Herpes zoster results from cutaneous activation of latent varicella zoster virus along a sensory nerve root dermatome. Pain or dysesthesia in an involved dermatome begins 3 to 5 days before lesions emerge. Erythematous papules develop first, progress to vesicular clusters, and these lesions crust after about a week. Herpes zoster of the ophthalmic branch of the trigeminal nerve, especially if accompanied by lesions on the nose, are concerning for possible eye involvement that can lead to keratitis or corneal ulceration (Fig. 155-1). A thorough eye exam should be performed (see Chapter 149, “Ocular Emergencies”). Generalized eruptions involving more than one dermatome may occur in immunocompromised patients.
A. Herpes zoster in trigeminal nerve distribution. Note lesion on the tip of the nose, which suggests nasociliary branch involvement. B. Dermatomes of the head and neck. cerv. = cervical; Gr. = greater; N. = nerve; Sm. = smaller. A. Reproduced with permission from Fleischer A Jr, Feldman S, McConnell C, et al. Emergency Dermatology: A Rapid Treatment Guide. New York, NY: McGraw-Hill; 2002. B. Reproduced with permission from Wolff K, Johnson R, Saavedra AP. Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology, 7th ed. New York: McGraw-Hill; 2013.
Diagnosis and Differential
The differential diagnosis for these kinds of skin eruptions may includes herpes simplex, impetigo, and contact dermatitis. The characteristic skin rash of herpes zoster presents in a unilateral distribution along a single sensory dermatome and is accompanied by localized pain at the site. A swab of the base of the vesicle can be sent for viral PCR to confirm the clinical diagnosis when uncertainty exists.
Emergency Department Care and Disposition
Antiviral medications started in the first 72 hours of illness shorten healing time, decrease formation of new lesions, and help prevent postherpetic neuralgia. Antiviral choices include acyclovir 800 mg PO five times per day for 7 to 10 days or valacyclovir 1000 mg PO three times a day for 7 days. Immunocompromised patients with severe disease can be treated with acyclovir, 10 mg/kg IV every 8 hours for 7 to 10 days.
Aluminum acetate compressions three times daily and analgesics provide symptomatic relief.
Advise patients that herpes zoster is contagious to anyone who has not had chicken pox or the varicella zoster vaccine.
Consult with an ophthalmologist if eye involvement is suspected.
HERPES SIMPLEX VIRUS INFECTIONS
Herpes simplex virus (HSV) lesions are painful grouped vesicles with an erythematous base. Primary disease may be preceded with or accompanied by constitutional symptoms. Tingling or burning precedes recurrent lesions. Oral lesions (“cold sores”) are usually caused by HSV1, but may also be caused by HSV2. The diagnosis can be confirmed with an HSV PCR test if necessary. Treatment (Table 155-1...