Symptoms:

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

Signs and tests:

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.