Erb's Palsy, also known as Brachial Plexus Paralysis is a condition which mainly due to birth trauma, can affect 1 or all of the 5 primary nerves that supply the movement and feeling to an arm. The paralysis can be partial or complete; the damage to each nerve can range from bruising to tearing. Some babies recover on their own; however, some may require specialist intervention.

References

Erb's Palsy Group NINDS