Cadaveric feasibility study of modified contralateral C7 nerve transfer for targeted functional recovery in hemiplegic upper extremity

Background: Contralateral cervical seventh (cC7) nerve to C7 transfer has been proven effective for treating spastic upper limb. However, for those whose major impairment is not in the C7 area, cC7 nerve transfer to other nerve(s) may achieve a better outcome. The aim of this study was to explore the optimal surgical approach for transferring cC7 to one or two nerves by cadaveric study and to discuss the possible applications for hemiplegic patients. Methods: Modified cC7 transfer to one (five procedures) or two nonadjacent (three procedures) nerve roots was proposed, and success rates of direct coaptation through two surgical approaches were compared: the superficial surface of longus colli (sLC) and the deep surface of longus colli (dLC) approaches. The length, diameter and distance of relevant nerves were also measured in 25 cadavers. Results: Compared with the sLC approach, the distance of the dLC approach was 1.1 ± 0.3 cm shorter. The success rates for the sLC and dLC approaches were as follows, respectively: cC7-C5 surgery, 94% and reached 98%; cC7-C6 surgery, 54% and 96%; cC7-C7 surgery, 42% and 94%; cC7-C8 surgery, 34% and 94%; cC7-T1 surgery, 24% and 62%; cC7-C5C7 surgery, 74% and 98%; cC7-C6C8 surgery, 54% and 98%. cC7-C7T1 surgery, 42% and 88%. Conclusions: The dLC approach greatly improved direct coaptation rate for cC7 nerve transfer. The modified cC7 nerve transfer procedures are technically feasible for further application in clinic.