EMBARGOED FOR RELEASE UNTIL TUESDAY, JULY 21, 1998 For more information contact: Sarah Parsons (651) 695-2732 or [email protected]
Muscle Abnormalities Found in Patients with Mysterious Pain Syndrome
ST. PAUL, MN (July 21, 1998) A new study has found muscle abnormalities in people with reflex sympathetic dystrophy, a disorder involving chronic pain in the arms or legs that can lead to severe disability. The study is published in the July issue of Neurology, the scientific journal of the American Academy of Neurology.
The disorder, which was recently renamed complex regional pain syndrome type I, usually develops after a minor injury or operation on the arm or leg.
"The study shows that there is indeed a real, objective abnormality in some of these patients, and the disorder is not primarily psychological, as some physicians may think when an explanation is not found for the pain and disability," said neurologist Michael Rowbotham, MD, of the University of California, San Francisco, who wrote an editorial on the study.
Dutch researchers studied eight patients with one leg amputated due to complete disability in the leg and with untreatable or recurring infections. (Amputation is not recommended as a treatment for the pain accompanying the disorder, Rowbotham said.)
Analyzing muscles and nerves from the amputated legs, researchers found several abnormalities in the muscles, including signs of oxidative stress, or cell damage caused by free radicals. Free radicals are unstable oxygen molecules that combine with other molecules and often damage or kill the cells they latch onto.
The researchers also found abnormalities in the muscle capillary blood vessels similar to the abnormalities seen in the muscles of diabetic patients. They hypothesize that an increase in free radicals may impair the bodyÃs ability to regulate its vascular system, leading to a disease in the fine blood vessels of the legs.
The patientsà nerves, however, showed some changes but no consistent abnormalities.
"This finding is in contrast with the main theory of this disorder, which holds that the pain results from an abnormal response by the sympathetic nervous system to an injury," said study author Lijckle van der Laan, MD, of University Hospital Nijmegen in the Netherlands. "The nerves that should be affected if this theory is accurate should have shown severe abnormalities."
Rowbotham said the study shows that "the affected tissues are truly abnormal, and abnormal in ways that cannot be readily explained by disuse or psychological factors."
He states that the findings do not explain the weakness, tremor and severe pain that often accompany the disorder. "But the inability to find an organic explanation does not prove a psychological cause," Rowbotham writes. "Absence of proof is not the same as proof of absence."
Improving care for patients with neurological disorders through education and research is the goal of the American Academy of Neurology, an association of more than 15,000 neurologists and neuroscience professionals. - end -
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