Following obstetrical brachial plexus injury, infants are unable to learn specific patterns of movement due to the disruption of neural pathways. Even with successful reinnervation (spontaneously or post surgical reconstruction), function can be suboptimal due to overactivity in antagonist muscles preventing movement of reinnervated muscles. Botulinum toxin type A (BTX‐A) was used to temporarily weaken antagonistic muscles early in the reinnervation process following brachial plexus injury, with the aim of facilitating functional improvement. A case series of eight children (five females, three males; mean age 12.5mo [SD 6.43]; range 5–22mo) with significant muscle imbalances but evidence of reinnervation were given BTX‐A injections into the triceps, pectoralis major, and/or latissimus dorsi muscles. After a single injection, all parents reported improvement in function. Active Movement Scale total score changed significantly between pre BTX‐A and 1 month (p=0.014), and 4 months (p=0.022) post BTX‐A injection. It is proposed that BTX‐A facilitated motor learning through improved voluntary relaxation of antagonist muscles while allowing increased activity in reinnervated muscles.

Object In the literature, the best recommendations are imprecise as to the timing and selection of infants with obstetrical brachial plexus injury (OBPI) for surgical intervention. There is a gray zone (GZ) in which the decision as to the benefits and risks of surgery versus no surgery is not clear. The authors propose to describe this category, and they have developed a guideline to assist surgical decision-making within this GZ. Methods The authors first performed a critical review of the medical literature to determine the existence of a GZ in other clinical publications. In those reports, 47–89% of infants with OBPI fell within such a GZ. Complete recovery in those reported patients ranged from 9 to 59%. Using a prospective inception cohort design, all infants referred to the OBPI Clinic at McMaster Children's Hospital were systematically evaluated up to 3 years of age. The Active Movement Scale scores were compared for surgical and nonsurgical groups of infants in the GZ to identify any important trends that would guide surgical decision-making. Results In the authors' population of infants with OBPI, 81% fell within the GZ, of whom 44% achieved complete recovery. Mean scores differed significantly between surgery and no surgery groups in terms of total Active Movement Scale score and shoulder abduction and flexion at 6 months. Elbow flexion and external rotation differed at 3 months. Conclusions There is compelling evidence that there is a group of infants with OBPI in whom the assessment of the risk/benefit ratio for surgical versus nonsurgical treatment is not evident. These infants reside within what the authors have called the GZ. Based on their results, a guideline was derived to assist clinicians working with infants with OBPI to navigate the GZ.

Obstetrical brachial plexus injury significantly affects the length of the arm and forearm. Early detectable limb length deficits are associated with the likelihood of requiring surgical reconstruction. Clinical limb length measurement can be performed reliably and noninvasively.

This is the first human study confirming growth discrepancy of an elbow flexor in EFC. Distinct biceps morphology is demonstrated, with a significantly shorter muscle belly and overall length, but longer tendon vs normal. This is termed the "Popeye muscle" for its irregular morphology. Findings are consistent with impaired limb growth in denervation.