An Intriguing Case of Expanded Dengue Syndrome With Co-existing Encephalitis, Pancreatitis, and Hepatitis: The Classic Thalamic "Double-Doughnut" Sign Revisited

Abstract

Background: Dengue neuro-infection can present with symptoms ranging from mild to severe. Atypical presentations, such as expanded dengue syndrome, pose diagnostic and therapeutic challenges. Neuroimaging findings, particularly the "double-doughnut" sign on brain magnetic resonance imaging (MRI), have emerged as one of the most valuable aids in diagnosing complex cases of central nervous system infection by dengue virus.

Case presentation: We report the case of a 35-year-old female from rural West Bengal, India, with expanded dengue syndrome. The patient presented with fever, headaches, body aches, and sudden disorientation over minutes, which progressed to a coma. Neurological examination revealed profound unconsciousness and nuchal rigidity. Laboratory findings were consistent with dengue infection, including altered liver and pancreatic enzyme levels. The diagnosis was facilitated by identifying the "double-doughnut" sign on the brain MRI, which suggested dengue encephalitis. This finding and clinical and serological evidence guided the treatment strategy.

Discussion: The "double-doughnut" sign, though not exclusive to dengue encephalitis, proved crucial in this case, aiding in differentiating from other causes of encephalitis. Recognition of this sign can be pivotal in diagnosing expanded dengue syndrome, facilitating timely and appropriate intervention, and improving patient outcomes. This case also underscores the importance of considering dengue in the differential diagnosis of encephalitis, especially in endemic areas. Also, this case's excellent outcome (both clinically and radiologically) was noteworthy.

Keywords: encephalitis; expanded dengue syndrome; hepatitis; pancreatitis; pleural effusion; “double-doughnut” sign.

Figure 1.

Axial T2-fluid-attenuated inversion recovery (A) and T2-weighted images (B) reveal hyperintense signals involving the bilateral thalamus (“double-doughnut” sign) (left more than right) and the right temporal cortex. Diffusion-weighted imaging sequences show diffusion restriction involving the bilateral thalamus (C), and postcontrast T1-weighted images show enhancement over the areas of diffusion restriction (D).

Figure 2.

Three-week follow-up axial T2-fluid-attenuated inversion recovery (A), T2-weighted (B), diffusion-weighted imaging (C), and postcontrast T1-weighted images show a decrement of lesions.