Reflex‐based grasping, skilled forelimb reaching, and electrodiagnostic evaluation for comprehensive analysis of functional recovery—The 7‐mm rat median nerve gap repair model revisited

INTRODUCTION: The rat median nerve injury and repair model gets increasingly important for research on novel bioartificial nerve grafts. It allows follow‐up evaluation of the recovery of the forepaw functional ability with several sensitive techniques. The reflex‐based grasping test, the skilled forelimb reaching staircase test, as well as electrodiagnostic recordings have been described useful in this context. Currently, no standard values exist, however, for comparison or comprehensive correlation of results obtained in each of the three methods after nerve gap repair in adult rats. METHODS: Here, we bilaterally reconstructed 7‐mm median nerve gaps with autologous nerve grafts (ANG) or autologous muscle‐in‐vein grafts (MVG), respectively. During 8 and 12 weeks of observation, functional recovery of each paw was separately monitored using the grasping test (weekly), the staircase test, and noninvasive electrophysiological recordings from the thenar muscles (both every 4 weeks). Evaluation was completed by histomorphometrical analyses at 8 and 12 weeks postsurgery. RESULTS: The comprehensive evaluation detected a significant difference in the recovery of forepaw functional motor ability between the ANG and MVG groups. The correlation between the different functional tests evaluated precisely displayed the recovery of distinct levels of forepaw functional ability over time. CONCLUSION: Thus, this multimodal evaluation model represents a valuable preclinical model for peripheral nerve reconstruction approaches.