April 4, 1996

NOTE: Dr. Bickel now works for the University of California-San Francisco. You can reach him at (415)923-0992.

NATURAL SUBSTANCES MAY FIGHT NERVE DAMAGE

A Johns Hopkins animal study suggests that a protective natural substance reduces pinched nerve damage and speeds recovery of the injured nerves. The finding may help to develop a treatment for sciatica and other common nerve injuries in people.

The sciatic nerve, the body's largest nerve, was compressed in a large group of rats to stop most of the blood flow through the nerve. The study's results showed the nerve suffered less damage and recovered faster in those animals given an antioxidant called deferoxamine. Antioxidants protect the body against oxygen-containing molecules called free-radicals, which damage tissues. Stopping blood flow to tissues causes damage, but restoring blood flow unleashes a flood of oxygen that can cause further damage.

The results are published in the April 5 issue of Annals of Plastic Surgery.

All the rats were tested to determine how much damage occurred when the blood flow stopped and restarted and how quickly the nerves recovered. Tests of nerve tissue showed the injury was three times greater and lasted longer in rats not receiving the antioxidant. Nerve tissue in the rats getting the antioxidant remained near normal or soon returned to normal.

"These findings suggest that this antioxidant protects the nerve from injury when blood circulation stops and restarts and yields a quick recovery from peripheral nerve compression injury," says Kyle D. Bickel, M.D., a study co-author and an assistant professor of plastic surgery and orthopedic surgery.

The Hopkins team tested the nerve tissue, in part, for malondialdehyde, a potentially damaging oxygen molecule that the scientists recently found to be a reliable indicator of tissue damage and recovery. Deferoxamine has been shown to reduce damage from blood flow stopping and restarting in other organs, including the heart, skeletal muscle and spinal cord. Free-radical molecules are cleared from the blood in normal circulation, but reduced or blocked blood flow allows free-radicals to build up. Deferoxamine, a free-radical scavenger, protects tissues by binding to and eliminating the harmful molecules. This study is believed to be the first time that deferoxamine has been shown to protect a peripheral nerve, or a nerve that connects the brain or spinal cord to distant parts of the body. Sudden or long-term compression of peripheral nerves in humans often is caused by slipped discs, fractures, dislocations, tumors and clots and other problems.

The study's other investigators were Yongbo Li, M.D., Michael J. Im, Ph.D., Liangbiao Hu, Ph.D., A. Lee Dellon, M.D., Craig A. Vander Kolk, M.D., and Paul N. Manson, M.D.

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