What is myelopathy?
Myelopathy is the term used to describe the consequences of spinal cord compression. It characteristically occurs due to spinal cord compression in the neck (the cervical spine), although can occur more uncommonly in the thoracic spine (the portion of the spine within the rib cage). The causes for myelopathy are the same as described for brachialgia, namely a disc prolapse or more longstanding spondylotic changes in the spine. The reason for developing myelopathy rather than brachialgia (arm pain) is simply due to the anatomical location of the narrowing and resultant compression of the neurological structures. In myelopathy, the narrowing affects the main spinal canal with resultant compression on the spinal cord contained within. With brachialgia, the narrowing affects the exit channels for nerves emerging from the spinal cord, rather than the spinal cord itself. Not infrequently myelopathy and brachialgia can co-exist if a disc prolapse is compressing both the spinal cord and an exiting nerve root.
What symptoms can myelopathy cause?
The symptoms from cervical myelopathy can initially be very subtle and, therefore, potentially overlooked. It is essentially a painless condition because pressure on the spinal cord produces loss of function rather than pain in the affected limbs. People with myelopathy will often describe a numb and clumsy feeling in their hands. They lose dexterity, particularly for fine tasks such as handwriting. They may also experience reduced grip strength and have a tendency to drop things. The altered sensation in the hands can range from slight numbness to a more profound sense that the hands are completely numb, swollen and functionally of little use. The legs can be affected in a similar way. People may describe a numb, clumsy feeling in their legs as though they have lost a degree of control of leg function. This results in a gait which is shuffling and unsteady, often tripping easily and having to carefully watch where one is walking.
How is myelopathy treated?
If you have been diagnosed with spinal cord compression giving rise to the symptoms of myelopathy, you will almost certainly require surgery for this. Without surgery, this condition is likely to be progressive, and the resultant neurological dysfunction is likely to be irreversible. The reason for this is simply that the spinal cord has very poor capacity for repair, and any damage done to the spinal cord as a consequence of pressure on it, is usually permanent. The principal aim of surgery is to halt progression of symptoms, and any recovery of neurological function is unpredictable. Surgery is therefore often done on an urgent basis to achieve preservation of function.
What does surgery for myelopathy involve?
The precise surgical procedure for myelopathy depends on the cause of spinal cord compression, and the site. Given that the vast majority of myelopathy occurs in the cervical spine, the surgery will usually entail a decompression from either the front or the back of the neck. Very occasionally both of these procedures will need to be combined.
If the cause of the spinal cord compression is a disc prolapse, then it will be recommended that you have an anterior cervical discectomy as detailed elsewhere.
However, if the cause is more generalised narrowing of the spinal canal as a consequence of thickening of facet joints and ligaments and osteophyte formation (bony spurs), then a wider decompression from behind may be required. This is called a decompressive cervical laminectomy. This surgery will be carried out under a general anaesthetic with you in a prone position (facing down). It involves a vertical incision in the midline at the back of your neck, and the large muscles overlying the spine are mobilised away to expose the bony structures at the back of the spine. X-ray is used during the procedure to guide your surgeon to the precise point where the decompression is required. The spinous processes and lamina of the spine are then removed at the level(s) in question, along with the ligament at the back to the spine (the ligamentum flavum) which is almost always very thickened and contributing significantly to the spinal cord compression. It is usually possible to remove these structures without compromising the stability of the spine, however if there is concern about destabilising the spine, then metalwork can be placed to reinforce the spine.
What is the recovery following surgery for myelopathy?
Following a cervical laminectomy, pain can be more of an issue than with an anterior discectomy due to the greater muscle dissection involved. However, your experienced anaesthetist will be doing their utmost to ensure that discomfort is kept to a minimum. You are encouraged to start getting out of bed within the first 24 hours of surgery, as well as doing stretching exercises for your neck to try and minimise pain, muscle spasm and neck stiffness. You will usually be fit for discharge home within 2 or 3 days of surgery, although full recovery will take some weeks.
The neurological recovery following this surgery is variable. As mentioned above, the principal aim of a decompression is to halt any neurological deterioration, rather than improve your symptoms. Your surgeon will not be able to predict to what extent your pre-operative symptoms will be reversible, but the assumption should be that they will remain after surgery. However, in a proportion of patients, there will be some improvement, usually in a very gradual fashion. If there is an element of reversibility to your myelopathy, it may be as long as 18 months before you will see what the full extent of your recovery will be. Your surgeon will oversee your rehabilitation with appropriate rehabilitation specialists.