Typically these conditions present with a prodrome which is nonspecific but indicative of a viral infection. Symptoms include fever, myalgia, rash, rigors and/or headache. Eventually CNS symptoms develop, which include dystonia, dyskinesia, tremor drooling, dysarthria and/or seizures 1.
There are over 70 Flaviviruses. The most important include:1-3
- Japanese encephalitis virus (Asia)
- West Nile virus (Middle East; North America)
- Tick-borne encephalitis virus
- Murray Valley encephalitis (Australia, New Zealand, Papua New Guinea)
- St Louis encephalitis virus (United States of America)
- Rocio virus (Brazil)
- Powassan virus (United States of America)
MRI is the modality of choice to evaluate all types of encephalitis.
Although the pattern of involvement varies from agent to agent, in general sites of involvement include 1:
- 1. Hegde AN, Mohan S, Lath N et-al. Differential diagnosis for bilateral abnormalities of the basal ganglia and thalamus. Radiographics. 31 (1): 5-30. doi:10.1148/rg.311105041 - Pubmed citation
- 2. Turtle L, Griffiths MJ, Solomon T. Encephalitis caused by flaviviruses. QJM. 2012;105 (3): 219-23. doi:10.1093/qjmed/hcs013 - Free text at pubmed - Pubmed citation
- 3. Solomon T. Flavivirus encephalitis. N. Engl. J. Med. 2004;351 (4): 370-8. doi:10.1056/NEJMra030476 - Pubmed citation