Imaging method really shows some nerve.

A new imaging technique that can help doctors distinguish between healthy and damaged nerves may cut down on the need for exploratory surgery in cases that would otherwise be difficult to diagnose.

Aaron G. Filler and his colleagues at the University of Washington in Seattle first demonstrated the technique, called magnetic resonance neurography, 3 years ago (SN: 3/20/93, p. 183). It works like standard magnetic resonance imaging (MRI) with some modifications to the machine and control software, Filler says.

Although the researchers knew they could see grossly damaged nerves with the technique, they weren't sure it could distinguish between less severely damaged nerves and normal ones. Filler, now at the University of California, Los Angeles, and his colleagues in Seattle and at St. George's Hospital Medical School in London report their most recent findings in the August Journal Of Neurosurgery.

They took 242 images of peripheral nerves in 148 people, both healthy volunteers and patients with specific nerve complaints. The images confirmed many conventional clinical diagnoses and helped resolve inconclusive ones.

Neurography proved to be particularly useful for locating problems in the brachial plexus, a "blind zone" where nerves run from the neck to the arm.

"There's no safe way to stick a needle in there" to measure nerve impulses in the standard way, Filler says. Exploratory surgery is normally the only reliable option.

An existing MRI machine could be modified to perform neurography at a cost of $80,000 to $400,000-10 to 20 percent of the machine's original price, Filler says. The technique is still a long way from being widely applicable, says Michael N. Brant-Zawadzki, a radiologist at Hoag Memorial Hospital in Newport Beach, Calif. "This extends the capability of MRI to visualize peripheral nerves and to show damage in those nerves," he says. "Whether it will work over and above existing technology remains to be seen."