Infant Brachial Plexus Injuries: When to Refer Immediately and When to Wait

Apurva S. Shah, MD, MBA

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April 30, 2019

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Management: What's on the Horizon?

Let's now talk about the older infant—a 3-month-old—with persistent evidence of injury. Are there newer therapy strategies or anything on the horizon that has improved outcome?

Let me first define what I mean by the child with incomplete recovery at 3 months of age. Not all of those kids go on to need surgical intervention. In fact, even then it's still the minority of the children that need surgical intervention. Many kids make a very good, though not full, spontaneous recovery. Children with the most severe injuries, where the nerve has been avulsed off the spinal cord or torn, go on to need surgery. But all will benefit from continued comprehensive physical therapy.

There have been several game-changing developments in the management of these children. I want to focus initially on kids who have a less severe injury.

Kids who have less severe injuries usually start to show signs of a spontaneous recovery early. Maybe they are not in that group that recovers their elbow flexion before 2 months of age; maybe they recover their elbow flexion at 3, 5, or 6 months of age. That's a sign that they're not going to make a full recovery, even though they've started to make a partial recovery.

Many of these children never fully recover their shoulder strength. In part, there is some level of permanent or significantly delayed recovery in function of the rotator cuff muscles, specifically the supraspinatus and the infraspinatus on the superior and posterior aspects of the rotator cuff. Although those are small muscles deep to the deltoid, they have a pretty profound impact on how the shoulder joint develops in an infant. Those muscles are not working properly when the muscles in the front of the shoulder, the pectoralis major and the subscapularis, are working relatively well, creating an imbalance in the muscle forces around the shoulder. This in turns seems to cause dysplasia of the shoulder joint.

There's been recent evidence to suggest that children can go on to a shoulder dislocation in infancy, as early as 3 or 4 months of age. A study published in 2017 suggested that limited shoulder external rotation can be a marker of shoulder dislocation.[2] You should be able to externally rotate a baby's shoulder with the arm at the side beyond 60°. If you cannot, that is an indication that ultrasound of the shoulder should be obtained for further assessment.

Figure 2. A. Ultrasound image showing the normal glenohumeral (shoulder) joint with a reduced humeral head. B. Ultrasound image showing a dislocated glenohumeral joint with posterior dislocation of the humeral head and retroversion of the glenoid.

One of the advances over the past 5-10 years in treatment of these shoulder imbalances is use of botulinum toxin. At CHOP, we treat kids who are developing progressive subluxation or dislocation of the shoulder during infancy with a botulinum injection of the pectoralis major muscle, the subscapularis muscle, and the teres major muscle. This temporarily weakens those three muscles to restore balance to the muscle forces around the shoulder, allowing the orthopedic surgeon to relocate the shoulder joint with manipulation and then cast the child in an externally rotated position in a shoulder spica cast for approximately 1 month. The cast is then removed and therapy reinitiated. In our experience, this has allowed the shoulder joint to develop more normally in about 60% or 70% of children, preventing the need for future surgery. That has been a really significant advance for kids who have a more mild injury. They've recovered a lot of their neurologic function, but there are still some areas that are weak, including the rotator cuff muscles that we discussed.

Should the degree of external rotation of the shoulder be assessed in the general pediatric setting? Or is that exam something that would be conducted by the brachial plexus team?

I think assessment should be left in the hands of a brachial plexus provider at the moment. But it's an evolving area. Much in the way that a pediatrician is expected to assess for development dysplasia of the hip, over time the pediatrician might be asked to understand the basics of shoulder stability in an infant. This exam for external rotation of the shoulder is a succinct examination that can be conducted by the pediatrician. With the arm at the side, can you rotate the shoulder to 60° or beyond? If you can, that child is very unlikely to have a shoulder dislocation. If you can't, then that child certainly needs a timely referral.

Shoulder dislocations don't typically happen until babies are 3 months of age or more. Because we usually recommend a referral by 1 month of age for a child who hasn't made a full recovery, they are hopefully already under the care of a provider who would be able to detect the shoulder dislocation. Shoulder dislocations can present pretty much like those of the hip—that is, without a precipitating traumatic event beyond birth and without pain.

One of the things that a therapist will work on is shoulder external rotation stretching to try to prevent dislocation. In my experience, a lot of parents notice a little bit of discomfort while doing those stretches, but it's not like a traumatic dislocation in an adolescent or adult, which would be immediately sore and painful. This can be completely asymptomatic, unless you're really doing deep stretches of the shoulder. It could be completely silent, other than progressive stiffness in the shoulder that the parents notice while dressing the baby or the provider notices when doing these external rotation stretches.

What is on the horizon for management of children with global injuries?

Children who have global injuries involving the entire brachial plexus, maybe with Horner syndrome, or kids who have a more isolated injury to the upper trunk or the upper-middle trunk and are not recovering by 6 months of age may be considered for reconstruction of the brachial plexus with surgery. Reconstruction can be in the form of nerve grafting or nerve transfers. Surgeons are moving more and more toward nerve transfers.

Conceptually, nerve transfers, which use functioning nerves either on the chest wall or in the neck or arm to swing over to nonfunctioning nerves, potentially allow quicker reinnervation of muscles and may be a more reliable method for recovery of neurologic function. They don't allow recovery of sensibility or sensation, which is a real downside compared with nerve grafting. Nerve transfer has changed armamentarium of the surgeon, but it still requires a lot of careful thought to decide the best treatment strategy (nerve transfer versus nerve grafting) for any particular child.

The brachial plexus program at CHOP, as I think is the case at many of the best centers, is multidisciplinary. It involves orthopedic surgery; neurosurgery; plastic surgery; therapy (as we've discussed); and often a diagnostic component, such as neurology. Management of brachial plexus injuries in children, which is substantially different from management of these injuries in older children or adults, really is more dependent on the expertise of the surgeon than on that surgeon's exact surgical discipline. I think in part because the field has been multidisciplinary, it has evolved very quickly, because research is occurring in multiple surgical disciplines.

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