Objective To investigate the relationship between graded spinal cord ischemia/reperfusion injury and somatosensory evoked potentials(SEP),neurologic function score（NFS）and the histopathological changes of spinal cord. Methods Forty rabbits were randomized and equally divided into 4 groups: shamoperation group, ischemia for 30min, 45min and 60min groups. The spinal cord ischemiareperfusion injury model was created by occlusion of the abdominal aorta in rabbits. SEP was monitored before ischemia,5,10minutes after ischemia, 15, 30 minutes, 1,2, 24 and 48 hours after reperfusion. NFS was evaluated at 6,12,24 and 48 hours after reperfusion.The pathological changes of spinal cord were observed after reperfusion 48 hours. Results The pathological characters with mild,moderate and severe spinal cord ischemia/reperfusion injury could be simulated by declamping after 30， 45 and 60 minutes infrarenal aorta crossclamping. SEP amplitude returned to normal after reperfusion 15 minutes（Pgt;0.05）and SEP latency returned to normal after reperfusion 30 minutes（Pgt;0.05）during mild spinal cord ischemia/reperfusion injury.SEP amplitude returned to normal after reperfusion 30 minutes（Pgt;0.05）and SEP latency returned to normal after reperfusion 60 minutes（Pgt;0.05）during moderate spinal cord ischemia/reperfusion injury. SEP latency increased and SEP amplitude decreased during severe spinal cord ischemia/reperfusion injury,compared with other groups, there were significant differences in SEP latency and SEP amplitude by clamping the infrarenal aorta for 60min（Plt;0.01）. With graded spinal cord ischemia/reperfusion injury, compared with shamoperation group, spinal cord ischemiareperfusion groups had significant differences in NFS（Plt;0.01）. Conclusion SEP is much quicker in the recovery of amplitude than latency during spinal cord ischemia/reperfusion. SEP is a sensitive and accurate index for spinal cord function during ischemia/reperfusion injury. SEP monitoring spinal cord ischemia/reperfusion injury during operation provides experimental basis for clinical application.
Objective To study the recovery and mechanism of nerve root under variable chronic injury and to determine the alerting index of the evoked potential of the irreversible injury to the nerve root, so as to offer the evidence for selecting treatment methods, judging prognosis and grasping treatment juncture.Methods Autogenous cancellous bones were planted into the right C7-8 and C8T1 intervertebral foramens in 30 cats with weight 3-5 kg to make chronicinjury models. The left side was for auto-contrast. By 24 weeks’ observation anddynamic supervisory of evoked potential, the injury degrees were ascertained and classified into Ⅰto Ⅴdegree groups. Then the operation of decompression was performed on every group. During the following 32 weeks, the evoked potential survey and pathological tissue examination were made every week to observe the function recovery of the injured roots.Results The tissue form and functionof the nerve roots with ⅠandⅡdegree injuries recovered well within 2 to 6 weeks. Those with Ⅲ degree injury began to recover in the 4th week, and graduallyrecovered to normal 12 weeks later. In the group of Ⅳ degree injury, the recoverywas slow. They could recover completely in 3 of 6 cats, partly in 2 and hardly recovered in 1. The function and tissue form of nerve roots with Ⅴdegree injury could hardly recovered. Conclusion In the case that the compression has been removed before the nerve roots suffer Ⅲ degree injury. The tissue form and function of the nerve roots will recovered satisfactorily, whereas they may suffer irreversibly injury by Ⅳdegree injury, and even can hardly recover by Ⅴdegree injury. During the supervisory process of the recovery of the injured nerve roots, sensitive evoked potential is a sensitive sign of early recovery and motion evoked potential is a reliable sign of recovery extent.
