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Lumbar Pinched Nerve

Background & Etiology

The lower back can be divided functionally and anatomically into three separate areas, the lumbar spine, the sacrum, and coccyx. The lumbar spine includes five lumbar vertebra (L1-L5), and five intervertebral discs.

The vertebra of the lumbar spine are the largest vertebra in the body because they carry the most weight and are subject to the greatest amount of stress. That being said, it is the area most frequently associated with back pain. The motions of the lumbar spine (in order of greatest to least) include flexion (bending forward), extension (bending backward), side bending, and rotation right and left (turning).

The two lowest levels (L4-L5) and (L5-S1) have the most flexion and extension motion stress, and the highest rate of injury. The intervertebral discs of these two levels also have the highest rate of disc degeneration and herniation. The L5 vertebra is the most common site of spondylosis and spondylolisthesis. The most common lumbar nerves that get pinched or entrapped are the L4, L5, S1 levels. Entrapment of these nerves may lead to a condition called Sciatica.

Spinal Nerves and Intervetebral Foramen

In the spine, there are areas where the intervertebral disc and facet joints join two lumbar vertebral bodies. Where this occurs, it forms two canals on either side of the spine. These canals are called intervertebral foramina. The nerves leave the spinal cord, and travel through the foramina, exiting the spinal column, where they travel out to the rest of body.

The size or diameter of the spinal foramina can vary from person to person. If anything compromises or encroaches on the canal, it may put pressure on the exiting nerve. This produces symptoms that may include pain, tingling, numbness or even weakness. Degenerative disc disease, degenerative joint disease, disc herniation, and bony spurs or osteophyte formation are conditions that can narrow the intervetebral foramen and compress the exiting nerves. This may produces symptoms in the back, buttocks and legs.

The spinal nerves are the electrical wires of the body. They originate at the spinal cord and exit the spinal column through the intervetebral foramen. Once out in the body the spinal nerves are considered peripheral nerves. They provide both sensation (afferent) and motor or muscle (myotomal) innervations to the body.

Nerves exiting the area of the lumbar spine provide sensation and motor control to the back, buttocks, legs and down to the foot. Damage or interference with the conduction (transfer of information) of these nerves can cause neurological problems such as pain, weakness, abnormal sensations, numbness and changes in spinal reflexes. These symptoms may occur in the back, leg and down to the foot.

The most common nerve irritation originating from the lumbar spine is Sciatica. This is an irritation of the sciatic nerve, which can produce pain, numbness, and weakness down the leg along the areas innervated by the sciatic nerve.

Causes

Anything that encroaches, decreases or narrows the space where the nerves exit the foramen can produce what is commonly known as a pinched nerve. Commons causes of pinched nerve include:

  • Degenerative disc disease that results in wear on the intervertebral disc and a reduction in disc height may result in loss of space at the intervertebral foramen.
  • Herniated discs can place pressure on the nerve, in addition to inflammation that irritates the nerve.
  • Degenerative joint disease resulting in the formation of bony spurs on the facet joints can narrow the intervertebral space placing pressure on the exiting nerve.
  • Trauma or muscle spasm can put pressure on the peripheral nerve, producing symptoms along that nerve’s distribution

Symptoms

The symptoms experienced as a result of a pinched nerve will be located along the same path that the nerve travels.

  • Pain in the back or radicular to the buttock, into the leg and extending down behind the knee, to the foot depending on the nerve involved and the severity of the encroachment.
  • Impairment of normal reflexes in the lower extremity.
  • Numbness or paraesthesia (tingling) may be experienced from the low back to the foot depending on the distribution of the affected nerve.
  • Muscle weakness may occur on any muscle that is innervated by the pinched nerve. Long-term pressure on the nerve can produce atrophy or wasting of that particular muscle.
  • Pain and tenderness localized at the level of the involved nerve.
  • Muscle spasm and changes in posture in response to the injury.
  • Pain with excess activity and relief with rest.
  • Pain and tenderness localized at the level of the involved nerve.
  • Loss of motion like the inability to bend backward, move sideways to the effected side, or stand erect for extended periods of time.
  • Sitting, standing and walking can be difficult if the irritation is severe.
  • Loss of the normal lumbar curvature or lordosis.
  • Development of stenotic-like symptoms.
  • Stiffness in the joints following a period of rest.

Common Pain Patterns

  • L1- Back and anterior, and inner surface of the thigh.
  • L2- Back and anterior, and inner surface of the thigh.
  • L3- Back and anterior, and inner surface of the thigh moving down.
  • L4- Back and anterior surface of the thigh, to the inner surface of the lower leg, to the foot and great toe.
  • L5- Back to the lateral thigh, anterior lower leg, the top and bottom of the foot to the middle toes.
  • S1 S2- Buttock, back of the thigh and the lower leg.

Treatment

Treatment of a pinched nerve or injury will depend on the severity of the condition. When treating acute back problems:

  • Rest: avoid the activities that produce the pain (bending, lifting, twisting, turning or bending backwards).
  • Medication to reduce inflammation (anti-inflammatory drugs and pain medication).
  • Ice in acute cases: apply ice to the neck or cervical spine to help reduce pain and associated muscle spasm. Apply ice right away and then at intervals for about 20 minutes at a time. Do not apply directly to the skin.
  • An exercise regiment designed specifically to address the cause of the symptoms associated with the pinched nerve and improve joint mobility, spinal alignment, posture, and range of motion.
  • A lumbar support may be necessary to reduce stress on the nerves, facet joints, muscles and cervical spine.
  • Steroidal medication to reduce inflammation in moderate to severe conditions.
  • Lumbar nerve or epidural injections
  • Physical therapy to reduce inflammation, restore joint function, improve motion, and help the return of full function.

