The condition can also be caused by excessive pulling on the shoulders during a vertex delivery (head first).
The injury often leaves patients with stunted growth in the affected arm with everything from the shoulder though to the fingertips smaller than the unaffected arm. This also leaves the patients with impaired muscular, nervous and circulatory development. The lack of muscular development leads to the arm being much weaker than the unaffected one, and less articulate, with many patients unable to lift the arm above shoulder height unaided, as well as leaving many with an elbow contracture.
The lack of development to the circulatory system can leave the arm with almost no ability to regulate its temperature, which often proves problematic during winter months when it would need to be closely monitored to ensure that the temperature of the arm was not dropping too far below that of the rest of the body. However the damage to the circulatory system also leaves the arm with another problem. It reduces the healing ability of the skin, so that skin damage takes far longer than usual to heal, and infections in the arm can be quite common if cuts are not sterlised as soon as possible. This will often cause many problems for children since they often injure themselves in the course of their childhoods.
The nervous damage is often the most problematic of the side effects to Erb's Pasly, but it is also the most varying. There have been cases of patients who have lost complete sensory perception within the arm after procedures whereas they had full sensory perception before. The most common area for a loss of sensory perception (except where the arm faces a total loss) is that between the shoulder and the elbow since the nerves which provide information from that area to the brain are also those first damaged in the initial causative trauma.
Neonatal / pediatric neurosurgery is often required for avulsion fracture repair. Lesions may heal over time and function return. Physiotherapeutic care is often required to regain muscle usage.
Although range of motion is recovered in many children under one year in age, individuals who have not yet healed after this point will rarely gain full function in their arm and may develop arthritis.
The three most common treatments from Erb's Palsy are: Nerve transfers (usually from the opposite leg), Sub Scapularis releases and Latissimus Dorsi Tendon Transfers.
The nerve transplants are usually performed on babies under the age of 9 months since the fast development of younger babies increases the effectiveness of the prodedure.They are not usually carried out on patients older than this because, although small babies nerves can recover to an extent, when the procedure is done on older infants, more harm than good is done and can result in nerve damage in the area where the nerves were taken from. Scarring can vary from faint scars along the lines of the neck to full "T" shapes across the whole shoulder depending on the training of the surgeon and the nature of the transplant.
Subscapularis releases, however, are not time limited. Since it is merely cutting a "Z" shape into the subscapularis muscle to provide stretch within the arm, it can be carried out at almost any age and can be carried out repeatedly on the same arm, however this will compromise the integrity on the muscle.
The Latissimus Dorsi Tendon Transfers involve cutting the Latissimus Dorsi in half horizontally in order to 'pull' part of the muscle around and attach it to the outside of the biceps. This procedure provides external rotation to varying degrees of success. A side effect of this may be increased sensitivity on the part of the biceps where the muscle will now lie since the Latissimus Dorsi has roughly twice the amount of nerve endings per square inch than other muscles.
The renowned British obstetrician William Smellie is credited with the first medical description of an obstetric brachial plexus palsy. In his 1768 treatise on midwifery, he reported a case of transient bilateral arm paralysis in a newborn after difficult labour.
In 1861, Guillaume Benjamin Amand Duchenne coined the term "obstetric palsy of the brachial plexus" after analyzing 4 infants with paralysis of identical muscles in the arm and shoulder, after publishing his initial findings in 1855. In 1874, Wilhelm Heinrich Erb concluded in his thesis on adult brachial plexus injuries that associated palsies of the deltoid, biceps and subscapularis are derived from a radicular lesion at the level of C5 and C6 rather than isolated peripheral nerve lesions.
Notable individuals afflicted by Erb's palsy were Wilhelm II of Germany, Joseph Stalin, Queen Victoria of Britain, and Canadian journalist Barbara Frum. Martin Sheen was injured during birth and developed the condition in his left arm. His difference in arm length and range of motion can be seen in his movies, especially Apocalypse Now. Another sufferer is British singer-songwriter and artist, Matt Parsons.