To Explore The Nerve Monitoring Of The Traction And Disconnection Injury Of The Recurrent Laryngeal Nerve In Rats And Microscopic Analysis

Objective:The purpose of this experiment is to observe the changes of amplitude and latency of electrical signal and its microscopic manifestations during the stretch and sever injury of the recurrent laryngeal nerve in rats,to explore the relationship between the extent and time of stretch and the degree of signal recovery,and to observe the microscopic manifestations and histopathological analysis of different degrees of injury of the nerve,so as to provide further reference for clinical surgery operation.Methods:Twenty healthy male adult rats weighing about 300 g were randomly divided into five groups(4 rats in each group of A,B,C,D and E).The normal signal value of the recurrent laryngeal nerve was detected and recorded by exposing the recurrent laryngeal nerve on both sides.The four groups of A,B,C and D were artificially induced unilateral stretch injury of the recurrent laryngeal nerve.The signal value of each group was reduced to 70%,50%,30% and 20% of the original signal value In the last group,two rats in each group were randomly selected to remove the recurrent laryngeal nerve,After fixation with the fixative solution,heavy metal staining was used in the later stage.The injury was observed under the electron microscope and graded as the degree of injury.The rest of the rats were covered with wet gauze ofnormal saline.The recovery degree of nerve signal was detected and recorded at 5,10,15 and 30 minutes and compared with the control side.The injury of the recurrent laryngeal nerve on the experimental side was observed under the electron microscope after staining with the above methods and to graded the degree of damage.Results:In animal experiments,the traction strength of RLN is positively related to the degree of nerve damage.When the signal of RLN is attenuated to more than 50% of the original signal value,the operation is stopped immediately.Usually,the signal value can be restored to the baseline level within 30 minutes after the operation is stopped.At this time,the nerve is observed under the electric microscope as the first and second degree of damage,and the axon responsible for nerve signal transmission receives.However,the nerve intima responsible for the directional regeneration of axon is intact,so the nerve function can be completely restored,causing reversible damage to the nerve.When the nerve signal attenuates to less than or equal to 50% of the original signal value,the third degree or above of nerve damage,axon,myelin sheath and inner membrane of nerve are all damaged under the electron microscope,and the nerve can not be recovered directionally,causing irreversible damage to the nerve.Conclusion:During the operation,we should try our best to reduce or even avoid the pulling and breaking of the nerve.On the basis of exposing the nerve,we should try our best to operate gently to reduce or even avoid the unnecessary damage to the nerve caused by the pulling and breaking operation.When the amplitude of the nerve signal attenuates to more than 50% of the original signal value,the operation should be stopped in time to avoid further damage to the nerve,which can ensure theintegrity of the inner membrane of the nerve,the damaged axon can be regenerated directionally,and the nerve function generally recovers completely within 30 minutes after the operation is stopped.On the contrary,when the signal value attenuates to less than or equal to 50% of the original signal value,the inner membrane of the nerve is damaged and the nerve is irreversibly damaged.