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Zoster usually presents as a painful unilateral dermatomal eruption. Zoster results from reactivation of varicella-zoster (chickenpox) virus which has been dormant.
Clinical Evaluation
Zoster is usually heralded by dermatomal pain, sometimes accompanied by fever. Within a few days, the skin overlying the dermatome reddens and blisters. A few vesicles are usually grouped on one erythematous base.
Zoster may occur in any dermatome, but the thoracic dermatomes are most often affected. In 90% of patients, pain eventually disappears completely zoster, postherpetic neuralgia, nuralgia, post herpetic, post-herpetic, shingles, shingle.
The frequency of zoster increases markedly after age 55, but people of any age can be affected. Less than 5% of immunocompetent patients who have one episode of herpes zoster will have another.
Laboratory evaluation
The diagnosis of herpes zoster can be made on clinical grounds.
Complications of herpes zoster
15% of patients with zoster have involvement of the ophthalmic branch of the trigeminal nerve. Hutchinson's sign, a lesion on the tip of the nose, indicates corneal involvement.
Therapy for zoster
Wet dressings or compresses with Burow's solution (Domeboro) will protect sensitive areas. Acetaminophen, nonsteroidal anti-inflammatory drugs, or analgesics.
Antiviral therapy for zoster
An antiviral can hasten the resolution of the rash by several days. Relief of acute pain occurs
Acyclovir ( Zovirax)
800 mg q4h while awake (5 times a day) for 7 days. [400, 800 mg tab].
Oral acyclovir does not have significant adverse effects; nausea, headaches, diarrhea,
Famciclovir (Famvir) is equally effective as acyclovir; it has a more convenient dosing interval; one 500-mg tablet tid for 7 days.
Valacyclovir (Valtrex), may be slightly more effective.
Foscarnet (Foscavir) is useful for acyclovir-resistant herpes infections.
Ophthalmic distribution zoster is a medical emergency which requires IV acyclovir.
Postherpetic neuralgia
PNH is the most common complication of herpes zoster. It is defined as chronic pain persisting for at least one month after the skin lesions have healed.
The incidence of PHN after an episode of herpes zoster is 5-50%.
Topical preparations
Capsaicin cream OTC ( Zostrix, Zostrix-HP) 0.025% tid-qid reduces
EMLA topical cream (lidocaine and prilocaine) qid may be useful.
Amitriptyline (Elavil) is often effective; 10-25 mg qhs, increasing in weekly increments of 25 mg as needed.
Gabapentin (Neurontin), 300 mg qd-tid, may be effective. Carbamazepine (Tegretol), 200 mg bid, has also been used.
Transcutaneous electrical nerve stimulation (TENS), lidocaine injections, nerve block injections, permanent nerve blocks.