Neuropathy, peripheral

Page last reviewed: 13/07/2011

Peripheral neuropathy is a term for damage to the peripheral nervous system.

The peripheral nervous system

The nervous system consists of two main two parts:

  • the central nervous system, which includes the brain and spinal cord
  • the peripheral nervous system, which includes all parts of the nervous system that lie outside the central nervous system, including the motor nerves, which the brain uses to control the muscles

The peripheral nervous system is made up of three main types of nerves, each with its own specific function:

  • Automatic nerves help regulate the automatic functions of the body, such as blood pressure, bladder function and sweat levels.
  • Motor nerves control the muscles of the body.
  • Sensory nerves pass sensations, such as cold, heat or pain, from the affected area of the body to the brain.

Peripheral neuropathy can cause one or more of the following symptoms:

  • numbness and tingling in the feet and hands
  • a burning, stabbing or shooting pain
  • loss of co-ordination in the affected body parts
  • muscle weakness

How common is peripheral neuropathy?

Peripheral neuropathy usually affects older people, with 8% of people who are 55 years of age or over being affected by it.

In Ireland and England, diabetes (both type 1 diabetes and type 2 diabetes) is the most common cause of peripheral neuropathy.

Over time, the high blood sugar levels associated with diabetes can damage the nerves. This type of nerve damage is known as diabetic polyneuropathy.

It is estimated that around one in five people with diabetes has diabetic polyneuropathy.

As well as being caused by diabetes, peripheral neuropathy can have a wide range of other causes. For example, it can be caused by a viral infection, such as HIV, or as a side effect of certain medications.

See Peripheral neuropathy - causes for more information.

Outlook

The outlook for peripheral neuropathy can vary widely depending on the underlying cause and what sort of peripheral nerves have been damaged.

For example, if the sensory nerves of the hands or feet are affected, the outlook is generally good. However, it is important that the underlying cause (diabetes) is aggressively treated.

This is because over time, diabetic polyneuropathy can cause a diabetic foot ulcer, an open sore that develops in the foot. If the ulcer becomes infected, there is a risk that the foot tissue will begin to die and it may be necessary to amputate the foot.

The outlook is not so good in cases where neuropathy affects the automatic functions of the heart and circulation system (cardiovascular automatic neuropathy). This is because the condition can increase the risk of sudden death as a result of the heart suddenly stopping beating (cardiac arrest).

Note on terms

Many neurologists now prefer to use the term ‘polyneuropathy’ rather than ‘peripheral neuropathy’ as the former term makes clear that multiple nerves are damaged simultaneously. 

In clinical terms, peripheral neuropathy could be used to describe cases where only one nerve is damaged.

However, as peripheral neuropathy is more widely used and understood by the public, this term will be used for the rest of this article.

Page last reviewed: 13/07/2011

Most cases of peripheral neuropathy affect the sensory and motor nerves. Symptoms usually first develop in the extremities of your body, such as your hands, feet, legs and arms. This type of neuropathy is called generalised sensorimotor polyneuropathy. 

Sensorimotor polyneuropathy

Symptoms of generalised sensorimotor polyneuropathy can include:

  • prickling and tingling sensation in the affected body part (pins and needles)
  • numbness and a reduced ability to feel pain or changes in temperature, particularly in your feet
  • a burning pain, usually in the feet and legs, followed by the hands and arms as the neuropathy progresses
  • sharp stabbing pain, which is often worse at night (again, the feet and legs are affected first, followed by the hands and arms)
  • muscle weakness
  • loss of co-ordination
  • muscle paralysis
  • increased risk of developing problems that affect the feet, such as skin infections and foot ulcers

Some people with peripheral neuropathy also develop dysesthesia. Dysesthesia is where you experience problems with your sense of touch, which can cause the following symptoms:

  • a burning or tingling sensation in your skin
  • abnormally sensitive skin that often causes severe pain when you come into contact with objects such as bedding or towels

Automatic neuropathy

Damage to the automatic nerves (automatic neuropathy) can result in a wide range of symptoms depending on where in the body the damage occurs.

Symptoms of automatic neuropathy include:

  • loss of co-ordination
  • loss of balance
  • problems swallowing (dysphagia)
  • nausea
  • vomiting
  • bowel incontinence
  • diarrhoea
  • constipation
  • excessive sweating
  • erectile dysfunction (impotence)
  • rapid heartbeat (tachycardia)
  • difficulty fully emptying your bladder of urine
  • low blood pressure (hypotension), which can make you feel very dizzy when standing up from a sitting or lying position

Mononeuropathy

In some cases, the damage that is caused by peripheral neuropathy is limited to a single nerve or group of nerves. This is known as mononeuropathy.

