Contralateral cervical seventh nerve transfer for spastic arm paralysis via a modified prespinal route: a cadaveric study.

Background: We proposed contralateral cervical seventh nerve transfer for spastic arm paralysis after central neurological injury in the New England Journal of Medicine (NEJM) in 2018. In this surgery, we applied a new surgical route for nerve transfer, the Huashan prespinal route. The objective of this study was to elaborate our new surgical technique, clarify its relationship to the vertebral artery, and provide anatomical data on this novel method.

Methods: The effectiveness and safety of the Huashan prespinal route in contralateral C7 nerve transfer were evaluated anatomically. Nine cadavers (4 males, 5 females) were available for this study. Among these, anatomical parameters of the vertebral artery were obtained from 6 cadavers, and the anastomosis of the bilateral cervical seventh nerve was observed on 3 cadavers undergoing contralateral C7 nerve transfer via the Huashan prespinal route.

Results: Tension-free anastomosis of the bilateral cervical seventh nerve was achieved through the Huashan prespinal route. The tilt angle of the vertebral artery to the sagittal plane (with thyroid cartilage as the origin) was 25.5 ± 4.5°, at 22.5 ± 1.6° and 28.7 ± 4.3° on the left and right side, respectively. The safe drilling angle to penetrate through the longus colli muscles for the creation of a longus colli muscle tunnel to avoid injury to the vertebral artery in our surgical technique was above 33.2°.

Conclusions: The cadaveric study confirms that the presented technique allowed simple, effective, and safe contralateral C7 nerve transfer. This technique can be used in the treatment of hemiplegia and brachial plexus injury. There is a safe scope of drilling angle for creating the longus colli muscle tunnel required for this surgical route. The anatomical parameters obtained in this study will be helpful for the performance of this operation.