LUMBAR SPINAL STENOSIS

Lumbar spinal stenosis is a result of aging and everyday wear and tear on the spine. Though these changes happen to all of us, not everyone will experience the symptoms of lumbar spinal stenosis (LSS). Features of LSS include persistent, progressive low back pain with or without radiation, numbness or weakness in the buttocks and legs, and symptoms that improve with resting, lying down or bending forward. Unfortunately, many patients with symptoms of spinal stenosis often suffer for a long period of time before seeking medical advice and, even then, can often be misdiagnosed and treated inappropriately. As such, many older people with LSS have had to give up active lifestyles despite conservative treatment with rest, medication, and physical therapy.

What Happens in Lumbar Stenosis?

In the normal spinal canal, the nerve roots are contained in the thecal sac and exit between each vertebra (foramina). The central spinal canal and the foramen contain the thecal sac and nerve roots respectively.

The canal and foramen are formed (Figure 1) by bony structures (vertebral body, facets, pedicles) as well as soft tissue structures (ligamentum flavum, facet capsules, intervertebral disc annulus). As we age, degenerative changes occur in our spine causing narrowing of the central spinal canal area, and/or the area where the nerve roots exit the spinal canal (foramina). One of these degenerative changes is the formation of extra bony growths called osteophytes. Additionally, the large connective "band" (ligamentum flavum) which runs along the inside the spinal canal can become coarse and thickened also causing narrowing of the central canal space.

Symptoms of Lumbar Spinal Stenosis

Lumbar spinal stenosis (LSS) can cause compression of the spinal nerves in the lumbar area (cauda equina). At the same time, the cauda equina between the levels of stenosis becomes congested due to alterations in the blood vessels that drain blood from the area. This congestion prevents the nerve roots from conducting effectively, especially when walking. When this happens, there can be a significant amount of pain, numbness, and/or weakness in the buttocks, thighs, and legs. Often, this can severely limit or altogether stop the patient from walking. The discomfort usually disappears after 5 -10 minutes of rest. Lying with the legs flexed, sitting, or squatting can also help as these maneuvers increase the area of the spinal canal. These symptoms may begin in the lower legs and progress upwards toward the buttocks or they may begin in the buttocks and progress downward. This is referred to a "sensory march." Low back pain is also a very common complaint. The symptoms may begin on one side but will often end up involving both sides. You may hear your doctor refer to this as neurogenic claudication.

Neurogenic claudication tends to occur more frequently in men than women and is usually seen after age 50. Most people will gradually decrease the walking distance until they reach a comfort zone. Typically, patients are able to walk at least 100 meters. Unfortunately, this condition is lifelong and can be progressive. Sometimes physical therapy, medical pain management and other non-surgical measures can provide adequate symptomatic relief. If your symptoms continue to progress or become too painful, surgery to widen the spinal canal may be your best option (surgical decompression).

It is important for your physician to differentiate neurogenic claudication from decreased blood flow to the lower extremities due to calcified blood vessels (peripheral vascular disease) since this condition also often occurs in older people and has similar symptoms. However, symptoms of peripheral vascular disease typically are not relieved by changes in posture and do not exhibit any of the "sensory march" symptoms.

Lumbar spinal stenosis can also cause pain extending down the leg along the area that corresponds to the affected nerve root. This occurs because the area where the nerve root exits the spinal canal (foramina) has become narrowed causing pressure on the nerve root. Foraminal stenosis is thus a form of LSS and can coexist with central stenosis and classic claudication symptoms. Often, foraminal stenosis does respond well to conservative treatment without surgery, but may require 6 to12 months for recovery. However, those with persistent severe pain will likely benefit from surgery to widen the foraminal space (surgical decompression).

Diagnosis

Diagnosis is made by a neurosurgeon based on your history, symptoms, a physical examination, and results of tests, including the following: