What is Spinal Stenosis?

The vertebrae are the bones that comprise the spinal column. The spinal canal runs through the vertebrae and, in the lower (or lumbar) spine, contains the nerves supplying sensation and strength to the legs. The fluid filled container in which the descending spinal nerves (or “cauda equina’) travel is known as the thecal sac. The thecal sac is analogous to a pool of water in which the nerves swim, and the nerves like to have space within this pool. Between each of the lumbar vertebrae are the intervertebral discs and the spinal facet joints. Both the anteriorly located (front) discs and posterior (back) facet joints allow for motion of our lumbar spines.

The discs become less spongy and less fluid-filled with age. This can result in reduced disc height and bulging of the hardened disc into the spinal canal. The bones, ligaments, and capsules of the spinal facet joints can also thicken and enlarge (because of “wear and tear” or “osteo-” arthritis ) resulting in a narrowing of the spinal canal. These combined processes result in a compressed spinal canal with a reduced area through which the descending nerves can travel. This degenerative narrowing of the lumbar spinal canal is known as lumbar spinal stenosis.

Spinal stenosis is similar the lime build-up on the inside of a garden hose. Over time, it narrows the diameter of the hose, just as spinal stenosis narrows the spinal canal. Another analogy which patients often find useful is picturing a garden hose which is intentionally bent or “kinked.” While the diameter of the hose is maintained on either end of the bend, at the site of the bend the diameter of the hose is markedly narrowed or “stenotic”. Similarly, the lumbar spinal canal can be stenotic at one segmental level with the adjacent levels having a more preserved and patent central canal.

What are the symptoms?
Lumbar spinal stenosis does not necessarily cause symptoms. Many people can have significant stenosis on imaging studies but fail to have symptoms. The spine literature confirms the importance of identifying which radiographic findings correlate with symptoms and which are clinically less relevant. The physiatrists of Long Island Spine Rehabilitation Medicine strive to proceed in a diagnosis specific fashion with each patient presenting with symptoms of stenosis. Such symptoms may include pain, cramping or numbness, or a sensation of fatigue affecting the back and or legs. Less commonly, and in more concerning neurological cases, weakness or bowel and/or bladder problems can result. Through a detailed history, examination, and review of your radiographs, your physiatrist will attempt to isolate which film findings are in fact resulting in your clinical symptoms. Such efforts can ultimately result in more targeted and appropriate therapies and improved clinical outcomes.

The symptoms arising from spinal stenosis are classically, but by no means exclusively, exacerbated with prolonged standing or walking. These symptoms may be intermittent and can vary in severity when they recur. Bending forward or sitting can result in a relative increase in the diameter of the spinal canal and is often described by patients as a means of reducing pain and lower extremity symptoms. The classic “shopping cart sign”, or relief realized with walking in the market and leaning forward upon a shopping cart likely follows this mechanism as it involves both unloading of the spine and forward flexion at the waist. Other conditions, such as peripheral vascular disease (narrowing of the arteries in the legs) and osteoarthritis of the hip can at times present with similar complaints and mimic a spinal stenosis presentation. The physiatrists at Long Island Spine Rehabilitation Medicine will perform an extensive spine and musculoskeletal evaluation to assure that your condition is accurately diagnosed.

How is it diagnosed?
As described, a complete history and a thorough physical examination will be performed by your treating phsyiatrist. As with many musculoskeletal and neurological syndromes, the information obtained through the history and examination is essential in both establishing a diagnosis and in guiding treatment.

Usually, a magnetic resonance imaging (MRI) study will be obtained for optimal assessment of your spinal anatomy. Sometimes, a computed axial tomography (CAT) scan and/or a lumbar myelogram may be advised if you are unable to undergo an MRI exam for any reason or if additional anatomic information is needed to complement the MRI findings. Each of these studies can provide information about the presence, location and extent of spinal canal narrowing and nerve root compression. As mentioned before, many patients with radiographic evidence of spinal stenosis may not develop symptoms.

In select cases where diagnostic uncertainty should remain, electrical studies of the nerves, also referred to as nerve conduction studies or EMG (electromyography) studies may be performed. These studies can detect evidence of nerve damage that can result from more longstanding and symptomatic stenosis.

In addition, such testing can help to rule out a non-spinal process such as a peripheral neuropathy which might mimic a primary spinal process. The physiatrists of Long Island Spine Rehabilitation Medicine have completed extensive training in performing these studies and are either board certified in electrodiagnostic medicine or board eligible for subspecialty certification in neuromuscular medicine. In our practice, these tests are performed with the latest diagnostic equipment and in a fashion which maximizes patient comfort.

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