Experimental Study Of The Mechanism Of Wrist And Finger Drop Caused By Obstetric Brachial Plexus Palsy

Objective To establish the animal model for imitating the clinical picture that the occurance of carpoptosis after birth palsy and root injury of adults.Methods72Sprague-Dawley male rats were divided, on the basis of age, into three groups of24each, i.e., two pup groups at the age of7days postnatal (P7) and of14days (P14), and one adult (3months old,250-300g) group. Each group was subdivided into three equally for performing the rupture of the right C56, C5-C7and C5-C8nerve roots respectively. In the3rd month postoperatively, the following tests were performed to estimate the recovery of each group:1.Compared the rate of carpoptosis of each group;2. Electrophysiological test to compared the latency delayed rate(LDR) and amplitude recovery rate(ARR) of CMAP in the forearm extensor;3.HE stain to compared the muscle weight maintaining rate(MWMR) and cross-sectional area recovery rate(CSARR), Von Geison stain to get the integrated optical density (IOD) for evaluate the fibrosis of the forearm extensor;4. Compared the regenerated nerve traversing rate of the radial nerve in each group;5. The NF200and Myelin protein P0of the affected radial nerve were measured by RT-PCR and Western blot.The occurrence rate of carpoptosis was measured by Fisher’s exact test. All the values were expressed as median (p25-p75) or mean±SD, according to the distribution of variables. Anova and Kruskal-Wallis test were performed whenever appropriate to analyze the differences among the groups. In addition, Bonferroni-corrected post hoc test was conducted to adjust the observed significant level for multiple comparisons if the null hypothesis was rejected. Statistical significance level was set at0.05.Results1)The ethology test:after the C56ruptured, there was no carpoptosis in each age group (P>0.05); After the C5-C7ruptured, there was1in8with carpoptosis of adults while7(6) in8with carpoptosis of P7(P14). The carpoptosis rate of the adult was lower than P7(P＜0.05) and P14(P>0.05) group. There was no significance between the P7and P14(P>0.05); After the C5-C8ruptured, all these rats were with carpoptosis.2) Electrophysiological test of radial nerve:after the C56ruptured, there was no significance of both the index between all the age groups (P>0.05); After the C5-C7ruptured, the LDR of CMAP of all the groups had no significance in the whole (P>0.05). The ARR of adult’s Extensor carpi radialis muscle and extensor digitorium communis were higher than P7and P14group (P<0.05). There was no significance between the P7and P14; After the C5-C8ruptured, there was no significance of both the index between all the age groups (P>0.05).3) Histological test of the extensors in forearm:after the C56ruptured, all the index of the extensors were not different statistically(P>0.05). After the C5-C7ruptured, the extensors’MWMRwas higher than P7and P14(P<0.05), There was no significance between the P7and P14; the extensors’CSARR was higher than P7and P14(P<0.05), there was no significance between the P7and P14. The extensors’IOD value of collagen fiber in the adult group were lower than that of the P7and P14(P<0.05), there was no significance between the P7and P14. After the C56ruptured, all the index of the extensors were not different statistically(P>0.05).4) Histological test of radian nerves:after the C56ruptured, all the index of the extensors were not different statistically(P>0.05). After the C5-C7ruptured, the NTR of adults were higher than that of the P7and P14(P<0.05), there was no significance between the P7and P14.After the C56ruptured, all the index of the extensors were not different statistically(P>0.05).5) Molecular Biological test:after the C56ruptured, the radial nerve’s mRNA relative content and protein level of NF200and PO were not different statistically. After the C5-C7ruptured, mRNA and protein level of NF200and PO in adult were higher than that of the P7and P14, there was no significance between the P7and P14. After the C56ruptured, the radial nerve’s mRNA and protein level relative content of NF200and PO were not different statistically. Conclusion The data showed us that the dorsal expansion of wrist and fingers had not be impaired after the C56rupture; after the C5-C7ruptured, the pup rats with severe dysfunction of wrist and finger expansion while the adults with no obvious disturbance of the wrist and finger expansion; after the C5-C8ruptured, all the rats presented carpoptosis. Objective By retrogradly labeling the motor neurons contributing to the radial nerve via upper trunk, middle trunk and lower trunk in pups and adult rats, We compared the percentage of labeled neurons of each trunk in the brachial plexus between the pups and adult rats for elucidate the neuromorphological mechanism of the carpoptosis in pup and adult rats.Method24Sprague-Dawley male rats