Parsonage Turner syndrome

Parsonage Turner syndrome is usually characterized by the sudden onset of severe pain in the shoulder and upper arm, which is often described as sharp, aching, burning, stabbing, or throbbing. In some cases, the pain may extend to the neck, lower arm and/or hand on the affected side. Rarely, both sides of the body are involved. Affected people typically experience constant pain that may become worse with movement. Intense pain can last from a few hours to several weeks, at which point the pain usually begins to subside. However, mild pain may continue for a year or longer.^[1][2] As the pain subsides, it typically is replaced by progressive weakness of the affected area, ranging from mild weakness to nearly complete paralysis. There may also be muscle wasting (atrophy), absent or reduced reflexes, or loss of sensation.^[1][2]

In some cases, nerves and muscles outside of the shoulder and upper arm region are affected, such as the lumbosacral plexus (causing symptoms in the legs) or phrenic nerve (affecting the diaphragm).^[3]

The exact cause of Parsonage Turner syndrome is unknown. Researchers suspect that most cases are due to an autoimmune response following exposure to an illness or environmental factor. In many cases, no triggering event or underlying cause can be identified. Factors known to trigger some cases include:^[1][2]

• Infections (both viral and bacterial)
• Surgery
• Vaccinations
• Childbirth
• Certain medical procedures, such as a spinal tap or imaging studies that require administration of radiologic dye
• Strenuous exercise
• Certain medical conditions, including connective tissue disorders and autoimmune disorders
• Injury

Some researchers believe that Parsonage Turner syndrome is a multifactorial condition, which means that it is caused by an interaction between environmental and genetic factors. In this case, a person may have a genetic susceptibility to PTS due to one or more genes, but won't develop the condition unless they are exposed to certain environmental triggers (such as one or more of those listed above).^[1][2]

Parsonage Turner syndrome, also known as idiopathic neuralgic amyotrophy, is not inherited. However, there is an inherited form of neuralgic amyotrophy called hereditary neuralgic amyotrophy. This form is inherited in an autosomal dominant manner.^[3]

A diagnosis of Parsonage Turner syndrome often is suspected based on the presence of characteristic signs and symptoms. Specialized tests may be recommended to further investigate the shoulder pain and/or muscle weakness, and to rule out other conditions that can cause similar features. These tests may include nerve conduction studies (tests that determine the ability of a specific nerve to relay a message to the brain), electromyography, magnetic resonance imaging (MRI scan), and/or an X-ray.^[1][2]

Treatment for Parsonage Turner syndrome (PTS) is focused on managing the signs and symptoms in each person. This may include imaging studies (such as MRI or high-resolution ultrasound) to identify any nerves that remain constricted or compressed. If compressed nerves are found, then surgery to de-compress the nerve may be an option. If nerve compression is ruled out, initial treatment involves pain control and physical and occupational therapy.^[4][5]

Pain medications may be prescribed depending on the severity of the nerve pain. After the acute phase, different medications known as co-analgesics may be administered. These include gabapentin, carbamazepine, and amitriptyline. These drugs specifically treat nerve pain. Other techniques for pain management include application of heat or cold, and transcutaneous electrical nerve stimulation, a method of pain relief in which a special device transmits low-voltage electrical impulses through electrodes on the skin to an area of the body that is in pain.^[1][2]

PTS symptoms may get better with time. However, it is not uncommon for some symptoms to persist. These symptoms are best treated by rehabilitation centers.^[6]  Surgeries such as nerve grafting or tendon transfer to restore movement and function to the shoulder muscles and joint may be considered if other treatment options are not effective.^[1][2]

The long-term outlook (prognosis) for people with Parsonage Turner syndrome varies. Some people may experience only a single episode of pain, and fully recover the strength and functionality of their shoulder. Others may have multiple episodes throughout their lives. It has been reported that approximately 80% of people recover within 2 years of the start of symptoms, and approximately 90% recover within 3 years. Traditionally, it was believed that most people would recover around 70-90% of their original strength and function level. However, more recent research suggests that long-term complications are more common than previously thought. People with bilateral (affecting both sides of the body) involvement or multiple episodes are more likely to have a poorer prognosis.^[1][2]

It is unclear exactly how many people have Parsonage Turner syndrome. Some suggest that about 1 in 1000 people may have this condition, but that many are not diagnosed.^[5]