Lumbar Spinal Stenosis
Spinal stenosis describes a condition where wear and tear changes in the spinal column cause a narrowing in the spinal canal. In the neck and thoracic spine this leads to compression of the spinal cord and a condition called myelopathy
The spinal cord finishes at the junction of the thoracic spine and lumbar spine ( bottom of the rib cage), therefore spinal stenosis below here doesn’t compress the spinal cord, but compresses the nerve roots after they have left the spinal cord and are passing to the legs, this leads to a condition called lumbar canal stenosis, or ‘neurogenic claudication’
The images above show a schematic diagram of a typical lumbar vertebra with no evidence of spinal stenosis, and on the right a cross-sectional (axial) MRI image of the normal lumbar spine. The nerve roots are seen as small grey dots surrounded by white spinal fluid on the MRI
The classical symptoms comprise pain in both legs caused by exercise, this may be associated with the legs feeling numb, clumsy, and weak. Bending forwards or squatting down down can make the pain easier. These symptoms stop the sufferer walking, and then recover with rest over a few minutes. Poor circulation in the legs can also cause these symptoms and many sufferers have already seen a vascular (blood vessel) specialist before a neurosurgeon
The investigation of choice is an MRI scan of the lumbar spine, in addition plain X-rays of the lumbar spine may be needed if any spinal instability is suspected
The images above show a schematic diagram of a lumbar vertebra with spinal stenosis, and on the right a cross-sectional (axial) MRI image of a stenotic lumbar spine. The calibre of the spinal canal has been narrowed by enlargement of the facet joints, loss of height of the intervertebral disc, and hypertrophy (enlargement) of the spinal ligaments. The nerve roots can no longer be seen as small grey dots and the white spinal fluid on the MRI is no longer visible due to compression
The above image illustrates how the enlarged facet joints (red arrows) contribute to lumbar stenosis and compression of the lumbar nerve roots as they leave the spinal canal in the lateral recess (green arrow). This image is taken from an CT scan with intrathecal contrast injected into the spine.
Exercises are aimed at improving flexion and improving muscle tone and include stationary cycling and abdominal muscle strengthening. Other treatments such as heat, cold, transcutaneous electrical nerve stimulation (TENS), and ultrasound may provide transient pain relief and increased flexibility
Natural Aging Process
There is some evidence that much of the pain can be controlled by limiting spinal extension (standing up straight). This can occur naturally as the spine develops more wear and tear changes, the disc spaces are lost and the facet joints fuse. This can have the effect of causing the spinal to become very stiff and thus greatly limit extension
Epidural Steroid Injection
This involves having an injection of steroid into the spine under local anaesthetic. It can be a temporary means of controlling symptoms but does not generally provide a long-term solution
For patients severely limited by symptoms of neurogenic claudication and clear lumbar canal stenosis on imaging, surgery remains a safe and effective treatment
The basis of surgery is to remove much of the extra bone and ligament that has formed and thus relieve the pressure on the nerves in the spinal canal and as the nerves leave the canal. This operation is called a lumbar laminectomy and is covered in more detail in the spinal operations section. This operation is very effective for the leg pain caused by lumbar stenosis with 80% of patients improving after surgery. Back pain due to the wear and tear in the spine does not tend to improve with a laminectomy
Recently there have been studies showng that a small interlaminar spacer can be inserted via a very small incision, one such device is the X-stop. Studies are still in progress to measure the outcomes of using this device.