Spinal (Lumbar) Fusion/Lumbar Spinal Stenosis - Pinched Nerves in the Back

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Introduction

The low back is a common place to experience pain.  This area of the back is called the lumbar spine.  The main function of the lumbar spine is to support the weight of your upper body.  The joints of the lumbar spine primarily allow you to bend forward or flex and extend or straighten at the waist.

Your spinal column is made of a series of short bones called vertebrae.  An opening in the center of each vertebra forms the spinal canal.  Your spinal cord and spinal nerves run through the protected canal and send messages between your body and brain.

Spinal Stenosis is a condition in which the spinal canal is narrowed.  The narrowed canal causes pressure on the spinal cord and nerves.  Spinal Stenosis may or may not produce symptoms.  Many cases of Spinal Stenosis can be treated without surgery.  However, some individuals experience severe or progressive nerve involvement, loss of function, and pain.  Surgical treatment can relieve nerve pressure and help restore function and relieve pain.

Anatomy

There are different areas of the spine, defined by their curvature and function.  The lumbar spine is located in your lower back.  It forms the curve below your waist.  The lumbar spine connects your upper body-- your head, trunk, and arms, to your lower body--your pelvis and legs.  Ligaments and muscles connect to your spinal column.  They provide stability while allowing movement.

Five large vertebrae make up the lumbar area of your spine.  The back part of the vertebra arches to form the lamina.  The lamina creates a roof-like cover over the back opening in each vertebra.  The opening in the center of each vertebra forms the spinal canal.  Your spinal cord and spinal nerves travel through the protective spinal canal.

Your spinal cord tapers near the first lumbar vertebra and forms a bundle of nerves called the cauda equina.  Your spinal cord and spinal nerves at the lumbar spine level send signals for sensation and movement between your brain and leg muscles.  The cauda equina is involved with regulating bowel and bladder functions.

There are discs between the vertebrae in your lumbar spine.  The discs are made up of strong connective tissue.  Their tough outer layer is called the annulus fibrosus.  Their gel-like center is called the nucleus pulposus. 

The discs and two small spinal facet joints connect one vertebra to the next.  The discs and joints allow movement and provide stability.  The discs also act as a shock-absorbing cushion to protect the lumbar vertebrae.

Causes

Spinal Stenosis is a condition in which one or more areas of the spine are narrowed.  It can involve the spinal canal in the center of the vertebrae and/or the "tunnels" where nerves branch out.  These areas are called foramina.  Spinal Stenosis is more common in people over the age of 50.  It can also occur in younger people that are born with a narrowed spinal canal.

Spinal Stenosis is most frequently caused by the gradual degeneration of the spine during the aging process.  The intervertebral discs become less fluid-filled and dry out with age.  They can lose height and bulge into the spinal canal.  The spinal facet joints and ligaments can thicken and enlarge, pushing into the spinal canal.  Arthritis is the main cause of these structural changes.

Arthritis is a major cause of pain, swelling, and structural changes in the lumbar spine.  Arthritis can occur for many reasons, including aging, “wear and tear,” injury, autoimmune disease, and inflammatory disease.  There are over 100 different types of arthritis.  Osteoarthritis and Rheumatoid Arthritis are types of arthritis that typically develop in the spine.

Osteoarthritis is the most common type of arthritis.  It is a chronic and degenerative condition.  Osteoarthritis tends to appear as people grow older.  It causes cartilage to gradually wear away bone to overgrow and cause "spurs".  These abnormal bone growths, called osteophytes can grow into the spinal canal and vertebral joints.  The bone spurs can compress the spinal cord and nerves disrupting their function.  Spondylosis is a condition that can result when Osteoarthritis affects the intervertebral discs and the vertebral facet joints.  Spondylosis causes disc degeneration and the overgrowth of bone into the spinal canal or nerve root canals.  A condition called spondylolisthesis causes one vertebra to slip forward on another.

Spinal tumors are abnormal soft tissue growths.  Acquired Spinal Stenosis develops when spinal tumors grow into the spinal canal or cause swelling.  A spinal tumor may also cause the vertebrae to shift out of place because of bone loss.  Acquired Spinal Stenosis can also develop when a spinal ligament ossifies.  Ossification occurs when calcium deposits form on a ligament and turn it into bone.  The posterior longitudinal ligament attaches to the spine and can cause stenosis if it ossifies and presses on the nerves in the spinal canal. 

Symptoms

Spinal Stenosis may or may not produce symptoms.  Many people with stenosis do not experience symptoms.  If you have symptoms, you may feel pain or numbness in your legs.  Your legs may cramp.  They may feel weak.  Your symptoms may come and go and vary in intensity. 

Prolonged standing or walking may cause your symptoms to increase.  If you bend forward or sit, your symptoms may be relieved.  These positions increase the room in the spinal canal and take pressure off of the spinal cord. 

If the spinal nerves in the lower end of the lumbar spine are compressed, a condition called Cauda Equina Syndrome may result.  This is an emergency.  Cauda Equina Syndrome can cause you to lose control of your bowel and bladder.  Other symptoms include low back pain, leg pain, leg weakness, lower body sensory deficits, and reduced or absent leg reflexes. 

Diagnosis

Your doctor can diagnose Spinal Stenosis by performing a physical examination and viewing medical images.  Your doctor will ask you about your symptoms and medical history.  You will asked to perform simple movements to help your doctor assess your muscle strength, joint motion, and spine stability.  Your doctor will order imaging studies to learn more about the location and extent of your spinal canal narrowing and nerve root compression.

