Low Back Pain (cont.)
What is the function of the low back?
The low back, or lumbar area, serves a number of important functions for the
human body. These functions include structural support, movement, and protection
of certain body tissues.
When we stand, the lower back is functioning to hold most of the weight of
the body. When we bend, extend or rotate at the waist, the lower back is
involved in the movement. Therefore, injury to the
structures important
for weight bearing, such as the bony spine, muscles, tendons, and ligaments,
often can be detected when the body is standing erect or used in various
movements.
Protecting the soft tissues of the nervous system and spinal cord as well as
nearby organs of the pelvis and abdomen is a critical function the lumbar
spine and its adjacent muscles.
What are common causes of low back pain?
Common causes of low back pain include lumbar strain, nerve irritation, lumbar radiculopathy, bony encroachment, and conditions of the bone and joints. Each of these is reviewed below.
- Lumbar strain (acute, chronic)
A lumbar strain is a stretching injury to the ligaments,
tendons, and/or muscles of the low back. The stretching incident results in
microscopic tears of varying degrees in these tissues. Lumbar strain is
considered one of the most common causes of low back pain. The injury can occur
because of overuse, improper use, or trauma. Soft-tissue injury is commonly classified as
"acute" if it has been present for days to weeks. If the strain lasts
longer than three months, it is referred to as "chronic."
Lumbar strain most often occurs in people in their
forties, but it can happen at any age. The condition is characterized by localized
discomfort in the low back area with onset after an event that mechanically
stressed the lumbar tissues. The severity of the injury ranges from mild to
severe, depending on the degree of strain and resulting spasm of the muscles of the low back.
The diagnosis of lumbar strain is based on the history of injury, the
location of the pain, and exclusion of nervous system injury. Usually, x-ray testing is only helpful to exclude bone abnormalities.
The treatment of lumbar strain consists of resting the
back (to avoid re-injury), medications to relieve pain and muscle spasm, local
heat applications, massage, and eventual (after the acute episode resolves)
reconditioning exercises to strengthen the low back and abdominal muscles. Long
periods of inactivity in bed are no longer promoted, as this treatment may
actually slow recovery. Spinal manipulation for periods of up to one month has
been found helpful in some patients that do not have signs of nerve irritation.
Future injury is avoided by using back-protection techniques during activities
and support devices as needed at home or work.
- Nerve irritation
The nerves of the lumbar spine
can be irritated by mechanical impingement or disease any where along their paths—from their roots
at the spinal cord to the skin surface. These conditions include lumbar disc
disease (radiculopathy), bony encroachment,
and inflammation of the nerves caused by a viral infection (shingles). See discussions of these conditions
below.
- Lumbar radiculopathy
Lumbar radiculopathy is nerve irritation that is
caused by damage to the discs between the vertebrae. Damage to the disc occurs
because of degeneration ("wear and tear") of the outer ring of the disc,
traumatic injury, or both. As a result, the central softer portion of the disc
can rupture (herniate) through the outer ring of the disc and abut the spinal
cord or its nerves as they exit the bony spinal column. This rupture is what
causes the commonly recognized "sciatica" pain that
shoots down the leg. Sciatica can be
preceded by a history of localized low-back aching or it can follow a "popping"
sensation and be accompanied by numbness and tingling. The pain commonly
increases with movements at the waist and can increase with coughing or
sneezing. In more severe instances, sciatica can be accompanied by incontinence
of the bladder and/or bowels.
Lumbar radiculopathy is suspected based on the above
symptoms. Increased radiating pain when the lower extremity is lifted supports
the diagnosis. Nerve testing (EMG/electromyogram and NCV/nerve conduction
velocity) of the lower extremities can be used to detect nerve irritation. The
actual disc herniation can be detected with radiology testing, such as CAT or MRI scanning.
Treatment of lumbar radiculopathy ranges from medical
management to surgery. Medical management includes patient education,
medications to relieve pain and muscles spasm, cortisone injection around the spinal cord (epidural injection), physical therapy (heat, massage, ultrasound, electrical stimulation),
and rest (not strict bed rest, but avoiding re-injury). With unrelenting pain,
severe impairment of function, or incontinence (which can indicate spinal cord
irritation), surgery may be necessary. The operation performed depends on the
overall status of the spine, and the age and health of the patient. Procedures
include removal of the herniated disc with laminotomy (a
small hole in the bone of the lumbar spine surrounding the spinal cord),
laminectomy (removal of the bony wall), by needle technique (percutaneous
discectomy), disc-dissolving
procedures (chemonucleolysis), and others.
