American Society for Peripheral Nerve

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A New Method for Prevention of Neuroma by Epineural Sheath Jacket in the Rat Sciatic Nerve Model
Adam Bobkiewicz1; Halil Safak Uygur, MD1; Grzegorz Kwiecien, MD1; Maria Madajka, PhD1; Joanna Cwykiel, MSc2 ; Maria Siemionow, MD, PhD, DSc2
1Department of Plastic Surgery, Cleveland Clinic, Cleveland, OH, 2Department of Orthopaedics, University of Illinois at Chicago, Chicago, IL

Introduction: Neuroma formation, which may occur due to nerve transection, causes severe pain and significantly impairs the quality of life. The purpose of this study was to assess the outcome of epineural sheath jacket (ESJ) application as a novel technique in neuroma prevention in the rat sciatic nerve model. Epineural sheath is a naturally occurring material, which supports nerve regeneration by expressing proneurogenic and proangiogenic markers.
Material and Methods: Thirty- six rats were divided into six experimental groups (n=6 each): Group 1: Nerve stump without any protection; Group 2: Nerve stump buried into the muscle; Group 3: Nerve stump covered with ESJ; Group 4: ESJ buried into the muscle; Group 5: ESJ filled with fat graft; Group 6: ESJ filled with fat graft and buried into the muscle.

A 20mm long sciatic nerve defect was created and fascicles were removed using pull out technique. The distal part of the conduit was ligated creating the ESJ, which was applied over the proximal nerve stump. Additionally, in groups 5 and 6 ESJ was filled with autologous fat. Animals were evaluated 6 months after surgery. Outcome assessment included: sensory pinprick, Tinel sign, autotomy score, histomorphometry, neural/connective tissue ratio (N/C) and retrograde neuronal labeling analysis (RNL).

Results: Significant adhesions were seen in Group 1 during nerve evaluation 6 months after surgery. The integrity of the ESJ was preserved in groups 3-6. In Groups 1 and 2 percentages with positive Tinel signs were significantly higher than in groups protected with ESJ. The average pinprick score was significantly increased in Groups 1 and 2, six months after surgery, which may indicate fibers sprouting, or hyperesthesia of the operated site. Nerve architecture was maintained in groups with ESJ protection, whereas in Groups 1 and 2 disorganization of the nerve fascicles was noticed using S-100 staining. N/C ratios evaluated by Masson trichrome staining, in groups 3 and 4 were comparable with the current gold standard of neuroma management muscle burying (Group 2). RNL analysis revealed significantly higher number of neurons in dorsal root ganglion in groups with ESJ protection compared to the controls. Quantitative nerve histological analysis is currently in progress.

Conclusions: This study confirmed feasibility of ESJ application as a novel technique in neuroma protection. The protective effect of ESJ was proved by functional and histological analysis in groups 3- 6 yielding comparable outcome to muscle burying - current gold standard of neuroma management.

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