OUTCOME Prompt recovery with an antiviral
Ms. L receives IV acyclovir 1,200 mg every 8 hours for 14 days. Just 48 hours after starting this antiviral medication, her bizarre behavior and catatonic features cease, and she returns to her baseline mental functioning. Olanzapine is discontinued, and lorazepam is progressively decreased. The CSF polymerase chain reaction assay indicates Ms. L is positive for VZV, which confirms the diagnosis of VZV encephalitis. A spine MRI is also performed and rules out myelitis as a sequela of the infection.
The authors’ observations
Chickenpox is caused by a primary encounter with VZV. Inside the ganglions of neurons, a dormant form of VZV resides. Its reactivation leads to the spread of the infection to the skin innervated by these neurons, causing shingles. Reactivation occurs in approximately 1 million people in the United States each year. The annual incidence is 5 to 6.5 cases per 1,000 people at age 60, and 8 to 11 cases per 1,000 people at age 70.8
In 2006, the FDA approved the first zoster vaccine (Zostavax) for use in nonimmunocompromised, VZV-seropositive adults age >60 (later lowered to age 50). This vaccine reduces the incidence of shingles by 51%, the incidence of postherpetic neuralgia by 66%, and the burden of illness by 61%. In 2017, the FDA approved a second VZV vaccine (Shingrix, recombinant nonlive vaccine). In 2021, Shingrix was approved for use in immunosuppressed patients.9
Reactivation of VZV starts with a prodromal phase, characterized by pain, itching, numbness, and dysesthesias in 1 to 3 dermatomes. A maculopapular rash appears on the affected area a few days later, evolving into vesicles that scab over in 10 days.10
Dissemination of the virus leading specifically to VZV encephalitis typically occurs in immunosuppressed individuals and older patients. According to the World Health Organization, encephalitis is a life-threatening complication of VZV and occurs in 1 of 33,000 to 50,000 cases.11
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