Page 161 - The Vasculitides Volumes 2

Central Nervous System Vasculitis Due to Infection 137

cryoglobulinemia, arthritis, and palpable purpura. There is an immune response to the Fc
portion of immunoglobulin, characterized by the Wa idiotype. The resulting immune complex
which contains virus, idiotypic antibody, and antibody precipitates in the cold and produces a
small vessel vasculitis. HCV can cause CNS vasculitis independent of cryoglobulinemia, and
CNS vasculitis may be the first clinical manifestation of hepatitis C infection [63, 64].

Affected patients present with progressive headache, multiple strokes, and typical
angiographic patterns. Therapy includes the antiviral agents interferon (IFN), ribavirin,
sofosbuvir, protease inhibitors, and corticosteroids. Both HBV and HCV have been
associated with polyarteritis nodosa (PAN) that typically involves the peripheral nervous
system (PNS), but unusual cases may involve the CNS [65]. In such cases antiviral therapy is
added to corticosteroids, and cyclophosphamide in more severe cases. This might involve the
virostatic agent lamivudine or INF-alpha for HBV and ribavirin for HCV [66]. Plasma
exchange and rituximab can be added in specific cases as needed.

Parvovirus B19

Parvovirus B19 is a small non-enveloped DNA virus that only infects humans. It causes
erythema infectiosum also known as fifth disease, a benign childhood condition characterized
by a classic slapped-cheek appearance. It can cause anemia with pre-existing disease as well
as arthritis. The cellular receptor for parvovirus B19 is an antigen of the P blood group
present on endothelial cells and erythroid progenitor cells [67]. Rare patients with CNS
vasculitis have been reported in association with Parvovirus B19 infection [67, 68]. The
diagnosis is based on serological studies and PCR testing. There is no specific antiviral
therapy for Parvovirus B19 infection; however both intravenous immune globulin (IVIG) and
corticosteroids have been used therapeutically.

West Nile Virus

West Nile virus is a flavivirus typically transmitted by the bite of infected culex
mosquitos. Less than 1% of patients develop invasive neurological disease that includes
meningitis, encephalitis, and resultant flaccid paralysis, with rarely reported cases of ischemic
infarction and CNS vasculitis [69-71] and occlusive retinal artery vasculitis. Patients with a
history of diabetes and alcohol abuse, and older individuals are at increased risk for ischemic
complications [72]. Diagnosis is based on IgM antibody and viral RNA detection, as well as
virus isolation. There is no antiviral therapy, but IVIG has been beneficial in individual
patients.

Fungal Pathogens

Aspergillus
Aspergillosis is the most common invasive mold infection worldwide.

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