Functional Outcome Following Single vs. Multiple Cable Nerve Grafting

The authors compared a single fascicle nerve (SFN) repair technique to the traditional nerve trunk autograft. A rat sciatic nerve model was used to determine if a thinner SFN autograft would provide adequate nerve regeneration for a nerve gap repair and result in more rapid nerve regeneration than the conventional nerve trunk grafting technique. The hypothesis was that a pure sensorial graft would allow return of both sensory and motor function as well as a mixed graft.

Thirty-six male Lewis rats were randomized into six experimental groups. The sciatic nerve of the animals was exposed and transected proximally and distally. The rats received one of six nerve repair techniques including: a control group with no repair; conventional nerve trunk autograft; tibial SFN repair; peroneal SFN repair; sural SFN repair; and a three SFN repair. Functional nerve recovery was assessed by three separate tests. Sensory and motor recovery were assessed weekly via the Mantel-Haenszel pin prick and toe spread tests. Electrophysiological studies were performed at the 6th and 12th postoperative week using SomatoSensory Evoked Potential (SSEP) testing.

Sensory and motor function evaluation demonstrated better recovery in the SFN autograft recipients, compared to the traditional nerve trunk autograft group. SSEP testing at the 6th and 12th weeks confirmed these results, and generated 4.32 milliseconds of P1/N2 latency values for the sural nerve group, which was similar to the non-operated control side. This was not observed in the conventional nerve trunk group in which P1/N2 latency values were within 7.65 milliseconds. All of the rats that received an SFN graft had regained complete sensory recovery by the 4th postoperative week; nerve trunk group recovery at 4 weeks regained 38% of sensory return and full recovery was seen at 8 weeks. In addition to demonstrating full sensory recovery, the sural SFN group exhibited complete motor recovery as early as 8 weeks, whereas the remaining groups including the traditional nerve repair group regained only 77% of their normal motor function.

This study introduced the concept that thin SFN autografts demonstrate better functional recovery, compared to traditional nerve autograft techniques. Among the three SFN grafting methods used (tibial, peroneal, and sural), the sural SFN autograft led to the best functional recovery. The advantages of utilizing an SFN graft over the traditional nerve grafting technique include less nerve graft needed for reconstruction of a nerve gap, reduced morbidity at the donor site, and significantly more rapid return of function.