An Anatomic Study of Contralateral C7 Nerve Transfer Through a Combined Anterior Supraclavicular Triangle and...

To investigate the anatomic feasibility and technical characteristics of a modified contralateral C7 nerve transfer through a combined anterior supraclavicular triangle and posterior C6-C7 interspinous tunnel approach under microscopy. This study aims to provide a modified surgical technique with minimized trauma and a safer pathway for treating conditions such as upper limb spastic hemiplegia following stroke.

The modified contralateral C7 nerve transfer was simulated on 8 fresh adult head-neck specimens. For the anterior approach, a 5 cm straight incision was made in the supraclavicular triangle on the healthy side. The brachial plexus was microsurgically dissected through a supraclavicular route to identify and mobilize the middle trunk, which was then transected distal to its bifurcation into anterior and posterior divisions. For the posterior approach, a midline posterior incision was made to expose the C6-T1 laminae and facet joints. Bilateral C7 transverse processes were drilled to enhance C7 nerve root exposure. A C6-C7 interspinous tunnel was created, through which the contralateral C7 nerve was routed to the affected side for tension-free end-to-end coaptation. Key anatomic parameters, including nerve transfer distance and usable nerve length, were measured and compared before and after drilling the transverse processes.

The anterior supraclavicular small incision effectively exposed the middle trunk of the brachial plexus. With the midpoint of the clavicle as the reference, the bifurcation of the middle trunk was located along a line deviated 38.7±4.0 degrees laterally from the perpendicular line from the clavicular midpoint to the middle trunk. The posterior approach confirmed that drilling the C7 transverse processes significantly reduced the nerve transfer distance (7.2±0.4 versus 6.1±0.2 cm, P<0.001) and increased the usable nerve length (7.1±0.3 versus 8.3±0.4 cm, P<0.001). The C6-C7 interspinous tunnel width (4.2±0.3 mm) was sufficient to accommodate the C7 nerve (diameter 3.2±0.4 mm) without compression. After removal of the transverse process, the contralateral C7 nerve root has sufficient length to allow transfer through the interspinous tunnel to the opposite side (6.1±0.2 versus 8.3±0.4 cm, P<0.001), ultimately achieving tension-free and nonrotated end-to-end coaptation of bilateral C7 nerves posterior to the facet joints.

This study demonstrates the anatomic feasibility of the modified contralateral C7 nerve transfer through a combined microscopic anterior supraclavicular triangle and posterior interspinous tunnel approach. The technique reduces trauma through a small anterior incision, utilizes a stable posterior interspinous tunnel to prevent nerve compression, and optimizes the transfer route and coaptation conditions by drilling the transverse processes, thereby providing a reliable anatomic basis for clinical application.