Diagnostic Imaging Online
November 18, 2002
Functional MRI zeroes in on back pain
Faulty pain-processing pathways in the brain may be responsible for lower back pain of unknown origin, according to University of Michigan researchers.
As the same team of investigators reported in May regarding the causes of fibromyalgia, functional MRI suggests that the brains of some patients experiencing back pain show an altered pain perception in response to stimulus that most would consider just as a gentle touch. The group presented results of the back pain study in October at the annual meeting of the American College of Rheumatology in New Orleans.
The Michigan researchers studied the brains of 15 people with lower back pain and no proven physical cause, such as a ruptured disc. They also included 15 patients with fibromyalgia and 15 healthy subjects in the study.
"The fMRI technology gave us a unique opportunity to look at the neurobiology underlying tenderness, which is a hallmark of both lower back pain and fibromyalgia," said Dr. Daniel J. Clauw, senior author and director of the Chronic Pain and Fatigue Research Center at the University of Michigan.
According to Clauw, the results of this study led the investigators to suspect that some pathologic process makes lower back patients more sensitive -- a neurobiological amplification of their pain signals.
"We found that among back pain patients there is a group with the same kind of signs as fibromyalgia patients with augmented pain processing," he said.
Using the insight gained from the fibromyalgia trial, which was the first to use fMRI to determine the mechanisms of abnormal sensitivity and pain, Clauw and his group replicated the techniques and methodology of that study and added a group of patients suffering from back pain. Patients who have this abnormal pain perception represent a major subset of people with chronic back pain, he said, but many of them appear normal on x-rays or MRI scans.
Even though there is no evidence that all patients with lower back pain of unknown origin may have this condition, diagnosis should not be restricted to musculoskeletal conditions, he said.
"It would be completely wrong to classify all back pain patients as having a musculoskeletal condition," Clauw said.
Studies are still preliminary, he warned. Future developments in this area, however, should lead physicians to look at chronic back pain in different ways, determining whether its causes are peripheral and can be treated with pain killers or anti-inflammatory drugs, or are musculoskeletal conditions requiring more aggressive treatment.
For more from the Diagnostic Imaging archives:
FMRI shows evidence of fibromyalgia patients' pain
-- By Harold Abella
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