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Shingles or herpes zoster is a painful and sometimes
debilitating viral disease that afflicts nearly one million Americans
annually. The incidence of herpes zoster increases with age and among
the immunocompromised; the highest incidence of shingles is among
those over age 75, and the majority of shingles patients are between
55 and 75 years of age [1]. As the U.S. population
ages and more people are immunocompromised by AIDS, cancer treatment
and organ transplantation, physicians can anticipate a rise in the
number of shingles cases they treat. As a result, the physician can
expect an increase in patients with post-herpetic neuralgia (PHN),
a painful complication of zoster. Like zoster, the incidence of PHN
increases with age. Between nine and 15 percent of zoster patients
suffer from PHN. [2]
Immediate Attention Is Imperative
The challenge to the physician is the prompt and proper diagnosis
and treatment of shingles. Herpes zoster is difficult to diagnose
in its prodromal stage and may often be misdiagnosed in its acute
phase. Early recognition is paramount; when treated within 72 hours
of eruption of vesicular rash -- and preferably well before 72 hours
-- the severity and duration of shingles is significantly lessened.
Acute pain responds to prompt treatment of herpes zoster, and immediate
therapy lessens the duration of pain in PHN patients.
The Cause: Varicella-Zoster Virus
Herpes zoster, an acute infection of the nervous system, is caused
by the varicella-zoster virus (VZV), the same virus responsible
for chickenpox. Whereas itching is the key symptom of the rash of
varicella (chickenpox), pain is the overriding characteristic of zoster.
More than 90 percent of Americans over age 15 have experienced chickenpox
[3], making them all susceptible to shingles at a later time.
It is estimated that between 10 to 25 percent of the population will
experience herpes zoster. It is unusual for children and young adults
to develop shingles. While chickenpox is highly contagious, zoster
itself is not transmissible. However, the lesions of shingles contain
infectious VZV and individuals who have not had chickenpox can develop
varicella from exposure to patients with shingles.
Following a bout of varicella, VZV remains dormant in the sensory
ganglia, usually for decades. Shingles is the often painful result
of the reactivation of the dormant virus in these nerves. This reactivation
is due to the decline in cellular immunity to VZV that can be the
result of aging and immunosuppression. The incidence and severity
of herpes zoster and PHN increase with advanced age. Some hypothesize
that psychological stress may play a role in the development of PHN
[4]. It is not known what triggers VZV to reactivate.
Gender does not affect the incidence of shingles or PHN
[5], and no genetic cause or association has been shown. A
multi-center study is underway to determine whether re-exposing the
elderly to VZV, through vaccination, will boost VZV immunity and thus
lessen the frequency and severity of herpes zoster in this population
[6].
Symptoms - Zoster
The major and most common symptom of zoster is pain that can be severe
and persistent. In the prodromal stage - on average
48 to 72 hours before the presence of rash -- diagnosis can be difficult.
Typical symptoms can include:
- Localized numbness;
- Localized tingling, burning or shooting pain that may be constant
or intermittent;
- Localized itching; and,
- Fever, headache, chills and nausea.
The eruptive stage is characterized by a painful rash
of blistered skin that typically is limited to a band on one side
of the body, often localized to the trunk, face or forehead. Thus
the names, Zoster, which is Greek for belt, and Shingles, which comes
from "cingulum," Latin for girdle or belt. The skin lesions of zoster
resemble those of varicella (progressing to vesicles, pustules and
scabs), but, unlike varicella, are usually painful and not disseminated
widely. When the eye is affected, unilateral blindness can result
[7].
Diagnosis in the eruptive stage is not always self-evident. The rash
of zoster has been misdiagnosed as allergic reactions and insect bites.
A rapid and specific diagnosis can be made by performing an indirect
immunofluorescence stain on a smear of cells recovered from the lesion
and transferred to a microscope slide.
