What is brachial plexus palsy?
The brachial plexus is a series of nerves that run from your neck into your arm. It controls all movement and sensation, and when you have an injury, or a palsy, to it, those nerves are either stretched or torn. The best way to think about it is to know that there are a series of five cords that run from your spinal cord down into your arm. Each is like a thick cable with about 10,000 nerve fibers within it, so it’s almost like a cable that runs into your house. The top two cables control shoulder motion and bend the arm. The middle one controls the ability to straighten the fingers and elbow, and the bottom ones go to the hand. When there is a brachial plexus injury, the nerves are stretched like small pieces of taffy. When they are stretched a little bit, they come back easily. When they are stretched more, they can actually tear apart.
Who is at high risk to have injury to the brachial plexus? It is often a birth injury, correct?
What’s interesting about brachial plexus injuries themselves is they all occur in a similar way, whether the baby is coming through the birth canal, whether the guy rides his motorcycle into a tree, or whether the football player spears the opponent. Usually, the head goes one way and the shoulder goes the other way, and that mechanism in itself stretches the nerves. It’s exactly the same in the birthing process as the baby comes through the canal.
How common are these injuries in newborns?
It’s 0.5 percent of all births. That doesn’t sound very common, but there are a lot of births each year so there are a fair amount of kids who suffer this injury. We see over 200 kids each year with brachial plexus injuries, and the majority of them are birth palsies.
If it’s a birth injury, what are some of the options that parents have to treat their children?
Fortunately, about two-thirds of brachial plexus birth palsies are stretch injuries. If the nerves are just stretched a little bit, early therapy can keep all the joints and movement supple, and then the nerves regenerate on their own. The other one-third of the injuries are obviously more severe, and that cable with those 10,000 fibers has part of the fibers within it, or in severe cases all of them, torn. Obviously, if the nerves are pulled apart in their entirety, nerve surgery is the primary option to place the nerves back together.
For the patients who do not have a full recovery, what are their physical constraints?
Of those one-third of patients who do not improve, the most common lack of motion is over-the-head shoulder motion and external rotation, and by positioning their shoulder in internal rotation that drives the ball out of the socket. Those are the patients who would benefit from arthroscopic reduction of the shoulder joint and tendon transfers to augment their motion and allow them to return to normal activity.
When a child experiences injury to these nerves, what are his or her long-term risks?
There are two problems. Number one is if the ball is not in the socket, it can not work normally so you can’t get full range of motion. Second is we know from imaging of other children as they have gotten older that the socket and the ball degenerate over time if the ball is not in the socket. That holds true for the shoulder as it does for the hip.