Harvard Health Letters

Shingles can be a painful rash that goes away after a few weeks -- or it can be hellish.

"Horrible" and "excruciating" is how some people describe postherpetic neuralgia, the painful aftermath that develops after the initial rash phase in about 10- to 20 percent of shingles cases. Postherpetic neuralgia pain is hard to predict. It can last for months, even years. Yet it can also end abruptly (and mercifully) for no apparent reason.

Doctors have several options for treating postherpetic neuralgia. Small doses of the tricyclic antidepressant medications (amitriptyline, desipramine, nortriptyline) act as pain relievers. Antiseizure medications, such as gabapentin (Neurontin) and pregabalin (Lyrica) can be used alone or in combination with the tricyclics.

Some study results suggest that antiseizure medications are particularly good in controlling piercing, knifelike pain. Topical creams containing capsaicin (the substance that makes chili peppers spicy hot) or lidocaine (which also comes as a patch) may provide a little relief. If all else fails, some patients benefit from injections of medications into the spinal canal.

Despite all the options, between 40 percent and 50 percent of the time, postherpetic neuralgia patients don't respond to any treatment.

Prevention, so often the road not taken, is once again the more prudent route. Early treatment of shingles with antiviral drugs has been shown to cut the risk of postherpetic neuralgia substantially.

Better yet, there's a shingles vaccine, sold under the name Zostavax. In the large (38,000 people), randomized trial that led to its FDA approval in 2006, the vaccine reduced the risk of shingles by half and of postherpetic neuralgia by an impressive two-thirds. And, by all accounts, it's safe.

Federal vaccine officials have recommended that everyone age 60 or older with a healthy immune system be vaccinated against shingles, advice that applies to people who've already had a case, because shingles can recur. Yet surveys indicate that probably less than 10 percent of the Americans who should get the vaccine have done so.

The wholesale price of Zostavax is about $200 per shot, so it's not a minor expense. The vaccine is covered by Part D Medicare plans, but they're set up to reimburse pharmacies, not physicians, so physicians run into difficulties billing for the shingles vaccine. Other adult vaccines are covered by Medicare Part B, which covers physician services, but so far, legislative and lobbying efforts to move the shingles vaccine into Part B have failed.

Merck, the manufacturer of Zostavax, has had problems keeping up with demand for the vaccine, due to manufacturing setbacks.

COMPROMISED IMMUNE SYSTEM

Shingles occurs when latent varicella virus particles escape a dorsal root ganglion and travel along sensory nerves to the skin. Shingles is caused by the varicella zoster virus, the same virus that causes chickenpox. The varicella zoster virus is in the herpesvirus family, so the more formal medical term for shingles is herpes zoster.

After a bout of chickenpox, leftover varicella virus hides out in the nervous system in an inactive state, held in check there by the immune system. If the immune system (more precisely, the T cells of the immune system) weakens, the snoozing varicella virus can come roaring back to life, replicate, and cause the havoc we experience as shingles and postherpetic neuralgia. The pain comes from inflammation and injury to nerves, as well as changes in how pain signals are processed.

The risk of shingles increases with age because the strength of the immune system declines as we get older. Shingles starts to become more common in our 50s; half of everyone who makes it to age 85 will have experienced shingles some time along the way. But anyone harboring the varicella virus in their nervous system, which is true of most everyone over age 40, and who has an impaired immune system is vulnerable. This includes people with HIV/AIDS, some kinds of cancer (especially Hodgkin's disease), and organ transplant recipients. Some studies suggest that stressful events can bring shingles on.

The classic shingles rash appears as a red band on one side of the torso. Shingles may affect nerves in other parts of the body, including those in the arms or legs, resulting in muscle weakness and wasting in the affected limbs. Some of the worst cases involve the trigeminal nerve in the face, particularly the branches that supply the area around the eye. Herpes zoster ophthalmicus, as it is called, can lead to inflammation in the cornea (keratitis) and even vision loss. It's also more likely than other sorts of shingles attacks to develop into postherpetic neuralgia.

LESS CHICKENPOX, MORE SHINGLES?

Children in this country started getting vaccinated against chickenpox in 1995. Now most young American children get the two-shot vaccine, so chickenpox is fast disappearing. The chickenpox vaccine is made with the same live, but weakened, strain of the varicella virus as the shingles vaccine, although the dose is much smaller.

The virus in the childhood chickenpox vaccine can seed itself in the nervous system just like "wild" varicella, so some people vaccinated as children may get shingles later on by virtue of having gotten the chickenpox vaccine. But studies so far suggest the risk and severity is far less than when children were exposed the old-fashioned way by getting chickenpox.

Yet having wild varicella virus in wider circulation may have had some benefits. It's thought that when adults who had chickenpox as children were re-exposed to the virus as adults, it served as a kind of immunological reminder, boosting the immune system's efforts to contain the varicella virus already in the body. With less wild varicella virus around because of the chickenpox vaccine, adult immune systems don't get those reminders, so they may let their guards down. As a result, shingles may become more common.

So far, the epidemiologic data are inconclusive on whether there has, in fact, been a large increase in shingles since the chickenpox vaccine was introduced. In 2009, there was an interesting report about children and teens and shingles in the Antelope Valley region of Los Angeles County (shingles in children and teens is unusual but not unheard of). The number of cases among children younger than age 10 declined by 55 percent between 2000 and 2006, but cases among 10- to 19-year-olds increased by 63 percent, possibly because they didn't get an immunological boost from exposure to wild varicella virus.

GETTING THE VACCINE

Results of a national survey of 600 general internists and family doctors reported in the Annals of Internal Medicine in 2010 showed that 88 percent recommended that their patients get the shingles vaccine, but half as many said they did so strongly.

Storage presents some problems: The shingles vaccine must be refrigerated at a lower temperature than other vaccines. The fact that Zostavax is backordered also means delays in receiving it once an order has been placed. But reimbursement is the bigger barrier. Less than half (45 percent) of the doctors surveyed knew that shingles vaccine was reimbursed through Medicare Part D, and 12 percent said they had stopped offering the vaccine because of the cost and reimbursement issues.

But you may not need to see a doctor to get the shingles vaccine. Some states now allow vaccines to be administered at pharmacies. All Part D plans must include the shingles vaccine in their formulary. Medicare beneficiaries should check about copayments and whether their Part D plan has contracts with particular pharmacies.

Some doctors let their patients "brown bag" the vaccine: People buy it at the pharmacy and then bring it to the doctor's office to be administered. The cost of the vaccine itself should be covered by the Part D plan, but usually the doctor will ask you to pay the cost of administering the vaccine out of pocket. You should get a receipt and submit it to your Part D plan for reimbursement, but you probably won't get all your money back. - Harvard Health Letter

 

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