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Spinal Stenosis

By Raphael Rey Roybal, M.D., M.B.A.

The human spine successfully performs the major functions of providing motion, support and protection for the body’s neurological structures. This complex interaction is possible because of the spine’s complicated structure. The delicately balanced bone and intervertebral discs form multiple mobile segments through which the spinal cord and its nerve roots pass. Unfortunately, degenerative changes within the spine, beginning with degeneration of the disc, may cause a narrowing, or stenosis, of the canal and foramina (a passage through bone) through which the spinal cord and nerves pass. Bulging discs, arthritic joints with bone spurring and hypertrophy or thickening of ligaments can all contribute to the breakdown of these neurologic structures. Usually trouble starts occuring with patients in their fifth decade of life. Problems become even more common with each following decade.

As spinal stenosis progresses, soft tissue structures such as the ligamentum flavum, a ligament which protects the dura or lining of the neurological structures, thickens in response to degeneration and aggrevates the stenosis. Ultimately, this thickening restricts the flow of cerebral spinal fluid. As a result, approximately 60 percent of the nutritional supply is cut off from the cauda equina – the bundle of nerve roots at the lower (lumbar) end of the spinal cord, which sends and receives messages to and from the pelvic organs and lower limbs. This compression which results in the restriction of cerebral spinal fluid may cause symptoms such as leg and buttock pain, tingling, numbness and sometimes weakness during activities such as walking when nutritional demands of the nerves are higher than the nutritional demands of nerves at rest. A key component in the diagnosis of spinal stenosis is that these symptoms are relieved with rest (such as sitting down) or with positional changes (such as leaning or flexing forward). Resting causes less nutritional demands from the nerves and leaning forward may decrease compression by preventing the ligamentum flavum from buckling which occurs when standing fully erect.

Historically, treatments for spinal stenosis has been conservative including physical therapy, activity modification, medications such as NSAIDS and potentially epidural steroid injections. Fortunately, although potentially progressive, spinal stenosis is not life or limb threatening. An individual’s quality of life can, however, be greatly compromised. The decision to pursue operative intervention in the presence of failed conservative treatment is a decision patients make with their physicians.

If surgery is indicated, laminectomy has historically been the gold-standard treatment. Kenneth Hansraj, M.D. and associates at the Special Spine Institute in Poughkeepsie New York reported 94 of 103 patients undergoing laminectomy for spinal stenosis were satified with their pain relief at a four year follow up. However, depending on the location of the stenosis, decompression surgeries, like laminectomies, may destabilize the spine. As a result, prospective trials have supported the emerging consensus that decompression with spinal fusion offer patients the best clinical results. Spinal fusion is achieved by grafting bone around the spine during surgery. The body then heals the grafts over several months – similar to healing a fracture – which joins, or fuses the vertebrae together. Unfortunately, decompression and fusion spinal surgery is not a good alternative for some patients with its associated increased operative time, blood loss, recovery and potential neurological complications.

Because of this unfortunate reality, less invasive, as well as motion restricting technologies have been developed to deal with spinal stenosis which is a condition usually occuring in an older, more fragile population. The X STOP implant was introduced to limit extention at stenotic motion segments (spinal motion segment is comprised of the disc, facet joints, spinous processes, central and lateral canals, and ligaments.) while preserving the spines ability to flex, rotate and bend laterally. The X STOP devise is implanted between the spinous processes (The spinous process of a vertebra serves for the attachment of muscles and ligaments) of the pathologic motion segment after minimal dissection and without disrupting the spinal canal or stability of the spine. As an interspinous process implant, the X STOP device has the added benefit of lessening the load of the degenerative motion segment. In a cadaveric study, using magnetic resonance imaging (MRI) to quantify the dimensions of the spinal canal and foramina in extention, the X STOP was shown to significantly increase all cross-sectional areas. Another similarly designed study demonstrated the X STOP to significantly decrease vertebral disc pressure at the implanted level while maintaining normal pressure and kinetics at adjacent, uninstrumented levels. Most importantly, in a randomized study comparing 100 X STOP patients with 91 control patients, the X STOP patients had significantly imroved outcomes and satisfaction rates while maintaining a very low and favorable complication rate.

The simplicity and ease of implanting the X STOP device complements its potential to greatly enhance the quality of life of patients suffering from spinal stenosis. Besides a very low complication rate, a very short operative time and minimal blood loss, the device and its associated technique has the added advantages of preserving the native spinal achitecture, providing a completely reversible treatment, maintaining spinal motion and the normal kinetics of adjacent spinal motion segments and allowing expedited recovery and rehabilitation. In a patient with spinal stenosis and positional, debilitating neurogenic claudication (cramp-like pain due to poor circulation to the leg muscles), interspinous process decompression with the X STOP device is proving to be a very good, minimally invasive, safe and effective option.

For more information about spinal stenosis or other spine concerns – contact Dr. Roybal at Chatham Orthopaedics, 4425 Paulsen Street, Savannah, GA 31405,
(912) 355-6615