Mild

In mild cases rest, ice and medication may be enough to reduce the pain. Many patients will do well with this regiment. Physical therapy is recommended to develop a series of postural, stretching and strengthening exercises to prevent reoccurrence of the injury. Return to activity should be gradual to prevent a return of symptoms.

Moderate to Severe

If the problem persists, consulting with your health care provider should be the next step. Your physician will perform a thorough evaluation to determine the possible cause of your symptoms, the structures involved, the severity of the condition, and the best course of treatment.

Medical Interventions

In addition to performing a thorough examination your physician may order the following tests to make a more concise diagnosis:

  • X-ray to determine if there is any joint degeneration, fractures, bony malformations, arthritis, tumors or infection present.
  • MRI to determine any soft tissue involvement, including visualization of the discs, spinal cord and nerve roots.
  • CT scans, which can give a cross section view of the spinal structures.

Medications

Your physician may recommend several medication options individually or in combination to reduce the pain, inflammation and muscle spasms that may be associated with facet joint injuries.

  • Over the counter medications for mild to moderate pain.
  • If over the counter medications are not effective your physician may prescribe stronger pain medication.
  • Anti-inflammatory drugs or prescription NSAIDS (non-steroidal anti-inflammatory drugs) to reduce inflammation following acute injury.
  • Muscle relaxers to reduce acute muscle spasm.
  • Injections like facet injections, nerve blocks or an epidural. These may involve the injection of corticosteroids to a specific structure to reduce local inflammation.

Severe or Non-responsive Condition

In the case of conditions that do not respond to conservative care surgery may be indicated. If you continue to experience some of the following symptoms:

  • Increase in radiating or radicular pain
  • Pain or nerve irritation that gets worse
  • Weakness with muscle atrophy
  • Associated disc involvement

If symptoms continue to get worse, surgery may be indicated to release entrapment and remove the degenerative changes that are compromising the nerve. One such procedure is called a Foraminotomy. Surgical options will also depend on what structure is causing the encroachment. Some examples include foraminotomy, laminotomy, spinal laminectomy, spinal decompression, and spinal fusion. Spinal surgery is not usually performed when the only symptom is back pain.

Physical Therapy

Physical Therapists are professionals, educated and trained to administer interventions. As defined by The Guide to Physical Therapist Practice, interventions are the skilled and purposeful use of physical therapy methods and techniques to produce changes consistent with the diagnosis, prognosis and the patient or client’s goals.

Your physical therapist will perform a thorough evaluation to assess and determine the following:

  • Spinal Examination: where the patient is put through a series of movements and tests to determine the most probable cause of the condition.
  • Strength: resisted testing is performed to determine if there is associated weakness or strength imbalances.
  • Flexibility: tight muscles can contribute to poor mechanics and weakness creating imbalances and making one more susceptible to disc and back injuries.
  • Posture Analysis, ADL’s and technique: discuss and observe the activity that may have started the problem. An examination of the dynamic and static postures that may have caused or contributed to the back problem. A review of your current activities at home and work that may or may not be causing or prolonging your present condition.

Physical therapy for a pinched nerve must remain conservative at the onset to avoid aggravating the condition. Emphasis will be on rest, reducing the inflammation, load and stress on the affected area. Once the initial inflammation has been reduced, a program of stretching and strengthening will be initiated to restore flexibility to the joints and muscles involved, while improving strength and stability to the spine. Your program design will be based on the structure and cause of your symptoms. A program not tailored to your problem could aggravate your symptoms.

Physical Therapy Interventions

Common Physical Therapy interventions in the treatment of a cervical pinched nerve include:

  • Manual Therapeutic Technique (MTT): hands on care including soft tissue massage, stretching and joint mobilization by a physical therapist to improve alignment, mobility and range of motion of the lumbar spine. Use of mobilization techniques also helps to modulate pain.
  • Therapeutic Exercises (TE) including stretching and strengthening exercises to restore joint mobility, range of motion, and strengthen muscles of the back and abdominals to support, stabilize and decrease the stresses place on the spinal joints, discs, and neck.
  • Neuromuscular Re-education (NMR) to improve posture, restore stability, retrain the patient in proper sleeping, sitting and body mechanics to protect the injured spine.
  • Modalities including the use of ultrasound, electrical stimulation, ice, cold laser, traction and others to decrease pain and inflammation of spinal structures.
  • Home programs including strengthening, stretching and stabilization exercises and instructions to help the person perform daily tasks and advance to the next functional level.

Prognosis

Most pinched nerves or entrapment problems can be managed conservatively without surgery and return to normal function. Duration of treatment can range from 4 to 12 weeks depending on the severity of the symptoms. Patients need to continue with a regiment of postural, stretching, strengthening and stabilization exercises. Use of proper mechanics, proper posture, body mechanics and awareness of the do’s and don’ts for a healthy back is necessary for a good long-term prognosis. The attitude of, “once you have a back problem, you have a back problem” goes a long way to preventing further injury. Staying on a regimented home program to treat the condition that caused the entrapment is important.