Effect of graded nerve pressure injuries on motor function

Abstract

Methods animalsThe experiments were performed on 42 adult female Wistar rats (180-220 g body weight; Japan SLC Inc.). All procedures were conducted in accordance with the NIH abbreviatioN SSI = static sciatic index. subMitted June 27, 2014. accepted September 11, 2014. iNclude wheN citiNg Published online March 6, 2015; DOI: 10.3171/2014.9.JNS141451. disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Effect of graded nerve pressure injuries on motor functionMika Karasawa, MM, Kumiko yokouchi, phd, akira Kakegawa, phd, Kyutaro Kawagishi, Md, phd, tetsuji Moriizumi, Md, phd, and Nanae Fukushima, Md, phd Department of Anatomy, Shinshu University School of Medicine, Matsumoto, Japan obJect The purpose of this study was to determine the minimum amount of nerve fibers required to maintain normal motor function after nerve injury in rats. Methods The authors first confirmed that a common peroneal nerve injury caused more aggravating effects on lower limb motor function than tibial nerve injury, as assessed by the static sciatic index (SSI). Thereafter, rats were subjected to varying degrees of crush injury to the common peroneal nerve. At 48 hours after the injury, motor function was assessed using the SSI and slope-walking ability (with slope angles of 30° and 45°). The tibialis anterior muscle, a main muscle innervated by the common peroneal nerve, was removed. Muscle sections were co-labeled with neuronal class III b-tubulin polyclonal antibody to identify the presence of axons and Alexa Fluor 488-conjugated a-bungarotoxin to identify the presence of motor endplates. results The evaluation of neuromuscular innervation showed a correlation between SSI scores and ratios of residual axons (r s = 0.68, p < 0.01), and there was a statistically significant difference between slope-walking ability and ratios of residual axons (p < 0.01). Moreover, the ratios of residual axons in the nerve-crushed rats with normal motor function (SSI above -20) ranged from 36.5% to 88.7%, and those ratios in the success group with slope-walking angles of 30° and 45° ranged from 14.7% to 88.7% and from 39.8% to 88.7%, respectively. coNclusioNs In this study of rodents, less than half of the motor axons were sufficient to maintain normal motor function of the lower limb.

Serum neurofilament light chain measurements following nerve trauma

“…Functional recovery measured using SSI was significantly worse following sciatic nerve crush injuries when compared with the common peroneal nerve injury group. SSI readings following sciatic or common peroneal nerve crush documented in other studies behave similarly to what has been reported in the present study 29,44–46 . The significantly higher serum NfL readings at 1‐ and 3‐days post‐injury in the sciatic nerve injury group when compared with the common peroneal nerve injury group suggest that these measurements may provide a valuable predictive marker of functional outcome.…”

“…SSI readings following sciatic or common peroneal nerve crush documented in other studies behave similarly to what has been reported in the present study. 29,[44][45][46] The significantly higher serum NfL readings at 1-and 3-days post-injury in the sciatic nerve injury group when compared with the common peroneal nerve injury group suggest that these measurements may provide a valuable predictive marker of functional outcome. This adds weight to reports which have shown significant links between serum NfL measurements and functional outcome in other neurological disorders.…”