Dengue encephalitis: “Double doughnut” sign

Amith S Kumar¹, Sahil Mehta¹, Paramjeet Singh², Vivek Lal¹,  
¹ Department of Neurology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
² Department of Radiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Correspondence Address:
Sahil Mehta
Department of Neurology, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
India

Full Text

A 22-year old primigravida presented with a 10-day history of fever and altered sensorium of 3-day duration. Cerebrospinal fluid (CSF) analysis showed lymphocytic pleocytosis with elevated protein (316 mg/dl) and normal sugar (76 mg/dl). IgG/IgM antibodies against dengue viral infections were positive in the serum and negative in CSF. IgM antibodies for Leptospira and Japanese encephalitis were negative. Magnetic resonance imaging (MRI) showed extensive parenchymal lesions in the bilateral thalami, midbrain, and deep cerebellar white matter. The lesions in bilateral thalami were hypointense on T1-weighted and hyperintense on T2 and fluid-attenuated inversion recovery (FLAIR); centre of the lesions showed intense diffusion restriction with presence of hemorrhage on susceptibility weighted images giving the appearance of double doughnut sign [Figure 1]a,[Figure 1]b,[Figure 1]c,[Figure 1]d,[Figure 1]e.{Figure 1}

Diagnosis of dengue encephalitis was made based on criteria laid down by Soares et al.[1]

Presence of fever;Acute signs of cerebral involvement such as altered consciousness or personality and/or seizures and/or focal neurological signs;Reactive IgM dengue antibody, NS1 antigen, or positive dengue polymerase chain reaction in serum and/or CSF;Exclusion of other causes of viral encephalitis and encephalopathy.

Thalamic involvement has been described in dengue encephalitis; however, to the best of our knowledge, this kind of appearance has not been reported in literature.[2],[3],[4],[5] Other imaging findings include involvement of brainstem, cerebellum, and medial temporal lobes. We propose to name the MRI finding in dengue encephalitis as “double doughnut sign.”

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References