were divided, on the basis of age, into three groups of8each, i.e., two pup groups at the age of7days postnatal (P7) and of14days (P14), and one adult (3months old,250-300g) group.5%CTB (cholera toxin B) was used for retrograde labeling via the radial nerve and the neuron count were corrected followed by the comparing between the pups and adult rats.Results Compared the total count of all the segments:P7(326.3±36.9) was more than P14(212.8±20.6) and adult(140.4±19.5). There were significant difference between any two of the three groups (PP7vsP14<0.0001, PP7vsAD＜0.0001, PADvsP14<0.0001).As to the percentage of labeled neurons of C5&C6in all the segments, the P7(34.2%) and P14(31.3%) were both more than AD (24.8%), PP7vs AD<0.05, PADvsP14<0.05. There was no significance between the P7and P14(P=0.606).As to the percentage of labeled neurons of C7in all the segments, the P7(28.4%) was more than AD(22.5%)(P＜0.05) and there was no significance between the P14(25.3%) and AD(P>0.05), P7and P14(P>0.05). AS to the percentage of labeled neurons of C8&T1in all the segments, P7(37.5%) and P14(44.7%) were both less than AD(50.7%), PP7vsAD<0.05, PADvsP14<0.05. There was no significance between the P14and P7(P>0.05).Conclusion The percentage of motor neurons of each trunk of brachial plexus various with aging. The dominant innervation from spinal roots to radial nerve shift from C5-C7in pups to C7-T1in adults. It was probably the reason for the difference of the impairment of wrist and finger expansion between the pups and adult rats after injury of the upper trunk and middle trunk. Objective Evaluate the influence of different surgical technique on the pup and adult rats after the rupture of upper trunk and middle trunk so as to find the best way of surgical therapy. Establish the experimental basis for clinic.Methods48Sprague-Dawley male rats were divided, on the basis of age, into two groups of24each, i.e., pup groups at the age of7days postnatal (P7) and one adult (3months old,250-300g) group. Each group was subdivided into three equally:A) left C56injured, B) C5-C7injured and C)control. The injured nerve roots were repaired immediately by autogenic nerve transplantation. In the3rd month postoperatively, the following tests were performed to estimate the recovery of each group:1.Compared the rate of carpoptosis of each group;2. Electrophysiological test to compared the latency delayed rate (LDR) and amplitude recovery rate(ARR) of CMAP in the forearm extensor;3.HE stain to compared the muscle weight maintaining rate(MWMR) and cross-sectional area recovery rate(CSARR);4. Compared the regenerated nerve traversing rate of the radial nerve in each group;5. The MyoD1and Myogenin of the affected radial nerve were measured by RT-PCR and Western blot. The statistical method in this part is the same to part I.Results1)The ethology test:there were no carpoptosis in group of adult A and pup A; the carpoptosis rate of pup B was higher than that of adult B (P＜0.05); the carpoptosis rate of pup C was higher than that of adult C (P<0.05); the carpoptosis rate of pup A is lower than that of B and C(P<0.05); there was no difference between carpoptosis rate of adult A and B,but they were both lower than C(P<0.05).2) Electrophysiological test of radial nerve:there was no difference between the LDR of all these pup groups (P>0.05). The ARR of pup group A, B and C descended progressively (P>0.05); there was no statistical difference between the LDR of adult group A, B and C(P>0.05); there was no difference between ARR of adult A and B,but they were both lower than C(P<0.05).3) Histological test of the extensors in forearm:The MWMR of pup A,B and C descended progressively (P＜0.05). The CSARR of pup A,B and C descended progressively (P<0.05). There was no difference between MWMR of adult A and B, but they were both lower than C(P<0.05). There was no difference between CSARR of adult A and B, but they were both lower than C (P＜0.05).4) Histological test of radian nerves:The NTR of pup A,B and C descended progressively (P<0.05). There was no difference between NTR of adult A and B,but they were both lower than C(P<0.05).5) Molecular Biological test:the mRNA of MyoD1and Myogenin in pup A,B and C increased progressively(P＜0.05). There was no difference between mRNA of MyoD1and Myogenin in adult A and B, but they were both higher than C (P＜0.05). The protein level of MyoD1and Myogenin in pup A, B and C increased progressively (P＜0.05). There was no difference between protein level of MyoD1and Myogenin in adult A and B, but they were both higher than C(P＜0.05).Conclusion In adult rats, there was no difference between the recovery of wrist extensor of the two surgical procedure after the C5-C7injured. The restoration of C5-C7but not C5-C6can do more good to the recovery of wrist extensor in pup rats. It’s important to repaire the C7by nerve graft after injury of C5-C7in newborn rats.