Neuropathy is a condition affecting the nervous system, where the nerve fibres become damaged as a result of an injury or disease.

It is often called peripheral neuropathy because it affects the peripheral nervous system. This is the network of nerves that run out from the brain and spinal cord (which together form the central nervous system) and carry impulses to and from the rest of the body, such as the limbs and organs. Peripheral nerves are responsible for the body’s senses and movements.

Because the peripheral nerves transmit signals to so many different parts of the body, the symptoms of neuropathy can vary depending on which nerves are damaged. For example, damage to the nerves leading to the muscles (the motor nerves) can cause muscle weakness or, in more extreme cases, muscle wasting and paralysis.

Some peripheral nerves, called sensory nerves, feed messages (stimuli) to the brain and spinal cord, so you feel certain sensations. For example, when you prick your finger, sensory nerves transmit this information to the brain and you will feel a sharp sensation. Someone with sensory nerve damage may feel numbness rather than pain.

Sometimes people do not know what the underlying cause of their neuropathy is (idiopathic neuropathy), but in most cases the neuropathy is caused by a known condition or injury. A common type of neuropathy is diabetic neuropathy, which is nerve damage resulting from the high blood sugar levels seen in diabetes.

Neuropathy can be short-term, rapid onset (acute), or long-term, slower onset (chronic), and many nerves may be damaged or just one (mononeuropathy).

Because there are so many different nerves in the peripheral nervous system there are many different types of neuropathy, and symptoms will vary depending on which nerves are affected. Common symptoms include:

• Muscle weakness and paralysis, muscle wasting and muscle twitches – caused by damage to the motor nerves.
• Numbness and temporary paralysis, loss of reflexes, loss of coordination, and loss of ability to detect pain or changes in temperature – caused by damage to certain sensory nerves.
• Burning, stabbing or shooting pain (called ‘neuralgia’ or ‘neuropathic pain’) – caused by damaged to certain sensory nerves.
• Inability to sweat normally, to control your blood pressure (causing dizziness and fainting) and to control organs such as the bladder or erectile function – caused by damage to certain ‘autonomic’ nerves (which control certain automatic functions).

Some people will inherit peripheral neuropathy, but it can also be acquired as a result of injury, disease, infection or an immune disorder:

• Injury: Broken bones, slipped disks and injuries from sports, road accidents or falls can damage the peripheral nerves.
• Disease: Diabetes mellitus often causes peripheral neuropathy because high blood sugar levels can damage nerves. Other diseases that can cause nerve damage are alcoholism, kidney disease, blood disease, malignant disease and vitamin deficiency. Some drugs may damage nerves.
• Infection: Bacteria or viruses infecting the body can cause peripheral neuropathy. For example, HIV and the herpes varicella-zoster virus (which causes shingles and chickenpox) can attack nerve tissue, as can the bacteria that cause Lyme disease.
• Immune disorder: This is where the body’s immune system attacks and damages the peripheral nerves (known as ‘autoimmune disease’). Guillain-Barre syndrome is a rare but serious autoimmune disease affecting these nerves.

Charcot-Marie-Tooth disease is the name given to a set of inherited conditions that cause peripheral neuropathy.

In the first stages of diagnosing peripheral neuropathy, your GP will ask you about your symptoms and whether there is any history of neuropathy in your family. They will then carry out a physical examination to look for evidence of the condition, such as muscle weakness or altered sensation. Your GP will also be looking for any disease that may be causing the neuropathy.

If neuropathy is suspected, you may be referred to a neurologist (a specialist who treats conditions of the nervous system) for further testing. Tests may include:

• Nerve conduction test: Electrodes placed on the skin measure the strength and speed of the signals that are being transmitted through your periphery nerves.
• Electromyography (EMG): A needle-shaped electrode is placed on your skin to measure the electrical activity of your muscles.
• Nerve biopsy: A tiny sample of a periphery nerve is removed for testing.
• Scans: Magnetic resonance imaging (MRI) and computerised tomography (CT) scans take detailed images of the organs, bones and tissues.