The Research Of TMS-MEP Evaluating Rats,Dyskinesia After Spinal Cord Injury

【Background】 Spinal Cord Injury (SCI) is the compression or rupture of the spinal cordcaused by the different kinds of external direct or indirect factors, and the correspondingsections will have some changes, for example, motor, feeling and muscle function obstacle,abnormal muscle tone and pathological reflex. It is a serious disabling injury, causing thepatients to have different degrees of paraplegia, influencing the patients’self-help skills ofthe life and the ability to participate in social activities seriously, which will bring a heavyburden of the family. Therefore, relevant clinical therapy and rehabilitation, basicneuroscience research of SCI is now medical researchers’hot spot. SCI causes the musclesparalyzed, but it is difficult to make an objective judgement to the peripheral nerve andmuscle function by clinical evaluation or visual method, especially in the forensicidentification, the patients don’t cooperate the examination subjectively, and exaggeratedysfunction degree of the spinal cord, even disguise function obstacle, which brings theforensic identification difficulties. In order to solve the problem, it is very necessary to lookfor and use a modern testing technology of electric physiology, to evaluate the dysfunctionand severity objectively to greatest extent. General clinical inspection method such aselectromyography，conduction velocity of the peripheral nerve can only evaluate underneurons and nerve fibers, effector objectively, but not spinal cord. Transcranial magneticstimulation motor evoked Potential (Transcranial magnetic stimulation motor evokedpotential, TMS-MEP) can overcome the shortcomings, which affects the brain cortex by the changed magnetic field without contact, the inductive current formed after the spacecoupling into the brain stimulate the cells, then causing the action potential of the nervefibers and effectors below stimulated point. Over the years, the technology has been widelyused in the research of the physiological changes. which evaluates the muscles dominatedby relevant nerves electrophysiology changes caused by head injury, spinal cord injury,physical trauma. But at present the researches about the rule of the TMS-MEP andmovement function after spinal cord injury are fewer. This experiment that through theobservation about MEP waveform, latency, amplitude and the changing characteristics andmovement function of the rats after spinal cord injury, Verifying the feasibility and theapplication of the regression curve, then use the TMS-MEP to determine the spinal corddamage degree and the state of movement function, and provide a theoretical support formuscle strength in forensic objective identification.【Objective】observe MEP waveform, latency, amplitude and the changing characteristicsand movement function of the rats after spinal cord injury, in order to set up digitalprediction model between TMS-MEP parameters and movement functions after spinal cordinjury, then use the TMS-MEP to determine the spinal cord damage degree and the state ofmovement function.【objects and Methods】100healthy adult female SD rats, weight (250.00±19.46) g, aredivided into three damage groups, a sham operation group and a normal control group, theywill be supplied for the quantitative mixed animal feed and enough water every day, cage-breeding in a quiet, ventilation, clean environment, feeding environment temperature iscontrolled in23to25℃, relative humidity is40%~70%. Damage groups are using20gneedle to hit the spinal cord at different height according to the literature:12.5mm group(group A, n=20),25mm group (group B, n=20),50mm group (group C, n=20). Thesham operation group does only exposure to the spinal cord, doesn’t be stroken (n=20).The normal control group (n=20) has no treatment. Above all of the groups are operated by the same experiment personnel. Preoperative and postoperative respectively of1,3,5days,1week to6weeks score the rats’spinal motor function according to the rats’spinalmotor function evaluation standard (Basso-Beattle-Bresnahan, BBB) and record TMS-MEPof the gastrocnemius in70%stimuli. After six weeks, the TMS-MEP results of thegastrocnemius related to the motor scores are analyzed to explore the relationship betweenthe TMS-MEP and changes in motor function after spinal cord injury.【Results】 After the spinal cord of group A and group B are hit, the BBB scores of thehindlimbs are the lowest. Movement function is beginning to recover (significant statisticalmeaning, P＜0.01).The second week, BBB scores increase more and more quickly andreach the highest score and then will be more stable, but not as normal levels. Group C rats,spinal cord injury is heavy, and the BBB score is very lower, the hindlimbs don’t rotate orswing until about3weeks, presenting a delayed paralysis, motor functional recovery ispoorer. The statistical analysis shows that MEP amplitude is associated with BBB scoresignificantly, With reference to the human body strength level standard, BBB score will bedivided into six rating class:0-V level. Then put experiment data into relevant experimentstudies before regression curve Y=0.4651X+4.6024(R2=1, P <0.001, Y representsBBB score, X represents amplitude), it has the height agreement that the BBB scorecalculated and that comes from experimenters’observation.【Conclusion】 BBB score is lower after spinal cord injury, latency is prolonged,amplitude is reduced, disappeared or deformity, with the extension of the time, the BBBscore is increasing more and more quickly, the latency is shorter, the amplitude is higher,tend to be normal, The experiment verifies the feasibility of the regression curve.