Spinal stenosis


 * Associate Editor-In-Chief:

Overview
Spinal stenosis is a medical condition in which the spinal canal narrows and compresses the spinal cord and nerves. This is usually due to the natural process of spinal degeneration that occurs with aging. It can also sometimes be caused by spinal disc herniation, osteoporosis, or a tumour. Spinal stenosis may affect the cervical spine, the lumbar spine or both. Lumbar spinal stenosis results in low back pain as well as pain or abnormal sensations in the legs.

Cervical spinal stenosis
The main causes of cervical spinal stenosis (CSS) include cervical spondylosis, diffuse idiopathic skeletal hyperostosis (DISH), or calcification of the posterior longitudinal ligament.

CSS is more common in males than females, and is mainly found in the 40-60 year age group.

Signs of CSS include spastic gait; upper extremity numbness; upper extremity, lower extremity weakness or both; radicular pain in the upper limb; sphincter disturbances; muscle wasting; sensory deficits; and reflex abnormalities.

Diagnosis
The best diagnostic and investigative tool is magnetic resonance imaging (MRI), while computed tomograghy (CT) is somewhat useful if MRI is unavailable. However, spinal stenosis can be found in asymptomatic patients.

Treatment
If the problem is mild, treatment may be as simple as physical therapy and the use of a cervical collar. If severe, treatments include laminectomy, hemilaminectomy, or decompression.

Lumbar spinal stenosis
The main causes of lumbar spinal stenosis (LSS) include hypertrophy of the facet joints or osteoarthritis; spondylolisthesis; diffuse idiopathic skeletal hyperostosis (DISH); and degenerative disc disease.

Usually, this condition occurs after the age of 50, and both genders are equally affected.

Signs of LSS include neurogenic intermittent claudication that causes leg pain, weakness, tingling and loss of deep tendon reflexes. Many of these leg symptoms are referred to as sciatica. Low back pain may or may not be present. With lumbar spinal stenosis, the patient's pain usually is worse while walking and will feel better after sitting down. The patient is usually more comfortable while leaning forward, such as walking while leaning on a shopping cart. On the other hand, pain is worse with extension of the back at the hips, which is why patients prefer to lean forward or to sit down, as these actions flex the body at the hip. This is also why patient complain of increased pain walking downhill as opposed to uphill.

Diagnosis
As with CSS, MRI is the best imaging procedure, though unlike with CSS, CT may be somewhat useful, and can be used if MRI is unavailable.

Treatment
Treatment includes weight loss, and activity modification, such as using a walker to promote a certain posture. Epidural steroid injections may also help relieve the leg pain.

If the symptoms are more severe, a laminectomy or foraminotomy may be indicated to take pressure off the spinal nerve.

Surgical laminectomy
Regarding indications for laminectomy, a complicated, nonrandomized analysis of a randomized controlled trial of laminectomy, in patients with:
 * "neurogenic claudication or radicular leg pain with associated neurologic signs, spinal stenosis shown on cross-sectional imaging, and degenerative spondylolisthesis shown on lateral radiographs obtained with the patient in a standing position. The patients had had persistent symptoms for at least 12 weeks and had been confirmed as surgical candidates by their physicians. Patients with adjacent levels of stenosis were eligible; patients with spondylolysis and isthmic spondylolisthesis were not."

found that patients:
 * "treated surgically showed substantially greater improvement in pain and function during a period of 2 years than patients treated nonsurgically."

New surgical developments
Recent developments include several new implants used in surgery to treat the symptoms of spinal stenosis, while preserving as much normal motion in the spine as possible. The only FDA approved non-fusion treatment is the X STOP, by St. Francis Medical Techologies, Inc. which works via indirect decompression, called Interspinous Process Decompression (IPD) Some other IPD technologies that are still being studied include the Wallis implant, by Aboott Spine, the DIAM by Medtronic and the Coflex by Paradigm Spine,. Other implant systems being studied include the Dynesys by Zimmer, the Stabilimax by Applied Spine, the TFAS by Archus Orthopedics and the Anatomic Facet Replacement System, by Facet Solutions.

In November 2005 the X-STOP was approved by the FDA for treatment of lumbar spinal stenosis with moderate symptoms. This procedure is a much less invasive surgery than decompression, but the treatment is still new and effectiveness, indications and potential risks and complications won't be well understood until the procedure has been in use for a longer period.

One recent implant system that was being studied in the US reportedly has problems that ended its enrollment, the TOPS implant by Impliant. This was reported by an investor in Impliant, Elron Ltd.

Also recently, Medtronic's non-fusion implant was recalled officially in the United Kingdom, though in the US the device has been withdrawn from surgeons but MDT has not issued a recall, probably due to the way inventory is handled rather than a difference in the product sold in the US vs. the UK.