Symptoms of mononeuropathy include:

  • double vision or other problems with focusing your eyes
  • eye pain
  • weakness or paralysis in one side of your face (Bell's palsy)
  • foot or shin pain
  • chest pain

Another type of mononeuropathy is known as carpal tunnel syndrome (CTS). The carpal tunnel is a small tunnel that runs from the bottom of your wrist to your lower palm. Running through the carpal tunnel is a nerve known as the median nerve. In cases of CTS, the space inside the tunnel shrinks, placing pressure on the median nerve. Compression of the nerve results in symptoms of pain and numbness.

It is estimated that almost 5% of women and 3% of men have carpal tunnel syndrome. The condition is more common in people with diabetes. It is estimated that up to 8% of people with type 2 diabetes and 85% of people with type 1 diabetes will develop carpal tunnel syndrome at some point in their life. 

See the Health A-Z topic about Carpal tunnel syndrome for more information.

When to seek medical advice

Generally, the sooner the different types of neuropathies are diagnosed, the lower your chances of experiencing serious complications. Therefore, it is important to remain alert for the early signs and symptoms of peripheral neuropathy, such as:

  • a cut, graze or ulcer on your foot that does not appear to be getting better
  • feelings of numbness, weakness, tingling or pain in your hands and feet
  • dizziness when standing up, which could be the result of low blood pressure (hypotension)
  • changes in your normal bowel and bladder functions, such as persistent diarrhoea or constipation, or a sudden episode of bowel incontinence

See your GP if you experience the above signs and symptoms. It is also recommended that people with pre-existing risk factors for peripheral neuropathy should have regular check-ups so that their nerve function can be assessed. See Peripheral neuropathy - causes for more information.

Page last reviewed: 13/07/2011

In Ireland, diabetes is the most common cause of peripheral neuropathy.

Diabetes

Neuropathy that is associated with diabetes is called diabetic polyneuropathy. Between 10% and 20% of people who are newly diagnosed with diabetes have diabetic polyneuropathy.

The longer you have diabetes, the greater your chances of developing diabetic polyneuropathy. It is estimated that half of all people who have been living with diabetes for 25 years or more have diabetic polyneuropathy.

Other risk factors for diabetic polyneuropathy include:

  • smoking
  • high blood pressure (hypertension)
  • heavy consumption of alcohol
  • being 40 years of age or over
  • having poorly controlled diabetes

It is thought that diabetes damages the peripheral nervous system in two main ways:

  • The high levels of glucose associated with diabetes triggers a number of biological changes that cause your nerves to break down.
  • The high levels of glucose damage the blood vessels that supply your nerves, which accelerates the breaking down of the nerves.

Other causes

As well as diabetes, there are a number of other potential causes of peripheral neuropathy.

Health conditions

Health conditions that can cause peripheral neuropathy include:

  • chronic liver disease
  • chronic kidney disease
  • HIV or AIDS
  • prolonged and excessive alcohol misuse
  • nutritional deficiency (not having the right levels of different nutrients in your diet), particularly a vitamin B deficiency
  • lymphoma, which is a cancer of the lymphatic system (a series of glands that are part of the immune system)
  • multiple myeloma, which is a cancer of a type of blood cell called plasma cells
  • Lyme disease, a bacterial infection that is spread by ticks
  • Charcot-Marie-Tooth disease, a genetic condition that causes nerve damage, particularly in the lower limbs
  • having high levels of toxins in your body, such as arsenic, lead or mercury
  • Guillain-Barré syndrome, a rare and poorly understood condition that damages the peripheral nervous system
  • diphtheria, a bacterial infection that is rare in England but common in other parts of the world, particularly in developing countries such as Haiti and Vietnam
  • Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP), a rare condition caused by the immune system damaging the peripheral nerves
  • Multifocal Motor Neuropathy with Conduction Block (MMNCB), a rare condition caused by the immune system damaging the peripheral nerves

Medication

A number of medications are known to cause peripheral neuropathy as a side effect in some people. These include:

  • antiretrovirals: a group of different medications that are used to treat HIV infections
  • microtubule inhibitors: a type of chemotherapy medication that is used to treat a number of different cancers, such as advanced breast cancer and lymphoma
  • metronidazole: a medication that is used to treat infections caused by parasites
  • thalidomide, a medication that is used to treat multiple myeloma
  • phenytoin, a medication that is used to treat epilepsy
  • disulfiram, a medication that is used to treat people who are dependent on alcohol

Page last reviewed: 13/07/2011

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

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

These are discussed in more detail below.

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).

EMG involves having a small needle-shaped electrode inserted through your skin and 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 to obtain a more detailed assessment of how well your nerves and muscles are functioning.

