What is the brachial plexus?
The brachial plexus is a network of five large nerves located between the neck and shoulder. Nerves are cord-like structures of tissue, formed from a collection of nerve fibres. A single nerve may contain thousands of fibres.
The nerves of the brachial plexus leave the spinal cord between the bones in the neck. The brachial plexus nerves travel from the neck, under the collarbone and into the arm. The brachial plexus then divides into individual nerves that travel to different muscles in the arm. The nerves of the brachial plexus are C5, C6, C7, C8 ,T1.
The nerve fibres carry electrical messages from the brain to the muscles and tissues of the arm and hand. For a muscle to work (contract), a message must travel from the brain along a nerve that goes directly to the muscle. The nerves in the brachial plexus are responsible for making the muscles in the arm and hand move and for the skin to feel things.
What is a brachial plexus birth injury?
During a difficult delivery of a baby, the brachial plexus can be injured. In most cases, the nerves in the brachial plexus are only stretched and will fully recover. In other cases, the movement and feeling in a baby’s arm and hand do not fully recover. This happens when the nerves in the brachial plexus are severely stretched and scarred (neuroma), torn apart (ruptured) or pulled out of the spinal cord (root avulsion).
When nerve fibres are damaged, the muscles connected to that nerve may be weakened. Damage to the nerves in the brachial plexus can cause your child’s arm to be weak and stiff.
The brachial plexus may be damaged during birth
Brachial plexus birth injury usually occurs during a difficult childbirth. If the baby is large relative to the mother’s pelvis, their shoulder can become trapped against the mother’s pelvis after delivery of the head. To free the shoulder, the head must be tilted to the opposite side. Tension on the brachial plexus may stretch or pull apart the fibres within one or more nerves. Extra force on the brachial plexus may rupture the nerves completely or pull them out of the spinal cord.
If the brachial plexus is damaged, weakness shows up immediately in the arm. Most brachial plexus injuries are mild and resolve on their own. However, babies who continue to have muscle weakness in their arm need to be referred to a multidisciplinary clinic which includes therapists (e.g., physical and occupational therapists), plastic surgeons, orthopedic surgeons, nurses, and social worker.
When nerve fibres are damaged, the muscles may be weakened
When a brachial plexus injury happens, scar tissue may form at the site of the injury. This scar tissue may prevent electrical messages from getting to the muscles. Damaged nerve fibres located outside the spinal cord (peripheral nerves) may be able to regrow and reconnect to the muscles, which can help to improve muscle function.
A nerve that is completely torn apart or ruptured is not able to completely repair itself. This means that only a small amount of muscle recovery is possible. Ruptured nerves can be surgically repaired, which gives the muscles a better chance to work.
Nerves that have been torn from the spinal cord cannot repair themselves. In this case, other nerves may be surgically connected to allow the muscles to work.
Nerve fibres regrow at a rate of about 1 mm a day or 1 inch a month. It may take many months for these fibres to strengthen the muscles in the arm.
Severity of the brachial plexus palsy
The severity of the injury depends on the number of nerves that are affected and the amount of damage to each nerve.
The more nerves that are affected by the brachial plexus damage, the weaker the arm and hand will be.
The first three nerves of the brachial plexus (C5, C6, C7) are most often involved in a brachial plexus birth injury. Weakness or paralysis of the muscles which are connected to the first two or three nerves is called Erb's palsy. With Erb's palsy, there is often weakness of the shoulder and elbow.
If all five nerves of the brachial plexus are affected, the entire arm and hand will be weak or paralyzed.
If the nerves have been only mildly stretched, your child may recover use of the arm quickly. If the nerves have been more severely stretched or pulled apart, the muscles will take longer to recover and/or will remain weaker.
Learning about your child's brachial plexus palsy
Your child's doctor may need to perform different examinations over time to find out how severe the damage is. Babies with a brachial plexus injury that have difficulty moving or feeling in their arm should be referred to a multidisciplinary team specializing in the management of brachial plexus injuries by 1 month of age. On each visit, the multidisciplinary health-care team will watch how your child moves and plays and observe the movements of your child's arm. These movements will be scored. This will help the team to keep track of how well the nerves are healing.
If the health-care team decides your child could benefit from surgery, your child may need other tests.
Treatment for children with brachial plexus palsy
Time
Most importantly, brachial plexus birth injury needs time to heal. Most nerve and muscle recovery will happen in the first year. You will notice a gradual improvement in both the movement and strength in your child's arm. Further recovery may happen in the second year, but the effects will be more difficult to see.
Physiotherapy
Physiotherapy should be started early in a baby who has brachial plexus birth injury. Physiotherapy can help prevent problems such as joint stiffness and delays in development. It will not help the nerves to heal faster.
The physiotherapist will teach you how to hold and move your baby, as well as teach you the best sleeping positions for your baby. You will also learn exercises to keep your baby's joints flexible and strengthen the muscles that are beginning to recover.
Occupational therapy
Occupational therapists evaluate and treat children with brachial plexus birth injury in order to help them feed, dress and take care of themselves, and participate in school and leisure activities to the best of their abilities. If surgery is being considered in older children, the occupational therapist helps guide the surgeon by defining problems in the use of the arm.
In some children, occupational therapists may provide an orthotic (splint) to help support their joints in a more functional position for play, school activities or sports. An orthotic or cast may also be recommended as treatment for stiffness in the arm. Elbow stiffness is common in children with brachial plexus birth injury.
For more information, please see the article Elbow flexion contracture related to brachial plexus birth injury.
Nerve surgery
In some patients, surgery may be recommended. Babies with brachial plexus birth injury are carefully monitored during the first year of life to record changes in muscle strength. If the muscle fails to strengthen beyond a certain point, and the baby's ability to move and use the arm is also limited, then the surgeon may suggest an operation to find out how severely the nerve is damaged. When the surgeon can observe the brachial plexus directly, they can decide on the best form of treatment. If your baby has an operation on the nerves of the brachial plexus, this will usually be done before your baby is one year old.
For more information, please see the article Brachial plexus operation.
Other types of surgery
Older children who still have movement problems or trouble using the arm may benefit from surgical procedures on the muscles, tendons or bones. Examples include tendon transfers and correction of bone alignment. Your child's surgeon will discuss these procedures with you and your child if they are recommended.
Most children regain good use of their affected arm
During the early months of life, it is hard to predict how your child's arm will heal. If muscle function returns quickly, it is a good sign. Many children regain good use of their affected arm and are able to do most of the activities that they want. Some muscle weakness may remain. In some cases, an injury to the brachial plexus may result in an elbow flexion (bent and stiff elbow).
At SickKids
The Brachial Plexus Clinic at The Hospital for Sick Children is a multidisciplinary clinic designed to assess and treat children with brachial plexus problems.
All patients require a referral to visit the Brachial Plexus Clinic. For more information, please visit: http://www.sickkids.ca/PlasticSurgery/What-we-do/Brachial-Plexus-Palsy/index.html
Coroneos CJ, Voineskos SH, Christakis MK on behalf of The Canadian OBPI Working Group, et al. Obstetrical brachial plexus injury (OBPI): Canada's national clinical practice guideline.
BMJ Open 2017;7:e014141. doi: 10.1136/bmjopen-2016-014141 from https://bmjopen.bmj.com/content/7/1/e014141
