Synopsis
Recognise neuralgic amyotrophy from its pain-then-weakness sequence, localise patchy plexus and individual-nerve injury, exclude cervical, structural and malignant mimics, and protect movement during slow axonal recovery.
- Brachial neuritis, also called neuralgic amyotrophy or Parsonage-Turner syndrome, typically begins with abrupt severe shoulder or upper-arm pain followed days later by patchy weakness and wasting.
- Pain is often relentless, worse at night and not consistently reproduced by neck movement; as pain settles, weakness becomes more apparent and may be mistakenly attributed to guarding.
- The upper trunk, long thoracic, suprascapular and anterior interosseous distributions are often affected, but lesions are multifocal and need not respect one plexus segment.
- Scapular winging from long-thoracic neuropathy, weak shoulder external rotation and inability to make an OK sign are useful localising examination clues.
- Sensory symptoms are variable and sometimes mild despite severe pain; a small lateral forearm or patchy upper-limb deficit is more typical than a clean dermatomal band.
- Immune triggers can include recent infection, surgery, strenuous exercise, childbirth and occasionally vaccination, but temporal association alone does not establish causation.
- Hereditary neuralgic amyotrophy should be considered with recurrent attacks, childhood onset, affected relatives or dysmorphic features and may involve SEPT9 variants.
- Electrodiagnostic testing is most informative after denervation has had time to develop and should sample clinically selected nerves and muscles rather than a generic limb screen.
- MRI of the brachial plexus or high-resolution nerve imaging can show multifocal enlargement or hourglass constriction and excludes mass, while cervical MRI addresses a root or cord differential.
- Evidence for corticosteroid early in the painful phase is limited; care centres on adequate analgesia, movement preservation, later targeted strengthening and specialist reconstruction for selected non-recovering constrictions.
Key red flags
New orthopnoea, sleep-related breathlessness, weak cough or an elevated hemidiaphragm after the pain syndrome indicates potentially important diaphragmatic neuropathy.
Investigation priorities
Localise weakness across roots, plexus trunks, fascicles and named nerves.
Management branches
Severe new shoulder or arm pain appears without a clear joint injury.
- Ask about chest and vascular symptoms, trauma, fever, cancer, rash, neck provocation and recent immune triggers, then perform cardiac, vascular, cervical and neurological examination.
- Document baseline scapular, shoulder, elbow, wrist and finger strength even if pain limits effort, arranging urgent alternative imaging for red flags.
- Provide a short, safe acute analgesic plan and early review because objective weakness may emerge after the first painful consultation.
Key medicines
NaproxenA time-limited adult oral regimen may be used from the current BNF with the lowest effective dose and gastroprotection selected by gastrointestinal risk.Avoid or review in kidney disease, ulcer, anticoagulation, heart failure, pregnancy and high cardiovascular risk; analgesia must not mask evolving weakness.
AmitriptylineStart a low oral night dose, often 10 mg, and titrate slowly under the BNF if persistent neuropathic pain disrupts sleep and function.Sedation, falls, anticholinergic burden, conduction disease and overdose toxicity require a pre-agreed review and stopping plan.