Lumbar Spinal Stenosis

Lumbar Spinal Stenosis

Lumbar spinal stenosis is a narrowing of the spinal canal and narrowing of the intervertebral foramen (nerve root canal).

There are two types of lumbar spinal stenosis- central and lateral. 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. Patients will have back pain that is better with flexion, or leaning forward like over a grocery cart. The pain will be worse with extension of the back. Leaning forward increases the foramen size by about 12%. Leaning backwards reduces the foramen size by about 20%. Neurological exam is normal in about 50% of the patients.

Central canal stenosis is responsible for giving neurogenic claudication. Patients may have leg pain, back pain, buttock pain, weakness, cramps of the calf, and a heavy sensation. Patients will exhibit grocery cart sign (flexion of the back). The patient history is key for making the 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. Physicians should look for other conditions such as hip problems, metastatic tumors, or vascular conditions. You should always examine the pulses. Neurogenic claudication and vascular claudication may coexist. Walking is bad for both neurogenic and vascular claudication. Sitting will relieve the symptoms in both neurogenic and vascular claudication. Stopping and standing is good for the vascular claudication but still causes symptoms for lumbar spinal stenosis. Using a stationary bicycle will relieve symptoms of lumbar spinal stenosis, however it will aggravate the symptoms in vascular claudication. In vascular claudication, pain starts within the calf and leg. In neurogenic claudication, pain starts proximally and then spreads distally. It seems like postural changes of the spine will make 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 of riding a bicycle. In neurogenic claudication, leaning over while riding the bicycle will relieve the symptoms in the same way as the shopping cart sign. Spinal stenosis can be treated operatively. In central canal stenosis, you should do a decompression by laminectomy. In lateral recess stenosis, you should do a medial facetectomy. You should add fusion for instability or if more than 50% of the bilateral facets are removed. You should look at the x-rays or the MRI. If there is a slip of the vertebrae, do a fusion in addition to the laminectomy. The risk of pseudoarthrosis is increased 500% by smoking.
Depression and other comorbidities can affect the outcome. In two years, patients who are treated with surgery are better in pain and function than the patient who is treated conservatively. The most common reason for failed surgery is recurrence of the disease (residual foraminal stenosis). Walking is bad without the aid of a shopping cart. Leaning over the shopping cart will relieve the symptoms. If you have a patient with lower back pain and gait disturbance (hyperflexia), then you have an upper motor neuron lesion. Think about the cervical spine. You need to get an MRI of the cervical spine after you examine the patient. Think of cervical spine myelopathy because lumbar stenosis does not give these findings. Patient with spinal stenosis, spondylolisthesis, or facet disease will have pain with extension of the lumbar spine. Pain with lumbar spine flexion will suggest a disc related disorder.