Nerve Imaging Could Revolutionize Treatment of Pain : Medicine: For first time, researchers are able to clearly define nerves inside the body. The technique holds promise for helping to ease a variety of conditions.
University of Washington researchers have for the first time been able to clearly image nerves inside the body, a development that could revolutionize the diagnosis and treatment of chronic pain and a variety of other nerve-related conditions.
The highly detailed images produced by the technique can greatly reduce the amount of surgery required to correct nerve damage or eliminate persistent pain because surgeons will be able to identify the precise location of the damage before the first scalpel cut is made, said Dr. Aaron Filler, a neurosurgeon at the University of Washington in Seattle. Filler says he and his colleagues have used the technique successfully on about a dozen patients.
Filler and his colleagues report Saturday in the international medical journal Lancet that they have devised a sophisticated electronic package to modify conventional magnetic resonance imaging scanners. With the new technology, images of all other tissues virtually disappear, leaving behind a three-dimensional picture of the nerve “like the smile of the Cheshire cat in ‘Alice in Wonderland,’ ” he said.
“The modification . . . is going to have a big impact,” Filler said. The diagnosis of nerve damage “is one of the last great blind spots of medicine. We’ve already used (the new technique) on several cases that would have been impossible to diagnose otherwise.”
“The real trick that they have done here is to find a (technique) for imaging which permits the isolation of the nerve” from other tissues, said Dr. Mark Hallett, clinical director at the National Institute of Neurological Diseases and Stroke in Bethesda, Md. “That, in fact, is remarkable. It certainly is promising as a diagnostic tool.”
MRI is a relatively recent technique that has revolutionized diagnostics. In MRI, the patient is immersed in a strong magnetic field and bursts of radio-frequency energy are used to stimulate water molecules. Water molecules in different tissues respond differently to the signal, and that response is detected by monitoring the magnetic field.
This process can produce highly detailed pictures of the interior of the body.
What Filler and his colleagues have done, in effect, is to identify the specific response of water inside nerves and tune the machine to use only that response in producing images.
Surprisingly, that was not what they set out to do. The team has been working for several years to develop contrast agents that would reveal nerves to the MRI scanner in much the same way that a barium enema reveals the colon to X-rays.
“We had been frustrated for a couple of years,” Filler said. “One day we put two or three different things together and suddenly everything else disappeared. We were hoping they would help a little, but we had no idea that it would work that well. . . . We could see the nerves far better than we ever expected.”
Neurosurgeons at Washington have used the technique to treat more than a dozen patients, said Dr. Michael Kliot, a co-author.
In the most dramatic example, Kliot and Filler examined a teen-age wrestler who had so much muscle development that it had compressed a nerve in the brachioplexus, the complex web of nerves extending from the head to the arm. The pressure caused weakness of the arm.
After conventional techniques failed to identify the site of the compression, an MRI of the arm using the new technique immediately showed where the compression was. The neurosurgeons then removed a small piece of the offending muscle to restore normal function.
“It was quite exciting,” Kliot said. “This is really useful because compressions and other lesions stand out very clearly.”
Kliot also said the technique was very useful in half a dozen patients with nerve tumors because it was impossible otherwise to tell whether the tumors were part of the nerve or simply a mass pressing against the nerve. “It’s important to know everything we possibly can about a tumor before we begin surgery,” he said.
The technique holds particular promise for treating the millions of people who suffer intractable pain in the back or elsewhere, Filler said. “Pain which could be only ineffectively treated . . . may now prove to be correctable by simple surgery, since it is now possible to locate the actual site of nerve compression or irritation causing the pain or weakness.” In the past, disability claims and lost days at work resulting from such pain have cost the U.S. economy billions of dollars.
So far, Filler and his colleagues have modified only the MRI scanner at Seattle. But they are negotiating with instrument manufacturers for their technique to be incorporated into newer models. Scanners at other medical centers can also be retrofitted relatively easily to use the new technique, he said.
