Erb's Palsy

The condition known as Erb’s Palsy is caused by an injury to the brachial plexus—the nerves surrounding the shoulder. Erb’s Palsy is not cerebral palsy, because it is not caused by brain injury or brain abnormalities. Erb’s Palsy is also called brachial palsy, Erb-Duchenned paralysis, or Klumpke paralysis.

Distinct Symptoms of Erb’s Palsy

Erb’s Palsy is characterized by weakness or paralysis of the arm. The disorder causes varying amounts of impairment. The levels of impairment are known by some of the other names for the condition. When the upper arm is the only part of the limb affected, the condition is simply called a brachial plexus injury.

The condition is designated Erb’s paralysis when it affects moving the upper arm and rotating the lower arm. If the condition affects the hand it is called Klumpke paralysis; this form of the condition can cause the eyelid to droop on the side opposite to the affected hand.

Causes of Erb’s Palsy

Erb’s palsy is the result of a nerve injury. All the arm’s nerves are connected to a group of nerves near the neck which is called the brachial plexus. The brachial plexus nerves are responsible for feeling and motion in the hand, fingers, and arm. Erb’s palsy can be caused by several things which can happen during a difficult delivery.

Approximately one or two babies per thousand births will have a brachial nerve injury. The brachial nerves can be injured if the baby’s neck and head are drawn to the side when the shoulders exit the birth canal. Pulling excessively on the shoulders as the baby comes out head first can also lead to a brachial nerve injury. During a breech birth (feet first), the arms are usually raised and may be injured from excess pressure.

Improved delivery techniques now prevent many brachial plexus injuries. Larger than average babies are at greater risk for this form of injury; larger than average birth weigh is called macrosomia and is defined as a birth weight of 8 lb, 13 oz or more. A breech birth (the baby presenting abnormally—feet first) also puts the baby at greater risk of injury.

Shoulder Dystocia

Larger than average babies are especially at risk for a problem during delivery called shoulder dystocia. In shoulder dystocia, the infant’s head is delivered normally, but one shoulder becomes stuck under part of the mother’s pelvic bones. This is a difficult situation for doctors to remedy. The mother’s position will be manipulated in an attempt to free the baby’s shoulder and the doctor will also manipulate the baby within the birth canal. If manipulation and gentle pressure fail, surgery may be needed.

Shoulder dystocia is dangerous to both the mother and the baby. A delivery in which shoulder dystocia occurs is most likely to cause injury to the brachial plexus, resulting in impaired movement of the injured arm. Women who are short or who have had gestational diabetes are at greater risk for the occurrence of shoulder dystocia. So are women with pelvic abnormalities. Prolonged labor also increases the risk.

Sometimes shoulder dystocia occurs when it anticipated that delivery will be normal. The only thing physicians can do help prevent injury in an unexpected situation is simply to be always prepared for an emergency during delivery and to have a medical team familiar with difficult deliveries on hand during even routine deliveries.

Use of forceps or a vacuum extractor should be avoided if possible during delivery, because use of these methods increases the risk of shoulder dystocia. In the case of an extra large baby or a delivery which is expected to be breech, the physician should advise the mother and her family of possible problems and what may be needed to safely deliver the baby.

Complications of Erb's Palsy

Most cases of Erb’s palsy are due to stretching of the nerve and will heal within six to twelve months of delivery; stretching shocks the nerve, but rarely leaves permanent damage. Occasionally a stretch injury will cause scar tissue to form around healthy nerves; in this case recovery may not be total.

Cases in which the nerves are torn are the most serious and will not completely heal on their own. In rare instances the nerve is actually torn apart from the spinal cord; this is called an avulsion. It is estimated that fewer than 10% of brachial plexus birth injuries result in permanent paralysis or impairment.

Age of Diagnosis

Because Erb’s palsy is caused by an injury at birth, it is almost immediately apparent. However, the extent of the injury may not be known for some months after the baby’s birth. Babies with Erb’s palsy may lack a Moro reflex on the affected side; the Moro reflex, present in healthy newborns, occurs when the infant is startled. A startled newborn will throw out the arms to the side with the palms up and the thumbs flexed.

A baby with Erb’s palsy may hold the affected arm tight against the body with the elbow flexed. There may be little spontaneous movement of the injured arm or hand. There may also be a lack of strength in the infant’s grip on the affected side. The affected arm may develop more slowly than the healthy arm and may be much smaller.

Treatments for Erb's Palsy

In cases of a simple stretch injury or mild tear, Erb’s palsy will heal on its own, but the baby should receive physical therapy so that the arm does not stiffen. Gentle massage and range of motion therapy are used to keep the muscles strong and the joint from becoming contracted. More extensive nerve damage may require surgery. If the nerves cannot function properly, tendon transplants are sometimes used.

Such options are generally not discussed until the child is three to six months old. Even with surgery, nerve injuries heal very slowly and it may take two years or more for a complete recovery. In some cases, the affected arm will always be weak; the range of motion may also be limited.

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