Brachial palsy is a loss of movement or weakness of the arm caused by damage to the collection of nerves around the shoulder. This bundle of nerves is called the brachial plexus.

Brachial nerve injuries can occur during a difficult delivery. For example, it can occur if the infant's head and neck are pulled toward the side as the shoulders pass through the birth canal.

The condition can also be caused by excessive pulling on the shoulders during a head first delivery or by pressure on the raised arms during a breech (feet first) delivery.

There are different forms of brachial palsy in an infant. The type depends on the degree of arm paralysis:

• Brachial plexus injuries typically affect only the upper arm.
• Erb's paralysis affects the upper arm and rotation of the lower arm.
• Klumpke paralysis affects the hand. Tthe infant may also have an eyelid droop on the opposite side.

The following increase the risk of brachial palsy:

• Breech delivery
• Larger than average newborn
• Shoulder dystocia

Symptoms are noticed immediately or soon after birth, and may include:

• Absent Moro reflex on the affected side
• Arm flexed at elbow and held against body
• Decreased grip on the affected side
• Lack of spontaneous movement in the upper or lower arm or hand

A physical exam of the infant may show that the Moro reflex is absent on the affected side. This reflex will usually be present in an infant with weakness or pseudoparalysis, although it might not be as noticeable on the affected side. (In pseudoparalysis, the infant has a fracture and is not moving the arm because of pain.)

The affected arm may flop when the infant is rolled side to side.