Electromyography as an intraoperative test to assess the quality of nerve anastomosis – experimental study on rats

BACKGROUND: Many factors contribute to successful nerve reconstruction. The correct technique of anastomosis is one of the key elements that determine the final result of a surgery. The aim of this study is to examine how useful an electromyography (EMG) can be as an objective intraoperative anastomosis assessment method. METHODS: The study material included 12 rats. Before the surgery, the function of the sciatic nerve was tested using hind paw prints. Then, both nerves were cut. The left nerve was sutured side-to-side, and the right nerve was sutured end-to-end. Intraoperative electromyography was performed. After 4 weeks, the rats were reassessed using the hind paw print analysis and electromyography. RESULTS: An analysis of left and right hind paw prints did not reveal any significant differences between the length of the steps, the spread of the digits in the paws, or the deviation of a paw. The width of the steps also did not change. Electromyography revealed that immediately after a nerve anastomosis (as well as 4 weeks after the surgery), better nerve conduction was observed through an end-to-end anastomosis. Four weeks after the surgery, better nerve conduction was seen distally to the end-to-end anastomosis. CONCLUSIONS: The results indicate that in acute nerve injuries intraoperative electromyography may be useful to obtain unbiased information on whether the nerve anastomosis has been performed correctly – for example, in limb replantation. When assessing a nerve during a procedure, EMG should be first performed distally to the anastomosis (the part of the nerve leading to muscle fibers) and then proximally to the anastomosis (the proximal part of the nerve). Similar EMG results can be interpreted as a correct nerve anastomosis. The function of the distal part of the nerve and the muscle remains intact if the neuromuscular transmission is sustained.