Peripheral neuropathy can cause a range of complications.
These very depending on the underlying cause of the condition, and can include foot ulcers and disturbances to the blood circulation and heartbeat.
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. Every year in the UK, around 5,000 people with diabetes have an amputation as a result of gangrene.
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 no 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 CAN is that your heart may suddenly experience an abnormal pattern of beating (arrhythmia), which could lead to a cardiac arrest, in which 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.