Degenerative disease of the spine involves arthritic changes in the bone, joints and ligaments. The spine consists of the vertebral bodies, intervertebral discs, facet joints, and several layers of ligaments. The spinal canal contains and protects the spinal cord and nerve roots. The vertebral column consists of:
Located in between these vertebrae are the intervertebral discs.
With aging, the intervertebral disc degenerates and narrows. This produces abnormal motion at that spinal level. In an attempt to repair this condition, the spine generates bone spurs and thickened ligaments. This process leads to gradual narrowing of the spinal canal, called spinal stenosis. Spinal stenosis can occur at any level of the spine, however it is most common in the lumbar and cervical spine.
Cervical stenosis and lumbar stenosis cause very specific symptoms depending on the level of compression.
Signs and symptoms of cervical stenosis include a spastic gait, upper extremity numbness, upper extremity and lower extremity weakness, radicular pain in the upper limbs, urinary incontinence, fecal incontinence, muscle wasting, sensory deficits, and reflex abnormalities.
Signs and symptoms of lumbar stenosis include neurogenic claudication (pain in the legs with walking, which is relieved by bending and sitting), leg weakness, leg numbness, and loss of deep tendon reflexes.
The diagnosis of spinal stenosis is usually made with an MRI which provides the best picture of the spinal cord and nerve roots. If MRI cannot be obtained, CT scan with myelography is an alternative.
The treatment of spinal stenosis depends on which level and how many levels of the spine are involved.
Conservative treatment is attempted first, unless there are significant neurological deficits. Rest and anti-inflammatory medications (ibuprofen, Motrin, Aleve) are helpful for mild symptoms. Exercise and physical therapy help rebuild fatigued muscles and encourage proper alignment of the spine. Most patients experience relief with conservative therapy, however progressive pain and weakness can be common.
For cervical stenosis several different operations may be applicable. An anterior cervical discectomy and fusion (ACDF) is performed if the majority of the compression is from the anteriorly located intervertebral disc. This procedure involves an incision
in the neck, which exposes the spine from the front. The disc is removed relieving any pressure on the spinal cord and nerve roots. Usually a bone graft is then placed in the space with a metal plate bridging the area.
A modification of this procedure involves actually removing the vertebral body in addition to the disc, followed by placement of a bone graft and metal plate. This is called a corpectomy and fusion.
Recently, artificial discs have been introduced in the treatment of cervical disc disease. A prosthetic disc can be placed into the disc space without having to place a bone graft. This has the advantage of maintaining normal mobility of the neck and, perhaps, preventing degeneration of adjacent levels.
If there is significant compression from the structures in the posterior part of the spine, such as the facets or ligaments, a laminectomy may be performed. This involves making an incision in the back of the neck and drilling away the bony structures covering the posterior spinal canal. The overgrown ligament and bone are removed decompressing the spinal cord. If multiple levels need to be decompressed, then a posterior fusion may be performed, as well.
The most common surgery for lumbar stenosis is a decompressive laminectomy. In this procedure, an incision is made in the back and the lamina (back part of the bone over the spinal canal) is removed to create more space for the nerves. In addition to removing the lamina, any bone spurs, herniated discs or overgrown ligaments are removed as well.
Using minimally invasive techniques, this procedure can be performed with a small incision, thus allowing for less post-operative pain and a quicker recovery time.
Occasionally it is necessary to perform a fusion if there is significant intervertebral disc disease or slippage of the vertebral bodies. A fusion permanently connects two or more vertebral bones. Wires, rods, screws, metal cages, and bone grafts may be used to hold the bones in place, while the bony fusion occurs.