A 65-year-old female resident of Ribeirão Preto, São Paulo, Brazil, presented with a 4-day history of a headache, fever, myalgia, mild dyspnea, painful respiration, and vomiting. After 4 days, her condition worsened with a loss of muscle tone, seizures, and a decreased level of consciousness. Physical examination showed Babinski sign bilaterally. A computed tomography scan performed on day 7 showed minimal hypodensity of the internal capsule. Her serum electrolyte and creatinine levels were normal. Two analyses of cerebrospinal fluid showed: total protein of 72-86mg/dL; leukocyte count of 1.0/mm³; glucose level of 77-91mg/dL, and a chloride level of 118-125mg/dL. immunoglobulin M (IgM) and immunoglobulin G (IgG) test results for dengue were positive, whereas venereal disease research laboratory, cytomegalovirus, toxoplasmosis, and rubella serology test results were negative. Brain magnetic resonance imaging (MRI) on day 8 revealed small areas of hyperintensity on T2/Fluid attenuation inversion recovery (FLAIR)/, bilaterally, on both the internal capsule and corona radiata (Figure A) with minimal signs of diffusion restriction of water on the apparent diffusion coefficient map (Figure B). The susceptibility weighted imaging showed no signs suggestive of bleeding. The features observed in the imaging studies together with the clinical presentation and laboratory tests were consistent with those likely to be found in acute dengue encephalitis1–3. Complementary investigations ruled out other possible causes of neurological disorders1–3. After supportive therapy in the ICU, the patient improved and subsequently discharged. A posterior brain MRI revealed a regression of the signal intensity abnormalities seen previously and signs of cerebral volume loss (Figure C).
