title: The efficacy of end-to-end and end-to-side nerve repair (neurorrhaphy) in the rat brachial plexus.
abstract: Proximal nerve injury often requires nerve transfer to restore function. Here we evaluated the efficacy of end-to-end and end-to-side neurorrhaphy of rat musculocutaneous nerve, the recipient, to ulnar nerve, the donor. The donor was transected for end-to-end, while an epineurial window was exposed for end-to-side neurorrhaphy. Retrograde tracing showed that 70% donor motor and sensory neurons grew into the recipient 3 months following end-to-end neurorrhaphy compared to 40-50% at 6 months following end-to-side neurorrhaphy. In end-to-end neurorrhaphy, regenerating axons appeared as thick fibers which regained diameters comparable to those of controls in 3-4 months. However, end-to-side neurorrhaphy induced slow sprouting fibers of mostly thin collaterals that barely approached control diameters by 6 months. The motor end plates regained their control density at 4 months following end-to-end but remained low 6 months following end-to-side neurorrhaphy. The short-latency compound muscle action potential, typical of that of control, was readily restored following end-to-end neurorrhaphy. End-to-side neurorrhaphy had low amplitude and wide-ranging latency at 4 months and failed to regain control sizes by 6 months. Grooming test recovered successfully at 3 and 6 months following end-to-end and end-to-side neurorrhaphy, respectively, suggesting that powerful muscle was not required. In short, both neurorrhaphies resulted in functional recovery but end-to-end neurorrhaphy was quicker and better, albeit at the expense of donor function. End-to-side neurorrhaphy supplemented with factors to overcome the slow collateral sprouting and weak motor recovery may warrant further exploration.
authors.affiliation: Institute of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Wen-Chieh
authors.initials: WC
authors.lastname: Liao
authors.forename: Jeng-Rung
authors.initials: JR
authors.lastname: Chen
authors.forename: Yueh-Jan
authors.initials: YJ
authors.lastname: Wang
authors.forename: Guo-Fang
authors.initials: GF
authors.lastname: Tseng
mesh_terms: D000200:Action Potentials; D000714:Anastomosis, Surgical / Q000379:methods; D000818:Animals; D020516:Brachial Plexus Neuropathies / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D006120:Grooming / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D009138:Musculocutaneous Nerve / Q000502:physiology / Q000601:surgery; D009186:Myelin Sheath / Q000473:pathology; D009412:Nerve Fibers / Q000473:pathology; D009416:Nerve Regeneration / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000502:physiology; D014459:Ulnar Nerve / Q000502:physiology / Q000601:surgery
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