Key points

Definition

Parsonage-Turner syndrome (PTS) is a rare disorder typically characterized by an abrupt onset of upper extremity pain followed by progressive neurologic deficits, including weakness, atrophy, and occasionally sensory abnormalities. The cause is unknown. The distribution of the nerves involved as well as the extent of involvement is variable. Any peripheral nerve may be affected but most commonly the upper trunk of the brachial plexus is involved. Recovery is often prolonged and incomplete. A hereditary form of the syndrome, hereditary neuralgic amyotrophy, has also been studied, although it occurs much less frequently. Clinically it presents similarly to PTS, but often at a younger age and has a higher incidence of recurrent attacks.

Although this clinical condition is most commonly referred to as Parsonage-Turner syndrome, neuralgic amyotrophy, or brachial neuritis, it can be found described in literature under many other names ( Box 1 ).

Definition

Parsonage-Turner syndrome (PTS) is a rare disorder typically characterized by an abrupt onset of upper extremity pain followed by progressive neurologic deficits, including weakness, atrophy, and occasionally sensory abnormalities. The cause is unknown. The distribution of the nerves involved as well as the extent of involvement is variable. Any peripheral nerve may be affected but most commonly the upper trunk of the brachial plexus is involved. Recovery is often prolonged and incomplete. A hereditary form of the syndrome, hereditary neuralgic amyotrophy, has also been studied, although it occurs much less frequently. Clinically it presents similarly to PTS, but often at a younger age and has a higher incidence of recurrent attacks.

Although this clinical condition is most commonly referred to as Parsonage-Turner syndrome, neuralgic amyotrophy, or brachial neuritis, it can be found described in literature under many other names ( Box 1 ).

History

One of the first descriptions of PTS dates back to 1887 when Julius Dreschfeld described 2 cases of recurrent episodes of nontraumatic brachial plexopathy. Over the next 60 years, there were several case reports describing similar clinical presentations, but it was not until 1943 that Spillane gave the first full description of the condition in his article, “Localised neuritis of the shoulder girdle.” Spillane described 46 patients with an “acute onset of pain in the shoulder, arm, and side of the neck, over the scapula and down the affected arm” persisting for 7 to 10 days. Several days later, usually after the pain subsided, the patients developed paralysis around the shoulder girdle. In 1948, M.J. Parsonage and John W. Alden Turner published an article titled, “Neuralgic amyotrophy: the shoulder girdle syndrome,” which more firmly established and detailed the clinical aspects of the syndrome. This article described a case series of 136 patients who experienced a sudden onset of pain across the shoulder blade lasting from a few hours to 2 weeks, followed by paralysis involving muscles of the shoulder girdle and in some cases patchy numbness along the lateral aspect of the upper arm. In 98 of the cases there was thought to be some precipitating factor, such as surgery, trauma, infection, lumbar puncture, air encephalogram, or antisyphilitic treatment.

Cause and pathophysiology

The exact cause and pathophysiology of PTS are complex and incompletely understood. Autoimmune, genetic, infectious, and mechanical processes have all been implicated. Of the many proposed causes, an infectious or immune-mediated process seems to be the most supported due to the high incidence of preceding infections and immunizations. An antecedent event has been identified in 30% to 70% of PTS cases. It is theorized that an event may trigger an immune-mediated response that incites the development of PTS. In 20% to 52% of cases, infection precedes the development of PTS. Approximately 15% of cases occur after immunization.

PTS has been associated with several surgical procedures, including coronary artery bypass surgery, oral surgery, hysterectomy, and a variety of orthopedic surgeries. Although in surgeries involving the chest or upper extremity, plexopathy may develop from a traction injury because of improper positioning or prolonged pressure over the nerve. However, PTS has been observed following surgical procedures that involve little to no traction on the brachial plexus or surrounding nerves. It may be difficult to distinguish a traction injury from PTS. What distinguishes PTS is nerve involvement without common innervation root, brachial plexus trunk, or cord distribution and muscles with common innervation may be unaffected. Other less frequently observed antecedent events are listed in Box 2 .

