Parsonage–Turner syndrome

Overview

Parsonage–Turner syndrome (PTS), also known as brachial neuritis or neuralgic amyotrophy, is a rare neurological disorder characterized by sudden, severe shoulder and upper arm pain followed by muscle weakness and atrophy. The condition affects the brachial plexus, a network of nerves that control the muscles and sensations in the shoulder, arm, and hand. PTS typically affects only one side of the body and can have a prolonged and unpredictable course. Although it can occur at any age, it is most commonly seen in adults between 20 and 60 years old. While the exact cause remains unclear, the condition often follows events like infections, surgeries, or vaccinations.

Causes

The precise cause of Parsonage–Turner syndrome is not fully understood, but it is believed to be immune-mediated, where the body’s immune system mistakenly attacks the brachial plexus nerves. Several triggers and associated factors have been identified:

• Viral infections: Such as Epstein–Barr virus, cytomegalovirus, hepatitis E, or influenza.

• Bacterial infections: Including Lyme disease and other systemic infections.

• Vaccinations: Rarely, PTS has been reported following immunizations like influenza or COVID-19 vaccines.

• Surgery or trauma: Particularly operations involving the neck, shoulder, or chest.

• Autoimmune disorders: Conditions like lupus or rheumatoid arthritis may increase susceptibility.

• Genetic predisposition: A hereditary form, hereditary neuralgic amyotrophy (HNA), is linked to mutations in the SEPT9 gene.

Symptoms

Parsonage–Turner syndrome typically presents in two phases: an initial painful phase followed by a weakness and atrophy phase. The onset is usually sudden and unilateral (affecting one side).

Initial Symptoms (Pain Phase)

• Sudden onset of severe shoulder and upper arm pain: Often described as burning, stabbing, or throbbing.

• Pain typically lasts for a few days to weeks: May be constant or intermittent, and often worsens with movement or at night.

Later Symptoms (Weakness Phase)

• Muscle weakness: Appears after the pain subsides, affecting the shoulder girdle, upper arm, forearm, or hand.

• Muscle wasting (atrophy): Due to nerve damage, visible in affected areas weeks after weakness begins.

• Numbness or tingling: Sensory symptoms may be present but are typically less prominent than motor issues.

• Limited range of motion: Particularly in shoulder movements like abduction or external rotation.

Diagnosis

Diagnosis of Parsonage–Turner syndrome is based on clinical history, neurological examination, and exclusion of other causes of shoulder pain and weakness. Tests are performed to confirm nerve involvement and assess the extent of damage.

Clinical Evaluation

• History: Acute onset of shoulder pain followed by weakness without significant trauma is highly suggestive.

• Neurological exam: Identifies patterns of muscle weakness and atrophy corresponding to affected nerves.

Diagnostic Tests

• Electromyography (EMG): Detects denervation and helps localize the affected nerves and muscles.

• Nerve conduction studies (NCS): Assess electrical activity in the brachial plexus and help exclude other neuropathies.

• Magnetic Resonance Imaging (MRI): Of the shoulder or cervical spine to rule out rotator cuff tears, cervical disc disease, or brachial plexus tumors.

• Blood tests: To evaluate for autoimmune or infectious triggers, or muscle enzyme elevations.

Treatment

There is no specific cure for Parsonage–Turner syndrome. Treatment focuses on managing pain, maintaining range of motion, and facilitating nerve recovery. A multidisciplinary approach involving neurologists, physiatrists, and physical therapists is often beneficial.

Acute Phase Treatment

• Pain management: Includes NSAIDs, corticosteroids (e.g., prednisone), and neuropathic pain medications like gabapentin or pregabalin.

• Activity modification: Avoiding activities that aggravate pain during the acute phase.

Rehabilitation Phase

• Physical therapy: Essential to prevent joint stiffness, maintain range of motion, and improve strength.

• Occupational therapy: Helps improve daily functioning and adapt to weakness or disability.

• Bracing or splinting: May be used to support weakened limbs or prevent contractures.

Advanced or Refractory Cases

• Surgical intervention: Rarely needed but may include tendon transfers or nerve decompression for persistent functional deficits.

• Immunomodulatory therapy: Considered in recurrent or autoimmune-associated cases, though evidence is limited.

Prognosis

The prognosis for Parsonage–Turner syndrome varies. While many patients recover well, complete recovery can take months to years, and some may be left with residual weakness or muscle wasting.

• Recovery time: Most patients show improvement within 6–18 months, but full strength may not return in all cases.

• Recurrence: Occurs in up to 25% of cases, sometimes affecting the opposite limb or different nerve distributions.

• Chronic pain or disability: A minority of patients may experience persistent symptoms requiring long-term management.

With early recognition, supportive care, and rehabilitation, many individuals with Parsonage–Turner syndrome are able to regain significant function and quality of life.