Traumatic Brachial Plexus Injury
When nerves that exit the cervical spine and pass down to the shoulder and arm are damaged, pain, numbness, and weakness in the shoulder, arm, and hand can occur.

Birth Brachial Plexus Injury
Nerves between the spine and the shoulder can be stretched and damaged during childbirth, possibly resulting in limb paralysis, which may be permanent.

Brachial Plexitis (Parsonage Turner Syndrome)
Bodily stress (e.g., surgery, flu, unusually excessive exercise) can cause the nerves in your neck or arm to become inflamed, a painful condition which limits use of the arm.

Shoulder Weakness after Surgery
Secondary to stretching or direct surgical irritation of the nerves that control shoulder function, patients may occasionally have shoulder paralysis after surgery.