because of impeded flow. If at fluoroscopy a constant defect or complete obstruction to the flow of contrast medium is demonstrated with the patient in a steep degree of head-downward tilt, a small lead marker is placed on the skin at this exact level, and the skin is later marked at this point as a guide to accurate surgical exposure. If some question exists as to the exact level or degree of spinal block, the lumbar puncture needle may be removed, and the fluoroscopic examination done with the patient supine, thus overcoming the disadvantageous course of the normal thoracic kyphosis that exists in the prone position. In addition to the importance of determining with accuracy that a significant intraspinal defect does exist and precisely identifying its location, two other points in this part of the examination bear emphasis. The first is that a lumbar puncture not be done unless one is prepared to introduce contrast medium at that time and proceed with a complete myelographic study. The second is that one should be prepared to proceed immediately with surgical exploration of any intraspinal lesion that is causing a complete subarachnoid block. These principles are based
Metastatic Tumors of the Spinal Canal
1353
upon clinical observations of cerebrospinal fluid distribution under abnormal conditions. One common observation is that if a lumbar puncture is attempted within 24 or 48 hours following a previous one, there may be difficulty placing the needle entirely within the subarachnoid space. Following the first tap, fluid may continue to leak through the arachnoid perforation into the subdural space, collapsing the normally distended arachnoid. Under this condition a subarachnoid tap cannot be done, but a subdural tap results. Pressure readings and cerebrospinal fluid flow are then greatly reduced, and contrast medium injected into this compartment will not flow readily for more than a few segments. Thus a definite hazard is created by a necessary delay in diagnosis. Another observation is the well-known fact that if an intraspinal tumor is creating a subarachnoid block, and fluid pressure in the thecal sac below this lesion is sharply reduced by lumbar puncture, acute cord compression may result at the site of the tumor. For the above reasons it is always preferable, in cases of suspected intraspinal neoplasm, that lumbar puncture and myelography be done within the schedule of the neurosurgeon. Once a subarachnoid block or a major defect is identified by myelography, the patient should be prepared for operation as soon as possible. In the course of impending paraplegia, if no defect is demonstrated by myelography, the cord lesion can be assumed to be due to vascular insufficiency of the spinal cord, and laminectomy is not indicated. Vascular insufficiency will occur in association with metastatic lesions of the paravertebral region and intervertebral foramina from mechanical compression of segmental vessels that accompany the nerve roots and contribute significantly to the total blood supply of the spinal cord. Thrombosis of the anterior spinal artery as a primary phenomenon, other than occurring as a painless condition, may bear a close resemblance to the clinical picture of malignant extradural tumor, but is readily differentiated at myelography by absence of any defect. Dissecting aneurysm of the aorta may at first produce symptoms resembling those of cord compression and, if not diagnosed on physical examination alone, will be attended with normal findings on myelographic study. SURGICAL DECOMPRESSION
When the clinical and roentgenographic evidence indicates that the cord compression does exist, surgical decompression should be done as an emergency operation. The proper conduct of this procedure, which is done with the patient prone, includes the availability of blood for transfusion, adequate support of chest and abdomen on bolsters to assure unimpeded respiratory movement, and general endotracheal anesthesia. The skin scratch made at the level of block during the
1354
JAMES
B.
GOLDEN
myelogram is used as a guide in making the skin incision. Exposure is planned so that laminectomy is begun one segment caudad to the level of block in order that removal of bone can be started over normal dura. Laminal arches and pedicles may be fragile from tumor invasion and heavy downward pressure with instruments should be avoided to prevent plunging through and damaging the spinal cord. Because of this possibility, it is preferable to separate the muscles from the spines and laminae by sharp dissection. Evidence of malignant tumor may be seen grossly in the laminae, facets, ligaments or paraspinal musculature. Laminectomy is then done, proceeding upward over the tumor and continuing cephalad until normal dura again comes into view. The bony decompression is then extended laterally on both sides. The malignant tumor that occupies the extradural space is easily removed piecemeal with grasping instruments. Tumor should be removed from the dorsal and lateral aspects of the dura, but the dura should not be retracted to remove all the tumor that may lie ventrally, since the spinal cord is unable to withstand such additional compression. It must be kept in mind that the object of surgical intervention is merely to relieve acute spinal cord compression and that it may not be possible by surgical means to accomplish complete eradication of tumor. Removal of tumor results in opening numerous extradural veins and is always accompanied by brisk bleeding. When bleeding has been controlled the deep layers are closed with wire to minimize later reaction, particularly if radiation treatment is to be given. Postoperative Management
Postoperative care is essentially the same as paraplegic care until the needs of a given case can be determined. Cardinal in this management are the prevention of skin injury and bladder distention and adequate relief of pain to permit proper respiratory expansion. The neurological status of the lower extremities must be determined frequently. If there is further progressive loss of function, one must consider the probability of postoperative blood clot and be prepared to reopen the wound. If the biopsy specimens indicate the neoplasm to be even possibly radiosensitive, radiation therapy should be started within a few days, as soon as postoperative edema has subsided. Again it must be kept in mind that surgical treatment is the safest means of alleviating cord compression, but any long-term control of a malignant neoplasm must be accomplished by adequate radiation therapy. The one exception to primary surgical intervention is the alternative course, in cases of known lymphoma, when the myelographic defect is small and neurological signs minimal, that radiation treatment be used without exploration and biopsy. In such cases it is necessary to watch for evidence of neurological progression during the course of therapy.
Metastatic Tumors of the Spinal Canal
1355
COMMENT
In treating metastatic tumors of the spinal canal, one can expect a rela tively high percentage of failures because of the irreversible vascular insufficiency of the spinal cord that will often result from extensive paraspinal neoplastic destruction. However, in those cases in which paralysis is mainly due to spinal cord compression, early surgical decompression followed by radiation treatment will often produce improvement and prevent paraplegia. The factors that determine results are so unpredictable that all cases with clinical and radiographic evidence of spinal block should be treated surgically. Even though overall prognosis may be poor for long life expectancy, an ambulatory patient with cancer is preferable to a paraplegic one. At the present time results of treatment can be improved only by earlier recognition and treatment. As our methods for the treatment and control of cancer improve, it becomes even more important to prevent severe incapacitating side effects of malignant disease. REFERENCES 1. Alexander, E., Davis, C. H. and Field, C. H.: Metastatic lesions of the vertebral
column causing cord compression. Neurology 6: 103-107, 1956. 2. Botterell, E. H. and Fitzgerald, G. W.: Spinal cord compression produced by extradural malignant tumors. Canad. M.A.J. 80: 791-796, 1959. 3. Bucy, P. C. and Jerva, M. J.: Primary epidural spinal lymphosarcoma. J. Neurosurge 19: 142-152, 1962. 4. Hayes, D. W., Bennett, W. A. and Heck, F. J.: Extramedullary lesions in multiple myeloma. Review of literature and pathologic studies. Arch. Path. 53: 262272, 1952. 5. Love, J. G., Miller, R. H. and Kernohan, J. W.: Lymphomas of spinal epidural space. Arch. Surge 69:66-75,1954. 6. Mullan, J. and Evans, J. P.: Neoplastic disease of the spinal extradural space. Arch. Surge 74: 900-907, 1957. 7. Perese, D. M. and Fracasso, J. E.: Anatomical considerations in surgery of the spinal cord. J. Neurosurg. 16: 314-325, 1959.