What is Erb’s Palsy?

Erb's Palsy or Brachial Plexus Birth Palsy is a form of obstetric brachial plexus injury, which is a complication of pregnancy and delivery.  A network of spinal nerves that transmit signals from the spine to the shoulder, arm, and hand is called the brachial plexus.  Brachial refers to the arm, and plexus refers to a network of nerves.  Paralysis or weakness of the muscles of the arm that is caused by damage to the brachial plexus is called Erb’s palsy.  The paralysis can affect any or all of the muscles that control the shoulders, hands, or the arms.  Erb-Duchenne palsy affects muscles around the shoulder and elbow and causes paralysis of the upper brachial plexus.  Klumpke’s palsy affects muscles of the forearm and hand and causes paralysis of the lower brachial plexus.  The severity and ultimate diagnosis of Erb’s palsy is dependent on the location and severity of the injury.

Anatomy of the Brachial Plexus

The brachial plexus consists of a network of spinal nerves, which originate in the area behind the neck and extend under the collarbone through the armpit, giving rise to nerves to the upper arm that are responsible for sensation and movement of the upper arm.  The brachial plexus is formed by the unification of sections of the fifth, sixth, seventh, eighth cervical nerves, and the first thoracic nerve.  All these nerves arise from the spinal cord.  Injuries to the upper brachial plexus involve the fifth and sixth cranial nerves, and injuries to the lower brachial plexus involve the seventh and eight cranial nerves, and the first thoracic nerve.

Neuropathology of Erb’s Palsy

The injury is generally where nerve roots form the trunks of the brachial plexus.  Erb’s palsy is caused by a lesion at Erb’s point where the fifth and sixth cranial nerves unite to form the upper trunk of the brachial plexus.  Severity of the brachial plexus injury can range from minimal to intermediary to severe and cause permanent injury. For more on this please check signs and symptoms.

Other Names and Variations of Erb's Palsy

Erb’s Palsy is known by several other names, which are used interchangeably by health care providers and patients. As a definition, paralysis or weakness of the muscles of the arm that is caused by damage to the brachial plexus is referred to as Erb’s palsy.

Erb-Duchenne Palsy

Affects muscles around the shoulder and elbow, which may result in paralysis of the upper brachial plexus.
Klumpke’s palsy affects muscles of the forearm and hand, causing paralysis of the lower brachial plexus. The severity of Erb’s palsy is dependent on the location and severity of the injury.

Shoulder Dystocia

This is an obstetric emergency, which can result in fetal demise if not managed properly. After the delivery of the infant’s head, the anterior shoulder is unable to pass below the pubic bone requiring significant maneuvering to pass below the pubic bone. The maneuver may result in brachial plexus injury due to the difficult birth of the baby.

Erb’s Palsy or Waiter’s Tip

This term is used to describe the arm hanging at the side with the elbow extended and the forearm pronated. There is loss of shoulder abduction, external rotation, and elbow flexion.

Radial Nerve Palsy

Affects wrist extension. It affects the radial nerve, which begins in the upper arm, runs down to the wrist, and fingers. It controls the movement and sensation of the hand and arm. In some cases, the symptoms may go away on its own.