title: Optimal axon counts for brachial plexus nerve transfers to restore elbow flexion.
abstract: BACKGROUND
  Nerve transfer surgery has revolutionized the management of traumatic brachial plexus injures. However, the optimal size ratio of donor to recipient nerve has yet to be elucidated. The authors investigated the axon count ratios of ulnar and median fascicular transfers to restore elbow flexion. The authors hypothesized that donor nerve axon counts would be correlated with historical success of various nerve transfers used to restore elbow flexion.
  
  
  METHODS
  Ten cadaveric specimens were used for a histomorphologic analysis of fascicular nerve transfers. Review of previously published axon counts and clinical results following transfer to the musculocutaneous nerve to restore elbow flexion was performed for the following donor nerves: medial pectoral, spinal accessory, intercostal, thoracodorsal, ulnar, and median fascicular.
  
  
  RESULTS
  The average number of fascicles identified was 7.9 in the ulnar nerve and 8.0 in the median nerve. The mean fascicular axon count was 1318 for the ulnar nerve and 1860 for the median nerve. Mean recipient nerve axon count was 1826 for the musculocutaneous biceps branch and 1840 for the brachialis branch. A significant correlation between axon count and clinical results of transfers to restore elbow flexion was observed. Donor-to-recipient nerve axon count ratios below 0.7:1 were associated with a decreased likelihood of a successful outcome.
  
  
  CONCLUSIONS
  In nerve transfers to restore elbow flexion, an appropriate size match between donor and recipient nerves appears to be a factor affecting clinical success. These data support a donor-to-recipient axon count ratio greater than 0.7:1 as the goal for brachial plexus nerve transfers to restore elbow flexion.
authors.affiliation: New York, N.Y. From the Center for Brachial Plexus and Traumatic Nerve Injury, Hospital for Special Surgery.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Schreiber
authors.forename: David J
authors.initials: DJ
authors.lastname: Byun
authors.forename: Mahmoud M
authors.initials: MM
authors.lastname: Khair
authors.forename: Lauren
authors.initials: L
authors.lastname: Rosenblatt
authors.forename: Steve K
authors.initials: SK
authors.lastname: Lee
authors.forename: Scott W
authors.initials: SW
authors.lastname: Wolfe
mesh_terms: D001369:Axons; D001917:Brachial Plexus / Q000601:surgery; D020516:Brachial Plexus Neuropathies / Q000601:surgery; D002102:Cadaver; D004551:Elbow Joint / Q000502:physiology*; D006801:Humans; D008475:Median Nerve / Q000033:anatomy & histology* / Q000637:transplantation*; D016067:Nerve Transfer; D016059:Range of Motion, Articular; D014459:Ulnar Nerve / Q000033:anatomy & histology* / Q000637:transplantation*