Anatomic Characteristics Of Contralateral C7 Nerve Transfer Through The Modified Prespinal Route

Objective:1. To observe anatomic characteristics of the modified prespinal route by gross anatomy; to provide anatomical basis for the contralateral C7 transfer throuth the modified prespinal route.2. To observe the primary application of direct anastomosis of contralateral C7 transfer through the modified prespinal route in clinic.Method:1. In this study, 32 adult cadaver sides were obtained. bilateral supraclavicular transvese incisions for exploration of the brachial plexus on both sides were used, to observe anatomic structures correlated with the modified prespinal route.The C7 nerve were sectioned at the junction site of trunk and division, to determine the length of havested C7 nerve roots.To determine the different distances from the harvested C7 nerve to the upper midpoint of opposite side clavicle through subcutaneous route, retro-sternocleidomastoid route, prespinal route and modified prespinal route respectively.2. One adult and one child who have been diagnosed as the total brachial plexus root avulsion were operated. The contralateral C7 transfer through the modified prespinal route was used for direct anastomosis with aimed nerve. Then, they were followed up for 20 weeks.Result:1. The results of anatomical research of modified prespinal route is as followed:(1) The modified prespinal route has its own anatomic characteristics as follows:①There are many significant tissure on the anterior surface of angular interval, such as vertebral artery, vertebral vein, truncus sympathicus cervicalis, recurrent laryngeal nerve, phrenic nerve, thoracic duct and so on. They are confusable and variable. On the contrary, There is no significant tissue under angular interval except C7 and C8 nerve root.②The triangle interval which is constituted by inferior oblique part of longus colli muscle, C6 transverse process, C6,C7 vertebra and intervertebral disk, can be passed through by the sectioned C7 nerve easily.③There is a certain angulation between esophagus and C7 vertebra, which is easy to be dissected.④C7 vertebra slope posterior in the sagittal plane, its anterior tubercle of transverse process is small or lacking, the pedicle originates more posteriorly.(2) The average length of sectioned C7 nerve root was 69.8±11.9mm, the shortest length was 48.6mm,and the longest was 95.8mm.(3) The average distance from the end of transferred C7 nerve to the upper midpoint of opposite side clavicle through 4 different routes were 145.6±20.72mm, 113.0±17.85mm, 71.7±15.92mm and 57.2±14.62mm respectively.2. The result of primary clinical observation has shown: the courses of operation were unhindered, two C7 nerves transferred were both sutured with lower trunk directly, all operations were uncomplicated, the follows-up for 20 weeks were approved.Conclusions:1. Contralateral C7 nerve transfer through modified prespinal route is feasible, which can avoid impairing significant vascular and nerve on the anterior surface of angular interval at donor side, and shorten the length of nerve neurotization.2. The primary clinical application has shown that contralateral C7 nerve transfer through modified prespinal route to repair aimed nerve directly is safe and valid.