An Overview of Parsonage-Turner Syndrome

Parsonage-Turner syndrome is a neurological disorder that causes severe pain in the shoulder and arm, and can cause lasting damage to muscles, nerves, and ligaments in the affected areas. PTS commonly occurs within the brachial plexus—a nerve network under the arm that bridges the cervical nerves of the neck along the clavicle and extending into the arm. PTS may also refer to other forms of peripheral nerve disorders elsewhere in the body. PTS is believed to be caused by an immune disorder, possibly secondary to a common viral infection, but the exact causes are still unclear. The overall lasting effect of PTS varies widely between individuals.

Symptoms

Parsonage-Turner syndrome (PTS) is a neurological disorder that causes severe pain in the shoulder and arm, typically on one side of the body. This pain can coincide with weakening and loss of muscle mass in the affected areas over a period of weeks. PTS affects 1.64 in 100,000 people per year, though the incidence of PTS may be underdiagnosed and somewhat higher.

The symptoms associated with PTS can be divided into acute, chronic, and recovery phases.

Acute Phase

The initial sign of PTS is usually a sudden pain in one or both shoulders, often affecting the corresponding side of the neck or arm, though one-sided pain is far more common. This initial pain may be sharp, burning, or a dull, throbbing ache. It may also present as a change in sensation in the area. From the initial pain level, the pain may increase quickly in some people or it may gradually ramp up.

Chronic Phase

After the acute phase, which may last anywhere from hours to a few weeks, the pain will eventually decrease. It may disappear completely or remain at a lesser intensity in some cases.  

Even after the acute symptoms of PTS have diminished, nerve damage may preclude some muscle movement and use. Lifting, bending, and other activities may cause pain to the nerves of the affected muscle areas. Besides pain, the lasting damage to muscles and nerves ranges from barely noticeable weakness to complete loss of movement. In the affected areas, this weakness can cause:

• Muscle atrophy 
• Decreased sensation or numbness
• Pins-and-needles sensation or burning
• Increased sensitivity to touch

Structurally, atrophy may cause changes in the position and function of:

• Shoulders
• Arms
• Wrists
• Hands

Recovery Phase

During or after the chronic phase, a secondary complication can occur with atrophy called subluxation, a dislocation of the shoulder joint. When certain tendons in the shoulder area change position, some mobility of the shoulder joint can be lost due to chronic pain and inflammation affecting the connective tissue. Damage and loss of movement to the shoulder joint capsule may reflect an inflammatory condition known as adhesive capsulitis.

Other lasting symptoms include circulatory issues. The skin of the hands and arms may swell (edema) and become discolored with blotches of red, purple, or spotting. Hair and nail growth may speed up. There may also be excessive sweating or poor temperature response in arms, hands, or fingers to temperature change in the environment.

Other forms of PTS affecting different parts of the body may lead to pain and dysfunction localized to specific nerves: 

• Lumbosacral plexus (lower back pain radiating into the legs)
• Phrenic nerve (weakening of the diaphragm can cause shortness of breath)
• Recurrent laryngeal nerve (hoarseness of the voice due to weakness or partial paralysis of the vocal cords)
• Facial or cranial nerves (rarely affected with unique impairments)

Causes 

The cause of the onset of PTS is not fully understood, but there are many potential environmental factors that may induce it, including:

• Surgery on the brachial plexus 
• Childbirth
• Unusually strenuous exercise 
• Physical trauma 
• Recent immunization 
• Bacterial, viral, or parasitic infection
• Anesthesia 
• Rheumatologic disease or tissue inflammation
• Autoimmune disorders

Hereditary Neuralgic Amyotrophy

PTS is sometimes also known as idiopathic neuralgic amyotrophy, and this name indicates a non-genetic or unknown cause. Hereditary neuralgic amyotrophy (HNA) is a hereditary form of PTS. 

It is estimated that 85% of the time, HNA is caused by a mutation in the SEPT9 gene, which produces a protein important to cell division. Loss of SEPT9 protein function also predicts higher cancer risks. Mutation of SEPT9 is expressed dominantly, so symptoms of HNA may occur even when just one copy of the gene is present. Targeted genetic testing is available for the SEPT9 gene. Family indicators of the hereditary form of PTS are:

• Short height
• Excess folds on neck and arm skin
• Cleft palate
• Split uvula
• Partially webbed fingers or toes
• Eyes positioned close together
• Narrowly opening eyelids
• Narrow mouth
• Facial asymmetry

Diagnosis

PTS can be diagnosed by a physician such as a neurologist by using patient history and reported symptoms, and specialized testing including a brachial plexus MRI and electromyogram (EMG) or nerve conduction study (NCS) to identify the source and intensity of symptoms. 

Testing 

Tests may include electromyography (EMG) to measure muscle and nerve health. If nerves are not conducting electrical impulses normally when stimulated by electrodes, a neuromuscular specialist can identify what specific nerves are affected by a PTS injury.

An MRI of the brachial plexus in the arm can be used to identify causes of shoulder pain, find the muscles affected by atrophy, and identify where damage affecting larger nerves has occurred.

In some cases, an X-ray or CT scan can be used to rule out other causes of pain or loss of movement that may affect the shoulder, besides PTS, and what may be responsible. 

Treatment

The purposes of PTS treatments are to alleviate symptoms that affect quality of life and recovery and, if necessary, restore normal function of the affected arm and shoulder. 

During the intense, acute phase of PTS, people may need to take medications to reduce pain. Commonly, the prescription use of NSAIDs or opioid pain medications may alleviate the discomfort. Physical therapy and therapeutic pain relief, such as hot-cold treatments, can also be used to reduce pain and to maintain muscle mass and range of motion. Use of a TENS unit, a machine that applies electrical impulses to muscle through the surface of the skin, may be an additional useful therapeutic option, reducing pain in some people. 

For chronic nerve pain that is extreme and unresponsive to other treatments, surgery (including nerve grafts and tendon transfers) may offer solutions that reduce pain and restore movement. Replacement of damaged tendon can help recover loss of movement in the shoulder, particularly two or more years after the initial onset of PTS if nerves and muscles are damaged and have not responded to other forms of treatment.

Intravenous immune globulin (IVIG) therapy may be an effective treatment, but further research is needed. 

Coping

Residual pain and immobility may be an issue in repetitive everyday tasks and manual labor. While most people regain most, if not all, of their strength within two to three years, management of pain during the acute and chronic phases of PTS is important.

Advanced symptoms, such as partial paralysis and intractable pain, may warrant physical therapy and surgery. These solutions can help prevent complete loss of the functions of nerves and muscles during the early phases, or help to restore them in the recovery phase.

Prognosis

It is difficult to predict how PTS will affect an individual. After the first PTS attack, there is a 25% chance of a recurring attack, and about 10-20% of people with PTS may have persisting pain or problems with shoulder movement. 

A Word From Verywell

Conditions that cause chronic pain are often frustrating and confusing. The outcomes of PTS vary, and it is important to discuss a plan with your healthcare team to manage pain relief and physical therapies. With more advanced symptoms, like partial paralysis or muscle atrophy, surgery may be an important option when considering your lifestyle needs. It is hard to predict how long the acute and chronic phases may linger, so work closely with your healthcare providers to ensure the condition is optimally managed.