Peripheral neuropathy

Peripheral neuropathy develops when the peripheral nerves are damaged. Which symptoms you get depends on which nerves are affected.

In the UK, it's estimated that almost 1 in 10 people aged 55 or over have peripheral neuropathy.

The peripheral nervous system is the network of nerves that lie outside the central nervous system (the brain and spinal cord). It includes the nerves in your feet and hands.

Peripheral nerves:

• transmit sensations like pain and touch
• control muscles
• regulate some body functions like blood pressure

Peripheral neuropathy comes in 4 types:

• sensory neuropathy: damage to the nerves that carry sensations like touch, temperature and pain
• motor neuropathy: damage to the nerves that control movement
• autonomic neuropathy: damage to the nerves that control bodily functions like digestion, bladder function and blood pressure
• mononeuropathy: damage to a single nerve outside the central nervous system

Many people have more than 1 type of peripheral neuropathy at the same time.

The symptoms of peripheral neuropathy aren't the same for everyone, because they depend on which type you have. They may also come on quickly for some people and slowly for others.

• a prickling or tingling feeling in the affected body part
• "pins and needles" in the affected body part
• a burning or sharp pain, usually in the feet
• numbness in the affected body part
• being less able to feel pain or changes in temperature, particularly in your feet
• being more able to feel pain, to the point that even a light touch hurts (allodynia)
• losing your balance or co-ordination (sensory ataxia)

• twitching and muscle cramps
• muscle weakness or paralysis that affects 1 or more muscles
• thinning (wasting) of your muscles
• foot drop (difficulty lifting the front part of your foot), which causes you to trip

• constipation or diarrhoea, particularly at night
• feeling sick, bloating and belching
• low blood pressure, which can make you feel faint or dizzy when you stand up
• rapid heartbeat
• problems with the amount you sweat (either too much or too little)
• problems with sexual function, like erectile dysfunction
• difficulty fully emptying your bladder

Mononeuropathy doesn't look the same in everyone, because the symptoms depend on which nerve has been affected. Some examples are:

• pain, weakness or altered sensation your fingers, feet or shins
• double vision or other problems with focusing your eyes, sometimes with eye pain
• weakness of one side of your face (Bell's palsy)
• Carpal tunnel syndrome

Diabetes, both type 1 and type 2, is the most common cause of peripheral neuropathy. When it happens this way, it's called diabetic polyneuropathy.

The high blood sugar levels that come with diabetes can damage the nerves. The longer you've had diabetes, the more likely peripheral neuropathy becomes.

Your risk of diabetic polyneuropathy is higher if:

• your blood sugar is poorly controlled
• you smoke
• you regularly drink large amounts of alcohol
• you're over 40 years old

There are many other possible causes of peripheral neuropathy. These can include:

• monoclonal gammopathy of undetermined significance (the presence of abnormal protein in the blood)
• cancers like lymphoma (cancer of the lymphatic system) and multiple myeloma (bone marrow cancer)
• low levels of vitamins like vitamin B12
• drinking too much alcohol for a long period of time
• malnutrition (poor diet)
• some types of chemotherapy for cancer, particularly those used for bowel cancer, breast cancer, lymphoma or myeloma
• genetic conditions that cause nerve damage, like Charcot-Marie-Tooth disease
• some medicines when taken for a long time, like metronidazole, nitrofurantoin, phenytoin, amiodarone and thalidomide
• physical injury to the nerves
• infections like shingles, Lyme disease, diphtheria, botulism and HIV
• hypothyroidism (an underactive thyroid gland)
• chronic kidney disease or liver disease
• conditions caused by an overactive immune system, like rheumatoid arthritis, lupus, Sjogren's disease or vasculitis (inflammation of the blood vessels)
• rare conditions like Guillain-Barré syndrome and amyloidosis
• exposure to high levels of toxins, like arsenic, lead or mercury

If you have symptoms of peripheral neuropathy, make an appointment with your doctor. They'll ask about your symptoms and may arrange some tests to help find the underlying cause.

If you're taking a medicine known to cause peripheral neuropathy, your doctor may stop it for a while or lower your dose, to see whether your symptoms get better.

Do not stop taking any prescribed medicine without checking with your doctor first. You could make yourself very ill.

If your doctor isn't sure what's causing the peripheral neuropathy, you may be referred to a neurologist. This is a specialist in conditions affecting the nervous system, and they may do some further tests.

In general, the sooner peripheral neuropathy is diagnosed, the better. Early diagnosis gives you the best chance of limiting the damage and preventing further complications.

See a doctor if you have:

• pain, tingling or loss of sensation in the feet
• loss of balance or weakness
• a cut or ulcer on your foot that isn't getting better

How things turn out with peripheral neuropathy is different for each person. It depends on:

• the underlying cause
• which nerves have been damaged
• how severe the damage is

If the cause of your peripheral neuropathy can be treated, the condition may get better with treatment and time. Take diabetes as an example. If your diabetes is well controlled, that may stop the neuropathy getting worse, and you may find it improves too.

Sometimes the underlying cause can't be treated. In that case the damage may be permanent, and it may get worse with time.

Peripheral neuropathy can lead to other health problems, and some of them can be severe. They include:

• cardiovascular autonomic neuropathy, where damage to the peripheral nerves causes problems with your heartbeat and blood circulation
• diabetic foot ulcers, where damage to your blood vessels means wounds take an unusually long time to heal, which can lead to further problems

Sometimes the cause of peripheral neuropathy can't be treated. Even then, you can still get help to manage your symptoms.

If you have nerve pain from peripheral neuropathy, the doctor may prescribe different types of medicine. Standard painkillers like ibuprofen and paracetamol often don't work well on nerve pain, which is why other medicines are used.

If the pain is in one particular area of your body, capsaicin cream may help. Capsaicin is the substance that makes chilli peppers hot. It's thought to stop the nerves sending pain messages to the brain, and that's why it can be useful for nerve pain. Menthol cream can have a similar effect.

If the pain only affects a small area of skin, you may be offered a lidocaine plaster. This is a large sticking plaster that contains a local anaesthetic, and the skin under the plaster absorbs it.

If these creams and plasters don't work, your doctor may consider a neuropathic agent. These include some types of anti-depressants.

If muscle weakness is a problem for you, physiotherapy may help. It can improve the weakness.

Occupational therapy can help you find new ways to do tasks that have become difficult.

If you have foot drop or you keep tripping, orthotics can help, and ankle supports are one option.

If you have hyperhidrosis (excessive sweating), your doctor may offer you botulinum toxin (botox) injections. These could help reduce your sweating.

If you're struggling to empty your bladder with peripheral neuropathy, your doctor may offer you urodynamic studies. Depending on the result, you may then be offered medicine or urinary catheterisation to help you.