EXPERIMENTAL NEUROLOGY 96,672-680 (1987) Repair of Severed Peripheral Nerves: Comparison of the “de Medinaceli” and Standard Microsuture Methods JULIAK.TERZISANDKENNETHJ.SMITH' Microsurgical Research Center, Eastern Virginia Medical School, P.O. Box 1980, Norfolk. Virginia 23501 Received December I I. I986 The return of function following transection of the rat sciatic nerve has been as- sessedafter repair by either(i) standard microsurgical techniques (i.e., the use of mi- crosutures to coapt the severed ends) or (ii) the new repair technique introduced by de Medinaceli and coworkers. The regeneration after transection was compared with that following sciatic nerve crush, i.e., a lesion in which the return of function is near optimal. Return of function was monitored serially using walking track analysis (i.e., the sciatic functional index, which indicates overall functional performance), the abil- ity to spread the toes (which indicates intrinsic function in the foot), and the determi- nation of muscle twitch tension ofthe middle digit. Function in the nerve crush group returned to within the normal range by 53 days, but function in the transection and repair groups did not return to normal before the rats were perfused at 85 postopera- tive days. However, the function regained when nerves were repaired with the de Medinaceli technique was significantly superior to that regained after repair with mi- crosutures. Histological examination of the repair site (at 85 days) revealed that the regenerated nerve fibers in the de Medinaceli group crossed the site of anastomosis in a relatively orderly fashion, whereas they were more randomly arranged when micro- sutures were used. However, there was no statistical difference between the two groups in the number of regenerated fibers present in the distal stump. The increase in func- tion in the de Medinaceli group may therefore arise primarily from an increase in the proportion of regenerating fibers which reach appropriate targets. If this explanation is correct, then a similar improvement in function may not occur in cases where a nerve graft is interposed between the severed ends of nerve. Q 1987 Academic press, IIIC. Abbreviation: WI-sciatic functional index. ’ The excellent technical help of Mr. R. Emory, Mrs. S. Jackola, Mrs. M. Jacobs, Mr. J. Ro- man, Mr. K. Rutledge, Mr. E. Sismour, and Mr. J. van Alphen is gratefully acknowledged. The work was supported by the Microsurgical Research Center of Eastern Virginia Medical School, 672 0014-4886/87 $3.00 Copyright 0 1987 by Academic Pms, Inc. All rights of reproduction in any form reserved.