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

Apurva S. Shah, MD, MBA


April 30, 2019

Editorial Collaboration

Medscape &

Injury Severity

Has there been any change in the percentage of injuries that are severe enough to require intervention?

I don't think that anyone knows the answer. Anecdotally, I haven't really seen a substantial change in injury severity in my own practice over the past 10 years. However, it is possible that not only the incidence, but also the injury severity, has decreased. That is a question that has yet to be answered. I would still say that we're seeing patients on all points of the spectrum. We have many children—I would estimate 80%—with mild injuries who go on to have a spontaneous recovery. However, there is a substantial minority of patients, approximately 20%, who do not have a full recovery.

Can children who will fall into that 20% category with more significant injury be determined at the time of birth?

No, this can't always be determined at the time of birth. Not all brachial plexus injuries in newborns are created equal. The brachial plexus has five nerve roots that weave together and then apart, forming a network of nerves that run from the spinal cord under the clavicle and then into the shoulder and the arm. That collection of five nerve roots combine to provide the motor function and sensory function of the hand and the arm. The majority of injuries result in Erb palsy (approximately 50%), which occurs in the upper trunk and affects the upper two nerve roots, C5 and C6. A smaller percentage of injuries involve C5 through C7 (approximately 30%), and these are often referred to as "extended Erb palsy." The minority of patients have a global injury involving the entire brachial plexus.

To some degree, the extent of the brachial plexus that's involved at the time of the initial injury provides some prognostic information. Approximately 85%-90% of children with Erb palsy go on to have a full spontaneous recovery. However, when you start to involve additional nerve roots, such as is seen in extended Erb palsy, only approximately 60% of those infants will have a full recovery. With global injury, only a minority of patients go on to a full recovery. So, the number of nerve roots involved, which we can determine at the time of birth, does have some impact on recovery, but is not always predictive. There are infants with Erb palsy who ultimately require surgical reconstruction, but they cannot always be identified at birth.

One predictor of severity is the presence of Horner syndrome, which is the constellation of signs and symptoms that are seen with injury to the sympathetic chain and can occur at the same time the brachial plexus is injured. Babies with Horner syndrome might present with ptosis (dropping eyelid) and miosis (constriction of the pupil) on the side of the affected arm. When there is Horner syndrome, we're often concerned that the nerve root has not only been stretched at the time of delivery, but actually torn or avulsed off of the spinal cord, which is a type of injury that we wouldn't expect to spontaneously recover.

Would a particularly traumatic delivery result in that severe of an injury?

That's a great question. No one perfectly knows the answer to this important question. Part of the reason we were interested in exploring the epidemiology of these injuries is that brachial plexus injuries are surrounded by a high rate of litigation, which can have a huge psychological impact on a family and a child. A question that can arise during litigation is whether or not the force or the difficulty of the delivery is responsible for the severity of the injury.

One of the issues that we looked at in our epidemiology study was infant hypoxia at the time of delivery. We asked whether infant hypoxia affects the risk for a brachial plexus injury and found that the answer was "yes."

So, I would speculate that there's probably multiple factors going on—not only the quality of the delivery, but also perhaps the setting and the stress to the overall infant at the time of delivery. If a baby is hypoxic, maybe there's dampened muscle tone or muscle reflex arc, and that doesn't allow a baby to protect himself or herself during the delivery process.