Bracial Plexus Injuries

Brachial Plexus: What Is It?

Brachial Plexus illustration

The brachial plexus is made up of five nerves, which are fibers that carry electrical messages from the brain to the muscles.

The brachial plexus nerves start in the spinal cord and branch out from the neck to the muscles and tissues down the arms. These nerves provide movement and feeling to the shoulders, arms, and hands.

What Causes a Brachial Plexus Injury?

Doctors assist a patient with a brachial plexus injuryA difficult delivery is the most common cause of brachial plexus lesions in infants. During birth, if the baby was large and his or her head was tilted to allow the shoulders to pass, an injury to the brachial plexus may occur.

However, the nerve fibers can become injured or bruised as a result of any force or pulling. This causes the muscles that are stimulated by those nerves to weaken or become nonfunctional. Nerves typically repair themselves at a rate of about 1 mm per day or 1 inch per month, but this process can take many months. Sometimes, if the nerve has been severed, it cannot repair itself and the muscle will not work.

What Determines the Severity and Outcomes of Brachial Plexus Injury?

Doctors assist a child with a brachial plexus injury.

How severe a brachial plexus injury is depends on two things:

  • the number of nerves affected
  • the amount of injury to the nerve

Although five nerves make up the brachial plexus, in many instances, the first two are the ones that are injured. When this occurs, the muscles stimulated by these nerves become weak or paralyzed, resulting in a condition called Erb's palsy. If all of the nerve roots are affected, then the arm becomes completely paralyzed.

A doctor assists an infant with a brachial plexus injury.

If the nerve has been stretched slightly and the bruise is mild, often it will heal completely and your child will regain the use of the muscle quickly. When multiple nerves are stretched or pulled, they may not regenerate and a scar may result. When this happens, the muscle becomes very weak, resulting in ongoing paralysis and a longer recovery.

It's difficult to predict whether there will be long-term effects to the arm. If the return of function is rapid, this usually is a good sign. Typically, most recovery of muscle strength occurs in the first year of life. Ultimately, most children are able to use their arms and hands to function in daily life. However, some residual weakness may remain.

View the Brachial Plexus Clinic Brochure (PDF).