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

If the results of these blood tests are still inconclusive, you may be referred to an oncologist, a cancer specialist, to check that your symptoms are not a complication of cancer, such as lymphoma (cancer of the lymphatic system) and multiple myeloma (cancer of the bone marrow).

Tests that your oncologist may carry out include:

  • X-ray, where radiation is used to study your bones
  • computerised tomography (CT) scan, where a scanner is used to take a series of X-rays, which it then assembles into a more detailed image
  • magnetic resonance imaging (MRI) scan, where strong magnetic fields and radio waves are used to produce a detailed image of the inside of the body
  • biopsy, where a sample of suspected cancerous tissue is removed so that it can be tested in a laboratory

Page last reviewed: 13/07/2011

Treatment for peripheral neuropathy will first address the condition's underlying causes.

For example, in cases of diabetic polyneuropathy, you will probably be advised to make a number of lifestyle changes to prevent further nerve damage. This may be:

  • giving up smoking
  • cutting down on your alcohol consumption, or ideally not drinking alcohol at all
  • maintaining a healthy weight, if you are overweight or obese
  • taking plenty of exercise

Neuropathic pain

As well as addressing the underlying causes of peripheral neuropathy, you may also require additional medication to treat the symptoms of nerve pain. The medical term for nerve pain is neuropathic pain.

Unlike most other types of pain, neuropathic pain does not usually respond well to treatment with widely used painkillers, such as paracetamol and ibuprofen. Therefore, alternative medications are usually required.

As many of these medications can cause a wide range of side effects, it may take some time to identify a medication that effectively controls your symptoms but does not cause side effects that are so unpleasant you prefer not to take it.

Therefore, you may need to try a number of the medications described below before you find one that suits you. In some cases, you may need to take a combination of different medications.

Initial treatments

Medications called amitriptyline, gabapentin and pregabalin are the initial treatments for people with neuropathic pain that is not associated with diabetes.

If you have diabetes, you should be offered a medication called duloxetine as your first treatment. If you are unable to take duloxetine for medical reasons - for example, because you have chronic kidney disease - amitriptyline may be used as an alternative.

Amitriptyline

Amitriptyline was originally designed to treat depression, but it has subsequently proved to be effective in treating some cases of neuropathic pain.

If you are prescribed amitriptyline, the lowest possible dose will usually be recommended. If the medication is not effective, your dosage can be gradually increased. This approach will help lower your risk of getting side effects.

Common side effects of amitriptyline include:

  • dry mouth
  • constipation
  • sweating
  • problems passing urine
  • slight blurring of vision
  • drowsiness

If you experience drowsiness or blurred vision, do not drive or operate machinery.

The side effects should ease after 7 to 10 days as your body gets used to the medication. However, if your side effects continue or if they become troublesome, tell your GP because it may be possible to change to a different medication that suits you better.

Some people have reported having thoughts of hurting or killing themselves while taking amitriptyline. If this happens to you, see your GP or go to your nearest hospital immediately.

It may be helpful to tell a close friend or relative that you are taking amitriptyline and ask them to keep an eye out for any changes in your behaviour. Do not drink alcohol when you are taking amitriptyline because the combined effects can make you feel very drowsy.

Pregabalin and Gabapentin

Pregabalin or gabapentin can be used as an initial treatment for neuropathic pain if you are unable or unwilling to take amitriptyline. As with amitriptyline, you will be prescribed the lowest possible dose necessary to control your symptoms. If required, the dose can be adjusted.

The two most common side effects of pregabalin and gabapentin are:

  • dizziness
  • tiredness

Do not drive if you experience these side effects.

Duloxetine

Duloxetine was originally designed to treat severe depression, but it has proved to be effective in treating neuropathic pain associated with diabetic polyneuropathy.

As with amitriptyline, there have been reports of people suddenly having thoughts of hurting or killing themselves after taking duloxetine. See your GP or go to your nearest hospital immediately if you experience such thoughts.

Common side effects of duloxetine include:

  • nausea
  • dry mouth
  • constipation
  • tiredness

Alternative medications

Nortriptyline and imipramine

Nortriptyline and imipramine are two alternative medications that can be used if the medications above do not work or cause distressing side effects.

Both these medications are similar to amitriptyline, but they have some important chemical and biological differences. Therefore, they may be an effective alternative treatment if amitriptyline does not work or causes too many unpleasant side effects.

If you experience side effects while taking nortriptyline or imipramine, they are likely to be similar to the side effects associated with amitriptyline (see above).

Topical lidocaine

Topical lidocaine is a mild local anaesthetic that numbs the skin and surrounding nerves. It is available as a cream, ointment, gel or spray. It may be recommended to treat localised pain if you cannot take the oral medications (tablets or capsules) above due to medical or other reasons.

