Photochemical Sealing of Microsurgical Neurorrhaphy Improves Functional Recovery

Intraneural scarring adversely affects the clinical outcome following microsurgical repair of peripheral nerve injury. The aim of this study was to determine if isolation of the nerve repair site using photochemical tissue bonding (PTB) in combination with a sleeve of autologous vein or human amniotic membrane could exclude ingrowth of fibrotic tissue and improve functional recovery.

Forty-eight Sprague-Dawley rats underwent transection of the right sciatic nerve. Epineurial nerve repair was then performed using 10-0 nylon sutures. Animals were then randomized to six experimental groups with 8 animals per group: neurorrhaphy, neurorrhaphy + PTB sealant, neurorrhaphy + amnion cuff + PTB, neurorrhaphy + amnion cuff + suture, neurorrhaphy + vein cuff + PTB, neurorrhaphy + vein cuff + suture. The left femoral vein was harvested in all animals to overcome any impact this might have on walking-track interpretation. Functional recovery was assessed at 2-week intervals postoperatively using walking-track analysis. At 30 and 60 days postoperatively, one animal from each group was perfused with a solution of Evans Blue-labeled bovine albumin to assess the integrity of the blood-nerve barrier. At 90 days, the remaining animals were sacrificed and nerves harvested for histomorphometry.

At 30 days postoperatively, there was good restoration of the blood-nerve barrier in animals treated with PTB sealed amnion cuffs. At 8 weeks postoperatively, animals in this group also showed marked improvement in functional recovery compared to animals treated with primary suture repair alone (mean SFI −55.74 ± 3.22 vs. −70.76 ± 4.24). Animals treated with amnion sleeves secured with sutures did not exhibit any improvement in functional recovery at 8 weeks. Similarly, autologous vein sleeves with or without PTB did not confer any functional benefits. Grossly, vein sleeves appear to have been resorbed as early as 30 days postoperatively. Initial data indicate that animals treated with PTB sealing of the repair site without use of a tissue cuff also leads to improved function at 8 weeks. Histomorphometric analysis was performed on all nerve samples.

Isolation of the peripheral nerve suture repair site using a combination of human amniotic membrane and photochemical sealant leads to early restoration of blood-nerve barrier integrity and improved functional recovery. Such benefits are not seen using autologous vein sleeves; this may be explained in part by early resorption.