Diagnosis - Peripheral neuropathy

A number of tests may be used to diagnose peripheral neuropathy and its underlying cause.

When you see a GP, they'll ask about your symptoms and examine the affected area of your body. This may involve testing sensation, strength and reflexes.

The GP may also arrange blood tests, especially to check for causes such as diabetes or vitamin B12 deficiency.

Confirming if you have a neuropathy

Some people may need to see a neurologist, a specialist in health conditions affecting the nervous system, in hospital for further tests.

These may include:

• a nerve conduction test (NCS), where small metal wires called electrodes are placed on your skin that release tiny electric shocks to stimulate your nerves; the speed and strength of the nerve signal is measured
• electromyography (EMG), where a small needle is inserted through your skin into your muscle and used to measure the electrical activity of your muscles

NCS and EMG are usually carried out at the same time.

Identifying the cause of a neuropathy 

The GP can usually identify the underlying cause of a peripheral neuropathy.

If diabetes is suspected, they can usually make a confident diagnosis based on your symptoms, a physical examination, and checking the levels of sugar in your blood and urine.

If you're taking a medicine known to cause peripheral neuropathy, the GP may temporarily stop or reduce your dose to see whether your symptoms improve.

If the cause is uncertain, you may be referred to a neurologist for more blood tests to check:

• whether you have a rare acquired cause that may be responsible
• whether you have a genetic abnormality, such as Charcot-Marie-Tooth disease

You may need a lumbar puncture to test a clear, colourless fluid that surrounds and supports the brain and spinal cord (cerebrospinal fluid) for inflammation.

Biopsy and scans

Occasionally, a nerve biopsy may be carried out as part of your diagnosis.

This is a minor surgical procedure where a small sample of a peripheral nerve is removed from near your ankle so it can be examined under a microscope.

It's then checked for changes that could be a sign of certain types of peripheral neuropathy. But nerve biopsies are rarely needed.

You may also need a scan to look for any underlying cause of your neuropathy, such as:

• an X-ray
• a CT scan
• an MRI scan