Peripheral Nerve Disorders Guide
A guide to sensory, motor, and autonomic nerve patterns, common causes, diagnostic tools including EMG, and treatment principles.
Contents
What peripheral nerves do
The peripheral nervous system carries signals between the brain and spinal cord and the skin, muscles, and organs. Sensory fibers carry touch, pain, temperature, and position; motor fibers control voluntary movement; and autonomic fibers carry automatic functions such as sweating, blood pressure, digestion, bladder, and sexual function. Fiber type and distribution produce different symptoms, including numbness, burning, allodynia, weakness, cramps, imbalance, or dizziness on standing. A length-dependent pattern beginning in the feet is common, but not every neuropathy follows it.
- Check a numb foot daily for pressure, heat injury, and broken skin.
- Report imbalance in darkness and falls.
- Mention autonomic symptoms; they can be diagnostically useful.
Common groups
A single-nerve entrapment, such as carpal tunnel or ulnar or peroneal neuropathy, follows a defined distribution. Polyneuropathy can result from diabetes, alcohol, medicines, toxins, kidney disease, vitamin deficiency, immune disease, or genetic causes, and sometimes remains unexplained. Guillain-Barré syndrome is an immune neuropathy that may progress over days and is an emergency; CIDP has a longer course. Charcot-Marie-Tooth is a common inherited neuropathy group, but foot shape alone cannot diagnose it.
| Group | Example | Clue |
|---|---|---|
| Entrapment | Carpal, ulnar, peroneal | Symptoms in one nerve territory |
| Polyneuropathy | Diabetic, toxic, metabolic | Often symmetric onset in feet |
| Immune neuropathy | GBS, CIDP | Rapid or stepwise weakness |
| Inherited neuropathy | Charcot-Marie-Tooth | Long course, sometimes family history |
How is neuropathy assessed?
History and neurological examination map the pattern. Blood tests are selected for possibilities such as diabetes, vitamin deficiency, thyroid, kidney or liver dysfunction, abnormal proteins, or immune causes; a broad panel is not required for everyone. Nerve-conduction studies measure speed and amplitude in large fibers, while needle EMG samples muscle activity. These tests can be normal in small-fiber neuropathy, when skin biopsy or autonomic testing may be considered. Ultrasound, MRI, and genetic testing are used for a relevant clinical question.
Treatment and quality of life
Treatment is based on cause, fiber type, and function. Diabetes management, safe replacement of a deficiency, clinician review of a responsible toxin or medicine, and selected immune therapies may address causes. Some antidepressant and antiseizure medicines can reduce neuropathic pain; sleepiness, falls, and other adverse effects need review. Splints, braces, appropriate footwear, physiotherapy, and occupational therapy may improve safety. Injection or surgery for entrapment is not appropriate for everyone; weakness and compression severity guide the decision.
- Avoid high-dose vitamins, including nonprescription B6, which can itself cause neuropathy.
- Avoid hot-water bottles and bare feet when sensation is reduced.
- Do not stop a medicine or chemotherapy yourself; discuss it with the responsible team.