Learning objectives
1) To have a better understanding of dengue encephalitis as a whole.
2) To be aware of various spectrum of imaging findings in MRI brain.
3) To play a pivotal role in diagnosing leading to aggressive management and improving outcome
Background
Dengue is a an arthropod borne disease (Mc vector: Aedes aegypti, occasionally,Ae. albopictus)
Caused by dengue virus (DENV): single-stranded RNA virus of the flavivirus genus. It has four serotypes: DEN1, DEN2, DEN3 and DEN4.
Spectrum of dengue involves:
Asymptomatic or subclinical
Dengue fever
Dengue hemorrhagic fever
Dengue shock syndrome
Others(encephalopathy, myocarditis, myocarditis)
Findings and procedure details
Dengue encephalitis: What is it ?
Dengue virus was considered non-neurotropic [1] of Flaviviridaegroup.
Dengue virus and anti-dengue IgM has been isolated from CSF of dengue serology positive patients with neurological manifestations.
DEN2 and DEN 3 have relatively greater likelihood of neurological manifestation.
Dengue encephalitis is a very rare manifestation with a prevalence of ~4-21% [2]
characterized by direct invasion of virus into brain parenchyma.
The reported incidence of neurological complications of dengue has been found to vary between 0.5% and 6.2% [3],
Encephalitis V/s...
Conclusion
There are many varieties of MR imaging spectrum in dengue encephalitis. The imaging appearance depends on mechanism of disease manifestation. They can be broadly concluded in following categories:
1.Reduced platelet count cause multifocal cerebral and cerebellar hemorrahges.
2.Hemoconcentration causes multiple areas of infarct.
3.Neurotropic effects causes encephalitis
4.Autoimmune reactions cause ADEM
5.Metabolic factors causes encephalopathy transient splenial hyperintensity or vasculitis or Posterior reversible encephalopathy syndrome.
Personal information and conflict of interest
S. Kale; Bengaluru+/IN - nothing to disclose D. P. Kumar; Bengaluru+/IN - nothing to disclose N. Panchal; Mumbai/IN - nothing to disclose S. Agrawal; Bangalore/IN - nothing to disclose
References
1.Nathanson N, Cole GA. Immunosuppression and experimental virus infection of the nervous system. Adv Virus Res 1970;16:397-428.
2.Domingues RB, Kuster GW, Onuki-Castro FL, Souza VA, Levi JE, Pannuti CS,et al.Involvement of the central nervous system in patients with dengue virus infection. J Neurol Sci 2008;267:36-40
3. Soni k, Das D S, George R A ,Aggarwal R, and Sivasankar R. MRI features in dengue encephalitis: A case series in South Indian tertiary care hospital. Indian J Radiol Imaging. 2017 Apr-Jun; 27(2): 125–128.
4 Solomon T, Dung...