New lesions may appear for up to five days. In the immunocompetent
patient, healing is usually complete within two to four weeks. Individuals
who are immunocompromised are most susceptible to more prolonged and
even repeat bouts of shingles [8].
Post-Herpetic Neuralgia
Post-herpetic neuralgia (PHN) is the name given to the pain that persists
one to three months or longer after the shingles rash has healed
[9]. The risk of developing PHN is directly related to the
patient's age when shingles appears, and patients with ophthalmic
zoster may be at increased risk. PHN is one of the most severe and
intractable of chronic pains, lasting months or years after the disappearance
of zoster blisters [10].
The pain of PHN may be sharp, piercing, throbbing or stabbing. It
is the result of injury to the peripheral nerves and resultant changes
in the signal processing of the central nervous system
[11]. The pain may extend beyond the margins of the original
zoster eruption [12]. The skin may be unusually
sensitive to even the lightest touch (as from clothing), to the smallest
breeze, and to changes in temperature (either hot or cold). The severity
and duration of pain appears to increase with age.
The devastating effect of PHN on quality of life for many patients
cannot be underestimated. Most debilitating can be allodynia, pain
triggered by otherwise trivial stimula, with some individuals remaining
housebound because they cannot tolerate the touch of clothing.
Treatment Options - Zoster
In selecting therapies to treat shingles and PHN, the patient's age
and health status should be taken into account. For example, immunocompromised
patients may fare better with an intravenous, rather than an oral,
antiviral drug.
Zoster:
Use of antiviral drugs is a key therapy because drugs
may limit the replication and spread of the reactivated virus within
the ganglion to the skin. Treatment with an orally-administered antiviral
drug within 72 hours of shingles eruption in healthy elderly patients
speeds healing of zoster blisters and the resolution of pain. The
earlier antiviral therapy is begun, the better the outcome.
Oral antivirals include acyclovir, famciclovir, and valaciclovir.
FDA approved dosages are: acyclovir, 800 mg five times a day for 10
days; famciclovir, 500 mg t.i.d. for seven days; and valaciclovir,
1000 mg t.i.d. for seven days [13]. These antivirals
generally are well tolerated. Side effects may include nausea, headache,
diarrhea, and vomiting [14].
Corticosteroids, taken in combination with an antiviral, lessen the
duration of pain in the acute phase of zoster, allow the patient to
resume normal activity and restore uninterrupted sleep
[15]. Corticosteroids are only recommended for healthy, elderly
individuals who experience moderate or severe pain; this population
seems to derive the greatest benefit [16].
Post-Herpetic Neuralgia:
Some tricyclic antidepressants -- notably amitriptyline, desipramine,
nortriptyline and maprotiline -- are effective as "analgesics" in
treating PHN [17]. Recent studies have also shown
that some nonopioids, opioids and adjuvant analgesic drugs are also
effective in treating PHN pain. Selective seratonin uptake inhibitors
(e.g., fluoxetine, sertraline, paroxetine) are less effective as analgesics,
and conventional analgesics such as ibuprofin are ineffective
[18]. Patients should be informed that a tricyclic drug is
being prescribed for its analgesic - not antidepressant - properties.
Once an appropriate dose level is attained, it may take up to 10 days
for the analgesic effect of the drug to be felt, and that dosage may
need to be adjusted.
Narcotic analgesics seem to benefit some patients with PHN. Cold packs
may offer temporary relief of pain.
Because the pain of PHN can be debilitating, negatively affecting
relationships and severely limiting professional and personal activities,
patients should be encouraged to consult a specialist in pain treatment.
Cognitive-behavior modification, biofeedback and relaxation training
are among the approaches used by these specialists.
