Herpes Zoster

Herpes Zoster is the reactivation of varicella zoster virus infection. It usually presents as a painful vesicular eruption with a dermatomal distribution.

PATHOPHYSIOLOGY
The varicella virus lives inactive in the dorsal root / cranial nerve ganglia after primary infection. Reactivation of this virus causes replication of the virus in the neuronal bodies and are then carried along the axons to the skin dermatomes, causing the inflammatory eruptions.

RISK FACTORS
1. Age (mostly seen in geriatric population)
2. Immunosuppressed state (pregnancy, HIV, malignancy)
3. Spinal surgery
4. Stress
5. Sleep disorders and sleep deprivation

CLINICAL FEATURES
– In the prodromal phase; causes tingling, itching and knife like pain
– In the active phase; causes fatigue, malaise, headache, low grade fever and dermatomal rash
– On exam the rash appears erythematous and maculopapular. Vesicles are grouped and may become pustular
– Hutchinson’s sign: vesicles on tip on nose, indicate invovlement of external branch of cranial nerve V – associated with ocular zoster

LABORATORY
Although diagnosis is clinical
– Viral culture
– Tzanck smear
– PCR
– Varicella zoster IgM
Are some lab tests that could be ordered

TREATMENT
General Measures
1. Calamine lotion to reduce itching and burning
2. Analgesics (NSAIDs, Acetaminophen)

Acute Treatment
1. Antivirals <72hours of skin lesions (Acyclovir 800mg Q4H x 7 days, Valacyclovir 1000mg TID x 7 days, Famciclovir)
2. Other analgesics (Anitriptyline 25mg bedtime, Lidocaine patch, Gabapentin, Pregabalin)
3. Refer to ophthalmology if ocular involvement

References:
1. Hales CM, Harpaz R, Ortega-Sanchez I, et al; for Centers for Disease Control and Prevention. Update on recommendations for use of herpes zoster vaccine. MMWR Morb Mortal Wkly Rep. 2014;63(33):729–731.