YOUR
QUESTIONS
ANSWERED

A reference for
patients & their physicians
from the
National Shingles Foundation

Copyright © National Shingles Foundation, Inc.

The National Shingles Foundation does not practice medicine and no information contained in this booklet is medical advice or a substitute for the advice of a physician. If you have any of the conditions or symptoms described in this booklet, you should consult a physician as soon as possible.

PHN

Each year, approximately 1,000,000 individuals in the United States develop shingles, or herpes zoster, an often-painful outbreak of rash or blisters on the skin. Approximately 20 percent of these shingles patients, or 200,000 individuals, go on to suffer from PHN, or post-herpetic neuralgia. PHN is caused by damage to the nervous system during the shingles infection that can result in debilitating pain persisting for months or even years. The pain of PHN may be sharp, burning, throbbing or stabbing. The skin may be unusually sensitive to even the lightest touch (as from clothing or bed sheets), to the smallest breeze, and to changes in temperature (either hot or cold).

To fully understand PHN, one must take a step back—actually two steps back—to chickenpox—varicella—and its cause, the varicella-zoster virus (VZV).

The varicella-zoster virus first strikes as chickenpox, now preventable through vaccination. Following an episode of chickenpox, the virus lies dormant, or asleep, in nerve tissues. However, the virus can reactivate or reawaken as shingles. The shingles rash usually occurs in a band on one side of the body, or clustered on one side of the face. In otherwise healthy individuals, shingles may disappear without major consequence in two to four weeks. But the risk of complications from shingles—chief among them, PHN—increases with age, weakened immunity and delay or lack of treatment.

I
t is the National Shingle Foundation’s hope that this booklet will more fully familiarize you with PHN and provide you and your physician with an update on PHN pain relief therapies.

(1) What is PHN?

PHN (post-herpetic neuralgia) is the name given to the pain that lingers for months or even years after the rash caused by an infection called shingles has healed. Shingles is an often-painful outbreak of rash or blisters on the skin.

(2) What causes shingles and who can get it?

Shingles is caused by a reactivation of the varicella-zoster virus (VZV), the same virus that causes chickenpox. Anyone who has had chickenpox can get shingles, although it is most common in individuals over the age of 50. It is estimated that 10 to 20 percent of all Americans—and 50 percent or more of individuals aged 85 and older—will experience shingles during their lifetime. Individuals who have conditions, or are undergoing medical treatments, that weaken their immune systems are also more likely to develop shingles. These include: HIV infection; chemotherapy or radiation therapy; corticosteroids; transplant operations and possibly stress.

(3) How is shingles treated?

One of three oral, antiviral medications are usually prescribed for shingles: acyclovir, famciclovir and valaciclovir. Early treatment with one of these drugs—ideally within 72 hours of the appearance of the rash—can lessen the duration of shingles and lower the risk for PHN. If a patient experiences moderate or severe pain during acute shingles, a physician may prescribe one or more of the pain management therapies used in the treatment of PHN, which are listed in the response to question 16.

(4) What causes PHN?

PHN results from injury to the nervous system caused by the varicella-zoster virus during the shingles infection.

(5) Is PHN the only serious complication of shingles? Where do these complications occur?

No. PHN is one of several, potential shingles complications. For example, shingles affecting the eye (ophthalmic shingles) may result in impaired vision, or temporary or permanent blindness. Other shingles complications include local muscle weakness, infection of the central nervous system, bacterial skin infection and scarring.

The location on the body where a complication manifests itself is usually dependent on where the shingles rash occurred.

(6) Who can get PHN?

PHN can strike any of the nearly one million individuals who develop shingles annually in the U.S. It is estimated that approximately one out of five shingles sufferers, or 200,000 individuals, develop PHN each year, and that half of shingles patients over age 60—and 75 percent of those 70 and older—will experience PHN to some extent.

In addition to advanced age, other factors which increase the likelihood PHN will strike include: the severity of the shingles rash; the severity of the acute pain during the rash; and whether the patient had pain or other abnormal sensations before the shingles rash appeared.

(7) What are the signs and symptoms of PHN?

