Intraoperative Electrical Stimulation In The Treatment Of Peripheral Nerve Injury

Objective: Through further evaluating the results of the repair of peripheral nerve injuries by intraoperative electrical stimulation and observing the process of regeneration of the compressed nerve, the relation of this method and the regeneration of the nerve is studied.Methods: A chronic nerve compression animal model was made according the method described by Machinnonic, the animals were anesthetized by an abdominal injection of ketamine (0.3ml/100g). The procedures were conducted under a surgical microscope with 10 magnifications and by the same person. The right sciatic nerve was exposed and identified. Its average diameter is 1.0mm. A 5mm long silastic tube with an internal diameter of 1.0mm was cut longitudinally and placed around the nerve. The cut of tube was sewn closed with 8/0 silk suture and the tube was reconstituted to its original diameter. With the growth of the nerve, the sciatic nerve would gradually be compressed. After the model was done, 60 healthy female SD rats (150~ 200g) were divided into two groups randomly. There were 30 rats in the experimental group and 30 rats in the control group. They were bred under identical conditions. After 3 month, the chronic nerve compression animal models were completed. Then after cutting the animal models open, sciatic nerve was observed and the diameter of the compressed tube was measured, and the subject was undergone EMG. Removed the compressed tube and cut the outer epineurium of the comprssed nerve, the sciatic nerve of the experiment animals was tested by the electrical stimulation. The first two steps were also applied to the controlled group. However the third step would not be applied to this group, that is to say, sciatic nerve of the controlled subjects wasn't stimulated by electrical current. On the 3rd, 14th, 28th, 56th and 84th day after the operation, six rats of each group were anesthetized respectively and were cut and uncovered their compressed sciatic nerves, which were tested by EMG and their results were compared. A part of the compressed nerve and the section above and below the compressed nerve were observed under the microscope, though which the changes in ultrastructure would be found.Results: The silastic tube of the compressed nerve graft was wrapped up by the soft connective tissue on 90th day after the sciatic nerve was compressed. But there was no adherence between them. After the silastic tube was taken out, the compressed nerve grafts became thin, its texture hardened and the amphi-nerve became thick. The surface of neuroma was white. In the 4th, 8th, 12th week after the operation, the diameter of the compressed nerve grafts became thicker, the thicken grafts of the amphi-nerve became thinner gradually. The compressed nerve in the experimental group became thick obviously. In the 4th week, there was no marked difference. However in the 8th, 12th week, there was marked difference between two groups. In the 3rd month after the sciatic nerve was compressed, the nerve conduction velocity decreased from 52.26±1.78m/s to 12.96±2.83 m/s. The nerve conduction velocities of two groups were both improved to the differential degree after the operation by the comparison of the result of two groups. As for the nerve regeneration,a great number of nerve fibers and Schwann cells with regular arrangement and regenerated myelln sheath were observed 4 weeks after the implantation. 12 weeks after the operation, the compressed nerves of experimental group were regenerated and restored to normal, while in the control group, only a small number of nerve fibers and Schwann cells with irregular arrangement and rare regenerated myelln sheath were observed. By the end of 12 weeks, the compressed free nerve with no electrical Stimulation did not restore as that with electrical Stimulation. The result showed that the electrophysiological index, the diameter and the myelin sheath thickness of regenerating nerve fibers, the degree of the connective tissue decrease were much better in experimental group than those in control group.Conclusions: After peripheral nerve was compressed, its physiological function would decrease or even disappear. If the situation was not settled, these changes might be aggravated and the compression force was increased. Once the compression on the nerve was found, decompression should be done as early as possible in order to avoid or minimize the peripheral nerve injuries. If the conservative treatment was not effective, it's advisable to have surgery immediately to avoid the further injuries of the nerve.Through the experiment, it was found that the latent period of sciatic nerve of the rats in experimental group shortened and the conduction velocity quickened, which proved that electrical stimulation would boost the proliferation of Schwann cell and circulation of nourishment in blood, ameliorate the condition of the nerve and, in all, accelerate the regeneration and rehabilitation of the nerve.