Womens Health

Low Back Pain -- When is Imaging Needed?

Frederick R. Jelovsek MD

Everyone gets an episode of low back pain once in awhile. The lower spinal cord is subject to strains, dislocations, injuries and diseases. Low back pain is difficult to treat and it is even more difficult to know when expensive imaging such as CAT (computerized axial tomography) scans or MRI (magnetic resonance imaging) is necessary.

The spine is composed of 24 mobile vertebrae that each have 3 joint articulations which allow bending forward or backward, bending to the side, and rotation allowing the head and shoulders to rotate almost 90 degrees left or right of the hip plane. Ligaments of the spine and back muscles along the spine help protect from bending or rotating too far as well as allowing lifting of weight. In between each vertebrae is a shock absorbing disk filled with fluid sort of like a shoe insert or cushioned sole that makes running less "bone-jarring". You could also look at it as a "mini-waterbed" in between each vertebrae; but what happens if the fluid leaks out of the waterbed?

In the normal aging process, routine wear and tear of the spinal cord structures start as early as age 30 and by age 50, 97% of autopsies of people who died from non-spinal problems show detectable degeneration of the spine. Intervertebral disks begin to wear or grind down, tear or even leak and put pressure on spinal nerves which pass from the spinal cord.

A recent article, Borenstein, DG et al.: A low-tech approach to low-back pain. Contemporary Ob/Gyn. 1998;40:80- 96, emphasizes that in most cases, the cause of low back pain is unknown with certainty, but it doesn't really matter because the treatment is the same regardless of the cause.

Since the start of x-rays in the 1930's, doctors have always assumed that x-ray or imaging changes explained a patient's back pain problem. Most experts now believe that imaging changes are mostly coincidental and do not explain the actual cause. So when is back pain a sign of something serious that needs to be accurately diagnosed?

When does back pain mean a severe or dangerous problem?

  • associated fever can mean bone infection (osteomyelitis) or central nervous system infection
  • recent weight loss can mean either benign or malignant tumors
  • pain worse in the morning (other than transient pain upon waking) that persists, rather than back pain that worsens late in the day may suggest diseases such as ankylosing spondylitis or Reiter's syndrome.
  • pain that radiates down below the posterior thigh may indicate nerve involvement (sciatica)
  • no improvement after 4-6 weeks

The above list also serves to tell when it is time to get an x-ray or MRI imaging study. You have to remember that there is controversy about MRIs. Up to 90% of all spinal MRIs can be read as abnormal. Some experts think this high frequency of abnormalities just represents normal aging changes over time, while others think, although common, these changes represent pathological disease processes.

Well what can you do to ease the pain for the 4-6 weeks that many back pain problems last for?

  • Heat application helps a muscle stiffness problem and should be tried to see if it benefits the pain.
  • Non steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen on a regular daily basis; not so much for the pain relief as for the anti-inflammation effect to heal up the injury.
  • Some herbal preparations for muscle pain relief and arthritis pain may be helpful.
  • Light to moderate activity (NOT bed rest) such as walking, swimming, back exercises and physical therapy.

The important thing to know is that most back pain will improve in 4-6 weeks and that trying to keep up with most normal activities is the best approach to take.

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