About the VZV Research Foundation
The urgent need for increased research and education on chickenpox,
shingles and PHN led to the formation of the VZV Research Foundation
(VZVRF) in 1991. This publicly-supported charity serves as an important
information resource to thousands of VZV sufferers, their families
and their physicians. The Foundation also sponsors international scientific
conferences on VZV and awards research grants to investigate the reasons
for the virus' reemergence, to develop new vaccines to prevent chickenpox
and shingles in the immunocompromised, and to seek out new treatments
for PHN pain.
VZVRF is guided by its Board of Directors and has a Scientific Advisory
Board consisting of more than 30 internationally renowned experts
on VZV.
For further information on the Foundation or its activities, please
contact:
VZV Research Foundation
40 East 72nd Street
New York, NY 10021
Tel. 212-472-3181
800-472-VIRUS (1-800-472-8478)
Fax: 212-861-7033
E-MAIL: VZV@VZVFoundation.org
The VZV Research Foundation is a tax-exempt, charitable organization
under section 501(c)(3) of the Internal Revenue Code, identification
number 13-3601316. Gifts to the Foundation are tax deductible to the
full extent permitted by law.
Footnotes:
- Ragozzino, M.W., Melton L.J. III, Kurland L.T.
et al., "Population-Based Study of Herpes Zoster and Its Sequelae,"
Medicine, 1982, Vol. 62, pp. 310-316.
- Hope-Simpson, R.E., "The Nature of Herpes Zoster:
A Long-Term Study and a New Hypothesis," Proc R Soc Med, 1965, Vol.
58, pp. 9-20; Burgoon, C.F., Jr., Baldridge, G.D., "The Natural
History of Herpes Zoster," Journal of the American Medical Association,
1957, Vol. 164, pp. 264-265.
- Straus, Stephen, "Shingles: Sorrows, Salves and
Solutions," Journal of the American Medical Association, April 14,
1993, Vol. 269, p. 1836.
- Dworkin, Robert, "Identifying the Likelihood of
PHN: A Research Update," VZV Focus, Vol. III, No. 1, Summer/Fall
1995, p. 4.
- Ragozzino, M.W., "Incidence of Herpes Zoster Per
100,000 Person Years" (figure), Archives of Dermatology, 1957, Vol.
75, pp. 193-196.
- Oxman, Michael, "Immunization To Reduce the Frequency
and Severity of Herpes Zoster and Its Complications," Neurology,
Vol. 45, No. 12, Supplement 8, p. S45.
- Pavan-Langston, Deborah, "Herpes Zoster Ophthalmicus,"
Neurology, Vol. 45, No. 12, Supplement 8, pp. S50-51.
- Shingles, National Institute of Neurological Disorders
and Stroke, October 1996.
- Nurmikko, Turo, "Clinical Features and Pathophysiologic
Mechanisms of Postherpetic Neuralgia," Neurology, Vol. 45, No. 12,
Supplement 8, p. S54.
- Kost, Rhonda, Straus, Stephen, "Postherpetic Neuralgia:
Pathogenesis, Treatment and Prevention," New England Journal of
Medicine, July 4, 1996, Vol. 335, No. 1, p. 32.
- Ibid., p. 33.
- Ibid.
- Physicians' Desk Reference 1996 Edition, Medical
Economics, pp. 1196, 1220, 2488.
- Ibid., pp. 1195, 1225, 2488.
- Kost, Rhonda, Straus, Stephen, "Postherpetic Neuralgia:
Pathogenesis, Treatment and Prevention," New England Journal of
Medicine, July 4, 1996, Vol. 335, No. 1, p. 37.
- Whitley, Richard J., et al., Annals of Internal
Medicine, 1996, 125:376-383.
- Kost, Rhonda, Straus, Stephen, "Postherpetic Neuralgia:
Pathogenesis, Treatment and Prevention," New England Journal of
Medicine, July 4, 1996, Vol. 335, No 1, p. 36; Watson, C. Peter,
"The Treatment of Post-Herpetic Neuralgia," Neurology, December
1995, Vol. 45, No. 12, Supplement 8, pp. S58-59.
- Ibid.