Parsonage Turner Syndrome

Parsonage Turner syndrome or brachial neuritis is a rare disorder which affects lower motor neurons of brachial plexus and/or nerves and their branches and is manifested by acute shoulder pain followed by weakness of the muscles of the shoulder. It is capable of leaving residual disability in 10-20% patients.

It  also known as neuralgic amyotrophy.

Parsonage Turner syndrome or brachial neuritis can be hereditary or idiopathic form.

The inherited form is autosomal dominant and has been linked to mutations in the SEPT9 gene on chromosome 17q.

In the idiopathic version, the pathophysiology is unknown, but the condition is generally thought to be an immune  mediated inflammatory reaction against nerve fibers of the brachial plexus.

Hereditary type recurs more than [75%] than idiopathic type [5- 26%]

The incidence of Parsonage Turner syndrome is reported to be 1-3 per 100,000 person-years. Males are affected two to four times more than females. The disease is mostly found in middle-aged adults but has been reported in as young as 3 years and as old 74 years.

Parsonage Turner syndrome generally involves one upper limb, but bilateral involvement has been reported.

The upper trunk of the brachial plexus, the suprascapular nerve, the long thoracic nerve, and the axillary nerves are the most commonly involved. Frequently reported, but less common, are the anterior interosseous, musculocutaneous, and spinal accessory nerves. Ulnar, radial, and median nerves are less common.

There is also rare involvement of the middle and lower trunks. Phrenic nerve involvement has also been reported.

Conditions Associated with Parsonage Turner syndrome

Following conditions are associated with the development of Parsonage-Turner Syndrome, though exact mechanism of influence is not known yet.

• Bacterial, viral and parasitic infection
• Surgical procedures and anesthesia
• Hereditary
• Rheumatic disease, connective tissue disorders (i.e., Ehlers-Danlos Syndrome), systemic lupus erythematosus, temporal arteritis, polyarteritis nodosa
• Trauma remote from the shoulder girdle, Stressful exercise
• Immunizations – Tetanus toxoid and antitoxin, diphtheria, pertussis, tetanus vaccine, smallpox, swine flu,
• Pregnancy and childbirth
• Procedures like radiation therapy, lumbar puncture, pneumoencephalogram, radiologic contrast dye administration, allergy desensitization

Presentation of Parsonage Turner Syndrome [Symptoms and Signs]

There is abrupt onset, high intensity pain in shoulder [mostly unilateral but bilateral involvement is known] that follows recent illness, surgery, immunization, or even trauma. The pain is exacerbated by movements of the shoulder.

Weakness around shoulder muscles appear after 1-2 weeks, around the time when pain subsides. Weakness affects a number of muscle. Supraspinatus, infraspinatus, serratus anterior, and deltoid muscles are most commonly involved muscles but any muscle supplied by brachial plexus could be affected.

[In some cases Low-grade pain may persist for up to a year.]

Along with weakness, muscle wasting is significant. If phrenic nerve is involved, it leads to shortness of breath as diaphragm cannot fully function.

On examination, muscle is tender on palpation. In acute settings wasting is not present but it is apparent at around two weeks after the onset.

Movements at the shoulder are painful. Movements of the neck are relatively pain free.

Muscle strength and reflexes are often reduced severely. Sensory loss is not prominent but may be present depending on nerve involved.

Differential Diagnoses of Parsonage Turner Syndrome

Acute poliomyelitis, adhesive Capsulitis, amyotrophic lateral sclerosis, cervical radiculopathy, HIV Infection, mononeuritis Multiplex, neoplasm, polymyalgia rheumatic, rotator cuff disease and thoracic outlet syndrome need to be considered as differentials when examining a patient with presentation as above.

Lab Studies in Parsonage Turner Syndrome

LAb parameters are usually within the reference range. Lab tests usually are not done for diagnosis of Parsonage Turner syndrome. These indicated only  if systemic disease is suspected on clinical grounds.  Complete blood count and erythrocyte sedimentation rate   are nonspecific indicators of systemic disease. For suspected HIV disease HIV serology is done. Antinuclear antibody is done as  marker for connective-tissue disease.

Imaging Studies

MRI may show nonspecific inflammatory changes in Parsonage Turner Syndrome but is not conclusive. MRI also helps to rule out cervical radiculopathy, carcinomatous or granulomatous infiltration.

A shoulder radiograph may be indicated to rule out specific shoulder pathologies. A chest radiograph  can be useful to rule out sarcoidosis or other granulomatous disease, as well as Pancoast tumor.

Electromyography

Electromyography can better identify, isolate, and grade severity of denervation and, after a period of time, reinnervation of the involved muscles.

Treatment of Parsonage Turner Syndrome

Treatment is largely symptomatic in patients with brachial neuritis. NSAIDs, Opoids, steroids help to ease the pain.

Heat, cold, transcutaneous electrical nerve stimulation [TENS] may be useful as adjunct pain relievers.

After initial pain has subsided, these patients should be put on physical therapy that includes range of motion exercises and strengthening exercises. Assistive devices and orthotics may be used, depending on the disabilities present.

In brachial neuritis, nerve grafting or tendon transfers may be considered for the few patients who do not achieve good recovery by 2 years. Surgery usually is aimed at improving shoulder abduction.

Prognosis of Parsonage Turner Syndrome

Eighty percent of patients with brachial neuritis recover functionally within two years and  90% recover functionally within 3 years.

Outcome for bilateral disease is less favorable than does unilateral disease.