What is Lumbar Spinal Stenosis?
This is a degenerative condition caused by gradual, age-related narrowing of the spinal canal, which contains the nerves that supply the legs, bladder, bowel and sexual organs. The problem usually affects people over the age of 60 but can occur earlier.
The narrowing is due to wear and tear of the facet joints and ligaments, which thicken and bulge into the spinal canal (Fig 1) causing nerve compression. In some patients, the compression is worsened further by a slipped vertebrae (degenerative spondylolisthesis), which can also cause back pain (Fig 2).
What are the symptoms?
The symptoms include pain, numbness, tingling and/or weakness in one or both legs and are typically typically brought on by standing or walking. The symptoms tend to be improved by sitting, leaning forwards or stooping.
The leg pain is gradual in onset, worsening over 6 to 18 months. The walking distance gradually deteriorates until leg symptoms occur after walking 50 metres or less, or standing for more than a few minutes.
Patients may find that their ability to tolerate the symptoms in a bent or sitting position, for example when cycling or leaning forwards on a shopping trolley, is much better than activities which require standing or walking upright. Some patients experience leg pain at night when lying flat on their back. They may be able to relieve the pain by sleeping on their side and curling up by pulling the knees up towards the chest.
What investigations are required?
Spinal stenosis is best diagnosed with a spinal Magnetic Resonance Imaging (MRI) scan which shows spinal structures in great detail (Fig 1).
What is the prognosis and treatment options?
Some patients with mild stenosis may remain stable with fluctuating, tolerable symptoms for several months. These Patients may benefit from Physiotherapy or a course of epidural steroid injections around the spinal nerves to reduce nerve inflammation.
In most cases, the spinal stenosis tends to worsen over time with gradual deterioration in the symptoms leading to reduced mobility and overall quality of life. Patients with advanced spinal stenosis seldom improve without surgical treatment, which provides the only long-term solution. The operation commonly performed for this condition is a Lumbar Decompression, which has a success rate of 80 - 90% in curing the leg pain and restoring mobility.