Brachial Neuritis Workup

Updated: Apr 23, 2018
  • Author: Nigel L Ashworth, MBChB, MSc, FRCPC; Chief Editor: Milton J Klein, DO, MBA  more...
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Workup

Laboratory Studies

Laboratory values are usually within the reference range. Laboratory studies are indicated 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.

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Imaging Studies

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] Some of the newer MRI techniques, especially high-resolution MR neurography, can show abnormalities in the proximal root/plexus that may not be apparent with other investigations. [32]

A study by Sneag et al indicated that in patients with brachial neuritis, hourglass nerve constriction can be localized through identification of a bull’s-eye sign on MRI scans. [33]

A study by Lieba-Samal et al indicated that MRI and high-resolution ultrasonography (HRUS) can be useful in diagnosing brachial neuritis, with all clinically affected nerves/trunks of the study’s six brachial neuritis patients revealing segmental swelling on HRUS. In the five patients who underwent MRI, all clinically affected nerves displayed T2-weighted hyperintensity. [34]

A shoulder radiograph may be indicated to rule out specific shoulder pathologies. A chest radiograph is not usually part of the initial workup; however, it can be useful to rule out sarcoidosis or other granulomatous disease, as well as Pancoast tumor.

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Other Tests

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  • Electrodiagnosis [8, 35, 36, 6, 37]

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

    • Specific localization can be made to various nerves.

    • Loss of sensory and motor amplitudes with relatively normal conduction velocity is frequent. Note, however, that this finding only begins to fall beyond the reference range after approximately 1 week.

    • Somatosensory evoked responses are not reliable for distinguishing radiculopathy from brachial plexus neuropathy, and F-waves are generally less helpful than routine conduction studies in localization.

    • Needle electromyogram (EMG) shows denervation (fibrillations, positive sharp waves, and/or motor unit potential changes) in affected muscles 2-3 weeks after onset; however, clinically uninvolved muscles also may show abnormalities. Approximately 50% of patients with unilateral clinical involvement demonstrate bilateral EMG abnormalities. EMG results for the paraspinal muscles usually are within the reference range. Electromyographic exclusion of a radiculopathy may be challenging. In addition, strict anatomic localization often is difficult.

    • Proximal conduction block has been reported in brachial neuritis; however, this finding should suggest focal forms of inflammatory demyelinating diseases. Proximal slowing also may occur from loss of large fibers, regenerating fibers, and/or segmental demyelination.

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Procedures

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  • Nerve biopsy usually is not indicated in brachial neuritis. Axonal loss rarely is identified with biopsies of the radial sensory branch.

  • Lumbar puncture usually is not indicated. Analysis of cerebrospinal fluid generally is within the reference range in individuals with brachial neuritis.

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