Brachial Neuritis

Updated: Mar 29, 2018
  • Author: Nigel L Ashworth, MBChB, MSc, FRCPC; Chief Editor: Milton J Klein, DO, MBA  more...
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Overview

Practice Essentials

Brachial neuritis (BN), also known as neuralgic amyotrophy or Parsonage-Turner syndrome, is a rare syndrome of unknown etiology affecting mainly the lower motor neurons of the brachial plexus and/or individual nerves or nerve branches. Brachial neuritis usually is characterized by the acute onset of excruciating unilateral shoulder pain, followed by flaccid paralysis of shoulder and parascapular muscles several days later. The syndrome can vary greatly in presentation and nerve involvement. [1, 2, 3] (See images below.)

The patient is a 43-year-old farmer, shown 6 month The patient is a 43-year-old farmer, shown 6 months after presenting with severe right shoulder pain and weakness. Note severe wasting of the right infraspinatus and deltoid and winging of the scapula.
Same patient as above. Note again severe supraspin Same patient as above. Note again severe supraspinatus and infraspinatus wasting on the right.

Workup

Laboratory studies are indicated in brachial neuritis only if systemic disease is suspected on clinical grounds. The complete blood count (CBC) and erythrocyte sedimentation rate (ESR) can be used as nonspecific indicators of systemic disease. Antinuclear antibody (ANA) values can be used as a marker for connective-tissue disease. Human immunodeficiency virus (HIV) serology can also be performed.

Magnetic resonance imaging (MRI) or computed tomography (CT) myelogram scanning should be considered initially to rule out cervical radiculopathy (particularly C5/C6). MRI of the brachial plexus can help to rule out carcinomatous or granulomatous infiltration, if clinically indicated. [4, 5] A shoulder radiograph may be indicated to rule out specific shoulder pathologies.

Electrodiagnosis should be considered initially to confirm neuropathic diagnosis and to rule out various other conditions (eg, radiculopathy, neuropathy, amyotrophic lateral sclerosis).

Management

Physical therapy for patients with brachial neuritis should be focused on the maintenance of full range of motion (ROM) in the shoulder and other affected joints. [6] Functional conditioning of the upper extremity may be helpful in patients with brachial neuritis. Assistive devices and orthotics may be used, depending on the particular disabilities present.

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.

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Pathophysiology

Brachial neuritis (BN) exists in an inherited and an idiopathic form. In the idiopathic version, the pathophysiology is unknown, but the condition is generally thought to be an immune system–mediated inflammatory reaction against nerve fibers of the brachial plexus. [7, 8, 9, 10, 11] Axonopathy with subsequent Wallerian degeneration appears to predominate, but proximal conduction block has also been described in over 33% of cases in the series by Lo and Mills. [12] The inherited form is autosomal dominant and has been linked to mutations in the SEPT9 gene on chromosome 17q. [13, 14, 15] Septins are involved in the formation of the cytoskeleton and in cell division, but how these mutations result in BN is unknown.

A study by Arányi et al described the ultrasonographic characteristics of brachial neuritis, finding the following abnormalities in a group of 14 patients:

  • Focal or diffuse nerve or fascicle enlargement
  • Incomplete nerve constriction
  • Complete nerve constriction with torsion
  • Fascicular entwinement

The investigators suggested that inflammation-related constriction precedes torsion, with the torsion encouraged by limb rotation. [16]

Using magnetic resonance imaging (MRI) to evaluate patients with brachial neuritis, a study by Sneag et al suggested that instead of being associated with changes to all or part of the brachial plexus proper, the condition involves one or more mononeuropathies. [17]

A study by Ferrante and Wilbourn of 281 patients with sporadic brachial neuritis found through electrodiagnostic testing that out of 379 assessable events, 174 (46%) involved a single nerve, with another 205 (54%) being multifocal. The investigators also found that most bouts of brachial neuritis purely involved motor nerves, with the second greatest number involving mostly motor nerves and the fewest involving a more even mix of sensory and motor nerves. [18]

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Epidemiology

Frequency

United States

The incidence of brachial neuritis is approximately 1-2 cases per 100,000 person-years.

International

In the United Kingdom, the incidence of brachial neuritis is approximately 3 per 100,000 person-years. [19] Brachial neuritis has also been described in many countries around the world, although specific rates of incidence have not been reported.

A prospective cohort study from the Netherlands suggested that the incidence of brachial neuritis is many times higher than currently thought. Using data from two primary care institutions, the study, by van Alfen and colleagues, found that out of 492 patients with new-onset neck, shoulder, or arm complaints, 14 were confirmed to have brachial neuropathy, putting the 1-year incidence rate for the condition at 1 per 1000 persons. According to the investigators, this indicated an incidence for the condition that is 30-50 times greater than currently believed. [20]

Mortality/Morbidity

Brachial neuritis is not a fatal condition, although the phrenic nerve may be involved. [21] The risk of 'significant' residual disability in the involved limb after 2 years is approximately 10-20%. [22] . A recent survey suggested that up to half of patients are left with residual shoulder pain and decreased endurance. [23]

Sex

Brachial neuritis occurs predominantly in males, with the male-to-female ratio for the condition ranging from 2:1 to 4:1.

Age

Brachial neuritis has been reported in individuals from age 3 months to 74 years; however, the condition's prevalence is highest in young to middle-aged adults. Onset in childhood should be considered suggestive of hereditary brachial neuritis. [24]

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