Surgery to Treat Spinal Stenosis

Spinal stenosis involves the compression of the spinal nerves due to the thickening of the wall of the vertebral foramen surrounding the spinal cord. There are also other types of spinal stenosis related to the thickening of the vertebral bones, the development of bony growths on the bone (bone spurs), and disc herniations that result in compression of the spinal nerves. The thickening of the vertebral arch causes the space reserved for the spinal nerves of the spinal cord to become smaller, compressing the spinal nerves. Spinal stenosis may occur in all sections of the spine, though it most often occurs in the cervical spine and lumbar spine. When this condition occurs in the lumbar spine (lower back), it is known as lumbar stenosis may result in lower back pain as well as the symptoms of sciatica. Symptoms of sciatica include pain and associated neurologic symptoms such a numbness, weakness, and tingling that may run the length of the sciatic nerve. The sciatic nerve itself runs from the hips, buttocks, all the way to the feet. When this condition occurs in the cervical spine, the condition is known as cervical spinal stenosis and it may cause neck pain as well as similar neurological symptoms in the shoulders, arms, and hands. Severe cervical spinal stenosis may lead to total body weakness and even paralysis if untreated. Let's take a look at the three types of spinal stenosis, and how they may be treated surgically to provide patients with back pain relief and the restoration of functioning in their bodies.

Foraminal stenosis: The spinal nerves roots descent through the spinal canal, within the spinal membranes, from the first cervical vertebra to about the 1st or 2nd lumbar vertebra. The spinal cord end at this point, but the spinal nerves continue beyond this point, exiting through the sides of the lumbar spine (intervertebral foramina) and sacral foramen. A pair of spinal nerves exit at the intervertebral foramina at each level of the spinal cord. The nerve root leaves the spinal canal through a side hole (lateral foramen). Due to degenerative changes to the vertebral bones, osteophytes (bone spurs) may develop in or near the lateral foramen, diminishing the size of the lateral foramen and constricting the exiting nerve root.

Then this constriction of the nerve occurs, it is called lateral spinal stenosis. This is far and away the most common type of spinal stenosis. When lateral spinal stenosis occurs, it occurs in the lowest lumbar level 72% of the time.

The sciatic nerve is a super nerve that is a combined from the spinal nerves L4 to S3. When foraminal stneosis occurs in one of the lower lumbar nerves, patients may experience the symptoms of sciatica.

Foraminal stenosis may occur as a result of osteophytes, as mentioned above, or herniated discs, in which the bulging or ejected disc material protrudes into the space occupied by the lateral foramen and exiting nerve root.

Central Spinal Stenosis: Though the spinal cord ends at the upper levels of the lumbar spine, the spinal nerves continue below this point in a loose configuration of individual nerves. This loose configuration has the appearance of a horse's tail on medical imaging pictures - hence its name (Cauda Equina or Cauda Equine) . The spinal nerves of the Cauda Equina are enclosed by a protective sac to protect these nerves. The condition is labeled as central stenosis when a choking of the central canal occurs, traumatizing this collection of nerves. Central spinal stenosis may be caused by a herniated disc or the major overgrowth or redundancy of the ligamentum flavum that is there to protect the dura. This thickening or abnormal growth of the ligament (ligamentum flavum) is caused by a degeneration of the disc between the adjacent vertebrae.

Far Lateral Stenosis: The spinal nerve may also become constricted just beyond the point where it exits the spinal canal. Spinal conditions which may cause compression of the nerves just outside the spinal canal include herniated discs, bulging discs, and osteophytes.

Surgery to treat spinal stenosis includes the microdiscectomy, lumbar decompression back surgery, discectomy with spinal fusion, and facet replacement or total element replacement.

Interspinous Process Devices: Recently, some innovative surgical techniques include the insertion of interspinous process devices that are designed to reduce the spinal instability causing the abnormal bone growths, as an alternative to maximally invasive surgeries such as spinal fusions. The purpose of these devices is to take the jumping of the disc and ligament that together are constricting the spinal canal. These devices are also designed to widen the nerve foramen. The implantation of devices is less likely to help treat far lateral or true bone spur foraminal stenosis. This device does prevent excessive extension at the segment, thus limiting posterior disc and ligament buckling. The X-Stop is one device that has been approved to specifically treat the central type of stenosis.