Nerve regeneration through an epineurial sheath: Its functional aspect compared with nerve and vein grafts

Although nerve graft is stilt the only reliable choice in repair of defects in peripheral nerve structure, it has the disadvantage of donor nerve morb idity and of sometimes being unavailable. It has long been researched in al ternate nerve grafts with other materials. Studies have shown that nerves c ould regenerate across short nerve gaps through various conduits, such as v eins, pseudosheaths, and bioabsorbable tubes, Despite encouraging studies, their functional results remain unclear. The present study used 40 rats, in which nerve grafts, vein grafts, and epineurial tubes were placed into 1-c m gaps in sciatic nerves created by resection. In one group, sciatic nerves were denuded of the surrounding epineurium, to assess the possible morbidi ty caused by epineurial sheath technique. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed using walking tr ack analysis. The number of myelinated fibers and fiber diameters was measu red and electron microscopic evaluation performed. Functionally, the index values were very close to each other in nerve graft and epineurial sheath g roups. Morphometric analysis showed significance between the groups. The re sult of denuded sciatic nerve group was the same as the base track values. It was concluded that the ready availability of epineurial sheath as a cond uit to span short nerve gaps could eliminate the morbidity associated with nerve graft harvest and capitalize on the potential benefits of neurotrophi sm in directing nerve regeneration. (C) 2001 Wiley-Liss, Inc.