Low Back Pain

Back Pain Health Summary
Back pain may be caused by sciatica, a herniated disc, spinal stenosis, fibromyalgia, injury and pregnancy. Possible symptoms include pain that radiates down the legs, pain that gets worse with activity or at night, or numbness or weakness in the leg. Treatment may involve sleeping with a pillow between the knees or taking ibuprofen or acetaminophen.
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Low Back Pain Overview

Pain in the lower back or low back pain is a common concern, affecting up to 90% of Americans at some point in their lifetime. Up to 50% will have more than one episode. Low back pain is not a specific disease, rather it is a symptom that may occur from a variety of different processes. In up to 85% of people with low back pain, despite a thorough medical examination, no specific cause of the pain can be identified. America spends approximately $50 billion a year on low back pain.

Back pain can have many underlying reasons, but often no specific cause will be found and the pain will stop. This chapter will review many of the causes of back pain and proper evaluation and diagnosis. Please be sure to discuss your individual symptoms as well as the suggested treatments with your health-care professional to determine the appropriate diagnostic and treatment plan for your circumstances.

  • Low back pain is second only to the common cold as a cause of lost days at work. It is also one of the most common reasons to visit a doctor's office or a hospital's emergency department. It is the second most common neurologic complain in the United States, second only to headache.
  • For 90% of people, even those with nerve root irritation, their symptoms will improve within two months no matter what treatment is used, even if no treatment is given.
  • Doctors usually refer to back pain as acute if it has been present for less than a month and chronic if it lasts for a longer period of time.

Low Back Pain Causes

Back pain is a symptom. Common causes of back pain involve disease or injury to the muscles, bones, and/or nerves of the spine. Pain arising from abnormalities of organs within the abdomen, pelvis, or chest may also be felt in the back. This is called referred pain. Many disorders within the abdomen, such as appendicitis, aneurysms, kidney diseases, kidney infection, bladder infections, pelvic infections, and ovarian disorders, among others, can cause pain referred to the back. Normal pregnancy can cause back pain in many ways, including stretching ligaments within the pelvis, irritating nerves, and straining the low back. Your doctor will have this in mind when evaluating your pain.

  • Nerve root syndromes are those that produce symptoms of nerve impingement (a nerve is directly irritated), often due to a herniation (or bulging) of the disc between the lower back bones. Sciatica is an example of nerve root impingement. Impingement pain tends to be sharp, affecting a specific area, and associated with numbness in the area of the leg that the affected nerve supplies.
    • Herniated discs develop as the spinal discs degenerate or grow thinner. The jellylike central portion of the disc bulges out of the central cavity and pushes against a nerve root. Intervertebral discs begin to degenerate by the third decade of life. Herniated discs are found in one-third of adults older than 20 years of age. Only 3% of these, however, produce symptoms of nerve impingement.
    Picture of a herniated lumbar disc
    Picture of a herniated lumbar disc
    • Spondylosis occurs as intervertebral discs lose moisture and volume with age, which decreases the disc height. Even minor trauma under these circumstances can cause inflammation and nerve root impingement, which can produce classic sciatica without disc rupture.
    • Spinal disc degeneration coupled with disease in joints of the low back can lead to spinal-canal narrowing (spinal stenosis). These changes in the disc and the joints produce symptoms and can be seen on an X-ray. A person with spinal stenosis may have pain radiating down both lower extremities while standing for a long time or walking even short distances.
    • Cauda equina syndrome is a medical emergency whereby the spinal cord is directly compressed. Disc material expands into the spinal canal, which compresses the nerves. A person would experience pain, possible loss of sensation, and bowel or bladder dysfunction. This could include inability to control urination causing incontinence or the inability to begin urination.
  • Musculoskeletal pain syndromes that produce low back pain include myofascial pain syndromes and fibromyalgia.
    • Myofascial pain is characterized by pain and tenderness over localized areas (trigger points), loss of range of motion in the involved muscle groups, and pain radiating in a characteristic distribution but restricted to a peripheral nerve. Relief of pain is often reported when the involved muscle group is stretched.
    • Fibromyalgia results in widespread pain and tenderness throughout the body. Generalized stiffness, fatigue, and muscle aches are reported.
  • Infections of the bones (osteomyelitis) of the spine are an uncommon cause of low back pain.
  • Noninfectious inflammation of the spine (spondylitis) can cause stiffness and pain in the spine that is particularly worse in the morning. Ankylosing spondylitis typically begins in adolescents and young adults.
  • Tumors, possibly cancerous, can be a source of skeletal pain.
  • Inflammation of nerves from the spine can occur with infection of the nerves with the herpes zoster virus that causes shingles. This can occur in the thoracic area to cause upper back pain or in the lumbar area to cause low back pain.
  • As can be seen from the extensive, but not all inclusive, list of possible causes of low back pain, it is important to have a thorough medical evaluation to guide possible diagnostic tests.
Medically Reviewed by a Doctor on 5/8/2014

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