Neuralgic amyotrophy

Neuralgic amyotrophy is a rare condition with which sharp pains suddenly occur in the arm. They typically begin at the shoulder joint, then radiate out to the upper arm and neck, and in the end affect the entire arm down to the hand. Muscle weakness and paralysis of some muscle groups may also occur. Usually only one arm or shoulder is affected, and usually on the right side of the body.

It is assumed that neuralgic amyotrophy is linked to an inflammation of the “brachial plexus”, a network of nerves at the junction of the neck and upper body. Why this inflammation occurs is still unclear.

Many people with neuralgic amyotrophy have long-term pain. The symptoms can be treated with drugs.

Typical are shooting, severe pains occurring in the evening or at night in the shoulder joint. The pains last for days or weeks. Over time they spread to the neck, the entire arm and the hands. Some muscles in the affected area relax, degenerate or show signs of paralysis. 

Most people with neuralgic amyotrophy are only affected on one side of the body, though around one-third have pain in both arms.

Less commonly, other areas of the upper body hurt too, for example the chest muscles or the areas around the shoulder blade or collarbone.

There are two types of neuralgic amyotrophy: hereditary and idiopathic (no known cause).

With hereditary neuralgic amyotrophy, parents pass on a particular genetic mutation to their children that makes them more prone to the condition.

In most people with neuralgic amyotrophy the cause is unclear. All that is known is that the disorder is accompanied by an inflammation of the brachial plexus, a network of nerves around the collarbone.

Doctors believe that the inflammation may occur in association with an immune reaction. Studies show that neuralgic amyotrophy is often preceded by disorders of the immune system, for example due to viral infections or certain autoimmune conditions.

The condition is rare: it is estimated that 2 to 3 people in every 100,000 per year have neuralgic amyotrophy.

When it occurs, most people are aged between 20 and 60. Men suffer twice as frequently as women, and children only very rarely.

The typical pains usually occur initially in the shoulder joint and then spread to the neck and the entire arm. Paralysis of some muscle groups can occur within hours. Particularly severe pains tend to occur during the first days to weeks. Many people have to put up with pain, muscle weakness or restricted movements for months or even years.

In most people with neuralgic amyotrophy the symptoms fade away within around 1 to 3 years. To prevent long-term health impairments, it is advisable to continue treatment with drugs and physiotherapy even after the acute pain has faded away. 

Detailed questioning by the doctor is followed by a physical and neurological examination.

Electroneurography and electromyography are also useful in identifying neuralgic amyotrophy. These methods are used to check the function of certain nerves and muscle activity that are often impaired by the condition. A magnetic resonance tomography (MRT) is also sometimes done or the cerebrospinal fluid (liquor) is tested.

As the cause of the condition is still unknown, doctors can as yet only treat the symptoms.

To alleviate the pain and paralysis, various painkillers and anti-inflammatory drugs such as corticosteroids can be used. Corticosteroids speed up healing and reduce the risk or new pain attacks. Local applications of heat also help soothe the symptoms.

Doctors also recommend physiotherapies to minimize physical limitations and prevent long-term symptoms.