Neuroendoscopy-Assisted Modified Anterior Approach for Contralateral Cervical 7 Nerve Transfer: A Cadaveric Study

Background: This study aims to investigate a safer and more minimally invasive method for transferring the contralateral C7 nerve in the treatment of central spastic paralysis of the upper limb, while also providing anatomic data to support this approach. Methods: Eight anatomic specimens from the head and neck were utilized: 4 dry specimens were used to measure anatomic data, whereas the other 4 fresh specimens were used to simulate the transposition of the contralateral C7 nerve for observing bilateral nerve anastomosis. Relevant anatomic landmarks and their surrounding relationships were examined using a neuroendoscope, and anatomic data were subsequently measured and analyzed. Results: The modified anterior vertebral approach, assisted by a neuroendoscope, can expose both the affected and contralateral C7 nerve roots, vertebral arteries, and the middle trunk of the brachial plexus on the contralateral side. It can also facilitate the completion of bilateral C7 nerve transfer within the affected side’s longus colli muscle tunnel, with tension-free suturing achieved without the need for nerve bridging. Measurement results from dry specimens: The angle between the C7 nerve and the spine was 63.6±3.8 degrees, the horizontal distance from the vertebral artery to the midline of the spine was 2.44±0.54 cm, and the horizontal distance from the C7 horizontal vertebral artery to the midline of the spine, as measured by imaging, was 2.46±0.14 cm. The difference between the 2 measurements was not statistically significant ( P >0.05). The measured nerve displacement in fresh specimens was 4.62±0.37 cm, and the length of the C7 nerve was 7.87±0.55 cm. Conclusion: The experiments confirmed that the neuroendoscopy-assisted modified anterior vertebral approach is a simple, effective, and safe method for contralateral C7 nerve transfer. This approach involves a short nerve transfer distance and does not necessitate nerve transplantation. It may serve as a safe and effective surgical method for treating central upper limb spastic paralysis. The anatomic parameters obtained in this study will aid in the implementation of this procedure.