Brachial Neuritis Clinical Presentation

Updated: Jan 18, 2017
  • Author: Nigel L Ashworth, MBChB, MSc, FRCPC; Chief Editor: Milton J Klein, DO, MBA  more...
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Presentation

History

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  • The onset of pain in brachial neuritis (BN) is often abrupt and may follow recent illness, surgery, [19] immunization, or even trauma (see Causes, below). Up to two thirds of cases begin during the nighttime.
  • The pain usually is localized to the right shoulder region, but it may be bilateral in 10-30% of cases.
  • The pain's intensity is very high (9+/10) and is maximal at onset.
  • Usually, the pain is described as sharp or throbbing in nature.
  • The pain usually is constant, but it is exacerbated by movements of the shoulder. Movements of the neck, coughing, and/or sneezing usually do not worsen the pain.
  • Intense pain can last from a few hours to several weeks and requires opiate analgesia.
  • Low-grade pain may persist for up to a year.
  • As the pain subsides, weakness becomes apparent.
    • In most cases of BN, this weakness manifests within about 2 weeks of onset.
    • Weakness is maximal at onset but can progress over 1 or more weeks.
    • A wide variety of muscles is affected, particularly those innervated by the upper trunk. The supraspinatus, infraspinatus, serratus anterior, and deltoid muscles are particularly susceptible, but many different single and multiple combinations of muscle involvement, including a pure distal form, have been reported.
    • The patient may notice considerable atrophy and wasting, as well as a deep aching in the affected muscles.
  • Numbness may occur, depending on the particular nerves affected, and usually is found in the nerve distribution corresponding to maximal muscle weakness. However, numbness is rarely a prominent complaint.
  • Phrenic nerve involvement occurs in up to 5% of cases and can result in significant shortness of breath. [20, 21, 22]
  • Variants of BN can present with isolated or multiple cranial neuropathies (IX, X, XI, XII). [23]
  • In 25-50% of patients, the medical history indicates a viral illness or vaccination that occurred days or weeks prior to the onset of symptoms. Some patients also may note recent trauma or severe exercise, surgery, infection, or immunization.
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Physical

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  • Due to the extreme pain involved, patients with brachial neuritis usually present acutely. Typically, the affected arm is supported by the uninvolved arm and is held in adduction and internal rotation.
  • Atrophy of the affected muscles becomes prominent after approximately 2 weeks.
  • Considerable muscle pain may be noted on palpation.
  • Passive and active attempts at shoulder and scapular movement result in a significant increase in pain. Movements of the neck are relatively pain free.
  • Muscle strength in affected muscles often is reduced severely (to 2 or less on the Medical Research Council [MRC] grading scale).
  • Reflexes may be reduced or absent, depending on which nerves are involved.
  • Sensory loss is not prominent but may be detectable (in particular, loss of axillary nerve sensation), depending on the specific nerves affected.
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Causes

The exact cause of brachial neuritis is unknown, but the condition has been linked to many antecedent events or illnesses, as follows:

  • Viral infection (particularly of the upper respiratory tract)
  • Bacterial infection (eg, pneumonia, diphtheria, typhoid)
  • Parasitic infestation
  • Surgery [19]
  • Trauma (not related to shoulder)
  • Vaccinations (eg, influenza, tetanus, diphtheria, tetanus toxoids, pertussis [DPT], smallpox, swine flu)
  • Childbirth
  • Miscellaneous medical investigative procedures (eg, lumbar puncture, administration of radiologic dye)
  • Systemic illness (eg, polyarteritis nodosa, lymphoma, systemic lupus erythematosus, temporal arteritis, Ehlers-Danlos syndrome)

A rarer, hereditary form of BN has been localized to the SEPT9 gene on chromosome arm 17q and should be considered a distinct disorder. This entity presents in a younger age group, affects males and females equally (autosomal-dominant inheritance), and is characterized by recurrent, often bilateral attacks. Dysmorphic facial features (eg, hypotelorism, long nasal bridge, facial asymmetry) can also be present.

A study from England and the Netherlands found that in samples of British and Dutch patients with brachial neuritis, about 10% had hepatitis E. In the combined retrospective (British)/prospective (Dutch) study, van Eijk et al found hepatitis E virus (HEV) infection in five out of 47 patients. Clinical and electrophysiologic examination indicated that the brachial neuritis was bilateral in all of the patients with hepatitis E. [24, 25]

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