What Is Postherpetic Neuralgia?
Postherpetic (post-her-Pet-ic) neuralgia is a very painful condition that affects the nerves and skin. It is a complication of herpes zoster—commonly called shingles.
Shingles is a painful, blistering skin rash caused by a reactivation of a virus called varicella-zoster, which people usually get during childhood. The initial infection with varicella-zoster causes chicken pox. Most people get chicken pox when they are children, but the virus can remain dormant in some of the body’s nerve cells and can reactivate many years later.
When the pain caused by shingles does not go away after the rash and blisters clear up, the condition is called postherpetic neuralgia. Postherpetic neuralgia is the most common complication of shingles. It occurs when a person’s nerves are damaged during a shingles outbreak. The damaged nerves cannot send messages from the skin to the brain and the messages can become confused. This results in chronic, severe pain that can last for months or years. About 20 percent of the people who get shingles also develop postherpetic neuralgia (Stankus, et al., 2000).
This condition is more likely to occur in people over the age of 60.
What Are the Risk Factors for Postherpetic Neuralgia?
The risk of getting shingles as well as postherpetic neuralgia increases with age.
People with lowered immunity due to other disorders like HIV and Hodgkin’s lymphoma (a type of cancer) are also at increased risk of developing shingles. For example, the incidence of shingles is up to 15 times higher in patients with HIV than in those who don’t have the virus (Stankus, et al., 2000).
What Are the Symptoms of Postherpetic Neuralgia?
Shingles typically causes a painful, blistering rash. Postherpetic neuralgia is a complication that occurs only in people who already have shingles. Common signs and symptoms of postherpetic neuralgia include:
- severe pain that continues for more than one to three months in the same place that the shingles occurred, even after the rash goes away
- burning sensation on the skin, even from the slightest pressure
- sensitivity to touch or temperature changes
How Is Postherpetic Neuralgia Diagnosed and Treated?
Tests are unnecessary. Most of the time, a doctor will diagnose postherpetic neuralgia based on the duration of pain symptoms following shingles.
Treatment for postherpetic neuralgia aims to control and reduce pain until the condition goes away. Pain therapy may include:
An analgesic is a drug that is specifically used to relieve pain. It is also known as a painkiller. Common analgesics used for postherpetic neuralgia include:
- capsaicin cream, an analgesic extracted from hot chili peppers
- lidocaine patches, a numbing medicine
- over-the-counter medications such as acetaminophen (Tylenol) or ibuprofen
- stronger prescription drugs like codeine, hydrocodone, or oxycodone
Tricyclic antidepressants are normally prescribed to treat depression, but they have been effective as part of the treatment for pain caused by postherpetic neuralgia. They often have side effects, like dry mouth and blurred vision, and do not act as quickly as other types of painkillers. Commonly used tricyclic antidepressants include:
- amitriptyline (Elavil)
- desipramine (Norpramin)
- imipramine (Tofranil)
- nortriptyline (Pamelor)
Anticonvulsants are normally used for seizures. However, clinical studies have shown that lower doses can be effective in treating the pain of postherpetic neuralgia as well. Commonly used anticonvulsants include
- carbamazepine (Tegretol)
- gabapentin (Neurontin)
- phenytoin (Dilantin)
How Can Postherpetic Neuralgia Be Prevented?
A herpes zoster vaccine called Zostavax reduces the risk of shingles by 50 percent. It also protects against postherpetic neuralgia. The Centers for Disease Control and Prevention (CDC) recommends that the vaccine be given to all adults over the age of 60. However, people with a weak immune system may not receive the vaccine because it contains a live virus (CDC, 2011).
The herpes zoster vaccine is different from the chicken pox vaccine that is usually given to children (Varivax). It has a concentration of live varicella virus of at least 14 times the amount found in Varivax. Zostavax cannot be used in children. Additionally, Varivax cannot be used to prevent herpes zoster.