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Epineural Sheath Jacket as a New Surgical Technique for Neuroma Prevention in the Rat Sciatic Nerve Model: A Preliminary Report
Adam Bobkiewicz, MD, Halil Uygur, MD, Grzegorz Kwiecie324;, MD, Maria Madajka, PhD, Maria Siemionow, M.D., Ph.D., D.Sc.
Cleveland Clinc, Cleveland, OH, USA.
PURPOSE: Neuroma may form as a result of nerve transection or
damage, causing pain and significantly impairing the quality of life. Although many techniques have been developed so far, none have been proven to be superior in prevention of neuroma formation. The aim of this study was to test the epineural sheath jacket (ESJ) as a new method for prevention of neuroma formation in the rat sciatic nerve model. Epineural sheath is a naturally occurring material, easily harvestable and expresses proneurogenic and proangiogenic markers supporting nerve regeneration.
METHODS: A total of seventy-two rats were divided into six groups (of
six each). Group 1: Control- Nerve stump without any protection; Group 2: Nerve stump buried into the muscle; Group 3: ESJ covering nerve stump; Group 4: ESJ covering nerve stump and buried into the muscle; Group 5: ESJ filled with fat graft covering nerve stump; Group 6: ESJ filled with fat graft covering nerve stump and buried into the muscle. Animals were evaluated at 12 weeks and 24 weeks follow-up.
Sciatic nerve was dissected and 2 cm segment of the nerve was
resected. Nerve fascicles were removed using pull out technique creating an empty epineural sheath conduit. The distal part of the conduit was closed and proximal part was trimmed creating 7 mm long tube of protective ESJ. Finally, ESJ was applied over the proximal nerve stump using epineural sleeve technique (Groups 3-6). In Groups 5 and 6, before ESJ application, autologous fat was harvested from the gluteal region and following appropriate fat processing, it was injected into ESJ.
Functional assessments included pin-prick (PP) test and Tinel sign were analyzed once a week. At the end of each time end point, somatosensory evoked potentials (SSEP) were recorded and nerve samples were harvested for histological and immunohistochemical analyses.
RESULTS: At 5 weeks, in Group 1 and 2, the PP test was elicited
above the ankle level (grade 1) and reached plantar region (grade 2) at 9
weeks. In contrast, in Groups 3-6 grade 1 of the PP test was observed at 8 weeks. Tinel sign confirmed by squeaking and aggressive behavioral pattern was observed in all experimental groups starting at 3 weeks and was still present in Group 1 and 2, whereas it gradually disappeared in groups treated with ESJ. SSEP measurements revealed shorter N2% latency values and lower amplitude values (Amp%) in Groups 1 and 2 when compared with Groups 3-6. During nerve exploration significant adhesions were seen in Groups 1 and 2, whereas neuroma-
like formation characterized by distension and disorganization of the proximal stump was observed in Group 1. In contrast, no signs of neuroma- like formation were observed morphologically in Groups 3-6. The structure and integrity of the ESJ was preserved.
CONCLUSION: This study confirmed feasibility of ESJ application as
a new method for prevention of neuroma formation. The protective effect of ESJ against neuroma formation was confirmed in Groups 3-6 by clinical and functional assessments. Histological and immunohistochemical analyses are in progress.
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