Picture of herniated disc between L4 and L5
Cross-section picture of herniated disc between L4 and L5
- Bony encroachment
Any condition that results in
movement or growth of the vertebrae of the lumbar spine can limit the space
(encroachment) for the adjacent spinal cord and nerves. Causes of bony
encroachment of the spinal nerves include foraminal narrowing (narrowing of the
portal through which the spinal nerve passes from the spinal column, out of the
spinal canal to the body), spondylolisthesis (slippage of one vertebra relative
to another), and spinal stenosis (compression of the nerve roots or spinal cord
by bony spurs or other soft tissues in the spinal canal). Spinal-nerve
compression in these
conditions can lead to sciatica pain that radiates down the lower extremities.
Spinal stenosis can cause lower-extremity pains that worsen with walking and are relieved by resting (mimicking
poor circulation). Treatment of these
afflictions varies, depending on their severity, and range from rest to surgical
decompression by removing the bone that is compressing the nervous tissue.
- Bone and joint conditions
Bone and joint conditions that lead to low
back pain include those existing from birth (congenital), those that result from
wear and tear (degenerative) or injury, and those that are from inflammation of
the joints (arthritis).
Congenital bone conditions—Congenital causes (existing from birth) of low
back pain include scoliosis and spina bifida. Scoliosis is a
sideways (lateral)
curvature of the spine that can be caused when one lower extremity is shorter
than the other (functional scoliosis) or because of an abnormal design of the
spine (structural scoliosis). Children who are significantly affected by
structural scoliosis may require treatment with bracing and/or surgery to the
spine. Adults infrequently are treated surgically but often benefit by support
bracing.
Spina bifida is a birth defect
in the bony vertebral arch over the spinal canal, often with absence of the
spinous process. This birth defect most commonly affects the lowest lumbar
vertebra and the top of the sacrum. Occasionally, there are abnormal tufts of
hair on the skin of the involved area. Spina bifida can be a minor bony abnormality without symptoms. However, the condition can
also be accompanied by serious nervous abnormalities of the lower extremities.
Degenerative bone and joint conditions—As we age, the
water and protein content of the body's cartilage changes. This change results
in weaker, thinner, and more fragile cartilage. Because both the discs and the
joints that stack the vertebrae (facet joints) are partly composed of cartilage,
these areas are subject to wear and tear over time (degenerative changes).
Degeneration of the disc is called spondylosis. Spondylosis can be noted on x-rays of the spine
as a narrowing of the normal "disc space" between the vertebrae. It is
the deterioration of the disc tissue that predisposes the disc to herniation and
localized lumbar pain ("lumbago") in older patients. Degenerative
arthritis (osteoarthritis) of the facet joints is also a cause of localized
lumbar pain that can be detected with plain x-ray testing. These causes of
degenerative back pain are usually treated conservatively with intermittent
heat, rest, rehabilitative exercises, and medications to relieve pain, muscle
spasm, and inflammation.
Injury to the bones and joints—Fractures (breakage of bone) of the lumbar
spine and sacrum bone most commonly affect elderly people
with osteoporosis, especially
those who have taken long-term cortisone medication. For these individuals,
occasionally even minimal stresses on the spine (such as bending to tie shoes)
can lead to bone fracture. In this setting, the vertebra can collapse (vertebral
compression fracture). The fracture causes an immediate onset of severe
localized pain that can radiate around the waist in a band-like fashion and is
made intensely worse with body motions. This pain generally does not radiate
down the lower extremities. Vertebral fractures in younger patients occur only
after severe trauma, such as from motor-vehicle accidents or a convulsive seizure. In both younger and
older patients, vertebral fractures take weeks to heal with rest and pain
relievers. Compression fractures of vertebrae associated with osteoporosis can also be treated with a procedure called vertebroplasty, which can help to reduce pain. In this procedure, a balloon is inflated in the
compressed vertebra, often returning some of its lost height. Subsequently, a "cement" (methymethacrylate) is injected into the balloon and remains to retain the structure.
Arthritis—The spondyloarthropathies are inflammatory
types of arthritis that can affect the lower back and sacroiliac joints.
Examples of spondyloarthropathies include reactive arthritis (Reiter's disease), ankylosing spondylitis,
psoriatic arthritis, and the arthritis of inflammatory bowel disease.
Each of these diseases can lead to low back pain and stiffness, which is
typically worse in the morning. These conditions usually begin in the second and
third decades of life. They are treated with medications directed toward
decreasing the inflammation. Newer biologic medications have been greatly
successful in both quieting the disease and stopping the progression.
Next: What are other causes of low back pain? »
- tramadol, Ultram - Read about tramadol (Ultram), a drug prescribed for chronic pain, and moderate to severe pain. Side effects, dosage, and drug interaction information included.
- CT Scan (Computerized Axial Tomography) - CT Scan (Computerized Axial Tomography, CAT scan) is a procedure that assists in diagnosing tumors, fractures, bony structures, and infections in the organs and tissues of the body.
- Sciatica - Read about sciatica pain causes, symptoms, diagnosis and treatment. Sciatic nerve irritation causes pain that radiates down the leg from the low back or buttocks.
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