Histologic studies have demonstrated evidence of an immune-mediated process. Suarez and colleagues showed the presence of inflammatory cells, particularly T-lymphocytes, within the brachial plexus of a small sample of patients with PTS. In addition, complement fixing antibodies to peripheral nerve myelin have been found elevated in the acute phase of PTS, and levels tended to decrease during the recovery phase.

van Alfen suggests that the pathophysiology of the condition involves an interaction between a genetic predisposition, mechanical vulnerability, and an autoimmune trigger. No mutations have been found in patients with idiopathic neuralgic amyotrophy but studies have shown mutations of the septin gene in some families with the hereditary autosomal-dominant form. The septin family of genes is highly expressed in glial cells in neuronal tissue. In some cases PTS is preceded by increased physical exertion, suggesting that biomechanical factors may also play a role in triggering the attack.

Epidemiology

One study suggests that the annual incidence of PTS is 1.64 per 100,000 in the United States. The actual incidence may be higher given the difficulty of recognition. It is described in patients ranging from age 3 months to 81 years but occurs most frequently between the third and seventh decades. PTS occurs more frequently in men than women. Studies have shown the ratio of male-to-female involvement ranges from 1.75:1 to 11.5:1. The hereditary form is thought to occur 10 times less frequently than the idiopathic form and typically occurs in the second decade of life.

Patient evaluation overview

The classic presentation of PTS begins with acute onset of severe pain lasting for several days to weeks, followed by the development of weakness and muscle atrophy. The presentation is highly variable and may present with a wide range of symptoms, including pain, paresthesias, and sensory disturbances. Patients typically do not have constitutional symptoms such as fever or malaise.

Pain is the predominant presenting symptom in 90% to 95% of patients. The pain is usually worse at night and frequently awakens patients from sleep. It is often described as “constant,” “sharp,” “stabbing,” “throbbing,” or “aching” and in some cases is associated with muscle tenderness. Characteristically the pain is located in the shoulder and often radiates into the arm or neck. The pain is commonly aggravated by movement of the shoulder but not typically by movement of the neck or Valsalva maneuvers. In rare cases, symptoms are localized outside the brachial plexus and in some cases in the lower extremity. The pain is usually unilateral, on the same side in which the weakness develops. Some patients experience bilateral pain followed by unilateral motor symptoms. Although the pain on average, lasts 1 to 2 weeks and then subsides, the duration of pain is highly variable, ranging from several hours to months. After the acute episode, a portion of patients develops a lingering neuropathic pain in the distribution of the affected nerve and or musculoskeletal pain in the affected muscles or compensating muscles.

Muscle weakness typically begins to develop days to weeks after the onset of pain and often worsens as the pain subsides. In a study of 99 patients, weakness began within the first 2 weeks after the onset of pain in 70% of the cases. The location of the initial pain does not necessarily correlate to the distribution of muscle weakness. It may be difficult to ascertain the exact onset of weakness because pain may limit the patient’s use of the extremity. In addition, weakness may be hard to recognize if the muscles involved are hard to isolate manually and test. Atrophy of the involved muscles usually occurs relatively quickly.

A characteristic feature of PTS is the patchy distribution of motor and sensory symptoms. Muscles innervated by one peripheral nerve, multiple peripheral nerves, one or more trunks of the plexus, or a combination of peripheral nerves and trunks may be affected. The most common pattern of weakness involves muscles supplied by the upper part of the brachial plexus, especially the long thoracic nerve. Muscles most commonly affected include the deltoid, supraspinatus, infraspinatus, serratus anterior, biceps, and triceps. Muscles that have been reported to be affected are listed in Box 3 .

Individual nerves in isolation or in multiple nerve distributions may be affected. Isolated involvement of the radial, long thoracic, suprascapular, axillary, median, and anterior interosseous nerves are most commonly described. Less frequently, nerves remote from the brachial plexus are involved, including the lumbosacral plexus, phrenic nerve, lower cranial nerves, and recurrent laryngeal nerve. Involvement of nerves outside the brachial plexus is seen more frequently in the hereditary form of the syndrome, hereditary neuralgic amyotrophy. Nerves that have been reported to be affected are listed in Box 4 .

Box 4

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