Clinical Outcomes after a Modified End-to-Side Nerve Transfer Using the Phrenic Nerve as a Donor for Treatment of Brachial Plexus Injury

Abstract

INTRODUCTION: End-to-side neurorrhaphy has not been widely utilized due to its potentially low sprouting capability. The phrenic nerve has a continuous firing rhythm that likely enhances side sprouting.1–4 Satisfactory clinical outcomes were obtained after end-to-side neurorrhaphy with the phrenic nerve as a donor for treatment of brachial plexus injury. METHODS: A total of 86 patients (27 adults, 59 children) from 1999 to 2010 with brachial plexus injury underwent modified end-to-side phrenic neurorrhaphy by the senior author (H.S.M). For this, the phrenic side was widely opened; one or two nerve grafts were interpositioned and sutured between the phrenic nerve side and the recipient nerve end. These transfers included various recipient nerve ends (targeting end muscles with ≤ grade 1 strength): musculocutaneous nerve, anterior or posterior division of the upper trunk, axillary nerve, suprascapular nerve, etc. Post operative muscle strength was then scored using the Medical Research Council (MRC) scale, and the greatest target end muscle score was utilized. The pediatric population was specifically followed for major complications such as those requiring immediate operative management or respiratory distress. RESULTS: The patients were followed postoperatively from 3 months to 69 months (mean 25.5 months). Sixty-seven had adequate clinical records for evaluation. 23/67 (34%) patients had MRC muscle grade 4; 26/67 (39%) patients had muscle grade 3; 10/67 (15%) patients had muscle grade 2; 8/67 (12%) patients had muscle grade 1. The total effective functional recovery (≥ MRC grade 3) has reached 73%. No major complications were noted during the postoperative period in the pediatric cohort. CONCLUSION: The phrenic nerve has strong side sprouting capability suitable for end-to-side nerve repair. This is likely due to its continuous firing rhythm. Satisfactory functional results may be obtained if the phrenic nerve side is widely opened to allow nerve grafting via an oblique end-to-side repair method for brachial plexus injury treatment.This technique should be considered in severe cases with limited donor options.