Neurotization Of The Phrenic Nerve With Vagus Nerve For High Cervical Spinal Cord Injury With Respiratory Distress: A Study On Human Anatomy And Animal Test

Objectives:1 To provide anatomic details on the vagus nerve and phrenic nerve for neuritisationin patients with high spinal cord injuries.2 To count of motor neurofibra employing the techniques of immunohistochemistricstaining.3 To find the proper aJ'ea in which the anastomosis of phrenic nerve and vagus nerveby endto side.4 To establish the experimental model of the respiratory function reconstruction inthe rats with upper cervical cord injuries through transposition of vagus nerve and phrenicnerve reconstruction The function testing method of the diaphragm is adopted to measurethe motion function ofthe diaphragm postoperatively.5 To study the features of the EMG of the diaphragm after the respiratory functionreconstruction in the rats with upper cervical cord injuries through transposition of vagusand phrenic nerve reconstruction.6 To study the features of the blood gas changes after the respiratory functionreconstruction in the rats with upper cervical cord injuries through transposition of vagusnerve and phrenic nerve reconstruction.7 To find the relationship between phrenic nerve and ambiguous nucleus after thetransposition of vagus nerve and phrenic nerve by the technique of CB-HRP retrogradelabeling.To investigate the feasibility of respiratory function reconstruction through thetransposition of vagus nerve and phrenic nerve in the rats with upper cervical cord injuryNew-method can be adopted to reconstruct the respiratory function in the patients withupper cervical cord injury in the clinical practice.Methods1 20 cadavers were dissected in the study．The width,length mad thickness of each vagus nerve and phrenic nerve above clavicle were measured The distances from several landmarks on vagus nerve to the origin and the end of phrnic nerve were measured too Then,the numbers of motor nerve fibers on different sections of the nerves were calculated using the technique of immunohistochemistry.2 The ereation of animal modelFifteen SD rat(male)weight 180-200g were divided ino three groups in random as A, B．C Group A:the anastomosis of phrenic nerve and vagus nerve by end to side Group B:the anastomosis of the phrenic nerve itself.GroupC:the control group Animals wereanesthetized intraperitoneally with pentobarbital(Nembutal,50 mg／kg)The bodytemperature was maintained between 36.5 and 37.5-C The surgical procedure wasperformed under a surgical microscope with the animal in a supine position Both phrenicnerve trunk(PN)and vagus nerve(RLN)were exposed by a ventral approach The PN wasdissected free down to 5 mm,sectioned and its distal extremity was anastomosed by one11-0 nylon microsuture to the proximal extremity ofthe vagus nerve.3 Ten months later,to assess diaphragm EMG activity,the animals were placed in asupine position,laparotomy was performed and the liver was gently separated to exposethe diaphragm muscle Both right and left diaphragm activity were investigated Sternal,antero-costal and mid-costal diaphragm parts were recorded The latency,the conductspeed and the wave were record before and after the complete C3 spinal transaction.4 Ten months later,0.2 ml of blood in the common carotid artery of the rats in threegroups were sampled for measuring the pH value,the partial pressure of oxygen,partialpressure of carbon dioxide and blood oxygen saturation with ABL50 blood-gas analyzemachine Tests were repeated every hour in the four hours after transecting the cervicalspinal cord at the C3／4 level At mean time,the blood gas of normal rats in group C wastested as control group The changing features of the blood gas were studied in the ratswith upper cervical cord injuries after the transposition ofvagus nerve and phrenic nerve.5 Ten months later,the displacements of the diaphragms of the rats in three groupswere measured by B-mode ultrasonic diagnostic equipment in the parts of Sternal,antero-costal and mid-costal on the diaphragm Each revovery rate of diaphragmdisplacement was goten by dividing the group A,B count into the group C count Then bothofthem were compared Then the cervical spinal cords were transected at the level of C3／4The displacements of diaphragms were measured as the sa2rle The recovery rate afterupper cervical spinal injury was gotten by dividing the groupA,B count into the group Ccount The numeric value oftwo groups was compared.6 Horseradish peroxidase was conjugated with cholera toxin(CB-HRP)as the tracingagent,and sodium tungstae was used as the stabilizer of CB-HRP．The agent was used totrace the relationship between the phrenic nerve and the ambiguous nucleus.Results1．The vagus nerve and the phrenic nerve were similar in width,thickness and the number of motor nerve fibers And the lengths of phrenic nerve were long enough for endto side anastomosis with vagus nerve.2．The conduct speed,latency and wave of group A and group B were significantlydifferent from that of group C (P<0.05)before C3 transection The recovery rate ofthew-ave is higher than that of conduct speed in group A and group B The rats were deadrapidly after the transaction of cervical spinal cord The conduct speed and the latency afterthe transection were no significant difference contrast to that before the transaction But thew-ave of group A after the spinal cord transection is more access to the control group.3．There is no significantly statistical difference in the pH value,the partial pressureof oxygen,partial pressure of carbon dioxide and blood oxygen saturation of the threegroups(P>0.05,before the transection The blood oxygen saturations of group C werestandard in two hours after the transaction The rats became mildly CO2 retention 3 hoursafter the transection The respiratory rate is step up One rat w-as dead 4 hours after thetransition of the spinal cord The blood oxygen saturations of three rats were descendingrapidly,and the rats became respiratory acidosis,which were dead in 20 min Only one wassurvive more than 5h.4 The recovery rates of the displacement of the diaphragm of group A and group Bwere 92.18±4 27％．90.46±6 73％respectively There is no significantly statisticaldifference between group A and group B(P>0.05)The displacements of diaphragm ofgroup B were disappearing after the transection of cervical spinal cord The respiration w-asinhibited temporarily after the transection of cervical spinal cord Then the displacement ofthe diaphragm became more and more enhanced,and even higher than that of the controlgroup.5 It was showed that the phrenic nerve fibers projected to the ambiguous nucleusWe can see the reaction product of CB-HRP in cell body of ambiguous nucleus is in blueand homogeneity．Conclusions:The path of phrenic nerve-vagus nerve-ambiguous nucleus was created after theanastomosis of the phrenic nerve and the vagus nerve The method could reconstruct therespiratory function ofthe rat with upper cervical spinal cord injury effectly.