An Update on Diagnostic Imaging Studies for Viral Encephalitis

Naoki Kawamura; Madoka Kizawa; Akihiro Ueda; Yoshiki Niimi; Tatsuro Mutoh


Future Virology. 2012;7(9):901-909. 

In This Article

Encephalitis Caused by HSV

As mentioned earlier, HSV is the most common virus causing severe encephalitis in humans. Herpes simplex encephalitis (HSE) typically exhibits an acute-onset syndrome characterized by fever, headache, seizures, focal neurological signs and impaired consciousness. So far, acyclovir has made a significant reduction in HSE mortality and morbidity possible,[6] although both of these used to be very high prior to the discovery of this therapy. Because HSV often involves brain regions such as the limbic area of the temporal lobe as well as the frontal lobe, it is important to make a correct differential diagnosis from limbic encephalitis caused by immune-mediated nonviral encephalitis.[7,8] Pathologically, necrotic, inflammatory or hemorrhagic lesions are often observed in brain parenchyma in HSE patients. Accumulating evidence suggests that brain MRI can contribute to making a correct diagnosis of this disorder and has demonstrated the superiority of MRI over computerized tomography, especially in the early course of HSE,[9] although the final firm diagnosis should be based on the detection of viral DNA by sensitive methods, such as real-time PCR of HSV in cerebrospinal fluid.