Novel model for end-neuroma formation in the amputated rabbit forelimb

<p>Abstract</p> <p>Background</p> <p>The forelimb amputee poses many reconstructive challenges in the clinical setting, and there is a paucity of established surgical models for study. To further elucidate the pathogenic process in amputation neuroma formation, we created a reproducible, well-tolerated rabbit forelimb amputation model.</p> <p>Methods</p> <p>Upon approval from the Institutional Animal Care and Use Committee, 5 New Zealand White rabbits underwent left forelimb amputation. During this initial surgery, the median, radial and ulnar nerves were transected 1.6-2.5 (mean 2.0) cm distal to the brachial plexus, transposed onto the anterior chest wall and preserved at length. Six weeks subsequent to the amputation, the distal 5 mm of each neuroma was excised, and the remaining stump underwent histomorphometric analysis.</p> <p>Results</p> <p>The nerve cross sectional areas increased by factors of 1.99, 3.17, and 2.59 in the median (p = 0.077), radial (p < 0.0001) and the ulnar (p = 0.0026) nerves, respectively. At the axonal level, the number and cross-sectional area of myelinated fibers demonstrated an inverse relationship whereby the number of myelinated fibers in the median, radial and ulnar nerves increased by factors of 5.13 (p = 0.0043), 5.25 (p = 0.0056) and 5.59 (p = 0.0027), and the cross-sectional areas of these myelinated fibers decreased by factors of 4.62 (p < 0.001), 3.51 (p < 0.01), and 4.29 (p = 0.0259), respectively.</p> <p>Conclusion</p> <p>Given that the surgical model appears well-tolerated by the rabbits and that patterns of morphologic change are consistent and reproducible, we are encouraged to further investigate the utility of this model in the pathogenesis of neuroma formation.</p

A quantitative evaluation of gross versus histologic neuroma formation in a rabbit forelimb amputation model: potential implications for the operative treatment and study of neuromas

<p>Abstract</p> <p>Background</p> <p>Surgical treatment of neuromas involves excision of neuromas proximally to the level of grossly "normal" fascicles; however, proximal changes at the axonal level may have both functional and therapeutic implications with regard to amputated nerves. In order to better understand the retrograde "zone of injury" that occurs after nerve transection, we investigated the gross and histologic changes in transected nerves using a rabbit forelimb amputation model.</p> <p>Methods</p> <p>Four New Zealand White rabbits underwent a forelimb amputation with transection and preservation of the median, radial, and ulnar nerves. After 8 weeks, serial sections of the amputated nerves were then obtained in a distal-to-proximal direction toward the brachial plexus. Quantitative histomorphometric analysis was performed on all nerve specimens.</p> <p>Results</p> <p>All nerves demonstrated statistically significant increases in nerve cross-sectional area between treatment and control limbs at the distal nerve end, but these differences were not observed 10 mm more proximal to the neuroma bulb. At the axonal level, an increased number of myelinated fibers were seen at the distal end of all amputated nerves. The number of myelinated fibers progressively decreased in proximal sections, normalizing at 15 mm proximally, or the level of the brachial plexus. The cross-sectional area of myelinated fibers was significantly decreased in all sections of the treatment nerves, indicating that atrophic axonal changes proceed proximally at least to the level of the brachial plexus.</p> <p>Conclusions</p> <p>Morphologic changes at the axonal level extend beyond the region of gross neuroma formation in a distal-to-proximal fashion after nerve transection. This discrepancy between gross and histologic neuromas signifies the need for improved standardization among neuroma models, while also providing a fresh perspective on how we should view neuromas during peripheral nerve surgery.</p

Treatment of Painful Nerves in the Abdominal Wall Using Processed Nerve Allografts

Summary:. Neuromas can be a debilitating cause of pain and often negatively affect patients’ quality of life. One effective method of treatment involves surgical resection of the painful neuroma and use of a processed nerve allograft to repair the injured nerve segment. Giving the nerve “somewhere to go and something to do” has been shown to effectively alleviate pain in upper and lower extremities. We present the first report of this concept to treat a painful neuroma of the abdominal wall that developed following a laparoscopic gastric bypass. The neuroma was excised, and the affected nerve was reconstructed using a processed nerve allograft as an interposition graft, with resolution of pain and gradual return of normal sensation. Patient-reported outcomes were measured using the Patient Reported Outcomes Measurement Information System. Neuroma excision with concurrent interposition grafting using processed nerve allografts may be a promising method of treatment for postsurgical painful neuromas of the trunk