American Society for Peripheral Nerve

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Cadaveric Study of Levator Scapulae Nerve as a Potential Donor in Brachial Plexus Reconstruction
Mark J Winston, MD; Eliana B Saltzman, BA; Steve K Lee, MD; Scott W Wolfe, MD
Hospital for Special Surgery, New York, NY

Introduction: Complete brachial plexus palsies represent a surgical dilemma given the paucity of available donor nerves for transfer. The spinal accessory nerve (SAN) is commonly transferred to the suprascapular nerve (SSN) to help with shoulder abduction and stabilization; however, other donors must be identified for additional reconstruction options. We hypothesize that the levator scapulae nerve (LSN) is a potential nerve donor in brachial plexus nerve reconstruction with tension free neurorrhaphy and appropriate donor to recipient axon count ratio.

Methods: Bilateral cervical and brachial plexus dissections were performed on six adult cadavers. Demographic data was recorded for each specimen. The SAN was identified on the anterior border of the trapezius. The phrenic nerve was identified and then was traced proximally to find contributions from C3, C4, and C5 nerve roots. We identified separate C3 and C4 branches to the LSN. The long thoracic nerve (LTN) was identified piercing the middle scalene. Each nerve (SAN, SSN, LTN, and LSN) was neurolysed to obtain maximum length. Nerve transfers were performed from the donor LSN and SAN to the recipient SSN and LTN. Overlap between donor and target nerves was measured. Finally, each nerve was cut and sent to histology lab for axon counts.

Results: The mean fascicular axon counts for examined nerves were as follows: LSN (mean = 841.8, SD = 198.3), SAN (mean = 1323.4, SD = 171.4), SSN (mean = 3361.7, SD = 627.4), and LTN (mean = 1737.7, SD = 332.4). The resulting axon count donor-to-recipient ratio was as follows: LSN to SSN 1: 4.0, LSN to LTN 1: 2.1, SAN to SSN 1: 2.5, and SAN to LTN 1: 1.3. The mean overlap distance from the LSN to SSN was 1.7 cm (SD = 3.1) and from LSN to LTN it was 2.9 cm (SD = 2.8). The mean overlap from the SAN to SSN was 4.5 cm (SD = 0.7) and from SAN to LTN it was 0.75 cm (SD = 1.0).

Conclusions: Levator scapulae nerve is a potential donor nerve for nerve transfers with target recipient nerves such as the SSN, LTN, and other nerves with the addition of a graft such as the nerve to triceps. Future studies are required to investigate the clinical outcomes for these potential nerve transfers.

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