Herpes Zoster
Symptoms and Signs
Symptoms and Signs
Herpes zoster (shingles) usually begins with a 1- to 2-day prodrome of pain or burning in a dermatomal distribution. The discomfort of zoster is deep like a neuralgia or superficial on the skin. The pain can be severe. In the chest or abdominal locations, prodromal pain can mimic cardiac, musculoskeletal, or intraperitoneal diseases.
The eruption consists of red papules or clear vesicles on a red base. The lesions, 2 to 4 mm in diameter, are frequently umbilicated, can be individual or grouped and are in a dermatomal distribution (Fig. 29-1). They often progress to confluent vesicles, which then erode and crust over. Secondary bacterial infection is common. Older patients are more likely to develop extensive involvement and severe pain. In severe cases and in immunocompromised patients, more than a single dermatome can be affected.
Herpes zoster is caused by the reactivation of varicella-zoster infection (chickenpox), usually suffered years before.
Differential Diagnosis
Herpes simplex recurrences are dermatomal, but typically appear on the lip or genitals. Insect bites, folliculitis, and tinea capitis can look the same as herpes zoster on the scalp. Cellulitis and erysipelas have considerable edema and erythema, especially when they affect the face. Human immunodeficiency virus (HIV) infection should be considered in all patients with herpes zoster.
How to Make The Diagnosis
Herpes zoster is often a clinical diagnosis but can be confirmed by some laboratory tests. Tzanck smear confirms infection with herpesviruses but
cannot differentiate between herpes simplex virus (HSV) and varicella-zoster virus (VZV). Tzanck smear is performed by unroofing a vesicle, scraping the base and smearing onto a glass slide, fixing with gentle heat or air dry, and staining with 5% methylene blue or Giemsa to look for multinucleated keratinocytes (see Chapter 28). Direct fluorescent antibody test confirms the presence of VZV or HSV within several hours. The test is done by the laboratory on a smear obtained in the same manner as for the Tzanck test (Fig. 28-3), or from centrifuged viral culture fluid. Biopsies and cultures may confirm the diagnosis but require several days.
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cannot differentiate between herpes simplex virus (HSV) and varicella-zoster virus (VZV). Tzanck smear is performed by unroofing a vesicle, scraping the base and smearing onto a glass slide, fixing with gentle heat or air dry, and staining with 5% methylene blue or Giemsa to look for multinucleated keratinocytes (see Chapter 28). Direct fluorescent antibody test confirms the presence of VZV or HSV within several hours. The test is done by the laboratory on a smear obtained in the same manner as for the Tzanck test (Fig. 28-3), or from centrifuged viral culture fluid. Biopsies and cultures may confirm the diagnosis but require several days.
Treatment
Because herpes zoster is self-limited, treatment is based on severity. Early treatment reduces the incidence and degree of postherpetic neuralgia. The dose of oral acyclovir for immunocompetent patients is 800 mg five times daily for 5 to 7 days. An alternative is valacyclovir, 1,000 mg three times daily for 10 days, or famciclovir, 500 mg or 750 mg three times daily for 7 days. For immunosuppressed patients, acyclovir 500 mg/m2 body surface area is given intravenously every 8 hours for 10 days.
For immunocompetent patients, adjunct systemic corticosteroids may reduce lesion healing time, acute neuritis, and the need for narcotic analgesia. One regimen is oral prednisone, 60 mg daily for 1 week followed by 30 mg daily for a second week together with antiviral agents.
Postherpetic neuralgia may require treatment with narcotic analgesics or tricyclic antidepressants such as amitriptyline 50 mg to 100 mg daily by mouth.
Oral antibacterial antibiotics are needed only if there is evidence of secondary infection: dicloxacillin, cephalexin, or erythromycin, 250 mg four times daily are equally effective.
Prognosis
Most cases of herpes zoster resolve with only mild scarring. Involvement of the tip of the nose is an important sign of potential corneal or conjunctival involvement because of the involvement of the ophthalmic branch of the trigeminal nerve, and ophthalmologic consultation is warranted. Ramsay Hunt syndrome (partial facial palsy) may occur when there is involvement of the geniculate ganglion. Recurrences are uncommon because immunity is boosted by an episode of herpes zoster. Postherpetic neuralgia is common in geriatric patients with severe disease. Immunocompromised patients can experience severe local or disseminated disease.
Herpes zoster is contagious to those who have not had varicella. Transmission is by direct contact with lesions.
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