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

Introduction:  End-to-side neurorrhaphy has not been widely utilized due to its potentially low sprouting capability.  However, the phrenic nerve has a continuous firing rhythm that likely enhances side nerve growth (1-4).  We evaluate the functional clinical outcomes in children and adults undergoing an end-to-side phrenic nerve transfer for treatment of brachial plexopathy.

Methods:  A review of 86 patients (59 children, 27 adults) from 1999 to 2010 with brachial plexus injury undergoing a modified end-to-side phrenic neurorrhaphy was performed. For this procedure, 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) such as: the musculocutaneous nerve, the anterior or posterior division of the upper trunk, the axillary nerve, the suprascapular nerve, etc.  Post-operative muscle strength was then scored using the Medical Research Council (MRC) scale. The pediatric population was specifically reviewed 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 of post-surgical target muscle function.  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.

Conclusions:

1. The phrenic nerve has strong side sprouting capability suitable for end-to-side nerve repair. This is likely due to its continuous firing rhythm.
2. 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.
3. This technique should be considered in all severe cases with limited donor options.