What is Post-herpetic Neuralgia?

November 12, 2012

What is Post-herpetic Neuralgia?

This condition is a complication of shingles and is usually excruciatingly painful.

Post-herpetic neuralgia is painful condition which is often the result of an attack of shingles; it is an extremely painful condition affecting nerve fibers and skin.

Neuralgia is the general name for pain which occurs due to changes in neurological structure or function when nerves are irritated or damaged. Neuralgic pain occurs along the affected nerve.

What is pain?

There are two distinct types of pain -

  • Nociceptive – this is the type of pain felt due to temperature, touch, vibration, etc. This type of pain is the result of the work of specific pain receptors.

  • Non-noiceptive pain however is not connected to pain receptors but rather is the type of pain experienced through a trapped nerve for example; a nerve which is damaged or faulty is responsible for this type or pain. Since neuralgia is a neuropathic pain it may also be referred to as non-nocieptive pain.

  • The pain associated with post-herpetic neuralgia is often described as a shooting or burning pain along the nerve.

Shingles

Shingles is a painful medical condition caused by the same virus as chicken pox – the herpes varicellar-zoster virus. Most people who get a bout of chicken pox make a complete recovery and their immune system generally prevents the virus from reactivating. However, later in life the virus may be reactivated and cause an outbreak of shingles. Shingles generally affects the nerves in the chest and abdomen on one side of the body – both the nerve and the surrounding skin are infected. An outbreak of shingles lasts for between two and four weeks, any pain continuing after this period is referred to as post-herpetic neuralgia – this pain affects around 20% of older patients, this type of pain rarely affects children.

Causes of post-herpetic neuralgia

Shingles causes damage to the affected nerve which then disrupts the correct function of that nerve – it becomes confused and starts to send uncontrolled pain signals to the brain, causing the characteristic burning pain along the nerve. The reasons why some people develop post-herpetic neuralgia and others do not remain a mystery. Research does show the possibility that shingles causes the formation of scar tissue adjacent to the nerves which results in increased pressure on the nerve and the incorrect pain signals. Because this type of pain is associated with a specific illness it is relatively easy for the doctor to make a definite diagnosis.

Symptoms

Generally speaking the symptoms of post-herpetic neuralgia are generally associated with the area of the initial shingles outbreak. For some patients the pain is so severe and debilitating that they are unable to carry out everyday tasks such as washing and getting dressed. These symptoms may include -

  • Extreme sensitivity of touch and any fluctuations in temperature

  • Sharp, burning, shooting or jabbing pain

  • Constant burning, throbbing or aching pain

  • Itching

  • Numbness

  • Headaches

  • Fatigue or sleeping difficulties.

Treatment

Treatment of post-herpetic pain varies according to the patients overall health and the type of pain present.

  • Antidepressants in low doses are useful for affecting the body¬ís interpretation of pain.

  • Anticonvulsants may be used to calm and normalize the electrical activity caused by injured nerves.

  • Steroids can only be used once the shingles rash has disappeared and are generally only prescribed for patients with persistent long term pain.

  • A TENS machine is found to provide relief for some patients but not for others.

  • Spinal cord or peripheral nerve stimulation work in a similar way to a TENS machine but are placed under the skin and are an efficient way to treat many types of neuropathic pain.

  • Lidocaine skin patches

Prevention

Anyone who suspects they may have shingles should seek the advice of their medical practitioner as soon as possible. Aggressive and rapid treatment of the shingles rash appears to reduce the risk of developing neuralgia.

The best prevention is avoidance – try to avoid being in close contact with anyone who has chicken pox or shingles. Both chicken pox and shingles vaccines are available but neither provides total immunity.

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