Diagnosing Peripheral Neuropathy

A number of tests can be used to confirm whether peripheral neuropathy is responsible for the patient’s
symptoms. These include:

• nerve conduction test and electromyography (EMG)
• nerve biopsy
• Nerve conduction test and electromyography (EMG)

A nerve conduction test measures the strength and speed of the signals transmitted through your peripheral
nerves. The peripheral nerves are the network of nerves that run from your brain and spinal cord to and from
other areas of your body, such as your limbs and organs.

During a nerve conduction test, small metal discs called electrodes are placed on your skin. The electrodes
release small 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.

Some types of peripheral neuropathy cause a distinctive change in the pattern of electrical activity, which can
be detected using electromyography (EMG).

Nerve biopsy

A nerve biopsy is a minor surgical procedure where a tiny sample of a peripheral nerve is removed from your
leg for testing.

Peripheral neuropathy can cause physical changes to the shape of the nerve, which can be seen under a
microscope. The biopsy is carried out under local anaesthetic, which means you will be awake but unable to
feel any pain.

Identifying the cause

Identifying an underlying cause is an important aim of diagnosing peripheral neuropathy. In many cases,
identifying the underlying cause is relatively straightforward.

For example, if diabetic polyneuropathy 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.

Alternatively, if you are taking a medication that is known to cause peripheral neuropathy, temporarily stopping
or reducing your dose to see whether your symptoms improve will help confirm whether that medication is
responsible.

If no obvious cause is suspected, you will probably be referred for a series of more extensive blood tests to
check:

• whether you have an infection that may be responsible
• how well certain organs, such as your liver and kidneys, are working
• the levels of nutrients in your blood, such as vitamin B
• whether you have any defective genes that are known to cause conditions associated with peripheral
  neuropathy, such as Charcot-Marie-Tooth disease, a condition that causes damage to the nerves,
  particularly in the feet