What is Spinal Stenosis?
This refers to a condition of the spine where the spinal cord or spinal nerve roots are compressed in the spinal canal. There are a number of different syndromes depending on the location of the nerve compression.
Lumbar Canal Stenosis
This is the most common subtype and is usually due to age-related degenerative changes in the spine that lead to disc bulging and facet joint swelling that combine to compress the nerve roots of the cauda equina in the lumbar canal. The condition can vary in severity from only occasional symptoms to very severe disabling pain that makes standing and walking very difficult.
Most patients complain of intermittent pain in the legs that may be associated with pins and needles or numbness. The symptoms tend to be worse when standing or walking and can improve with sitting or bending forward (flexion of the spine). Sometimes the legs can just feel heavy or weak and in severe cases there is loss of co-ordination and balance. In many cases there is no significant back pain but for some patients there can be associated back pain but for most patients the leg pain is more severe. (this is pattern 4 back/leg pain- need link to understand your pain page)
Stenosis means “tightening”, and when the canal is “tight” the nerves get compressed and the conduction of electrical impulses is slowed leading to weakness and poor sensory feedback to the brain. The compression of the nerves also causes pain that is felt in the legs where the nerve supplies an area of skin (see dermatome).
In most cases the cause is benign and the condition progresses slowly with time. Uncommonly there can be more rapid progression of the pain and disability associated with this condition.
Degenerate Spondylolisthesis and Spinal Stenosis
A subgroup of patients with spinal stenosis also have spondylolisthesis due to severely worn facet joints. For these patients there is often a history of back pain that itself can be very severe. The back pain is mechanical in nature – that is it is worse with standing and walking and better with rest. In these cases the condition is often progressive and may eventually require both decompression and stabilisation of the spine with surgery.
Degenerate Scoliosis and Spinal Stenosis
These patients can have a more severe level of symptoms with both back and leg pain. The neurological compression is often worse in the foraminae where the dorsal root ganglion resides and this can be particularly painful. (see link to Degen scoliosis)
Treatment options for spinal stenosis vary depending on the severity and duration of symptoms.
- For many patients simple measures like modification of activity or using a walking aid can help to relieve symptoms enough.
- Sometimes cortisone injections into the spinal canal (epidural steroid injection) can be used to relieve symptoms.
Posture advice and exercises to strengthen the abdominal (CORE) muscles can also be useful to improve symptoms and function.
- Analgesic medication can also be trialled and may consist of paracetamol, NSAIDs, or nerve modulating agents.
- Surgery to decompress the nerves, laminectomy, is used when simple measures fail to adequately relieve the symptoms or if neurological deterioration is evident.
Decompression laminectomy is the most common operation performed and gives relief by making more room for the nerves in the spinal canal. Wide decompression is the traditional technique of laminectomy but more recently surgeons are performing less aggressive surgery that mainly removes the thickened soft tissue and part of the facet joint rather than the entire lamina. Sometimes the prolapsed disc may also be removed if that is contributing to the stenosis. This is termed “selective laminectomy” and preserves much of the bone covering the spinal canal. In severe cases, however, it may be necessary to perform wide decompression. Both types of operation are effective at relieving the leg pain associated with spinal stenosis.
Laminectomy and fusion
If there is associated instability of the spine, such as spondylolisthesis or severe scoliosis the surgeon may decide to stabilise the spine at the same time as the decompression. There are many different stabilising or fusion techniques that typically involve some form of bone grafting and many times some sort of device for internal fixation.