you scrape your knee or elbow or burn your hand, it heals and the
pain ends. For some people, though, the wound goes away, but the
pain remains. Along with the pain, the wounded area may swell and
sweat, and the skin color and temperature may change. All of these
symptoms are often way out of proportion to the original injury.
These are the symptoms of a medical condition
called complex regional pain syndrome-1 (CRPS-1). CRPS-1 is hard
to treat because doctors do not know the cause.
And, sadly, sometimes the patients have been treated as if the CRPS-1 pain was in their head (psychological) rather than in their body (physiological). They may become
depressed and occasionally suicidal. The pain is described as
excruciating, but until now its physiological basis was not revealed
by any standard test. By designing and confirming a diagnostic
procedure, and by explaining the biological basis for the pain,
Dr. Oaklander's team has laid the groundwork for possible treatments
for patients and has given an important psychological boost to
patients: they can now confirm their experience with a simple
As a step to learning more, Dr. Anne Louise Oaklander and a team of researchers at Massachusetts General Hospital's Nerve Injury Unit in Boston conducted a study of adults with and without CRPS-1.
Dr. Oaklander and her colleagues studied the skin from 18 adults with CRPS-1. To serve as a
they also studied 7 adults who did not have CRPS-1, but did have other painful conditions such as
of the knee.
The skin from each person was studied in two ways. The first was to test the skin for
Sensory function tests measured the person's perception of pain when areas of the skin were touched, pressed, and stimulated with heat and cold using special machines made for this type of evaluation. In people with CRPS-1, the sensory function tests found that a light touch or slight heat was felt as extremely painful in the affected areas compared to other parts of their body. The wound that had healed somehow left behind an area of increased painful sensitivity, which was so sensitive that clothing touching the skin produced unbearable pain. The control group, the people with painful conditions but not CRPS-1, did not show any change in sensory perception.
In the second evaluation, each patient was studied
by taking skin samples with a skin
punch, which removes about 3 mm (about a tenth of an inch)
of tissue; this process is called a biopsy.
Each person had three skin biopsies under anesthesia. One biopsy
was from the area of the most pain, a second biopsy was from a
nearby pain-free spot, and the third biopsy was the mirror image
site on the opposite side of the body. For example, if the right
knee was most painful, a biopsy would be taken from the right
knee, the right thigh and the left knee. The right thigh and the
left knee were the pain-free areas. The skin samples were prepared
and stained so the nerve cells could be examined under a high
power microscope. The researchers found that the areas identified
as painful in people with CRPS-1 had fewer small-fiber nerve cells
compared to other parts of their body. Fewer nerve cells make
the skin super-sensitive, which produces the painful feelings
reported by these people. In contrast, the control group
did not have any nerve damage, indicating the pain of osteoarthritis
arises from undamaged nerve cells.
From the results, Dr. Oaklander and colleagues
concluded that CRPS-1 is a condition in which the nerves on the
skin have been damaged. For now, the first treatments are drugs
to relieve the pain because there is currently no cure for CRPS-1.
If drugs are not effective, surgical options are to block nerve
conduction, called an anesthetic block, or implant electrodes
under the skin to electrically stimulate the injured nerves. This
latter treatment may rewire damaged nerves back to a more normal
pathway of sensation. Researchers are hopeful that continued studies
will lead to a cure in the future.
Equally important for people with CRPS-1 pain, there is now scientific evidence that their suffering originates in damaged tissue in their bodies and not psychologically. That, too, is important to the well being of patients.
Dr. Anne Louise Oaklander is a
who has spent most of her career studying pain and what causes it. She is the Founder and Director of the Nerve Injury Unit at Massachusetts General Hospital, Boston, MA. She travels around the world teaching physicians and patients about pain-related diseases and their treatment. In Boston, she teaches at Harvard Medical School and conducts research on the causes of nerve pain in her laboratory.
To Learn More:
About organizations helping those with CRPS:
- Groopman J., When Pain Remains.
The New Yorker, October 10, 2005: pages 36-41.
- Oaklander AL, Rissmiller JG, Gelman LB, Zheng L, Chang Y,
Gott R. Evidence of focal small-fiber axonal degeneration
in complex regional pain syndrome-1 (reflex sympathetic dystrophy).
Pain 2006; 120:235-243.
About Treatments for CRPS-1:
- Hord ED, Oaklander AL. Complex regional pain syndrome: a review of evidence-supported treatment options. Current Pain and Headache Reports 2003; 7:188-196.
- Oaklander, AL. Evidence-based pharmacotherapy
for CRPS and related conditions. In: CRPS: Current
Diagnosis and Therapy, Progress in Pain Research and Management
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Dr. Anne Louise Oaklander
Dr. Anne Louise Oaklander
and a team of researchers at Massachusetts General Hospital's
Nerve Injury Unit in Boston
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