• Epidemiology
  1. Incidence: 1.64 per 100,000 (rare)
  2. Age: 30 to 70 years old
  • Etiology
  1. Post-Viral (reported in 25% of cases)
  2. Allergic Reaction
  3. Post-Trauma
    1. Postoperative
    2. Pitching
    3. Backpacker palsy
      1. Hikers or military carrying a heavy backpack for hours
      2. Results in compression and traction at the Brachial Plexus
  • Symptoms
  1. Shoulder weakness follows pain within 1 to 30 days
  2. Hand Paresthesias may be present
  3. Acute severe Shoulder Pain or arm and Neck Pain for 1-2 weeks
    1. Sharp, intense pain
    2. Worse at night
    3. Pain of short duration
  • Signs
  1. Scapular Winging
  2. Weakness occurs in multiple ShoulderMuscle groups
    1. Deltoid Muscle
    2. Rotator cuff Muscles
    3. Biceps Muscle
    4. Triceps Muscle
  3. Non-dermatomal sensory loss typically develops
    1. Especially lateral antebrachial cutaneous (radial aspect of Forearm)
  • Diagnostics
  1. Electromyogram shows neurogenic atrophy
  • Differential Diagnosis
  1. Cervical Radiculopathy
    1. Dermatomal Distribution of deficits (non-dermatomal in Acute Brachial Neuritis)
    2. Spurling's Test typically positive (negative in Acute Brachial Neuritis)
  2. Rotator Cuff Syndrome
  3. Extremity Trauma
  4. Acute Shoulder Arthritis
  5. Adhesive Capsulitis
  • Management
  1. Symptomatic care
  2. Corticosteroids may be considered (but not consistently supported by literature)
  • Prognosis
  1. Full recovery in 89% by 2-3 years
  2. Recurrence in up to 25%
  • References
  1. Delaney, Orman, Herbert in Herbert (2016) EM:Rap 16(12): 3-4
  2. Simon (2023) Am Fam Physician 107(5): 503-12 [PubMed]