The spinal cord is the great nerve that runs from the base of the brain to the bottom of the back. Throughout its length it lies in a canal within the vertebrae, the bones of the spine, which protect the sensitive nerve tissue.
As it passes through each of the vertebrae the spinal cord gives off the roots of nerves which pass through holes in the vertebrae. These nerve roots go on to form the nerves supplying all the muscles and skin of the various parts of the body. Different parts of the spinal cord supply the nerves for different parts of the body, for example the part of the cord which lies in the neck and upper chest provides the nerves for the arms whereas the nerves for the leg come from part of the cord which lies in the lower part of the back, the lumbar spine.
Spinal cord compression is a condition that causes pressure on the spinal cord, leading to narrowing or distortion of the nerve tissue. There are many different causes of spinal cord compression including injuries, and 'slipped discs' as well as cancer.
When spinal cord compression is caused by cancer it usually develops in one of two ways. Either there is damage to one or more of the vertebrae from cancer cells(which have usually come from cancers elsewhere in the body). This causes swelling, distortion or collapse of the bone which then presses on the spinal cord, damaging the nerve tissue. Alternatively these cancer cells may come to lodge between the bony vertebrae and the spinal cord, as these grow they then squeeze the cord against the vertebrae and, once again, causing pressure on the nerve.
Although secondary cancers in the vertebrae are quite common only a small proportion will actually lead to spinal cord compression.
When a cancer causes pressure on the spinal cord two main types of symptom can occur. Firstly there is likely to be pain in the back at the level of the spine which is affected. Secondly there is likely to be damage to the nerve roots at this level and this can lead to symptoms in other parts of the body. For example if the cord compression is in the lower part of the spine then parts of one (or both) leg(s) may be affected with numbness, tingling and loss of power and movement. Similarly if the problem lies in the upper part of the spinal column then there may be a loss of power and sensation in parts of the arm(s) or hand(s).
If the cord compression gets more severe it can also lead to weakness below the place where there are secondary cancers and can sometimes affect bladder and bowel function.
If these symptoms develop then rapid treatment is needed in order to avoid any permanent damage to the sensitive nerve tissue of the spinal cord.
Usually MRI or CT scans will be done to confirm the diagnosis. Often, whilst these are being arranged, high doses of steroids will be given (usually a tablet called dexamethasone) as this reduces the inflammation and pressure on the spinal cord, and can help improve symptoms (such as pain) until other treatment is given.
Depending on the type of cancer, its position in the cord and its size the actual treatment of cord compression may either be an operation to remove the tumour, a short course of radiotherapy or some chemotherapy (or sometimes a combination of two or more of these).
The results of treatment vary but often there is excellent relief of symptoms. However, it is important, that cord compression is diagnosed and treated quickly, as this gives the best chance of treatment being successful. So any patient who has cancer and develops unexplained tingling, numbness or weakness in any of their limbs should seek immediate medical help.