This article includes discussion of varicella-zoster virus infections of the nervous system, herpes zoster, shingles, Zona, VZV infections of the nervous system, zoster sine herpete, acute disseminated encephalomyelitis, congenital varicella syndrome disseminated zoster, herpes zoster meningitis, herpes zoster myelitis, herpes zoster ophthalmicus, herpes zoster ophthalmicus and contralateral hemiplegia, herpes zoster oticus, postherpetic neuralgia, Ramsay Hunt syndrome type 2, varicella zoster virus meningitis, varicella-zoster virus meningitis, varicella-zoster virus encephalitis, and zoster sine herpete. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Varicella-zoster virus causes chickenpox (varicella) during primary infection, often in childhood. The virus becomes latent in dorsal root ganglia and can reactivate years later to produce shingles (zoster, zona) in adults, as well as postherpetic neuralgia and vasculopathies, which may involve brain, spinal cord, cranial nerves, or peripheral nerves or plexus. Diagnosis of varicella-zoster virus infection of the central and peripheral nervous system is critical as antiviral therapy can suppress productive infection with clinical benefit.
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• Varicella-zoster virus central nervous system infection can have various presentations, including encephalitis, meningitis, cranial neuropathies, vasculopathy, and myelitis.
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• Varicella-zoster virus has been identified as accounting for 15% to 23% of viral encephalitis in the United States (63).
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• The absence of a rash or history of shingles does not exclude the possibility of varicella-zoster virus meningoencephalitis, myelopathy, or vasculopathy (19; 57).
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• Identifying varicella-zoster virus as the etiology of CNS involvement can be challenging especially in the setting of no preceding rash. However, a rapid and accurate diagnosis is paramount as early initiation of antivirals is likely to improve patient outcomes.
Historical note and terminology
Varicella-zoster virus causes chickenpox (varicella) as a primary infection in childhood or, more rarely, in adults. The virus then becomes latent in neurons of dorsal root ganglia, cranial nerve ganglia, and autonomic ganglia. Varicella-zoster virus can reactivate years later to produce shingles (zoster) in adults. Chickenpox is a generalized exanthem, whereas shingles is usually limited to 1 or more adjacent sensory dermatomes. However, in immunocompromised individuals, systemic involvement can be seen in the setting of reactivation. Herpes zoster was described in medieval literature, and it was recognized as caused by varicella-zoster virus by the end of the 19th century (70). The relationship between varicella and zoster was not recognized until the end of the 19th century partially because varicella was not differentiated from variola (smallpox) (54). In 1888 Von Bokay suggested that chickenpox and shingles were related after observing that susceptible children could acquire chickenpox after exposure to adults with shingles (67). Varicella was shown to be infectious in 1875 by Steiner, and shingles in 1925 by Kundratitz (64; 37). The characteristic intranuclear inclusion bodies seen in varicella-zoster virus infections were described in chickenpox lesions by Tyzzer in 1906 and in shingles lesions by Lipschultz in 1921 (66; 42). In 1943 Garland suggested that shingles was due to the reactivation of latent varicella-zoster virus (16). The tissue culture and serologic studies of Weller and colleagues firmly established that chickenpox and shingles were due to a single etiologic agent (70; 71).
Developments include the use of polymerase chain reaction and in situ hybridization techniques to demonstrate that varicella-zoster virus DNA is latently present in trigeminal and thoracic ganglia (44). Specific prophylactic and therapeutic agents have also become available. Intravenous acyclovir is the mainstay of treatment for varicella-zoster virus dissemination and neurologic complications. Although not indicated for neurologic involvement, varicella-zoster virus immune globulin can prevent varicella infection in exposed seronegative pregnant women and immunocompromised children and newborns (05). A report of 2 neonates with severe varicella, despite intravenous immunoglobulin, suggests that infected infants should also receive acyclovir (60). In 1995 the U.S. Food and Drug Administration approved a live attenuated varicella-zoster virus vaccine (Varivax-Merck); this vaccine has been recommended for people 12 months of age or older, who are in good health and without a history of prior varicella-zoster virus infection (05).