Low Back Pain (cont.)
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
In this Article
- Low back pain facts
- What is the anatomy of the low back?
- What is the function of the low back?
- What are common causes of lower back pain?
- What are other causes of lower back pain?
- What are uncommon causes of low back pain?
- What are other symptoms and signs sometimes associated with low back pain?
- How is low back pain diagnosed?
- What is the treatment for low back pain?
- What is the outlook (prognosis) for low back pain?
- Can low back pain be prevented?
- Back Pain - Slideshow
- Understanding Sciatica Pain Slideshow
- Take the Back Pain Quiz!
- Back Pain FAQs
- Find a local Orthopedic Surgeon in your town
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 support the weight of the upper 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 adjacent muscles of the low back.
What are common causes of lower back pain?
Common causes of low back pain (lumbar backache) 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 stretch 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 40s, 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 reinjury), 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. Initial treatment at home might include heat application, acetaminophen (Tylenol) or ibuprofen (Advil, Motrin), and avoiding reinjury and heavy lifting. Long periods of inactivity in bed are no longer recommended, as this treatment may actually slow recovery. Spinal manipulation for periods of up to one month has been found to be helpful in some patients who 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 pressure (impingement) by bone or other tissues, or from disease, anywhere along their
paths -- fromtheir 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 descriptions 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 of a herniated disc that shoots from the low back and buttock 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. The sciatica of lumbar radiculopathy typically affects only one side of the body, such as the left side or right side, and not both.
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 imaging tests, 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 muscle spasms, cortisone injection around the spinal cord (epidural injection), physical therapy (heat, massage by a therapist, ultrasound, exercises, electrical stimulation), and rest (not strict bed rest but avoiding reinjury). 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.
- 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, commonly as a result of arthritis), 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 the pains of poor circulation). Treatment of these afflictions varies, depending on their severity, and ranges from rest, and exercises to epidural cortisone injections and 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 due to inflammation of the joints (arthritis).
Picture of herniated disc between L4 and L5
Cross-section picture of herniated disc between L4 and L5
- Congenital bone
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
Injury to the bones and
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 or kyphoplasty, 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 and height of the body of the vertebra. Pain is relieved as the height of the vertebra is restored.
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