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Home :: Herpes Zoster
Herpes Zoster
Herpes zoster (HZ) is an acute dermatomal infection associated with reactivation of varicella-zoster (VZV) and is characterized by unilateral pain and a vesicular or bullous eruption limited to a dermatome(s) innervated by a corresponding sensory ganglion. The major morbidity is postherpetic neuralgia (PHN).
Causes of Herpes Zoster
Most physicians believe there is a temporary weakness in the body's ability to fight off disease. This allows the virus to start reproducing and move along nerve fibers toward the skin. The fact that the disease occurs more often in people older than age 50 (although children can get it, too) supports this since the immune response is believed to be weaker in older people. Trauma or possibly stress may also trigger a zoster attack.
Symptoms of Herpes Zoster
Symptoms may include:
- skin hypersensitivity in the area where the herpes zoster appears
- mild rash, which appears after five days and first looks like small, red spots that turn into blisters
- blisters which turn yellow and dry
- rash which usually goes away in one to two weeks
- rash is usually localized to one side of the body
Diagnosis
Prodromal Stage Suspect HZ in older or immunocompromised individual with unilateral pain.
Active Vesiculation Clinical findings usually adequate; may be confirmed by Tzanck test and possible DFA or viral culture to rule out HSV infection.
PHN By history and clinical findings.
Treatment
Goals of management Relieve constitutional symptoms; minimize pain; reduce viral shedding; prevent secondary bacterial infection; speed crusting of lesions and healing; ease physical, psychological, emotional discomfort; prevent viral dissemination or other complications; prevent or minimize PHN.
Antiviral therapy In individuals at high risk for reactivation of VZV infection, oral acyclovir can reduce the incidence of HZ. In prodromal stage: begin antiviral agent if diagnosis is considered likely; analgesics. With active vesiculation: antiviral therapy begun ≤72 h accelerates healing of skin lesions, decreases the duration of acute pain, and may decrease the frequency of PHN when given in adequate dosage.
- Acyclovir 800 mg PO qid for 7-10 days. The 50% viral inhibitory concentration of acyclovir is three to six times higher for VZV than for HSV in vitro, and drug dose must be increased appropriately. The bioavailability of acyclovir is only 15 to 30% of the orally administered dose. For ophthalmic zoster and HZ in the immuno compromised host, acyclovir should be given intravenously. Acyclovir hastens healing and lessens acute pain if given within 48 h of the onset of the rash.
- Valacyclovir 1000 mg PO tid for 7 days, 70 to 80% bioavailable.
Supportive therapy for acute HZ
- Constitutional symptoms Bed rest, NSAIDs.
- Sedation Pain often interferes with sleep. Sleep deprivation and pain commonly result in depression. Doxepin, 10 to 100 mg hs, is an effective agent.
Chronic stages (PHN) Pain is that of reflex sympathetic dystrophy.
- Pain management Severe prodromal pain or severe pain on the first day of rash is predictive of severe PHN. Gabapentin: 300 mg tid. Tricyclic antidepressants such as doxepin, 10 to 100 mg PO hs. Capsaicin cream every 4 h. Topical anesthetic such as EMLA or 5% lidocaine patch for allodynia. Nerve block to area of allodynia. Analgesics.
Prevention
- Immunization Immunization with VZV vaccine may boost humoral and cell-mediated immunity and decrease the incidence of zoster in populations with declining VZV-specific immunity.
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