Journal of Medical Imaging and Radiation Oncology •• (2014) ••–•• bs_bs_banner
R ADIOLO GY—CA SE R E P O RT
Rare case of acute dengue encephalitis with correlated MRI findings Rishi Philip Mathew,1 Ram Shenoy Basti,1 Pavan Hegde,2 Jaidev M Devdas,2 Habeeb Ullah Khan2 and Mario Joseph Bukelo2 Departments of 1Radio-Diagnosis and 2Pediatrics, Father Muller Medical College, Mangalore, Karnataka, India
RP Mathew MBBS; RS Basti MBBS, MD; P Hegde MBBS, MD; JM Devdas MBBS, MD; HU Khan MBBS, MD; MJ Bukelo MBBS. Correspondence Dr Rishi Philip Mathew, Department of Radio-Diagnosis, Father Muller Medical College, Kankanady, Mangalore-575002, Karnataka, India. Email: [email protected]
Summary Dengue encephalitis is extremely rare, with most patients showing no significant abnormality on neuroimaging (CT/MRI). We report one of the very few documented cases of dengue encephalitis, with abnormal signal intensities on all major sequences on brain MRI. Key words: dengue; encephalitis; MRI.
Conflict of interest: None. Submitted 21 October 2013; accepted 21 March 2014. doi:10.1111/1754-9485.12182
Introduction Dengue viral infections are common in Asia and are endemic in more than 100 countries worldwide. They are caused by an arbovirus transmitted by the Aedes mosquito. They have a variety of clinical presentations, of which dengue encephalitis is among the rarest; very few cases of it have been documented on MRI.1,2
Case report A 9-year-old boy presented to the paediatric outpatient clinic with the complaint of a sudden onset of high-grade fever (40°C). On examination, he was conscious and lucid. On the third day of admission, he developed chills and one episode of generalized seizures lasting for 5 min, following which he went into altered sensorium for 2 days. Blood analysis revealed low platelet counts (42 000/ mm3). The patient tested positive on the dengue NS1 antigen test for anti-dengue virus IgM. Polymerase chain reaction testing of the cerebrospinal fluid (CSF) showed dengue virus. Non-contrast axial T1-weighted brain MRI (Fig. 1a) showed hypointense thalami. T2-weighted (Fig. 1b) and © 2014 The Royal Australian and New Zealand College of Radiologists
T2/FLAIR (fluid-attenuated inversion recovery) (Fig. 2) images revealed hyperintense thalami, midbrain and pons. Diffusion-weighted MRI (Fig. 3a) and apparent diffusion coefficient map (Fig. 3b) revealed diffusion restriction in the thalami and cerebellum. Postcontrast axial T1-weighted images (Fig. 4) revealed patchy enhancement of the involved areas along with ventriculitis. Given these findings, the patient was diagnosed with dengue encephalitis. He was treated with intravenous fluids, antipyretics, antivirals (acyclovir injection), antiepileptics (phenytoin injection) and antibiotics. He was discharged afebrile with a Glasgow Coma Scale score of 15/15 and no neurological deficits. Post-treatment follow-up brain MRI after 2 months (Fig. 5) revealed almost complete resolution of the abnormal signal intensities, albeit with mild persistence in the left hemipons.
Discussion The clinical spectrum of dengue ranges from asymptomatic infection to dengue fever, dengue haemorrhagic fever and dengue shock syndrome. Neurological complications in dengue are uncommon. Unlike encepha1
RP Mathew et al.
Fig. 1. (a) T1-weighted MR image showing hypointense thalami. (b) The thalami were hyperintense on T2-weighted sequence.
lopathy, encephalitis is a rare presentation of dengue. The major differences between the two have been outlined in Table 1. There is increasing evidence for dengue virus neurotropism, with several documented cases of direct isolation of dengue serotypes 2 and 3 from the CSF and from the midbrain.1–4 Nervous system involvement is more commonly seen with serotypes 2 and 3.4 To our knowledge, only three other articles reporting abnormal brain MRI findings in dengue have been written.2–4
Management of viral encephalitis involves airway maintenance, hydration, anti-epileptics and mannitol for increased intracranial pressure. Use of corticosteroids is controversial and not considered safe.4 At the time of writing, there exists no antiviral drug or vaccine for dengue.1,5 Imaging differentials the radiologist may consider in patients coming from endemic areas include Japanese encephalitis, West Nile virus, herpes simplex virus, rabies, chikungunya and Nipah virus.4
Fig. 2. (a) T2/FLAIR (fluid-attenuated inversion recovery) axial image showing a hyperintense midbrain. (b) T2/FLAIR sagittal image showing hyperintense thalami and pons.
2
© 2014 The Royal Australian and New Zealand College of Radiologists
Rare case of acute dengue encephalitis
Fig. 3. (a) Diffusion-weighted MR image showing hyperintense thalami and cerebellum. (b) Thalami and cerebellum were hypointense on the apparent diffusion coefficient map, suggestive of diffusion restriction.
Fig. 4. Postcontrast axial T1-weighted images showed patchy enhancement of (a) thalami and (b) pons, with ependymal enhancement suggestive of ventriculitis.
Table 1. Differentiation between encephalopathy and encephalitis
Fever Headache Focal neurological deficits Seizures Blood analysis Cerebrospinal fluid analysis MRI
© 2014 The Royal Australian and New Zealand College of Radiologists
Encephalopathy
Encephalitis
Uncommon Uncommon Uncommon Generalised Leucocytosis uncommon Pleocytosis uncommon Usually normal
Common Common Common Generalised/focal Leucocytosis common Pleocytosis common Focal changes present
3
RP Mathew et al.
