Neuropathy, peripheral - Diagnosing peripheral neuropathy

A number of tests can be used to diagnose peripheral neuropathy and any underlying cause.

A doctor will ask about your symptoms and examine the affected area of your body. This may involve testing sensation, strength and reflexes.

Your doctor may then arrange blood tests, especially to check for diabetes and vitamin B12 deficiency.

Confirming if you have a neuropathy

Some people may need to see a neurologist (a specialist in conditions affecting the nervous system) at a hospital appointment and have more specialised tests, such as a nerve conduction test and electromyography (EMG).

During a nerve conduction test, small metal wires called electrodes are placed on your skin. The electrodes release tiny electric shocks that stimulate your nerves. The speed and strength of the nerve signal is measured. An unusually slow or weak signal could indicate peripheral neuropathy.

EMG involves having a small needle inserted through your skin into your muscle. The needle is used to measure the electrical activity of your muscles.

Both types of test are usually carried out at the same time.

Identifying the cause of a neuropathy 

Identifying the underlying cause of a peripheral neuropathy is often straightforward and can be done by your GP.

If diabetes is suspected, a diagnosis can usually be confidentially made by asking you about your symptoms, carrying out a physical examination and checking the levels of glucose in your blood and urine.

If you are taking a medication known to cause peripheral neuropathy, temporarily stopping or reducing your dose to see whether your symptoms improve may help confirm whether the medication is responsible.

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

• whether you have an infection that may be responsible
• how well your liver and kidneys are working
• the levels of nutrients in your blood, such as vitamin B12
• whether you have a genetic abnormality, such as Charcot-Marie-Tooth disease

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

Further tests

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 is then checked for changes that could be a sign of certain types of peripheral neuropathy. However, nerve biopsies are rarely needed.

You may also need an X-ray, a computerised tomography (CT) scan or a magnetic resonance imaging (MRI) scan to look for any underlying cause of your neuropathy.