When repairing severed or damaged motor nerves with a donor nerve graft, surgeons have traditionally used a sensory nerve from another area of the patient's body. However, these patients often do not fully regain function in the injured area.
But now a team of surgeons at Washington University School of Medicine in St. Louis and Barnes-Jewish Hospital has found that repairing a motor nerve in rats with an intact motor nerve yields better results than using a sensory nerve. The research appeared in the March issue of the journal Microsurgery.
Motor nerves control movement in the muscles, while sensory nerves receive sensory stimuli, such as pain. A significant difference between the two types of nerves is that motor nerves have much larger axons, the thread-like extensions of the nerve cell that carry nerve impulses throughout the body.
The researchers, led by Gregory H. Borschel, M.D., a plastic and reconstructive surgeon at the School of Medicine and senior author of the paper, defines the question of this work as seeking to determine why motor nerves were regenerating more successfully than sensory nerves. Was it because of the nerve's own structure, or architecture, or because supporting cells such as Schwann cells were boosting the regeneration"
To find an answer, the researchers broke down the nerve architecture by chopping up motor, sensory and mixed nerves. They divided the minced nerves into groups by type, inserted the mush into tiny silicone tubes and encouraged severed motor nerves to regenerate through the mixtures in the tubes.
The researchers found that disrupting the nerve's architecture by mincing it abolished the benefit of repairing a motor nerve with an intact motor nerve. "It turned out there was no difference in regeneration using motor versus sensory nerves through the chopped-nerve tissue," Borschel said.