Synopsis
Localise peripheral nerve symptoms by fibre type and distribution, identify rapidly progressive or vasculitic emergencies, and choose focused metabolic, neurophysiological, genetic or biopsy investigation.
- Localise before listing causes: decide whether symptoms fit length-dependent polyneuropathy, focal mononeuropathy, mononeuritis multiplex, plexopathy, radiculopathy, neuromuscular junction or myopathy.
- Large-fibre loss causes vibration and joint-position impairment, sensory ataxia and reduced reflexes; small-fibre loss causes burning pain and temperature or pinprick change with preserved routine nerve conduction.
- A symmetrical stocking pattern progressing slowly from toes upward suggests length-dependent axonal polyneuropathy, commonly metabolic, toxic, nutritional or idiopathic.
Key red flags
Prominent weakness, diffuse areflexia and neurophysiological slowing, conduction block or temporal dispersion raises acquired or hereditary demyelinating neuropathy.
Investigation priorities
Map modalities, weakness and reflexes to a fibre type, nerve, root, plexus or length-dependent distribution.
Management branches
Numbness, pain, weakness or imbalance could arise from peripheral nerve disease.
- Define onset, tempo, symmetry, proximal versus distal distribution, pain, autonomic symptoms and exposure or family history.
- Map pinprick, temperature, vibration, joint position, power and reflexes, while checking gait, cranial nerves and central long-tract signs.
A stable peripheral neuropathy pattern is established without an emergency.
Key medicines
Amitriptyline for neuropathic painCommonly start 10 mg at night and titrate cautiously according to benefit, daytime sedation, age, cardiac risk and local formulary limits.
Duloxetine for neuropathic painA common adult start is 30 mg once daily, increasing to 60 mg daily if needed and tolerated under the licensed or local regimen.