Possible side effects of topical lidocaine include:

  • redness
  • swelling
  • irritation
  • itchiness

These side effects are usually mild.

Tramadol

Tramadol is a powerful opiate-based painkiller that can be used to treat cases of neuropathic pain which do not respond to any other treatment.

Like all opiates, tramadol can be addictive if it is taken for a long time. Therefore, it will usually only be prescribed for a short period, such as while you are waiting to be referred to a specialist in treating neuropathic pain.

Common side effects of tramadol include:

  • nausea
  • dizziness
  • constipation
  • sweating
  • dry mouth
  • confusion
  • headache
  • vomiting 

St John’s wort

Many of the medications discussed on this page can react unpredictably if they are taken in combination with the herbal supplement St John’s wort.

St John’s wort has been widely promoted as a herbal treatment for depression and is available to buy in most health stores without the need for a prescription.

It is strongly recommended that you do not take St John’s wort if you are taking one of the medications described on this page (with the exception of topical lidocaine).

Page last reviewed: 13/07/2011

Diabetic foot ulcer

A diabetic foot ulcer is an open wound or sore that develops on the skin. These types of ulcers are a common complication of peripheral neuropathy that is caused by diabetes (diabetic polyneuropathy).

Foot ulcers can develop due to reduced sensation in your foot. This makes it easy to damage or injure your foot by treading on something sharp. They can also occur if you unknowingly develop a blister due to badly fitting shoes. As you do not feel any pain, you may continue walking without protecting the wound. If the wound gets worse, it may develop into an ulcer.

High blood sugar can damage your blood vessels, causing the blood supply to your feet to become restricted. A reduced blood supply to the skin on your feet means it receives a lower number of infection-fighting cells, which will cause wounds to take longer to heal.

Gangrene

If you have reduced sensation in your feet, you are more likely to develop an ulcer. The reduced blood supply means that the ulcer is more likely to become infected. In turn, the infection is likely to restrict the blood supply further, which could lead to gangrene (tissue death).

It is only possible to stop severe cases of gangrene from spreading by amputating the foot. People with diabetes are 15 times more likely to have an amputation due to gangrene than people who do not have diabetes.

If you have type 1 or type 2 diabetes, it is essential to take extra care of your feet. Get your feet checked regularly by a podiatrist (a medical professional, also known as a chiropodist, who specialises in foot care).

Cardiovascular automatic neuropathy (CAN)

Cardiovascular automatic neuropathy (CAN) is another potentially serious complication that is common in people with diabetic polyneuropathy.

CAN occurs when damage to the peripheral nerves disrupts the automatic functions that control your blood circulation and heartbeat. CAN is estimated to occur in 5-10% of people who have had diabetes for 20 years or more.

The two main noticeable symptoms of CAN are:

  • an inability to exercise for more than a very short period of time
  • orthostatic hypotension

Orthostatic hypotension is a type of low blood pressure that develops when you move from a sitting or lying position to a standing position. It occurs because the problems caused by CAN mean that your circulatory system can longer compensate for the effects of gravity when you move to an upright position.

This means that the top half of your body, in particular your brain, can become starved of blood. This causes symptoms such as:

  • dizziness
  • nausea
  • headache
  • vision problems, such as blurred vision
  • mental confusion
  • fainting

You may be able to control the symptoms of orthostatic hypotension by using a number of self-care techniques, such as:

  • not standing or sitting up quickly
  • drinking plenty of fluids to increase the volume of your blood and raise your blood pressure
  • wearing compression stockings to help prevent blood from falling back down into your legs

In some cases, medication may be required to treat orthostatic hypotension. Two widely used medications are:

  • fludrocortisone, which works by increasing the volume of your blood
  • midodrine, which works by restricting your blood vessels

Side effects of fludrocortisone include:

  • an increase in appetite 
  • weight gain
  • insomnia
  • fluid retention
  • mood changes, such as feeling irritable or anxious

Side effects of midodrine include:

  • itching of the skin
  • tingling of the scalp
  • flushing of the skin

A more serious concern with CAD is that your heart may suddenly experience an abnormal pattern of beating (arrhythmia), which could lead to a cardiac arrest (your heart stops beating altogether). To prevent this, you may be prescribed medication to help regulate the beating of your heart, such as:

  • flecainide
  • beta-blockers
  • amiodarone

Side effects of these medications include:

  • tiredness
  • cold hands and feet
  • disturbed sleep
  • erectile dysfunction (impotence)
  • nausea
  • vomiting

You will probably be referred for annual check-ups so that your heart function can be monitored regularly.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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