Rick is 63 years old. Like many people his age, he suffered through chickenpox as a child and was glad when it was over. Almost fifty years after that episode, he was surprised one day by a painful, blistering rash that wrapped itself in a “belt-like” band from his back to his chest. His doctor said that Rick had shingles – an illness that was caused by his long-ago bout with chickenpox. How was that possible? Worse yet, the awful pain from this new rash wouldn’t quit, even after the shingles blisters had gone away.
Rick didn’t know it at the time, but this type of nonstop, burning pain can sometimes happen after an attack of shingles. It’s called postherpetic neuralgia.
How it all starts
Let’s start with the original culprit: the varicella herpes zoster virus that causes chickenpox.
When Rick was young, there was no vaccine against chickenpox. As a result, he was one of the 4 million children in the U.S. that came down with the illness each year. But for these sick kids, there was a little surprise in store after their itchy rashes had cleared up: Some of the virus that had made them ill went into hiding and stuck around, sleeping. After 40 or 50 years (or more), this virus could become active again, causing a case of shingles.
One out of every three people in the U.S. gets shingles at some point in their lives. Most cases happen in adults over the age of 60. When the virus goes back into action in a grownup, it affects that person’s nerve fibers; it also affects the parts of the skin’s surface that are linked to those nerves. A few days or weeks in advance, the affected area might tingle or feel itchy. It finally erupts into the painful and blistering signature rash of shingles. This problem happens most often on a person’s chest, side, or back, although it can occur just about anywhere.
Shingles is a one-time event for many people: It clears up within a month, and the pain goes away. This painful time frame may be shortened if the person gets prompt treatment with an antiviral drug like acyclovir at the first sign of symptoms.
Unfortunately for Rick, though, the pain from his shingles kept going, weeks after his rash had disappeared. And this pain seemed worse, too – not only did it sting and burn all the time, but the affected area was very sensitive to temperature changes and wind. Even light pressure from clothing or bed sheets was agony.
Rick went back to the doctor and learned that:
- Pain that keeps going for three months or more after a shingles outbreak is called postherpetic neuralgia (PHN).
- Shingles causes irritation to the nerves in the original area of the rash. When nerve fibers are hurt, they no longer send normal pain messages to the brain. The signals can get mixed up, causing pain sensations that are unusual, or worse than expected.
- Age makes a difference: Postherpetic neuralgia happens to 60% of shingles patients over the age of 60, and to 75% of shingles patients over the age of 70.
- PHN doesn’t last forever. Seventy-five percent of patients are pain-free again within six months, and only one out of every 20 is still hurting within a year of the original shingles rash.
Is there a vaccine?
In 2006, the FDA approved ZostavaxTM vaccine for the prevention of shingles in adults over the age of 60. Stopping shingles before it starts is the best way to guard against the later pain of PHN. The vaccine works well: There are 50-64% fewer cases of shingles in Zostavax-vaccinated people. And if a vaccinated person develops shingles anyway, the pain doesn’t last as long.
Once again, though, age makes a difference. The vaccine is recommended for every person over the age of 60 who has had the chickenpox, unless there are specific medical reasons against using it. But people who get the vaccine after the age of 70 aren’t protected as well as those who get the shot when they’re younger.
How about treatment?
There are several different ways for healthcare providers to treat the pain of postherpetic neuralgia:
- With a prescription patch that can be applied to the skin (lidocaine patch 5%)
- With an antidepressant medication like amitriptyline
- With an antiseizure medication like gabapentin
Remember Rick? Thanks to the right medications, he’s now starting to feel better – there’s finally some light at the end of his painful PHN tunnel.
National Institute of Neurological Disorders and Stroke (NINDS)
http://www.ninds.nih.gov (search on “postherpetic neuralgia”)
http://www.mayoclinic.com (search on “postherpetic neuralgia”)
http://emedicine.medscape.com (search on “postherpetic neuralgia”)
U.S. Food and Drug Administration
http://www.fda.gov (search on “Zostavax”)