Spinal Stenosis

What is Spinal Stenosis?

Spinal stenosis is a common condition that occurs when the space around the nerves or spinal cord narrows. This narrowing puts pressure on the spinal cord and/or the spinal nerve roots, often leading to symptoms of pain, tingling, numbness and muscle weakness. The condition usually begins gradually and progresses over time as the narrowing increases.

When the narrowing takes place in the lumbar spine, these symptoms are felt in the lower back, buttocks, thighs, legs and feet. In essence, spinal stenosis is a “space issue” where the nerves compete with bone and soft tissues for space, and the nerves always lose. The goal of treatment for spinal stenosis is to decompress or relieve pressure against the nerves.

Who Gets Spinal Stenosis?

Spinal stenosis affects men and women equally and is most common in older adults (50+); typically, the normal “wear-and-tear” effects of aging and arthritis of the spine cause it. (Degenerative changes of the spine are seen in up to 95% of people by the age of 50!) However, it may occur in younger people who are born with a small spinal canal or those who have a herniated disc.

Where Can Spinal Stenosis Occur?

The most common forms of spinal stenosis are cervical (the neck) and lumbar (the lower back). Thoracic spinal stenosis, which affects the mid-back, is much less common. Many people show evidence of spinal stenosis on MRI scans but have no signs or symptoms, even when the MRI findings are moderate to severe. This is because of the gradual occurrence of “typical” spinal stenosis and the way the body can accommodate and adjust over time. Symptoms generally develop slowly over time (again, most patients are over 50) and the symptoms can come and go. Unfortunately, these symptoms can eventually become chronic and quite debilitating. Symptoms vary, depending on the location, type and severity of spinal stenosis.

What Is the Most Common Type of Stenosis?

Lumbar spinal stenosis is the most common form of spinal stenosis. An estimated 400,000 Americans suffer from leg pain and/or low back pain caused by lumbar spinal stenosis.

What Are the Symptoms of Lumbar Spinal Stenosis?

Lower back pain is a common symptom. The pain is from the degenerative disc disease and degenerative (arthritic) facets that often accompany aging.

Pain, tingling, weakness and numbness are symptoms that can radiate from the lower back into the buttocks, legs (sciatica) and feet.

Loss of walking endurance is another hallmark of lumbar spinal stenosis. This results from pain and cramping in the legs, thighs or feet that is sometimes referred to as pseudoclaudication. The pain from spinal stenosis can mimic the symptoms of vascular claudication caused by diminished blood perfusion of the legs with peripheral vascular disease. Loss of sexual drive and activity frequently accompanies painful back conditions like spinal stenosis.

What Are the Most Serious Symptoms?

Abnormal function or loss of bowel and/or bladder control (cauda-equina syndrome) is very serious. This may be considered a surgical emergency as the onset of symptoms can occur quickly.

Partial or complete leg paralysis is also serious, especially if it occurs over a short period of time. Cauda-equina and paralysis can be considered medical emergencies that require a trip to the emergency room as quickly as possible.

What Aggravates and Relieves the Symptoms?

Leaning backward or extend your back can aggravate symptoms, especially when you walk downhill. Even just standing up straight for prolonged periods can cause back and leg symptoms.

The pain gets better, sometimes almost immediately, by certain positions, like flexing your spine forward (when you walk uphill) or leaning forward to push a grocery cart. Symptoms can dissipate when sitting or laying down.

What Are 5 Causes that Contribute to Spinal Stenosis?

The bottom line of stenosis is a narrowing of the tunnels or canals that allow passage of the nerves. There are certain conditions that contribute to these phenomena of narrowing.

Aging

There are certain effects of “wear-and-tear” that cause either structural changes or inflammation that begin the narrowing process. Arthritis can cause both. All of the factors below occur with normal aging and may cause the tunnels in the spine to narrow:

Your body’s ligaments can thicken and fold over on itself (ligamentum flavum) as the disc spaces narrow. The ligamentum flavum is a thick tissue that lines the inside of the tunnels and canals of the spine. Aging can give rise to bone spurs develop on the vertebrae and facet joints that protrude into the spinal canal. Herniated discs are more common with age and can protrude into the spinal canal and put pressure on the nerves.