OBJECTIVE: To investigate the characteristics and the pathologic classification of electrical-injury nerve using somatosensory evoked potential(SEP) technique. METHODS: SEP were detected and evaluated in 12 cases with electrical-injury nerve during operation, electrical stimulation was commenced from distal side of nerve where the structure of nerve looks normal under operating microscope, up to proximal side until evoking out a stable SEP predeterminate virtual value. Pathological examination and the following functional evaluation were compared with the values of SEP. RESULTS: At the site of nerve looking normal under operating microscope, perineurium appears normal or slightly thicken. But there are obvious fibrosis and fibrotic proliferation between fascicular and intrafascicular. Vessel plexus is not seen. At SEP stabilizely evoked site, nervous construction is normal, there are visible interfascicular vessel plexus and connective tissue appears loose. Comparing SEP values with pathological section, amplitude and latency of SEP is positively correlative with the quality of nerve. Eight cases repaired with SEP technique to select the anastomosis site for nerve transplantation were followed up, two-point discrimination reached grade III (America hand surgery association criterion) within 62.5% cases. CONCLUSION: SEP technique is valuable method for functional evaluation of electrical- injury nerve which has a complicated pathology. The pathology of electrical-injury nerve can be classified into 4 types, type A: fibrosis of nerve; type B: nerve looking normal under operation microscope, perineurium appears thicken, and there are obvious fibrosis and fibrotic proliferation between fascicular and intrafascicular, vessel plexus is rarely to see; type C: nerve looks normal, lymphocyte infiltration exists and it is obvious that there are many physalis-like, retrogressive construction in the section; type D: nervous construction is normal, there are visible interfascicular vessel plexus, and connective tissue appears loose, SEP always can be stably evoked.
In order to investigate the clinical significance of electron-neurogram for evaluating the degree and prognosis of acute traumatic cervical spinal cord injury without fracture or dislocation, electron-neurogram and sensory evoked potential (SEP) of the upper limbs in 4 such cases were recorded from the 3rd to 30th day after the injury. The results showed SEP and MEP could be obtained from every nerve in both upper limbs, and continous monitoring of SEP and MEP could provide valuable data to judge the degree and prognosis of the injury in spinal cord.
Injury of dorsal root ganglia (DRG) may cause sensory and motor dysfunction. In order to investigate the changes of somato-sensory evoked potential (SEP) and histological characteristics of DRG in different causes and different periods of injury, fifty-two rabbits were chosed to build the models. The rabbits were divided into 4 groups: Control group (n = 4); mechanical compressing group (n = 16); inflammatory injury group (n = 16); and treatment group (2% lidocaine with hydroprednisone was administered locally, n = 16). After one to eight weeks, SEP was determined and samples of DRG were obtained to observe the histological and ultrastructural changes every week. The result showed that the gap junction of microvascular endothelium in DRG had been destroyed by the mechanical compression was the major cause of the vessel permeability increasing. The increasing of endothelial pinocytic vesicles transportation and widening of endothelial gap junction were the main causes of inflammatory irritation of DRG. The local infiltration with 2% lidocaine and hydroprednisone could obviously ameliorate inflammatory injury in DRG.
The capacity of embryonic spinal cord tissue in the repair of injured structure of spinal cord has been noted for years. In order to investigate the embryonic spinal cord graft in the repair of motor function of injured spinal cord, the embryonic spinal cord tissue was transplanted to the hemisection cavity in spinal cord in adult rat. One hundred adult Wistar Rats were used to simulate the hemisectional injury of spinal cord by drilling 2-3 mm cavity in lumbar enlargement. Sixty rats were treated with rat embryonic spinal cord tissue grafting while the other forty were chosen as control. The outcome was evaluated according the combined behavioural score (CBS) and motor evoked potential (MEP) in the 1, 2, 4 and 12 weeks. The grafting group was superior to the control as assessed by CBS (P lt; 0.05), especially within 4 weeks. (P lt; 0.01). The restoration of the latent peak of early wave(P1, N1) was better in the grafting group, too. This suggested that embryonic spinal cord graft could improve the recovery of motor function of injured spinal cord in adult rat. The effect of the embryonic spinal cord tissue graft might be concerned with its secretion of several kinds of neurotrophic factors, nerve growth factor, nerve transmitted factor, or adjustment of hormone.
This paper is an introduction about the resultsof SEP monitoring in 36 case from 179 cases ofperipheral nerve injuries which have been followedup at least 6 months,since the beging of 1985 tothe end of 1989 in Dapin Hospital. These cases were injured by nerve overstretching 5 cases, complicated with fracture in 14patients, sharp instrument cutting in 17 patients.Of them injured in brachial plexus 3 cases ,axil-lary nerve 1 case, median nerve combined with ul-nar nerve 3 cases, ulnar nerve 12 cases, sciatic nerve, posterior tibial nerve, common peroneal nerve and femoral nerve were 1 case. All the SEP examination results showed closely coordination with clinical entities. Therefore, SEP monitoring peripheral nerve injuries manifested very importent significance in judgement of the injured nerve function.