Li H J, Zhang X, Zhang F, Wen X H, Lu L J, Shen J
From the Department of Radiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangdong, China.
AJNR Am J Neuroradiol. 2014 Aug;35(8):1608-14. doi: 10.3174/ajnr.A3977. Epub 2014 May 29.
Alternative use of molecular approaches is promising for improving nerve regeneration in surgical repair of neurotmesis. The purpose of this study was to determine the role of MR imaging in assessment of the enhanced nerve regeneration with toll-like receptor 4 signaling activation in surgical repair of neurotmesis.
Forty-eight healthy rats in which the sciatic nerve was surgically transected followed by immediate surgical coaptation received intraperitoneal injection of toll-like receptor 4 agonist lipopolysaccharide (n = 24, study group) or phosphate buffered saline (n = 24, control group) until postoperative day 7. Sequential T2 measurements and gadofluorine M-enhanced MR imaging and sciatic functional index were obtained over an 8-week follow-up period, with histologic assessments performed at regular intervals. T2 relaxation times and gadofluorine enhancement of the distal nerve stumps were measured and compared between nerves treated with lipopolysaccharide and those treated with phosphate buffered saline.
Nerves treated with lipopolysaccharide injection achieved better functional recovery and showed more prominent gadofluorine enhancement and prolonged T2 values during the degenerative phase compared with nerves treated with phosphate buffered saline. T2 values in nerves treated with lipopolysaccharide showed a more rapid return to baseline level than did gadofluorine enhancement. Histology exhibited more macrophage recruitment, faster myelin debris clearance, and more pronounced nerve regeneration in nerves treated with toll-like receptor 4 activation.
The enhanced nerve repair with toll-like receptor 4 activation in surgical repair of neurotmesis can be monitored by using gadofluorine M-enhanced MR imaging and T2 relaxation time measurements. T2 relaxation time seems more sensitive than gadofluorine M-enhanced MR imaging for detecting such improved nerve regeneration.
分子方法的替代应用有望改善神经断伤手术修复中的神经再生。本研究的目的是确定磁共振成像在评估神经断伤手术修复中通过Toll样受体4信号激活增强神经再生方面的作用。
48只健康大鼠，其坐骨神经被手术切断后立即进行手术吻合，术后第7天前，腹腔注射Toll样受体4激动剂脂多糖（n = 24，研究组）或磷酸盐缓冲盐水（n = 24，对照组）。在8周的随访期内进行连续的T2测量、钆弗塞胺M增强磁共振成像和坐骨神经功能指数测量，并定期进行组织学评估。测量并比较脂多糖处理组和磷酸盐缓冲盐水处理组神经远端残端的T2弛豫时间和钆弗塞胺增强情况。
与磷酸盐缓冲盐水处理的神经相比，注射脂多糖处理的神经功能恢复更好，在退变期钆弗塞胺增强更显著，T2值延长。脂多糖处理的神经中T2值比钆弗塞胺增强更快恢复到基线水平。组织学显示，Toll样受体4激活处理的神经中巨噬细胞募集更多、髓鞘碎片清除更快、神经再生更明显。
在神经断伤手术修复中，通过钆弗塞胺M增强磁共振成像和T2弛豫时间测量可监测Toll样受体4激活增强的神经修复。对于检测这种改善的神经再生，T2弛豫时间似乎比钆弗塞胺M增强磁共振成像更敏感。