Arthritis

As you age, the spinal discs, which act as shock absorbers between the vertebrae, become drier and start losing their spongy quality and structural integrity. This loss of structural strength subjects them to defects in the disc’s exterior (or annulus) that may allow some of the soft inner material to escape and press on the spinal cord or nerves (disc herniation). At the same time, the bones and ligaments of the spine can thicken due to long-term swelling (inflammation) and osteoarthritis, leading to stenosis.

Osteoarthritis is a chronic, degenerative process of joints that is more likely to occur in middle-aged and older people. Osteoarthritis of the facet joints breaks down the cartilage in your joints and is often accompanied by overgrowth of bone, formation of bone spurs and impaired function. The overgrowth of bone is the problem that crowds the spinal canal. A degenerative facet can also result in a synovial cyst that “herniates” into the spinal canal.

Heredity

When a spinal canal is too small at birth it can result in spinal stenosis caused by relatively minor things, like a small disc herniation.

 Trauma

Accidents and injuries can cause displaced bone from a spinal fracture to damage the contents of the spinal canal.

Tumors in the Spine

Irregular growths of soft tissue (malignant or benign) on the inside of the spinal canals can press on the spinal cord and nerves.

When Should Surgery Be Considered & What Are 5 Surgical Options?

If your pain does not respond to conservative treatments, or if you lose movement or strength, you may need surgery. However, surgery might be considered immediately if you have acute weakness that interferes with walking, impaired bowel or bladder function, or other neurological deficits. The bottom line with surgery for stenosis is to decompress the nerves that are pinched or compressed. Beyond this, the next question is whether decompression is enough or does a fusion need to be done too.

Decompressive Laminectomy 
The most common type of surgery for spinal stenosis is the laminectomy. This is an open back surgery that involves the complete removal of the lamina (a portion of the vertebra), ligamentum flavum and bone spurs may also be removed. The surgery requires making an incision into the back (usually 2 to 6 inches) and may include spinal fusion.

Decompressive Laminotomy 

This refers to partial removal of the lamina to take the pressure off the affected nerves. This can be done with an open surgery as well.

Endoscopic Spine Surgery

The goal of endoscopic surgery is decompression and to avoid a spinal fusion when possible. Endoscopic spine surgeons believe that, if surgery is necessary, then it should be performed through the smallest possible incision, with minimal disturbance of soft tissues and usually without a fusion. This procedure can address both soft tissues and bone overgrowth (stenosis). The size of the tubes are small, so the soft tissue trauma and scar tissue formation will be minimal, and less surgical exposure (less than ½ inch), means less pain postoperatively and a quicker recovery. Endoscopic spine surgery is the least invasive because of the small incision.

Endoscopic success rates are vary

In the event that endoscopic spinal surgery does not provide enough relief, a fusion can still be performed. But, one cannot perform a fusion first and then easily go on to do an endoscopic spinal surgery, expecting the same results.

Spinal Fusion 

When the vertebrae shift (spondylolisthesis), slip or move excessively (instability) in relation to each other, spinal stenosis can occur. The abnormal motion between the vertebrae can be eliminated with a spinal fusion. There are many variations of the spinal fusion, but the bottom line is that motion is eliminated with some hardware (rods, screws, cages for example) and bone graft material. In such cases, spinal fusion surgery (also an open back procedure, with a 3 to 6 inch incision into the back) may be required in addition to decompression, in order to stabilize the involved vertebrae.

Intervertebral Spacers

One of the main causes of spinal stenosis is the collapse of the intervertebral discs. This occurs with age and is the primary reason that people get shorter with age. The collapse of the disc spaces causes the facet joints to get arthritic and the ligamentum flavum to double up on itself. Both of these things contribute to the stenosis.

One solution to this problem has been to insert a spacer between the spinous processes on the backside of the spine. This spacer holds the spinous processes apart and acts a “jack” to hold the vertebrae apart. It compensates for the loss of height that the disc provided. One problem is that there is not a large enough spinous process on sacral 1 to hold a spacer, so these cannot be used for the L5-S1 level.

Each of these procedures has benefits, shortcomings and results to discuss in upcoming posts. Stay tuned.