Anatomical Study and Clinical Application of Cross-transferring the Contralateral Cervical 7 Nerve Through the Posterior Cervical Pathway for the Treatment of Spastic Paralysis of the Upper Limbs

Objective: To investigate the anatomical basis and clinical effect of contralateral cervical 7 nerve transfer via the posterior cervical approach in the treatment of central upper limb spastic paralysis. Methods: Five fresh head and neck anatomical specimens, including 3 males and 2 females, were selected to simulate cervical 7 nerve transfers through the posterior cervical approach. The cervical 7 nerve was separated and exposed under a microscope, the vertical distance between the cervical 7 nerve and the inner edge of the clavicle was measured, and the cervical 7 nerve root was incised. The lamina and cervical 7 nerve were exposed through the posterior cervical approach, a small hole was made in both inner rear walls of the bilateral intervertebral foramen, the cervical 7 nerve on the left side was extracted, and the cervical 7 nerve on the right was incised. The left extracted C7 nerve was transferred and sutured to the distal end of the C7 nerve at the right posterior wall hole of the intervertebral foramen through the spinous process gap. The length of the left cervical 7 nerve leading out through the posterior cervical approach and the shortest distance of the cervical 7 nerve transferring were measured, and the minimum width of the hole in the posterior wall of the intervertebral foramen was also measured. The clinical data of a patient who underwent cervical 7 nerve transfer surgery via a posterior cervical approach at Northern Jiangsu People’s Hospital affiliated with Yangzhou University were analyzed. The patient was a 45-year-old male who was clinically diagnosed with spastic paralysis of the central upper limb after parietal hemorrhage. Cervical 7 nerve transfer surgery was performed through the posterior pathway. Changes in muscle tension and muscle strength on the healthy side and the affected side were observed after the operation. Results: The cervical 7 nerve was located deep in the middle point of the clavicle. The vertical distance between the C7 nerve root and the medial edge of the clavicle was measured to be 1.8 to 2.5 (2.1±0.4) cm. The length of the cervical 7 nerve from the posterior cervical approach was 6.6 to 7.4 (7.1±0.4) cm. The shortest distance of cervical 7 nerve transfer was 3.9 to 4.3 (4.0±0.2) cm. The minimum width of the hole in the posterior wall of the intervertebral foramen was 4.6 to 5.3 (4.8±0.3) mm, and the ratio of the minimum hole width of the posterior wall of the intervertebral foramen to the facet joint distance was 33.6 to 38.2 (35.8±0.4)%. Anatomical studies have shown that the cervical 7 nerve transfer surgery can be performed through the posterior cervical approach without the need for bridging nerves. One patient with central upper limb paralysis underwent cervical 7 nerve transfer surgery via a posterior cervical approach. After the operation, the muscle strength of the healthy side of the upper limb was normal, accompanied by sensory pain and numbness. After 1 month, the patient completely recovered, the spasm symptoms on the affected side of the upper limb were significantly relieved, and the muscle strength recovered to grade I+. The patient’s postoperative wound healed well. Conclusions: Anatomical research of the posterior cervical pathway for the cervical 7 nerve transfer revealed that the position of the cervical 7 nerve is relatively constant and that the cervical 7 nerve transfer distance is short. It is a safe and effective surgical scheme for the treatment of central upper limb spastic paralysis.