What is a brachial Plexus injury?
The brachial plexus is a network of nerves that conducts signals from the spine to the shoulder, arm, and hand. Brachial plexus injuries are caused by damage to those nerves. Symptoms may include a limp or paralyzed arm, lack of muscle control in the arm, hand, or wrist, and lack of feeling or sensation in the arm or hand. Although injuries can occur at any time, many brachial plexus injuries happen during birth. There are four types of brachial plexus injuries: avulsion, the most severe type, in which the nerve is torn from the spine; rupture, in which the nerve is torn but not at the spinal attachment; neuroma, in which the nerve has tried to heal itself but scar tissue has grown around the injury, putting pressure on the injured nerve and preventing the nerve from conducting signals to the muscles; and neuropraxia or stretch, in which the nerve has been damaged but not torn. Neuropraxia is the most common type of brachial plexus injury.
How does it occur?
The nerves to the arm, hand and fingers exit the spinal cord between the bones (vertebrae) of the neck and travel into the arm below the collarbone (clavicle). The nerves to the arm exit high in the neck; those that go to the hand and fingers exit lower in the neck, just above the chest. These nerves branch and join together near where the neck joins the shoulder, in an area called the brachial plexus.
Brachial plexus injuries in newborns usually occur during a difficult delivery, such as with a large baby, a breech presentation, or a prolonged labor, when the person assisting the delivery must exert some force to pull the baby from the birth canal. One side (sometimes both sides) of the baby's neck gets stretched; which can damage the nerves by stretching or tearing them. If the upper nerves are affected, the condition is called Erb's Palsy. The infant may not be able to move the arm, but may be able to move the fingers. Injuries that involve both the upper and lower nerves are more severe and result in a condition called global palsy.
There are four types of nerve injuries to the brachial plexus.
- Avulsion injuries- The nerve is torn from its attachment to the spinal cord. This is the most serious type of injury.
- Rupture injuries- The nerve is torn, but not at the spinal cord.
- Neuroma injuries- These injuries result from scar tissue that forms and puts pressure on the nerve.
- Stretch injuries- These injuries, known as neurapraxia (new-rah-PRAK-see-ah) are the most common. The nerve is damaged but not torn. Normally, these injuries heal spontaneously; usually within three months.
The symptoms of a nerve injury (paralysis and loss of feeling) are the same, regardless of the type of injury. However, the severity of the injury does affect both treatment decisions and the extent of recovery possible. A newborn with Erb’s Palsy will have the arm straight down at the side and will not move it. Sometimes, the arm may be slightly turned, with a bent wrist and straight fingers. A droopy eyelid on the affected side may indicate a more severe injury. The doctor may order an X-ray or magnetic resonance image (MRI) to see if there is any damage to the bones and joints of the neck and shoulder. The doctor may also use an electromyogram (EMG) or nerve conduction studies (NCS) to see if any nerve signals are present in the upper arm muscle.
Because some newborns with Erb's Palsy recover without surgery, your baby will be examined again at one month and at three months to see if the nerves are recovering by themselves. Even children who seem to fully recover by this time may experience difficulties in the future. During this time, range of motion exercises must be performed and are very important in keeping the baby's joints from getting stiff and developing joint contractures.