A spinal tumor is a growth that can originate from the sac that surrounds the spinal cord (meninges) or from the substance of the cord itself.

Tumors of the spinal cord most often begin with very subtle deficits that slowly progress to marked dysfunction.

Prognosis for spinal tumors is fair for those that are extradural if they are situated in an area accessible to the surgeon for removal.

What is a Spinal Tumor?

• A spinal tumor is a growth that can originate from the sac that surrounds the spinal cord (meninges) or from the substance of the cord itself.
• Tumors of the bones of the spinal bones can also compress the spinal cord. These may include osteosarcoma, chondrosarcoma, or fibrosarcoma.
• Spinal cord tumors can be from spread from tumors located in other parts of the body. About 30% of hemangiosarcoma tumors (tumors of the spleen and liver) spread to the brain and spinal cord. Lymphoma is possible as well.
  
   
  

Clinical Signs

• Perhaps the feature of spinal cord tumors that distinguishes them from most orthopedic causes of spinal dysfunction is the clinical history.
• Tumors of the spinal cord most often begin with very subtle deficits that slowly progress to marked dysfunction.
• Pain is seldom a major feature of the clinical course, although its presence or absence does not rule definitively on the existence of a tumor. It is true that occasional cases of disk prolapse will present with relatively long and progressive histories, and that a myelogram (and possibly surgery) might be required to clearly distinguish between these atypical disk prolapses and tumors in the spinal canal. In general spinal cord signs that progress over more than a 2-week period strongly suggest either tumor or degenerative myelopathy.
• The nature of the progressive neural deficits depends, of course, on the location of the tumor within and along the spinal cord. Often the deficits begin or are most marked on one side or the other. For spinal tumors this is the side on which the lesion is predominantly located. As the tumor expands to occupy more space, the severity of the deficits becomes more marked and more deficits may begin to appear.
• Possibly because of the slower growth, proportionately more compromise of the spinal canal seems to be required by tumors than by disk prolapse to produce equivalent clinical deficits. Consequently, if an animal's condition is severe enough to warrant myelography, the radiographic results are often diagnostic in the case of spinal tumors. On occasion, however, a tumor may so impede the flow of dye in the subarachnoid space that only one limit of the tumor may be defined by a single injection. In such situations it is a good idea to make a second injection (i.e., a lumbar injection if the first was cisternal) to define the other limit of the tumor so that the entire extent of the tumor can be determined prior to the final decision regarding the feasibility of surgery.
   
  

Diagnosis

• Other special studies such as needle electromyography (EMG) may also be used to confirm the location of spinal pathology produced by tumors.(2) The value of these studies is dubious at best, however, since myelographic evidence is required before surgery is contemplated. Further, the value of EMG studies in the location of focal spinal cord pathology is lessened by the fact that many older dogs have mild focal signs of denervation in the epaxial musculature that may be related to mild subclinical root disease. Needle EMG may help serve as evidence against focal gray-matter disease in certain suspected spinal tumor cases in which myelography has failed to demonstrate a space-occupying lesion (see below). Tumors of the spinal canal can be divided into three types on the basis of their location with respect to the spinal cord and dura: Extradural, outside the spinal cord; intradural extramedullary, in the dura but not invading the neural substance of the spinal cord; and intramedullary, growing within the substance of the cord. The prognosis of each case can be based on two principal factors: the anatomical type of the tumor, which can often be discerned from the myelogram, and the cell type of the tumor, which can be determined only from histopathology. A more complete discussion of tumor types has been presented by deLahunta.(3)
   
  

Prognosis

• Prognosis for spinal tumors is fair for those that are extradural if they are situated in an area accessible to the surgeon for removal. If the entire tumor is removable, the prognosis is dependent upon the histologic tumor type. Unfortunately, many of the extradural tumors are metastatic in nature.(3) Intramedullary tumors are essentially inoperable and have a poor prognosis

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