If an individual, whose shingles rash has healed, experiences significant pain in the area where the shingles rash occurred, or beyond that area, it could be PHN. In addition, if touching the skin causes pain, the patient may be experiencing allodynia, a frequent symptom of PHN. Allodynia is a condition in which the skin is unusually sensitive to normally painless stimuli, such as the touch of clothing or a gust of wind.

(8) Where does the pain of PHN usually occur?

PHN occurs in either the area, or a portion of the area, where the shingles rash appeared. The shingles rash usually occurs on either the trunk, back, chest, head, face, lower part of the spine or neck, but it also may occur on the limbs.

(9) What does PHN pain feel like?

The pain of PHN may be sharp, burning, throbbing or stabbing. The skin may be unusually sensitive to even the lightest touch (as from clothing or bed sheets), to the smallest breeze, and to changes in temperature (either hot or cold). The pain may be continuous or intermittent.

(10) How long does PHN last? Will it ever go away?

The duration of PHN varies widely. In some patients, it can last for months or even years. However, for many patients, the pain will lessen over time. Furthermore, there are a growing number of pain relief options for PHN that are proving to be effective for many patients.

(11) Is PHN contagious?

PHN is not contagious.

(12) Can PHN cause depression?

The pain of PHN can interfere with a patient’s daily routines and quality of life, resulting in depression. If a patient feels depressed and demoralized, he/she should discuss these feelings with a physician.

(13) What type of physician should be consulted to treat PHN?

If one suspects PHN, a physician should be seen as soon as possible. The physician may make a referral to a pain specialist, neurologist or anesthesiologist who has experience in working with PHN patients.

(14) Can PHN be cured?

Currently, PHN cannot be cured. The relief of the pain it causes is the focus of treatment. However, the effectiveness of treatment for PHN varies widely among patients.

(15) Can PHN be prevented?

Currently, PHN cannot be prevented in all patients. However, prompt medical treatment for shingles can lessen the duration of shingles and lower the risk for PHN. Specifically, the effectiveness of antiviral medication (acyclovir, famciclovir or valaciclovir) is well-established if it is taken within 72 hours after the appearance of the shingles rash.

There is a major study underway – The Shingles Prevention Study – whose aim is to determine if vaccination can decrease the incidence and/or severity of shingles and its complications in older adults. The study is also trying to determine if vaccination can protect against PHN. The outcome of this study will help scientists determine whether PHN prevention is a valid strategy using this vaccine.

(16) How is PHN treated?

The following is a brief summary of PHN treatments and their relative effectiveness as assessed in a paper published in the May 2000 edition of the journal Drugs, entitled, "Treatment of Postherpetic Neuralgia: An Update."1 In this article, authors Ghassan E. Kanazi, M.D., Robert W. Johnson, MB, BS, FRCA, and Robert H. Dworkin, Ph.D., reviewed the findings of recent studies.

Each pain relief medication or procedure assessed is referenced. Reference is also made to studies conducted on other medications that fall under the same classes of drugs, but that were unable to be included in this text due to space limitations. All study references are provided so that physicians can learn more about each treatment, including potential side effects.

One’s physician, who is most familiar with an individual’s case of PHN, will be able to determine which of these or other treatments can best relieve an individual’s PHN-related pain. Please note that the opinions expressed are those of the article’s authors and not the VZV Research Foundation, which is not licensed to practice medicine.

I. Pharmacological Approaches
(A) Topical Agents

Topical agents include the lidocaine patch (Lidoderm), a patch containing a solution of lidocaine, which is the same medication used by dentists. The lidocaine patch was approved by the U.S. Food and Drug Administration (FDA) in 1999 to treat PHN.

In their article in the journal Drugs, Drs. Kanazi, Johnson and Dworkin cite studies that found "a majority of patients treated with the…patch…reported moderate or greater pain relief." 1,2,3,4

Capsaicin cream is sold as a pain reliever for arthritis and PHN. Drs. Kanazi, Johnson and Dworkin stated, in their article, that capsaicin cream "continues to play a minor role in the treatment of patients with PHN. Compliance…is low because of the intense burning after application, which may, however, lessen with time." 1 These authors also reported a recent review concluded there is no evidence of significant improvement following capsaicin treatment. 1,5

