Fascicular topography of the suprascapular nerve in the C5 root and upper trunk of the brachial plexus: a microanatomic study from a nerve surgeon's perspective.

Background: In patients with supraclavicular injuries of the brachial plexus, the suprascapular nerve (SSN) is frequently reconstructed with a sural nerve graft coapted to C5. As the C5 cross-sectional diameter exceeds the graft diameter, inadequate positioning of the graft is possible.

Objective: To identify a specific area within the C5 proximal stump that contains the SSN axons and to determine how this area could be localized by the nerve surgeon, we conducted a microanatomic study of the intraplexal topography of the SSN.

Methods: The right-sided C5 and C6 roots, the upper trunk with its divisions, and the SSN of 20 adult nonfixed cadavers were removed and fixed. The position and area occupied by the SSN fibers inside C5 were assessed and registered under magnification.

Results: The SSN was monofascicular in all specimens and derived its fibers mainly from C5. Small contributions from C6 were found in 12 specimens (60%). The mean transverse area of C5 occupied by SSN fibers was 28.23%. In 16 specimens (80%), the SSN fibers were localized in the ventral (mainly the rostroventral) quadrants of C5, a cross-sectional area between 9 o'clock and 3 o'clock from the surgeon's intraoperative perspective.

Conclusion: In reconstruction of the SSN with a sural nerve graft, coaptation should be performed in the rostroventral quadrant of C5 cross-sectional area (between 9 and 12 o'clock from the nerve surgeon's point of view in a right-sided brachial plexus exploration). This will minimize axonal misrouting and may improve outcome.