American Society for Peripheral Nerve

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The Dorsal Cutaneous Branch of the Ulnar Nerve as a Donor for Median Nerve Sensory Reconstruction: A Cadaveric Study
Michael D Wigton, MD; Tianyi David Luo, MD; Ian R Smithson, MD; Wayne A Chen, MD; Benjamin Berwick, MS; Zhongyu Li, MD, PhD
Wake Forest University, Winston Salem, NC

Introduction: Hand sensibility is extremely important but most difficult to achieve in upper extremity reconstruction. Loss of median nerve (MN) distribution sensation disables hand function after upper brachial plexus injury and failed MN repair. Motor fascicular and/or tendon transfers are commonly used strategies for motor restoration. However, options for sensory reconstruction are limited. The common digital nerve (CDN) to ring and small of the ulnar nerve may be used for first web space sensory restoration, but it further sacrifices ring and small finger sensation. The current study describes anatomical considerations and feasibility of transferring the dorsal cutaneous branch of ulnar nerve (DCBUN) to the MN for sensory restoration. We hypothesize the DCBUN is a feasible donor nerve and provides more than one branch for transfer without sacrificing existing volar sensation.

Methods & Methods: Seven fresh cadaveric upper limb specimens were used for this study. The DCBUN was identified proximally and dissected distally identifying and preserving all branches. The MN was dissected within the carpal tunnel; CDNs were identified. The DCBUN was isolated from the ulnar nerve proximally. Nerve transfer was performed after transecting the branches of the DCBUN distally. The DCBUN was transferred volar for coaptation with the MN CDNs. The branching point, length, isolation point, and transfer length were measured utilizing the wrist crease as a reference point. Samples of each branch from the MN and DCBUN were analyzed histologically.

Results: The DCBUN had 2-4 branches. The longest branch consistently innervated the dorsal 4th web space (7.6 0.82 cm). The 2nd, 3rd, and 4th longest had lengths of 4.7 2.01, 3.8 3.89, and 2.7 1.19 cm, respectively. After transfer to the palm, the DCBUN branch lengths were 7.9 0.90, 6.2 1.33, 5.1 3.71, and 2.4 1.28 cm distal to the wrist crease, respectively. The DCBUN could be isolated from the ulnar nerve proper 10.5 2.7 cm and 17.8 5.45 cm proximal to the wrist crease before and after internal neurolysis, respectively. On histology, the MN CDNs and DCBUN branches had mean nerve surface areas of 1.44 1.14 and 0.40 0.34 mm2, respectively, and mean axon counts of 10.4 4.57 and 4.05 2.48, respectively.

Conclusion: The DCBUN reliably provides 2 or more branches suitable for transfer to the MN CDNs. It has the potential to reconstruct all 3 CDNs of the MN without sacrificing function of the 4th CDN.

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