State of mind may
contribute more to low back pain than torn discs
BY KRISTA CONGER
When a person suffers from
debilitating lower back pain, a torn vertebral disc is
often pinpointed as the cause, and physicians frequently
turn to invasive surgery to correct the condition. But a
new study by Stanford University Medical Center
researchers indicates that these tears can be found in
lots of people, even those who have no trouble twisting,
turning and bending. The results suggest that the
duration and severity of the pain may have as much to do
with the patient's state of mind as with the presence of
a damaged disc.
"For better or for
worse, the identification of a certain kind of torn disc
has been one of the main tools used to diagnose the cause
of low back pain, and now it looks like it's a false
start in many patients," said Eugene Carragee, MD,
lead author of the study. He will present his findings on
April 12 at the annual meeting of the International
Society for the Study of the Lumbar Spine.
The study, which may
revolutionize the way physicians diagnose and treat back
aliments, will receive the 1999 Volvo Corporation Award
for the Clinical Study of Low Back Pain. The
international award recognizes research that has a
fundamental impact on low back health care, which is an
increasing concern in the United States and other
countries.
Carragee, a Stanford
associate professor of functional restoration, estimates
that up to five percent of the working population in the
United States is disabled by low back pain on any given
day. Medical treatments and disability expenses related
to the condition cost up to $150 billion each year in
this country alone, he said.
Until now, tears in the
vertebral discs that cushion the spine have been thought
to be the culprit for most of these low back pain
complaints. Like spongy coasters sandwiched between each
vertebra, the cartilaginous discs protect the bones from
banging against each other during running or jumping. But
if the hard coating of the disc tears or ruptures, the
soft interior can sometimes protrude, pressing on
sensitive nerves and causing pain.
According to Carragee,
acting as the body's shock absorber takes its toll. Discs
become increasingly susceptible to tears or rupture as
they age. Virtually everyone will develop disc tears at
one time or another, although not everyone will have
painful side effects; and in those that do, the pain is
usually mild or of short duration, he said.
Tears in the flat,
saucer-shaped discs can appear as bright areas, or 'high
intensity zones' on a magnetic resonance imaging (MRI)
scan. The presence of a tear is confirmed by a
discography, in which a physician injects a dye into the
suspect disc. Dye leaking out of the disc center into the
surrounding area sometimes causes pain. Additionally,
escaping dye can be confirmed with an X-ray of the lower
back.
Until now, physicians have
thought that the identification of a high intensity zone
coupled with discomfort during a discography confirmed
that the damaged disc was the source of the patient's
back problems, and planned their treatment accordingly.
But when the Stanford
researchers completed a rigorous comparison of the MRI
and discography results of 96 patients with known risk
factors for disc degeneration, they found something
surprising. People whose discs had high intensity zones
were only slightly more likely to experience back pain
during normal activity than those without obvious disc
problems. Additionally, high intensity zones were found
in 25 percent of people who -- despite their known
degenerative disc disease -- had no corresponding
symptoms of low back pain.
The Stanford team
concluded that the presence of the high intensity zones
-- and thus torn discs -- doesn't automatically mean that
the patient is experiencing pain during everyday
activities, or that they will feel pain during a
discography. This suggests that not every disc tear is
painful, and not all low back pain results from a damaged
disc.
A better predictor of
pain, they found, is an abnormal result on psychometric
testing administered to all the study patients before the
examinations.
"Basically what we
showed is that the amount of discomfort that people have
with the injection is, in many patients, most closely
related to psychological and social issues," said
Carragee. They found that people with poor coping skills
or who have ongoing workers compensation claims or
personal litigation related to a back injury are more
likely to perceive discography as painful and to have
symptoms of low back pain during their daily activities.
The results suggest that
physicians must be acutely aware of the emotional or
psychological factors that may be affecting how patients
perceive their back pain. Carragee believes it is vital
to the patient's recovery to get to the true root of the
problem, which may have both physical and emotional
dimensions. It is especially important to avoid
unnecessary, invasive and expensive treatments, such as
back fusions, that reinforce the perception that the
patient has a grave disease of the spine, he said.
Currently a standard
treatment for severe, persistently painful, vertebral
disc tears, back fusions require physicians to remove the
damaged disc. The two neighboring vertebrae are then
fused together to prevent painful friction between the
bones and to provide stability to the spine. As many as
30,000 back fusions are performed annually in the United
States, Carragee estimated, although they are often not
very successful at relieving the patient's pain.
In contrast, Carragee has
found that many patients respond well to reassurance and
an active physical fitness program, which can improve
both their back pain and sense of well-being. In some
people, treatment for depression can complement this
supportive approach. However, if the back pain is
compounded by problems at work or home, or is reinforced
by pending worker's compensation issues, even more
intensive psychiatric treatment may have only marginal
success at relieving the patient's symptoms.
Carragee's collaborators
on the study include Steve Paragioudakis, MD, staff
physician of functional restoration, and Sanjay Khurana,
MD, resident in orthopaedic surgery. The study results
will be published in the December issue of Spine, which
will be devoted to the research of the 1999 Volvo Award
winners. SR
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