Answer for BIR CoW 09 Aug 2020
Dengue Encephalitis
Findings
Bilateral thalami are enlarged with T2 hyperintensities, restricted diffusion and hemorrhage on SWI giving the appearance of double doughnut sign. T2 hyperintiesities with restricted diffusion & hemorrhage on SWI also noted in posterior limb of internal capsule, external capsule, posterior midbrain, pons, bilateral cerebellar hemispheres, bilateral medial frontal, para-median parieto-occipital cortical - subcortical regions. Mild obstructive hydrocephalus due to compression of 4th ventricle by edematous enlargement of pons and cerebellar hemisphere. CT Brain shows – Edematous enlargement of bilateral thalami hemorrhagic foci within. Edema also seen in the bilateral cerebellar hemispheres with effacement of the cerebellar foliae.
Discussion
Dengue can involve the brain in the form of encephalopathy or encephalitis. Encephalitis occurs due to direct neurological invasion by virus causing inflammation of brain parenchyma. On imaging, focal abnormalities are suggestive of encephalitis rather than encephalopathy. Encephalopathy is usually secondary to multisystem derangement such as encephalitis, hepatic failure, shock, coagulopathy, and bacterial infections. It presents as diffuse involvement of brain without any specific findings on imaging. Imaging Features • CT - hyperattenuating intraparenchymal foci representing spontaneous macrohaemorrhages. • MRI – The MRI changes are brain edema, intracerebral hemorrhage, basal ganglia and thalamic involvement, cortical, subcortical white matter changes. The four most commonly affected regions of brain include 1. basal ganglia- thalamic complex, 2. cerebral hemispheres, 3. brainstem and 4. cerebellum. Focal lesions caused by dengue appear hyperintense on T2, hypointense on T1 weighted imaging and show restricted diffusion. Hemorrhagic foci may be seen which show blooming on SWI. Double doughnut sign – Restricted diffusion in the centre of bilateral thalami with blooming in susceptibility weighted imaging due to petechial hemorrhages gives the appearance of Double Doughnut. Differential Diagnosis • ADEM - hemorrhage is uncommon. • Japanese Encephalitis - hemorrhagic findings, although described, are less common. • Herpes simplex Encephalitis – Bilateral temporal lobes, insula, basifrontal lobes are most commonly involved in herpes encephalitis. Usually spares the basal ganglia.
References:
1.Bhoi SK, Naik S, Kumar S, Phadke RV, Kalita J, Misra UK. Cranial imaging findings in dengue virus infection. J Neurol Sci 2014;342:36-41. 2.Rastogi R, Garg B. Findings at brain MRI in children with dengue fever and neurological symptoms. Pediatr Radiol 2016;46:139-44.
3.Madi D, Achappa B, Ramapuram JT, Chowta N, Laxman M, Mahalingam S. Dengue encephalitis-A rare manifestation of dengue fever. (2014) Asian Pacific journal of tropical biomedicine. 4 (Suppl 1): S70-2.
4.Carmo RLD, Alves Simão AK, Amaral LLFD, Inada BSY, Silveira CF, Campos CMS, Freitas LF, Bonadio V, Marussi VHR. Neuroimaging of Emergent and Reemergent Infections. (2019) Radiographics : a review publication of the Radiological Society of North America, Inc. 39 (6): 1649-1671.
5.Nadarajah J, Madhusudhan KS, Yadav AK, Gupta AK, Vikram NK. Acute hemorrhagic encephalitis: An unusual presentation of dengue viral infection. Indian J Radiol Imaging 2015;25:52-
6. Brijesh K Soni,Debasheesh S R Das,R A George ,R Sivashankar et al MRI features in dengue encephalitis:A case series in south Indian tertiary care hospital,Indian journal of radiology and Imaging,2017; Vol 27 ( 5 ): 125-128.
Findings
Bilateral thalami are enlarged with T2 hyperintensities, restricted diffusion and hemorrhage on SWI giving the appearance of double doughnut sign. T2 hyperintiesities with restricted diffusion & hemorrhage on SWI also noted in posterior limb of internal capsule, external capsule, posterior midbrain, pons, bilateral cerebellar hemispheres, bilateral medial frontal, para-median parieto-occipital cortical - subcortical regions. Mild obstructive hydrocephalus due to compression of 4th ventricle by edematous enlargement of pons and cerebellar hemisphere. CT Brain shows – Edematous enlargement of bilateral thalami hemorrhagic foci within. Edema also seen in the bilateral cerebellar hemispheres with effacement of the cerebellar foliae.
Discussion
Dengue can involve the brain in the form of encephalopathy or encephalitis. Encephalitis occurs due to direct neurological invasion by virus causing inflammation of brain parenchyma. On imaging, focal abnormalities are suggestive of encephalitis rather than encephalopathy. Encephalopathy is usually secondary to multisystem derangement such as encephalitis, hepatic failure, shock, coagulopathy, and bacterial infections. It presents as diffuse involvement of brain without any specific findings on imaging. Imaging Features • CT - hyperattenuating intraparenchymal foci representing spontaneous macrohaemorrhages. • MRI – The MRI changes are brain edema, intracerebral hemorrhage, basal ganglia and thalamic involvement, cortical, subcortical white matter changes. The four most commonly affected regions of brain include 1. basal ganglia- thalamic complex, 2. cerebral hemispheres, 3. brainstem and 4. cerebellum. Focal lesions caused by dengue appear hyperintense on T2, hypointense on T1 weighted imaging and show restricted diffusion. Hemorrhagic foci may be seen which show blooming on SWI. Double doughnut sign – Restricted diffusion in the centre of bilateral thalami with blooming in susceptibility weighted imaging due to petechial hemorrhages gives the appearance of Double Doughnut. Differential Diagnosis • ADEM - hemorrhage is uncommon. • Japanese Encephalitis - hemorrhagic findings, although described, are less common. • Herpes simplex Encephalitis – Bilateral temporal lobes, insula, basifrontal lobes are most commonly involved in herpes encephalitis. Usually spares the basal ganglia.
References:
1.Bhoi SK, Naik S, Kumar S, Phadke RV, Kalita J, Misra UK. Cranial imaging findings in dengue virus infection. J Neurol Sci 2014;342:36-41. 2.Rastogi R, Garg B. Findings at brain MRI in children with dengue fever and neurological symptoms. Pediatr Radiol 2016;46:139-44.
3.Madi D, Achappa B, Ramapuram JT, Chowta N, Laxman M, Mahalingam S. Dengue encephalitis-A rare manifestation of dengue fever. (2014) Asian Pacific journal of tropical biomedicine. 4 (Suppl 1): S70-2.
4.Carmo RLD, Alves Simão AK, Amaral LLFD, Inada BSY, Silveira CF, Campos CMS, Freitas LF, Bonadio V, Marussi VHR. Neuroimaging of Emergent and Reemergent Infections. (2019) Radiographics : a review publication of the Radiological Society of North America, Inc. 39 (6): 1649-1671.
5.Nadarajah J, Madhusudhan KS, Yadav AK, Gupta AK, Vikram NK. Acute hemorrhagic encephalitis: An unusual presentation of dengue viral infection. Indian J Radiol Imaging 2015;25:52-
6. Brijesh K Soni,Debasheesh S R Das,R A George ,R Sivashankar et al MRI features in dengue encephalitis:A case series in south Indian tertiary care hospital,Indian journal of radiology and Imaging,2017; Vol 27 ( 5 ): 125-128.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!