Experimental Study Of Related Factors To Monitoring Of Intraoperative Evoked Potential In Spinal Cord

BackgroundsIt was first reported by Nash in 1977, cortical somatosensory evoked potentials (somatosensory evoked potentials SEPs) are used in orthopedic Surgery, the foreign research in this field increased since 1980's,in 1990,the domestic SEP monitoring of intraoperation First reported by the Wei Xinrong. In 1980, MertonI first reported that a movement Evoked potential (mortor evoked MEPs) can be make by a single pulse transcranial electric stimulation in normal waking state. MEPs become graduallythe most comm -only used in order to monitor the spinal cord since MEPs is used intraoperative Monitoring in 1985. Meanwhile electromyography is used to dscribe contraction of musculus facialis for observation facial nerve function. from then,brainstem auditory evoked potentials are applide in tumor surgery of posterior fossa and slope.In conclusion,The technology of intraoperative nerve monitoring with its comprehensive, accessible and practical characteristics become most commonly used method in spinal surgery, monitoring records have legal effect in the U.S monitoring has become the most common for the spinal surgery in manyhospitals across the country, its clinical value has been widely recognized.However, the study found that a single monitoring method can not fully check the function of the spinal cord, clinical monitoring is gradually transformed into multi-modal monitoring.It is found that many factors impact monitoring signals recorded. Muscle relaxants is a great impact on the MEPs. Clinically, cisatracurium amines usually adminishrate by a single intravenous injection, in a period of time after treatment, motor evoked potential is often not detected. To ensure the safety of surgical operations, often earlier intravenous injection, that is 50 minutes before the operation.as a result, motor evoked potentials are recorded, but often because of insuitable degree of muscle relaxation, cause the difficult operating surgeon or even dangerous. Methylprednisolone is often used in prevention and treatment of acute spinal cord injury, while Methylprednisolone is appled in surgical operations, will false positive and a false negatie of intraoperative monitoring produce? It is aim at trying to explore whether methylprednisolone improve waveform of evoked potential。Objectivesl.to determine the best way given to drugs of muscle relaxants, the impact of the MEPs is Minimized.2. By comparing amplitude and latency of somatosensory evoked potential in rabbit after the injection of large doses of methylprednisolone and the same dose of Nacl,the effective monitoring period is explored so that avoiding the spinal a false negative or false positive of somatosensory intraoperative evoked potential is braught about at the time of intraoperative spinal injection of methylprednisolone。 content and methods1.Thirty normal rabbits were randomly divided into 3 groups of 10 each,A group is given the single intravenous injection of 0.08mg/kg, B group 0.04mg/kg at first, half an hour later,0.04mg/kg once again, C group 0.06mg /(kg/h) through micropump continued to pump MEPs of the rabbit lower limb is recored at the time TO (before administration) T1(10min after administration) T2 (30min), T3 (50min), T4 (60), T5 (90min).Data were analyzed using MANOVAV of repeated measures,test levelα=0.05 inspection levelα=0.05.2.Twenty-four normal rabbits were randomly divided into 2 groups of 12 each, A group is given Methylprednisolone through intravenous injection of 30mg/kg, B group the same dose,all through micropump. SEPs is recorded in the left lower extremity, before injection, every 5 minutes fromlOminutes after administration to 120minutes. Data were analyzed using MANOVAV of repeated measures LSD is used for Multiple comparisons.test levelα=0.05.Result1 latency extensed and amplitudein decreased in both A and B groups within 10min after administration, even disappears gradually, but MEPs recover in the A group 45-60 minutes after administration, not in the B group until the end of the experiment.The MEPs were successfully recorded throughout experiment in the C group. T1,T2, TO was statistically significant between A and C group.the other time points were not statistically significant,it were statistically significant at T3,T4,T5 moment among the three groups (P<0.05) 2.Twenty-four normal rabbits were randomly divided into 2 groups of 12 each, A group is given Methylprednisolone through intravenous injection of 30mg/kg, B group the same dose, all through micropump. SEPs is recorded in the left lower extremity, before injection, every 5 minutes from10minutes after administration to 120minutes. Data were analyzed using MANOVAV of repeated measures LSD is used for Multiple comparisons, the latency of SEPs began to shorten and amplitude increased 20min after injection in group A, both don't change in group B. it is significantly different bewetten two groups. (P<0.05).Conclusions1. The greatest impact on the MEPs is the way through intermittent intravenous injection,it Should be avoided.2. Methylprednisolone can improve SEPs in rabbits.latency of SEPs change the most at 20min, the change begin from 10min to 60min Intraoperative somatosensory evoked potential monitoring should be in the use more 60min after injection of methylprednisolone in order to avoid false-negative.