Amyotrophy is a descriptive term for muscle wastage and neuralgia refers to pain in the nerves. In the specific condition called neuralgic amyotrophy, those affected experience both these symptoms in the arms and shoulder area of the body. Paralysis is also a feature of this rare disease, but as the condition occurs in individual flare-ups, the symptoms often resolve over time. Although some people have specific genes that cause the disease, other cases have no known cause, as of 2011.
Neuralgic amyotrophy is also known as brachial neuritis,or Parsonage-Turner syndrome. A typical patient suffering from the condition first experiences severe pain in one shoulder. The muscles of the affected area then become weaker and appear wasted, and the patient becomes unable to move the muscles. The paralysis appears to be due to damage to the nerves that,in healthy people, instruct the muscles to move. The nerves that send sensation information to the brain can also be affected, and some patients experience numbness or abnormal feelings like tingling in the affected area.
The condition occurs in distinct episodes. People who have neuralgic amyotrophy because of genetics tend to have the first episode when they are between twenty and thirty years of age, but some people are younger. Patients who produce neuralgic amyotrophy symptoms later in life are more likely to have the form of the disease that scientists have not yet found a cause for. Typically, an episode strikes quickly, but the patient may take years to get better. As time goes by, and more episodes occur, a patient may suffer damage to the area and feel some chronic pain.
One possible explanation for the symptoms of the condition is that the body's own immune system causes the problems. This type of disease is called an autoimmune disease, where the molecules of the immune system attack healthy cells inadvertently. It is possible that autoimmune reactions can specifically damage the nerves of the shoulders and arms, and therefore result in wastage and paralysis, as well as pain. This concept of the immune component of the condition means that corticosteroids, which interact with the immune system, are one possible avenue of alleviation, although as of 2011, no effective treatment or cure exists.
A genetic cause has been identified for some people. This is a mutation in a gene called SEPT9. In healthy people, SEPT9 contains the instructions for the body to make a molecule called septin-9. If a person has one or more copies of SEPT9 that make a different form of septin-9, then that person can develop neuralgic amyotrophy. The exact manner in which abnormal forms of septin-9 cause the symptoms of the disease remains under ivestigation.