Anatomic Study and Clinical Application of C7 Nerve Transfer Surgery via the Anterior Vertebral Approach for Central Upper Limb Spastic Paralysis
Authors: Yan Zhengcun , Luo Wenmiao , Gu Jiaxiang , Liu Hongjun , Meng Zhaoxiang , Wang Xiaodong , Wei Min , Wang Xingdong , Wang Yongxiang , Zhang Hengzhu 
Published: October 2024

Objective:
To explore the anatomic characteristics of C7 nerve localization, course, and length during cross-transfer surgery of the C7 nerve through the anterior vertebral approach and investigate the feasibility, safety, and clinical efficacy of C7 nerve transfer surgery through the anterior vertebral approach for the treatment of central upper limb spastic paralysis.

Methods:
Four fresh-frozen adult head and neck samples were selected. C7 nerve transfer surgery was simulated through the anterior vertebral approach. The vertical distance between the C7 nerve and the medial edge of the clavicle, the length of the C7 nerve, and the shortest distance of C7 nerve transfer required through the anterior vertebral approach were measured. This was a retrospective analysis of the clinical data of 2 patients with central upper limb spastic paralysis after C7 nerve transfer surgery at Northern Jiangsu People’s Hospital affiliated with Yangzhou University. The patients were all female, aged 50 to 51 years, with upper limb paralysis on the affected side. The muscle strength was grade 0 or grade 1, and the muscle tension was relatively high. Both patients underwent C7 nerve transfer surgery through the anterior vertebral approach. Upper limb sensation and motor function were observed.

Results:
Bilateral C7 nerves can be fully exposed and located through the anterior vertebral approach. The C7 nerve runs between the anterior and middle scalene muscles, with a vertical distance of 1.7 to 2.5 (2.1±0.3) cm from the inner edge of the clavicle. The length of the C7 nerve is 5.6 to 6.8 (6.4±0.5) cm, and the shortest distance of C7 nerve transfer through the anterior vertebral approach is 4.8 to 5.7 (5.3±0.4 cm). Two patients with central upper limb paralysis successfully underwent C7 nerve transfer surgery using the anterior vertebral approach. Two patients had normal motor function in the healthy upper limb after surgery but experienced pain and numbness in the healthy upper limb. Both patients recovered within 1 month. Two patients experienced significant relief of spasticity symptoms in the affected upper limb. One patient was followed up for 15 months, and, at the last follow-up, sensation in the affected upper limb was normal, with proximal muscle strength at level 3 and distal muscle strength at level 2. Another patient was followed up for 11 months, and at the last follow-up, sensation in the affected upper limb was normal, with proximal muscle strength at level 1+ and distal muscle strength at level 1.

Conclusion:
For central upper limb spastic paralysis, C7 nerve transfer surgery through the anterior vertebral approach is safe and feasible and is a good treatment option. Related anatomic research can effectively guide clinical surgery and assist in locating the C7 nerve, and incising the musculus longus colli can shorten the distance of C7 nerve transfer.