Your doctor will order X-rays to see the condition of the vertebrae in your spine and to identify narrowed discs or thickened facet joints.  Sometimes doctors inject dye into the spinal column to enhance the X-ray images in a procedure called a myelogram.  A myelogram can indicate if there is pressure on your spinal cord or nerves from herniated discs, bone spurs, or tumors.  A bone scan may be used to show fractures, tumors, infections, or arthritis.  A bone scan requires that you receive a small harmless injection of a radioactive substance several hours before your test.  The substance collects in your bones in areas where the bone is breaking down or repairing itself. 

Your doctor may also order Computed Tomography (CT) scans or Magnetic Resonance Imaging (MRI) scans to get a better view of your spinal structures.  CT scans provide a view in layers, like the slices that make up a loaf of bread.  The CT scan shows the shape and size of your spinal canal and the structures in and around it.  The MRI scan is very sensitive.  It provides the most detailed images of the discs, ligaments, spinal cord, nerve roots, or tumors.  X-rays, myelograms, bone scans, CT scans, and MRI scans are painless procedures.

Treatment

Most cases of Spinal Stenosis can be treated with non-surgical methods.  Over-the-counter medication or prescription medication may be used to reduce pain.  If your symptoms do not improve significantly with these medications, your doctor may recommend physical therapy or epidural steroid injections.

Epidural steroid injections may be performed by your doctor or by a pain management specialist.  The injections are placed into the space around your spinal cord and nerves.  The steroid (a type of cortisone) "leaks" around the nerves to decrease inflammation and irritation.  The injections are often given in a series of three - once per week for three weeks.  The results of these injections are variable.

Occupational or physical therapists can help you strengthen your back, stomach, and legs.  Persons with weak stomach muscles or spinal degeneration may wear a lumbar brace or corset during activities to provide support.  Stretching exercises will help to keep your back flexible.  Cardiovascular exercises help to build up your endurance and improve blood circulation to your nerves.  This can help to relieve the symptoms of Spinal Stenosis.  Your therapist can also recommend durable medical equipment to aid your safety and activity performance.  Such devices could include a cane for walking or a shower chair.

Surgery

Non-surgical treatments for Spinal Stenosis are designed to relieve pain and restore function, but they cannot correct the narrowing of the spinal canal.  Surgery is recommended when non-surgical treatments have provided minimal or no improvement of your symptoms.  Surgery is also advised if your leg weakness becomes progressively worse or if you experience associated bowel and bladder problems.

The most common surgery for Spinal Stenosis is Lumbar Laminectomy, also called Lumbar Decompression Surgery.  The goal of this surgery is to relieve pressure on the spinal cord and nerves by enlarging the spinal canal where it has narrowed.  To do so, the surgeon removes all or part of the lamina on the effected vertebrae.

During a Laminectomy, the surgeon makes an incision down the middle of the lumbar spine.  The surgeon detaches the muscles and tissues along the back of the spine to gain access to the spinal bones.  Next, the surgeon removes part or all of the lamina.  The surgeon also removes bone spurs, diseased tissue, or the sections of a disc that have extended into the spinal canal.

Sometimes the facet joints on the vertebrae are unstable after the Laminectomy.  They may also be enlarged and fragile because of arthritis.  In such cases, the surgeon may perform an additional surgical procedure called Lumbar Spinal Fusion.  The purpose of Lumbar Spinal Fusion is to permanently connect two or more vertebrae to stop movement and relieve pain caused by movement.

Posterior Lumbar Spinal Fusion is the most common type of fusion surgery for the lower back.  In this procedure, your surgeon uses bone graft from your pelvis, or from another source, to make the spinal levels heal to each other, forming a single block of bone and eliminating painful motion.  Surgical hardware, such as screws and rods secures the vertebrae together and allows the bone grafts to heal.

At the close of the Posterior Lumbar Spinal Fusion, a drainage tube may be placed to help remove fluid from the surgical area.  The drainage tube is usually kept in place for one to two days.  You will most likely wear a rigid brace to support your spine while it heals.

Recovery

Most people stay overnight in the hospital following a Spinal Lumbar Laminectomy.  Individuals that undergo a Lumbar Spinal Fusion stay in the hospital a bit longer.  You may need a little help from another person during the first few days or weeks at home.  If you do not have family members or a friend nearby, talk to your doctor about possible alternative arrangements.

The recovery process is different for everyone.  It depends on the type of surgery you had and the extent of your condition.  Your surgeon will let you know what to expect.  Generally, the recovery time for a Lumbar Laminectomy is four weeks for resuming light activity and up to several months for a full recovery.  Lumbar Spinal Fusion has a longer recovery time. 

Physical therapy for both surgery types usually begins at about six weeks following surgery.  At first, your therapists will apply treatments to help reduce pain.  You will gradually learn exercises to strengthen your lower back and improve your endurance.  The rehabilitation process is longer for individuals that had Lumbar Spinal Fusion.

Prevention

It is important that you adhere to your exercise program and safety precautions when you return home.  You should stay as active as possible, but remember not to overdo it.  You should notice a steady improvement in your strength and endurance.  Do not smoke.  Smoking increases the risk of surgical complications and hinders bone fusing.

Your therapists will teach you ways to safely position your body to protect your back during movements.  You should use proper body mechanics during all activities.  The use of proper body mechanics is important for preventing future injury.  Additionally, you should continue to use your durable medical equipment, such as shower chairs or toilet risers, as advised.

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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.