Parsonage-Turner Syndrome Health Article

Definition

Parsonage-Turner syndrome (PTS) is a rare syndrome of unknown cause, affecting mainly the lower motor neurons of the brachial plexus. The brachial plexus is a group of nerves that conduct signals from the spine to the shoulder, arm, and hand. PTS is usually characterized by the sudden onset of severe one-sided shoulder pain, followed by paralysis of the shoulder and lack of muscle control in the arm, wrist, or hand several days later. The syndrome can vary greatly in presentation and nerve involvement.

Description

PTS, also known as brachial plexus neuritis or neuralgic amyotrophy, is a common condition characterized by inflammation of a network of nerves that control and supply (innervate) the muscles of the chest, shoulders, and arms. Individuals with the condition first experience severe pain across the shoulder and upper arm. Within a few hours or days, weakness, wasting (atrophy), and paralysis may affect the muscles of the shoulder. Although individuals with the condition may experience paralysis of the affected areas for months or, in some cases, years, recovery is usually eventually complete.

Local pain around the shoulder girdle is the prevalent symptom of Parsonage-Turner syndrome. It is usually sudden and often severe, often awakening persons during the night. The pain worsens progressively for up to two days. Described as a constant, severe ache associated with tenderness of the muscles, the pain is not affected by coughing. However, it is accentuated by arm movements and muscular pressure, but almost unaltered by movements of the neck. The pain is commonly distributed across the back of the scapula (shoulder blade) and the tip of the shoulder. Pain often radiates down the outer side of the arm and up along the neck, and seldom spreads down as far as the outer side of the forearm, below the elbow. There is no exact correlation between the localization of the pain and the distribution of the subsequent muscle paralysis.

However, in general, pain radiating below the elbow is associated with involvement of the biceps or triceps, and radiation into the neck involves the sternocleidomastoid and trapezius muscles. Usually the severe pain lasts from a few hours to three weeks and then disappears rather suddenly; at the same time, muscular wasting and weakness are occurring. A less severe pain may persist considerably longer.

As the pain subsides, paralysis of some muscles of the shoulder girdle, and often of the arm, develops. Usually, muscle weakness appears suddenly, but sometimes gradually increases over two or three days, or up to one week in rare cases. The paralysis involves limpness and rapid wasting of the affected muscles. Tendon reflexes might be affected, depending on the severity and extent of muscular paralysis and wasting. Weakened reflexes are frequently encountered, and fasciculations (fine tremors) occasionally occur.

Demographics

In the United States, the incidence is approximately 1.64 cases per 100,000 people per year. Internationally, PTS has been described in many countries around the world, although specific rates of incidence have not been reported. There is a male predominance in PTS with a male-to-female ratio ranging from 2:1–4:1. Individuals as young as three months or as old as 74 years can be affected with PTS; however, the prevalence is highest in young to middle-aged adults. When a child develops Parsonage-Turner syndrome, hereditary PTS should be considered.

Causes and symptoms

The exact cause of PTS is unknown, but the condition has been linked to many previous events or illnesses such as:

• viral infection (particularly of the upper respiratory tract)
• bacterial infection (e.g., pneumonia, diphtheria, typhoid)
• parasitic infestation
• surgery
• trauma (not related to shoulder)
• vaccinations (e.g., influenza, tetanus, diphtheria, tetanus toxoids, pertussis, smallpox, swine flu)
• childbirth
• miscellaneous medical investigative procedures (e.g., lumbar puncture, administration of radiologic dye)
• systemic illness (e.g., polyarteritis nodosa, lymphoma, systemic lupus erythematosus, temporal arteritis, Ehlers-Danlos syndrome)

In addition to these possible causes, a rare hereditary form of PTS has been localized to a defect on chromosome 17, and should be considered a distinct disorder. This form of the disorder occurs in a younger age group, affects males and females equally (autosomal-dominant inheritance), and is characterized by recurrent attacks that often cause pain on both sides of the body.

Acute pain in the shoulder girdle or arm is almost always the first symptom. Shortly thereafter, muscle weakness and wasting in the shoulder girdle and arm occur. The pain, which may be extraordinarily severe for a short time, eventually abates.