Effect of graded ligature compression on nerve conduction.

It has been reported that compression over a 12-mm nerve segment in vitro (rubber cuff) or over a 5-cm nerve segment in vivo (using a blood pressure cuff) produces conduction block in large myelinated A fibers before affecting small unmyelinated C fibers. It was concluded that large fibers are more sensitive to compression than are small C fibers. We found, however, when a nerve in vitro was compressed over a short segment (0.5 to 1 mm) using a ligature technique, conduction in small unmyelinated C fibers is blocked before conduction in large myelinated A fibers. These findings have some clinical implications.