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Table of Contents    
Year : 2017  |  Volume : 65  |  Issue : 3  |  Page : 670-671

Dengue encephalitis: “Double doughnut” sign

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

Date of Web Publication9-May-2017

Correspondence Address:
Sahil Mehta
Department of Neurology, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/neuroindia.NI_723_16

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How to cite this article:
Kumar AS, Mehta S, Singh P, Lal V. Dengue encephalitis: “Double doughnut” sign. Neurol India 2017;65:670-1

How to cite this URL:
Kumar AS, Mehta S, Singh P, Lal V. Dengue encephalitis: “Double doughnut” sign. Neurol India [serial online] 2017 [cited 2023 Dec 7];65:670-1. Available from:

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: MRI brain (a). Hypointensity in bilateral thalami in T1W images (b). Hyperintensity in bilateral thalami in T2W images (c and d). Intense diffusion restriction at the centre of bilateral thalami in DW and ADC images (e) with hemorrhages in the centre of bilateral thalami in SWI

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

  1. Presence of fever;
  2. Acute signs of cerebral involvement such as altered consciousness or personality and/or seizures and/or focal neurological signs;
  3. Reactive IgM dengue antibody, NS1 antigen, or positive dengue polymerase chain reaction in serum and/or CSF;
  4. 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.”

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 » References Top

Soares CN, Marzia PS. Diagnosis criteria of dengue encephalitis. Arq Neuropsiquiatr 2014:72:263.  Back to cited text no. 1
Borawake K, Prayag P, Wagh A, Dole S. Dengue encephalitis. Indian J Crit Care Med 2011;15:190-3.  Back to cited text no. 2
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Kamble R, Peruvamba JN, Kovoor J, Ravishankar S, Kolar BS. Bilateral thalamic involvement in dengue infection. Neurol India 2007;55:418-9.  Back to cited text no. 3
[PUBMED]  [Full text]  
Varatharaj A. Encephalitis in the clinical spectrum of dengue infection. Neurol India 2010;58:585-91.  Back to cited text no. 4
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Garg RK, Malhotra HS, Jain A, Malhotra KP. Dengue-associated neuromuscular complications. Neurol India 2015;63:497-16.  Back to cited text no. 5
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