Introduction: Dengue is a common febrile illness caused by Dengue virus and spread by Aedes mosquitoes. The neurological complications like encephalopathy or encephalitis or immune-mediated neurological syndromes are uncommon though. Discrete neuroimaging findings in this setting are even rarer. We report a case of dengue encephalitis with uncommon MRI features in a young female.
Case presentation: The patient presented with complains of fever, vomiting, weakness in all limbs and difficulty in speech. Neurological examination revealed bilateral horizontal gaze palsy with impaired oculo-cephalic reflex, bulbar dysarthria and quadriplegia with bilateral planters up-going. Laboratory reported anemia, thrombocytopenia and positive NS1 antigen while excluding other tropical and immunological diseases. Brain MRI revealed extensive thalamic involvement as unique "double-doughnut" sign along with lesions in brainstem. The patient received supportive treatment in intensive unit and was discharged following improvement in clinical condition and laboratory reports.
Clinical discussion: Dengue can infect the central nervous system directly as encephalitis or can have neurological consequences following multi-organ dysfunction and shock as encephalopathy or post-infection immunological syndromes as Guillain-Barré Syndrome or cerebrovascular complications or dengue muscle dysfunction. The MRI appearance of "double-doughnut" sign points towards dengue encephalitis in appropriate setting.
Conclusion: A high index of suspicion is required to make a diagnosis of dengue encephalitis. The "double-doughnut" sign in MRI sequences has the potential to become a diagnostic marker for dengue encephalitis.
Keywords: ADC, Apparent Diffusion Coefficient; DWI, Diffusion-weighted imaging; Dengue; Double-doughnut sign; Encephalitis; FLAIR, Fluid-attenuated inversion recovery; GRE, Gradient echo sequence; NS1, Nonstructural protein 1; Neurological complications.
© 2022 The Authors.