The Effect of Fascicular Composition on Ulnar to Musculocutaneous Nerve Transfer (Oberlin Transfer) in Neonatal Brachial Plexus Palsy
Brandon W Smith, MD, MS; Nick Chulski, BA; Ann Little, MD; Kate Wan-Chu Chang, MA, MS; Lynda Yang, MD, PHD; University of Michigan, Ann Arbor, MI
Neonatal brachial plexus palsy (NBPP) continues to be a problematic occurrence impacting approximately 1.5 per 1000 live births in the United States, with 10-40% of these infants experiencing permanent disability. These children lose elbow flexion, and one surgical option for recovering elbow flexion is the Oberlin Transfer. Published data supports the use of the ulnar nerve fascicle that innervates the flexor carpi ulnaris as the donor nerve in adults, however, no analogous published data exists in infants. This study investigated the association of ulnar nerve fascicle choice with functional elbow flexion outcome in NBPP.
Our study included a retrospective cohort of 13 infants who underwent ulnar to musculocutaneous nerve transfer for NBPP at a single institution. We collected patient demographics, clinical characteristics, active range of motion (AROM), and intraoperative nerve monitoring (IOM) data (using 4 ulnar nerve index muscles). Standard statistical analysis compared pre- and post-operative motor function improvement between specific fascicle transfer (1-2 muscles for either wrist flexion or hand intrinsics) and non-specific fascicle transfer (>2 muscles for wrist flexion and hand intrinsics) groups. The institutional review board (IRB) approved the study.
The average age at initial clinic visit was 2.9 months old, and the average at surgical intervention was 7.4 months. All NBPP were unilateral; the majority were female (61%), Caucasian (69%) with right-sided NBPP (61%), and Narakas III-IV (54%). IOM recordings for the fascicular dissection revealed a donor fascicle with non-specific innervation in 6 (46%) subjects, the remaining 7 (54%) patients had donor fascicles with IOM recordings specific innervation. At 6-month follow-up, the AROM improvement in elbow flexion in adduction was 38° in specific fascicle transfer versus 36° in non-specific fascicle transfer with no statistically difference (P=0.93). The AROM improvement in supination was 66° in specific fascicle transfer versus 84° in non-specific fascicle transfer with no statistically significant difference (P=0.72).
Our results demonstrate that both specific and non-specific fascicle transfers lead to functional recovery, but that the composition of the donor fascicle had no impact on early outcomes. In infants, ulnar nerve fascicular dissection places the ulnar nerve at risk for iatrogenic damage. Our data suggests that the use of any motor fascicle, specific or non-specific, produces similar results and that the Oberlin transfer can be performed with less intrafascicular dissection, less time of surgical exposure, and less potential for donor site morbidity.
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