The Experimental Study On The Reinnervation Of Diaphragmatic Muscle Via Hybrid Neurorrhapy

Objectives1、To establish the experimental mode of Hybrid neurorrhapy, In-situ phrenic nerveneurorrhapy, Sham operation as the experimental group (Group A), the experimentalcontrol group (Group B), the blank control group(Group C) respectively after the SD ratswere randomly assigned. All the members of every group were assigned randomly andaveragely into2subgroups according to the postoperative3month or6month after theestablishment of models.2、 To investigate the myelinated fiber of phrenic nerve at the distal end of neurorrhapy viahistochemical method and evaluate the difference among the groups.3、To study the characteristics of motor evoked potentials (MEP) on the diaphragmaticmuscle and the comparison among the groups.4、 To investigate the diaphragmatic muscle through histochemical method and thecomparison difference among the groups.Methods1、30juvenile male SD rats weighted100g in total were randomly and averagely assignedinto3groups, All the members of every group were assigned randomly and averagely into2subgroups according to the postoperative3month or6month after the establishment ofmodels. Group A: the end-to-side neurorrhapy of phrenic nerve-vagus nerve wereperformed in the left side of neck, and the end-to-end neurorrhapy of phrenicnerve-recurrent laryngeal nerve in the contralateral side were executed also; the proximalextremity of phrenic nerve and the distal extremity of recurrent laryngeal nerve werecoagulated into the muscles to avoid spontaneous axonal regrowth. Group B: the phrenicnerves were exposed at the neck and the in-situ anastomosis of that was performed at the similar location of Group A. Group C (Sham operation) was considered as blank controlgroup.2、The phrenic nerve tissue located in5mm distal to the anastomosis were obtained. Thematerials were fixed in10%paraformaldehyde, sectioning, staining with toluidine blue.The use of IMS cell image analysis system on myelinated nerve fiber count distalextremity of phrenic nerve was analyzed and compared the difference among the groups.3、The EEG electrode was placed in5mm proximal to anastomosis as the stimulatingelectrode. the cocentric circular electrode were inserted into the junction of the anterioraxilla line and the inferior border of the9th rib as the recording electrode. The amplitudeand latency of motor evoked potentials (MEP) were recorded and analyzed after thestimulation of proximal to the anastomosis.4、A piece of2millimeter of the diaphragm was cut bilaterally, then conventional paraffinsections, HE staining were performed continuously. The cross-sectional area ofdiaphragmatic muscle fiber was measured utilizing IMS cell image analysis system andcompared respectively among the groups.Results1、There are significant differences on the myelinated fiber count of phrenic nervebilaterally on the same postoperative period in Group A (P<0.05). Additionally, therecovery outcome of myelinated fiber on posteroperative6month was better than that onposteroperative3month (P<0.05). There is still significant difference on the myelinatedfiber count of phrenic nerve among the groups on the same postoperative period（P<0.05）.2、There are no significant differences on the motor evoked potential (MEP) bilaterally onthe same postoperative period in Group A (P>0.05), while the latency of MEP in the leftside was longer than that in the contralateral side on posteroperative3month (P<0.05).Moreover, the outcome of MEP on the diaphragm on posteroperative6month was betterthan that on posteroperative3month (P<0.05). There is still significant difference on themotor evoked potential (MEP) of diaphragm between Group A and B on the samepostoperative period（P<0.05）.3、There are no significant differences on the cross-sectional area (CSA) of diaphragmbilaterally on the same postoperative period in Group A (P>0.05). Furthermore, therecovery outcome of CSA on the diaphragm on posteroperative6month was better thanthat on posteroperative3month (P<0.05). Nevertheless, there is still significant difference on the CSA of diaphragm among the groups on the same postoperative period（P<0.05）.Conclusions1、There is significant difference on the myelinated fiber count of distal extremity on thephrenic nerve bilaterally in the Group A, which also prove that the end-to-side neurorrhapy(ESN) hardly can achieve the recovey outcome of the end-to-ed neurorrhapy (EEN).Additionally, the significant difference exists among the three goups.2、According to the results of MEP, the recovery outcome via ESN is inferior to that viaEEN on the3month posteroperatively, while that is no significant on the6monthposteroperatively. The result of MEP on the6month posteroperatively is superior to thaton the3month posteroperatively.3、The result of CSA on the6month posteroperatively is obviously superior to that on the3month posteroperatively in Group A and B, while the significant difference compared withblank control group. There is no significant difference on the CSA between the ESN ofphrenic nerve-vagus nerve and the EEN of phrenic nerve-recurrent laryngeal nerve. TheCSA via Hybrid neurorrhapy can achieve the similar outcome with in-situ anastomosis, butwas inferior to the blank control group.4、Preliminary research reveals that the reinnervation of diaphragm via Hybrid neurorrhapyis satisfactory. Nevertheless, the further study on how to retard the process of atrophybefore reinnervation should be considered.