Erb's Palsy (Brachial Plexus Birth Palsy)
What is the Brachial Plexus?
The brachial plexus is a network of nerves that originates at the spinal cord near the neck and passes down your upper arm from under your collarbone. It consists of 5 nerve roots:
- Nerve roots from the lower cervical segment of the spinal cord known as C5, C6, C7 and C8
- Nerve root from the first thoracic spinal cord segment known as T1
These nerves join to form the upper, middle and lower trunks of the brachial plexus, which split into nerves that supply your upper limbs, controlling your shoulder, elbow, wrist and hand.
What is Brachial Plexus Birth Palsy?
Erb's palsy or brachial plexus palsy is an injury to any part of the nerves of the brachial plexus, which can stop signals to and from the brain and may partially or completely paralyze your arms.
What is Erb's Palsy?
Obstetric brachial plexus injury includes Erb's palsy, which affects the upper brachial plexus nerves, C5, C6 and sometimes C7, and disrupts functions of the shoulder and elbow muscles. This is the most common pattern of brachial plexus injury in infants
Types of Brachial Plexus Birth Palsy
The types of brachial plexus injuries that may occur in infants include:
- Neurapraxia : The nerves are stretched, but their internal architecture is maintained. With time, they are likely to recover more or less completely.
- Axonotemesis : The nerves are stretched, and their internal structure is partially damaged with the outer sheath still intact. Such nerves are likely to recover over time, to a greater or lesser extent, depending on the magnitude of damage.
- Rupture : nerves stretch to a point where they tear at a region some distance from their origination from the spinal cord.
- Avulsion : the nerve roots are torn completely out from the spinal cord.
Causes of Erb's Palsy/Brachial Plexus Birth Palsy
Injury to the brachial plexus can occur during the birthing process when the baby's shoulder gets lodged in the birth canal, requiring external force for the baby to be delivered. This force can stretch or tear the nerves of the brachial plexus. This type of injury is commonly seen during a complicated delivery or in larger than average babies born to diabetic mothers.
Other causes for brachial plexus injury in babies include:
- Extended period of labor
- Breech presentation: baby positioned with feet or buttocks near the vaginal opening
- Mothers with a small birth canal
Signs and Symptoms of Erb's Palsy/Brachial Plexus Birth Palsy
You may be able to observe the symptoms of injury in your child immediately after birth. Common symptoms include:
- • Limp arm and loss of flexion in elbows
- • Inability to move or rotate the arm from the shoulder
- • Inability to move fingers, or decreased grip strength on the affected side
Subsequent Course of Erb's Palsy/Brachial Plexus Birth Palsy
As mentioned above, the injury to nerves is incomplete in majority of cases. Thus, in about three-fourths of cases, there is complete or near-complete recovery of function over a period of months.
During the process of recovery or nerve regeneration, some nerves may get misdirected or cross-innervate. This causes opposing groups of muscles to contract and is called co-contractions. Uncoordinated muscle recovery may cause muscle imbalance. Co-contractions and muscle imbalance together can lead to contracture (rigidity) of muscles and joints, ultimately causing shoulder and elbow deformities.
Diagnosis of Erb's Palsy/Brachial Plexus Birth Palsy
When your child presents with symptoms of Erb's palsy brachial plexus injury, the pediatrician will first take your child's medical history, conduct a physical examination and order tests to diagnose Erb's or birth palsy. Physical examination will help the doctor identify the limited movement and range of motion of the upper extremity.
Imaging tests such as X-rays, CT and MRI may be ordered to detect damage to the bones, joints or nerves. Electromyography may be ordered to evaluate the muscle response of your child's injured arm.
Nerve conduction studies may also be ordered to determine the speed of the nerve impulses, i.e., the time taken for impulses to pass between two electrodes placed apart on your child's arm.
Treatments for Erb's Palsy/Brachial Plexus Birth Palsy
Most obstetric brachial plexus injuries heal or recover on their own by the age of 3-12 months. During this time, your doctor will regularly monitor your child.
Physical therapy may be recommended to maximize the use of your child's affected arm. Your child's physical therapist will educate you on range of motion exercises to be performed on your baby to improve the functioning of the shoulder, elbow, wrist and hand, and avoid joint stiffness.
In infants with mild obstetrical brachial plexus injury of the C5 or C6 nerves, 80% generally recover spontaneously and do not require surgery. Recovery depends on the type and severity of nerve injury.
Nerve Surgery for Erb's Palsy/Brachial Plexus Birth Palsy
Your doctor may consider Gilbert's criteria to indicate a requirement for surgery. This criteria states that when the injury fails to recover, surgery should be indicated at 3 months in infants with Erb's palsy.
Surgery performed within the first six months of life yields the best results. Injuries involving rupture or avulsion may require microsurgical intervention that includes a nerve graft or nerve transfer. Several surgical options are available, depending on your child's condition:
- Nerve graft surgery involves replacing the damaged section of the nerve with a nerve section removed from another part of the body.
- Neurotization or nerve transfer surgery is performed to connect the lower end of the damaged nerve to a less important upper end of an intact nerve from the spinal cord.
- Musculo-skeletal surgery is performed in older children (above 2 years) who have had partial recovery from the nerve injury.
- Contracture release is performed in some children who develop tightness of the shoulder joint because of decreased mobility.
- Muscle or tendon transfer surgery may be necessary if the arm muscles have deteriorated. This involves transfer of a muscle or tendon from another part of your body to the damaged part of your arm.
- Capsulorraphy surgery can be performed to place the head of the humerus, the bone of the upper arm, back into the shoulder joint in order to treat shoulder dislocation or joint instability caused by muscle weakness.
- Osteotomy involves cutting the bones of the upper arm or forearm and reorienting them in a better position.
Risks and Complications of Erb's Palsy Surgery
As with any surgery, there can be certain risks and complications involved. Associated risks of nerve reconstruction surgery may include:
- Tingling and weakness to the upper extremity
- Failure to improve
Prognosis of Erb's Palsy/Brachial Plexus Birth Palsy
Prognosis depends on the type of brachial plexus injury sustained and if associated fractures to the ribs, shoulders or arms are present. Mild injury to the brachial plexus may resolve within 3 to 6 months, whereas severe injuries may require treatment for over a year and regular follow-ups. Prognosis is best when treatment is started within 4 weeks of birth.