Abstract
Computerized gait analysis is a common evaluation method in rat models of hind limb nerve injuries, but its use remains unpublished in models of segmental nerve injury of the forelimb. It was the aim of this work to investigate if computerized gait analysis is a feasible evaluation method in a rat model of segmental median nerve injury and autograft repair. Ten male Lewis rats underwent 7-mm resection of the right median nerve with immediate autograft repair. The left median nerve was resected without repair and served as an internal control. Animals were assessed for 12 weeks after surgery via CatWalk (CW) gait analysis every 2 weeks. Evaluation of motor recovery by means of the grasping test was performed weekly while electrophysiological measurements were performed at the end of the observation period. CW data were correlated with grasping strength at each post-operative time point. CW data were also correlated with electrophysiology using linear regression analysis. Principal component analysis was performed to identify clusters of outcome metrics. Recovery of motor function was observable 4 weeks after surgery, but grasping strength was significantly reduced (p < 0.01) compared to baseline values until post-operative week 6. In terms of sensory recovery, the pain-related parameter Duty Cycle showed significant (p < 0.05) recovery starting from post-operative week 8. The Print Area of the right paw was significantly (p < 0.05) increased compared to the left side starting from post-operative week 10. Various parameters of gait correlated significantly (p < 0.05) with mean and maximum grasping strength. However, only Stand Index showed a significant correlation with compound muscle action potential (CMAP) amplitude (p < 0.05). With this work, we prove that computerized gait analysis is a valid and feasible method to evaluate functional recovery after autograft repair of the rat median nerve. We were able to identify parameters such as Print Area, Duty Cycle, and Stand Index, which allow assessment of nerve regeneration. The course of these parameters following nerve resection without repair was also assessed. Additionally, external paw rotation was identified as a valid parameter to evaluate motor reinnervation. In summary, computerized gait analysis is a valuable additional tool to study nerve regeneration in rats with median nerve injury.
Highlights
In experimental research on peripheral nerve injury, the sciatic nerve model is the most frequently used (Tos et al, 2009; Vela et al, 2020)
Print Area At WPO2, right front/right hind (RF/right hind limb (RH)) Print Area (Figure 2A) was highly significantly (p < 0.01) reduced to
Given the fact that Swing Time was categorized as a pain-related parameter of gait (Deumens et al, 2007) and alterations in Swing Speed are more likely related to loss of motor function (Heinzel et al, 2020b), we suggest that Swing Time is the parameter mainly affected by median nerve neurotmesis, which is than counterbalanced by a decrement of Swing Speed
Summary
In experimental research on peripheral nerve injury, the sciatic nerve model is the most frequently used (Tos et al, 2009; Vela et al, 2020). Automutilation is a common problem in rats experiencing neuropathic pain after sciatic nerve injury (Irintchev, 2011) This results in amputation of the toes or parts of the paw and in consequence only limited or even impossible functional evaluation (Weber et al, 1993). The median nerve provides sensory fibers to the medial aspect of the paw and digits I–III (Jackson, 1936; Bertelli et al, 1995) An advantage of this model is its translational potential given the predominance of upper limb nerve injuries in human patients (Foster et al, 2019; Karsy et al, 2019).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
