Ko Jason H, Kim Peter S, O'Shaughnessy Kristina D, Ding Xianzhong, Kuiken Todd A, Dumanian Gregory A
Department of Surgery, Division of Plastic and Reconstructive Surgery, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA.
J Brachial Plex Peripher Nerve Inj. 2011 Oct 13;6:8. doi: 10.1186/1749-7221-6-8.
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.
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.
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.
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.
神经瘤的外科治疗包括在大体“正常”束状结构水平近端切除神经瘤；然而，轴突水平的近端变化对于切断的神经可能具有功能和治疗意义。为了更好地理解神经横断后发生的逆行“损伤区”，我们使用兔前肢截肢模型研究了横断神经的大体和组织学变化。
4只新西兰白兔接受前肢截肢，同时横断并保留正中神经、桡神经和尺神经。8周后，朝着臂丛神经从远心端到近心端获取截肢神经的连续切片。对所有神经标本进行定量组织形态计量学分析。
所有神经在神经远心端治疗组和对照组肢体之间的神经横截面积均有统计学意义的增加，但在神经瘤球近端10 mm处未观察到这些差异。在轴突水平，所有截肢神经的远心端可见有髓纤维数量增加。有髓纤维数量在近端切片中逐渐减少，在近端15 mm或臂丛神经水平恢复正常。治疗组神经所有切片中有髓纤维的横截面积均显著减小，表明萎缩性轴突变化至少向近端延伸至臂丛神经水平。
神经横断后，轴突水平的形态学变化以远心端到近心端的方式延伸至大体神经瘤形成区域之外。大体神经瘤和组织学神经瘤之间的这种差异表明需要改进神经瘤模型之间的标准化，同时也为我们在周围神经手术中应如何看待神经瘤提供了新的视角。
