Very Late Spinal Accessory Nerve-to-Infraspinatus Nerve Transfer to Restore Glenohumeral External Rotation in Brachial Plexus Birth Injury.

BACKGROUND

Poor recovery of active glenohumeral external rotation (aGHER) after brachial plexus birth injury (BPBI) is common. Late spinal accessory nerve-to-infraspinatus motor branch (SAN-IS) transfer has been reported as effective. The authors investigated its efficacy in children older than 4 years with BPBI.

METHODS

This case series involved children with no aGHER undergoing SAN-IS transfer. Indications included absent aGHER in shoulder abduction and a positive external rotation drop test. Subscapularis release was done for passive GHER less than 30 degrees in patients without glenohumeral dysplasia, whereas external derotational humeral osteotomy was performed for those with dysplasia and passive GHER less than 0 degrees. Data collected included demographics, Narakas group classification, preoperative and postoperative hand-to-neck Mallet scores, postoperative aGHER, aGHER strength (British Medical Research Council scale), and parental satisfaction.

RESULTS

Twenty-six patients, with a mean age of 9.9 years (range, 4 to 26 years) and mean follow-up of 27.9 months (range, 12 to 74 months), were included. Five patients (19%) had a concurrent upper subscapularis release, and 8 (31%) underwent derotational humeral osteotomy. Infraspinatus was macroscopically normal and contractile in all but 2 cases. Twenty-one patients (80%) achieved a mean aGHER of 71 degrees (range, 60 to 80 degress). Of these, 90% scored M4 on the British Medical Research Council scale, and 85% had a hand-to-neck Mallet score of 4. Shoulder forward flexion improved a mean of 35 degrees (range, 20 to 60 degrees) in 40% of patients. Parents were satisfied in 6 cases and extremely satisfied in 20 cases.

CONCLUSION

Late SAN-IS transfer is both effective and safe for restoring aGHER in patients older than 4 years with BPBI.