We all know what toothache or a bad-headache feels like and how glad we are when these painful conditions subside. It’s almost beyond our capability to imagine pain which doesn’t always go away and which might even last for years. Picture someone very close to you, in desperation because of neuropathic pain in the feet, going outside at four o’clock on a winter’s morning and standing on a frozen lawn to lessen the pain and burning sensations. This is a real-life example, by no means extreme, of how this type of pain may affect a person.
In the UK alone such significant suffering is believed to affect at least half a million people today.
Neuropathic pain may be defined as pain arising from a disturbance of function or pathological change in a nerve. The multiple kinds of abnormal pain sensations may suggest that several different changes from the normal healthy state of the nerves has taken place. Some people, for example, may experience severe pain as a result of just light pressure from clothing, air movement, or changes in temperature. Others may even experience spontaneous pain for which no obvious cause can be determined. Such pain may be continuous or may even occur in intermittent bursts.
When tests and examinations are performed on people affected in this way, it is common to also discover different areas of numbness, due to the damaged nerves. There is a growing awareness amongst doctors that our perception of pain is complex and that many different factors are involved. Ideally, how pain is defined and how it is treated should take account of these factors.
Causes of Neuropathic Pain
The term ‘neuropathic pain’ covers a number of different causes and types of pain, examples are:
‘Diabetic neuropathy’, at it’s simplest, is most often experienced as pain and/or numbness in the feet and is one of the complications of having diabetes.
After someone has had chicken pox, the virus (varicella zoster) becomes permanently resident in nerve cells, although this in itself does not cause symptoms. However, in some patients, the virus can become reactivated to cause the acutely painful condition of shingles or herpes zoster. In a small number of patients with shingles the affected nerve can become permanently damaged to give neuropathic pain long after the shingles has resolved. This is known as post herpetic neuralgia.
• Amputation of a limb:
When people have a limb amputated some people may experience ‘phantom limb pain’. They feel pain in the amputated limb, even though the limb is no longer there.
Neuropathic pain is experienced by some people with cancer as a result of either the tumour or the treatment given.
• Trigeminal neuralgia:
This is a type of neuropathic pain that occurs in the face. It is due to problems with one of the facial nerves.
• HIV infection:
Having the HIV virus can result in HIV related painful peripheral neuropathy. Some treatments for HIV may also cause the condition.
• Multiple Sclerosis:
Pain can be a symptom of multiple sclerosis because the layer of insulation around the nerve becomes damaged (demyelination).
Some people who have a stroke develop neuropathic pain.
• Surgery and trauma:
Pain can follow surgery or trauma due to accidental damage to a nerve.
Some drugs can cause a peripheral neuropathy.
• Back problems:
Some people who have back pain also experience sciatica. Sciatica is the term given to a neuropathic pain down the leg. This is caused by irritation of the sciatic nerve which is the main nerve into the leg.
In some instances is it not always possible to discover the underlying cause and these cases are described as ‘idiopathic’ or ‘cryptogenic’.