- Painful weakness of shoulder muscles (with atrophy). Beware radiculopathy or cord pathology.
- Brachial neuritis (BN) is a rare syndrome affecting LMN of brachial plexus or mononeuritis.
- The syndrome can vary greatly in presentation and nerve involvement.
- Aetiology is unknown but probably immune-mediated inflammatory reaction against nerve fibres of the brachial plexus.
- Wallerian degeneration and proximal conduction block are seen.
Incidence / Prevalence
- In the US is over 1 case per 100,000 person-years.
- M: F = 3:1, any age (young adults especially).
Key Clinical Features
- Sudden onset unremitting constant shoulder pain (right > left, occasionally bilateral).
- Acute onset of excruciating unilateral (R>L, 10% bilateral) shoulder pain, followed by flaccid paralysis and wasting of shoulder and parascapular muscles several days later.
- Check for scapular winging (early sign of muscle weakness), long thoracic nerve of Bell.
- Pain maximal at onset, atypical in nature, but often exacerbated (initially) by shoulder movement.Generally not pleuritic.
- Numbness (sometimes myotome and dermatome differ) not very prominent.
- Possible rtecent drugs / trauma / bugs as trigger.
- Weakness, maximal at onset, several days after onset pain. Typically involves rotator cuff muscles and deltoid.
- Phrenic nerve or cranial nerve involvement very rare.
- Consider shoulder views to exclude calcific tendonitis.
- CXR to exclude sarcoidosis or mitotic disease.
- FBC, ESR, inflam. markers & autoantibodies (connective tissue disease)?
- HIV if at risk history.
- Consider MRI to exclude cervical radiculopathy
- Consider EMG studies (looking for denervation and proximal block and exclude amyotrophic lateral sclerosis).
Treatment and management
- NSAIDs (± opiates in acute setting).
- Consider neuropathic pain medications (e.g. TCADs).
- Physiotherapy (important to m,aintain shoulder ROM).
80% recover functionally by 2 years; 90% by 3 years.
Red flags and pitfalls
- Acute Poliomyelitis, Amyotrophic Lateral Sclerosis.
- Frozen shoulder.
- Biceps tendonitis or Rotator Cuff Disease.
- Cervical Disc Disease or Mononeuritis Multiplex.
- Thoracic outlet syndrome.