Development of a novel experimental rat model for neonatal pre-ganglionic upper brachial plexus injury.

A neonatal upper brachial plexus injury, referred to as Erb's palsy, is a serious obstetric problem. Some surgical methods are used to treat this injury, but they are inadequate. To seek new treatments for Erb's palsy, we used a model for cervical preganglionic root transection in neonate rats and evaluated the behavioral and histological compatibility of this model with Erb's palsy. Two groups were used in this study. In the group, receiving the Erb operation, the left anterior and posterior roots of spinal vertebra C5-C7 were transected at the preganglionic level, and the results were compared with those of a group that received a sham operation. In the group, receiving the Erb operation, walking difficulties and behavioral abnormalities were observed. These observations were noted on the side where the transection took place, and the problems were attributed to proximal muscle weakness in the forelimb. Additionally, the forepaw grip was not impaired. Furthermore, in this group, the number of anterior horn cells in the cervical cord on the transected side was significantly lower than that on the contralateral side (P < 0.001). The results of this study indicate that the model fulfills the criteria for the clinical symptoms of Erb's palsy and that it may also serve as a new method for enabling treatment of the condition.