  • Scientific articles covering other topical agents: 1,5,6,7

(B) Oral Medications

Antidepressants
In their article, Drs. Kanazi, Johnson and Dworkin stated that tricyclic antidepressants (TCA) are the only type of antidepressants—drugs which are used to treat depression—that have been shown to be effective in managing the pain of PHN. 1 According to these authors, the TCAs include nortriptyline (e.g. Pamelor), which has been found to have a significant analgesic effect in treating PHN pain, and has "fewer (adverse) side effects than amitriptyline, (the TCA which) has been the most widely used antidepressant in the treatment of PHN." 1,8

  • Scientific articles covering other antidepressants: 1,9,10,11

Anticonvulsants
Anticonvulsants, which were originally designed to prevent seizures in patients with epilepsy, include gabapentin (Neurontin). Drs. Kanazi, Johnson and Dworkin make reference, in their article, to a study which found gabapentin "significantly reduced (PHN) pain" and resulted in "improvements in sleep, mood and quality of life." 1,12

  • Scientific articles covering other anticonvulsants: 1,13,14

Analgesics
The article by Drs. Kanazi, Johnson and Dworkin notes the controlled-release opioid analgesics include controlled-release oxycodone (OxyContin), which, a study found, provides "significantly greater (PHN) pain relief, reduction of allodynia, decreased disability…than patients receiving placebo." 1,15

  • Scientific articles covering other analgesics: 1,16

Ketamine and N-methyl-D-aspartate (NMDA) Receptor Antagonists
In their article, Drs. Kanazi, Johnson and Dworkin reported recent studies have shown NMDA receptor antagonists provide some pain relief, but some may have adverse effects. 1,17,18,19,20

(C) Nerve Blocks

The article by Drs. Kanazi, Johnson and Dworkin cites a review of several studies, which found "the use of sympathetic nerve blocks…may be effective in relieving pain during acute shingles, (however) these blocks do not appear to provide prolonged relief in patients with longstanding PHN. (Therefore) it has been suggested their use be limited to special occasions where short-term relief is an important treatment goal." 1,21

II. Physical Treatments

In their article, Drs. Kanazi, Johnson and Dworkin note the use of natural fiber clothing, rather than artificial fibers, may help reduce the skin sensitivity (allodynia) often caused by PHN. 1 The authors report that: Transcutaneous Electrical Nerve Stimulation (TENS) has been "occassionally helpful" 1,22, but one study reported no benefit. 1,23; ultrasound "has a poor record in a few small series of patients with PHN" 1,24,25; and acupuncture "…seems to provide little benefit in PHN." 1,26 The authors also state that cold packs "often provide short term relief and are always worth trying." 1

III. Psychosocial Interventions

Drs. Kanazi, Johnson and Dworkin write, in their article, that cognitive-behavioral therapy, "…including such specific interventions as relaxation training, biofeedback and hypnosis, has a well-established role in the treatment of patients with chronic pain. 1,27,28 Although no studies have been reported that have specifically examined this…treatment (for) PHN, there is no reason to doubt cognitive-behavioral therapy provides as significant a benefit in PHN as it does in…other chronic pain syndromes…studied." 1

IV. Neuroinvasive Measures

In their article, Drs. Kanazi, Johnson and Dworkin cite a comprehensive review that was conducted of studies evaluating surgical procedures used for the treatment of PHN, including skin excision, dorsal root entry zone lesions, cordotomy and spinal cord and deep brain stimulation. 1,29 Drs. Kanazi, Johnson and Dworkin noted these studies "examined a small number of patients…none have been controlled, and the duration of patient follow-up has often been inadequate. Although some surgical procedures may provide significant relief for a small number of patients with PHN, these procedures are not without risk and are seldom recommended for the treatment of PHN." 1

Conclusion

Unfortunately, PHN cannot be prevented or cured…at least, not yet. The good news is twofold: (1) over time, the pain usually lessens; and (2) there are new, emerging pain relief therapies that appear to be helping greater numbers of patients.

The purpose of this text is to educate you and your physician about PHN and new research into PHN pain relief therapies. Please note, however, that the National Shingles Foundation does not practice medicine and no information contained in this text is medical advice or a substitute for the advice of a physician. If you have any of the conditions or symptoms described in this text, you should consult a physician as soon as possible.

REFERENCES

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