Lumbar Spinal Stenosis
Lumbar stenosis is narrowing of the spinal canal and narrowing of the intervertebral foramen, which is the nerve root canal. Hypertrophy of the facet joints, hypertrophy of the ligamentum flavum, disc degeneration, or arthritis are all examples of conditions which constrict the nerve root canals, causing compression of the spinal nerves and sciatica. There are two types of lumbar stenosis- central and lateral.
In patients with lumbar spinal stenosis, their pain will be better with flexion, or leaning forward over an object (like a shopping cart). However, the pain will be exacerbated with extension of the back. Leaning forward helps relieves some pain because it increase the foramen size by about 12%, but leaning backwards worsens the pain because it reduces the foramen size by about 20%. A neurological exam is normal in about 50% of patients with spinal stenosis.
Central canal stenosis is responsible for giving neurologic claudication. Patients may have leg pain, back pain, buttock pain, weakness, cramps of the calf, and a heavy feeling sensation. Flexion of the back relieving pain is a positive sign for spinal stenosis, but history is the key for making a diagnosis of spinal stenosis.
Lateral recess stenosis will give radicular symptoms. It can occur in the nerve root canal.
Neural foraminal stenosis occurs in the intervertebral foramen.
If spinal stenosis is found, look for other conditions, such as hip problems, metastatic tumors, or vascular conditions. The pulses should also always be examined. Neurogenic claudication and vascular claudication may coexist!
In both neurogenic and vascular claudication, walking is bad, but sitting will relieve the symptoms in both conditions. One difference between the neurogenic and vascular claudication is when a patient stops and stands still- this is good for vascular conditions, but will still cause painful symptoms for lumbar spinal stenosis. Another way to differentiate lumbar spinal stenosis is by using a stationary bicycle. This exercise will relieve symptoms of lumbar spinal stenosis, but will aggravate the symptoms of a vascular claudication, as leaning over on the bike will also help relieve some neurogenic symptoms. In a patient with vascular claudication, the pain will start within the leg and calf. On the other hand, in neurogenic claudication, the pain starts proximally and then spreads distally. Overall, it seems like postural change of the spine makes the neurogenic claudication worse, however, this will not affect the vascular claudication. Vascular claudication will be affected by muscle movement or muscle function, such as walking or riding a bicycle.
Treatment for spinal stenosis most often involves surgery. The surgery of choice for central canal stenosis is a decompression by laminectomy. For lateral recess stenosis, a medial facetectomy should be performed. If there is also instability in the spine, a fusion can also be performed. A fusion should also be done if more than 50% of the bilateral facets are removed. The x-rays and/or MRIs will need to be looked at. If there is a slip of the vertebrae, a fusion, in addition to the laminectomy, will need to be done.
The risk of pseudoarthrosis is increased 500% by smoking after surgery. Depression and other comorbidities can also affect the outcome. The most common reason for failed surgery is recurrence of the disease (residual foraminal stenosis). After two years, patients treated who were treated with surgery rate their pain and function better than the patients who were treated with conservative management.
If a patient presents with low back pain and gait disturbance (hyperreflexia), the patient has an upper motor neuron lesion. In this instance, the cervical spine should come to mind. An MRI of the cervical spine will need to be obtained after the patient is examined. Lumbar stenosis should not give these findings, therefore cervical myelopathy should be examined for.
Patients with spinal stenosis, spondylolisthesis, or facet disease will have pain with extension of the lumbar spine. On the other hand, pain with lumbar spine flexion should suggest a disc related disorder, such as a disc herniation.