Fig. 5. Post-treatment follow-up brain MRI. (a) T2-weighted axial, (b) FLAIR (fluid-attenuated inversion recovery) and (c) T2-weighted coronal images showed almost complete resolution of abnormal signal intensities, albeit with mild persistence in the left hemipons.
Conclusion In the past few years, dengue virus has been found to show features of neurotropism. In patients diagnosed with dengue, dengue encephalitis should be considered among the differentials of encephalopathy. Neuroimaging and CSF analysis must be carried out in such cases. With early detection and adequate treatment, it is possible to reverse the pathological changes revealed on neuroimaging, as proven in our case.
References 1. Varatharaj A. Encephalitis in the clinical spectrum of dengue infection. Neurol India 2010; 58: 585–91.
4
2. Wasay M, Channa R, Jumani M, Shabbir G, Azeemuddin M, Zafar A. Encephalitis and myelitis associated with dengue viral infection clinical and neuroimaging features. Clin Neurol Neurosurg 2008; 110: 635–40. 3. Rao S, Kumar M, Ghosh S, Gadpayle AK. A rare case of dengue encephalitis. BMJ Case Rep 2013. doi:10.1136/bcr-2012-008229. 4. Acharya S, Shukla S, Thakre R, Kothari N, Mahajan SN. Dengue encephalitis – a rare entity. IOSR-JDMS 2013; 5: 40–2. 5. Wan SW, Lin CF, Wang S et al. Current progress in dengue vaccines. J Biomed Sci 2013; 20: 37. doi:10.1186/1423-0127-20-37.
© 2014 The Royal Australian and New Zealand College of Radiologists
R ADIOLO GY—CA SE R E P O RT
Rare case of acute dengue encephalitis with correlated MRI findings Rishi Philip Mathew,1 Ram Shenoy Basti,1 Pavan Hegde,2 Jaidev M Devdas,2 Habeeb Ullah Khan2 and Mario Joseph Bukelo2 Departments of 1Radio-Diagnosis and 2Pediatrics, Father Muller Medical College, Mangalore, Karnataka, India
RP Mathew MBBS; RS Basti MBBS, MD; P Hegde MBBS, MD; JM Devdas MBBS, MD; HU Khan MBBS, MD; MJ Bukelo MBBS. Correspondence Dr Rishi Philip Mathew, Department of Radio-Diagnosis, Father Muller Medical College, Kankanady, Mangalore-575002, Karnataka, India. Email: [email protected]
Summary Dengue encephalitis is extremely rare, with most patients showing no significant abnormality on neuroimaging (CT/MRI). We report one of the very few documented cases of dengue encephalitis, with abnormal signal intensities on all major sequences on brain MRI. Key words: dengue; encephalitis; MRI.
Conflict of interest: None. Submitted 21 October 2013; accepted 21 March 2014. doi:10.1111/1754-9485.12182
Introduction Dengue viral infections are common in Asia and are endemic in more than 100 countries worldwide. They are caused by an arbovirus transmitted by the Aedes mosquito. They have a variety of clinical presentations, of which dengue encephalitis is among the rarest; very few cases of it have been documented on MRI.1,2
Case report A 9-year-old boy presented to the paediatric outpatient clinic with the complaint of a sudden onset of high-grade fever (40°C). On examination, he was conscious and lucid. On the third day of admission, he developed chills and one episode of generalized seizures lasting for 5 min, following which he went into altered sensorium for 2 days. Blood analysis revealed low platelet counts (42 000/ mm3). The patient tested positive on the dengue NS1 antigen test for anti-dengue virus IgM. Polymerase chain reaction testing of the cerebrospinal fluid (CSF) showed dengue virus. Non-contrast axial T1-weighted brain MRI (Fig. 1a) showed hypointense thalami. T2-weighted (Fig. 1b) and © 2014 The Royal Australian and New Zealand College of Radiologists
T2/FLAIR (fluid-attenuated inversion recovery) (Fig. 2) images revealed hyperintense thalami, midbrain and pons. Diffusion-weighted MRI (Fig. 3a) and apparent diffusion coefficient map (Fig. 3b) revealed diffusion restriction in the thalami and cerebellum. Postcontrast axial T1-weighted images (Fig. 4) revealed patchy enhancement of the involved areas along with ventriculitis. Given these findings, the patient was diagnosed with dengue encephalitis. He was treated with intravenous fluids, antipyretics, antivirals (acyclovir injection), antiepileptics (phenytoin injection) and antibiotics. He was discharged afebrile with a Glasgow Coma Scale score of 15/15 and no neurological deficits. Post-treatment follow-up brain MRI after 2 months (Fig. 5) revealed almost complete resolution of the abnormal signal intensities, albeit with mild persistence in the left hemipons.
Discussion The clinical spectrum of dengue ranges from asymptomatic infection to dengue fever, dengue haemorrhagic fever and dengue shock syndrome. Neurological complications in dengue are uncommon. Unlike encepha1
RP Mathew et al.
Fig. 1. (a) T1-weighted MR image showing hypointense thalami. (b) The thalami were hyperintense on T2-weighted sequence.
lopathy, encephalitis is a rare presentation of dengue. The major differences between the two have been outlined in Table 1. There is increasing evidence for dengue virus neurotropism, with several documented cases of direct isolation of dengue serotypes 2 and 3 from the CSF and from the midbrain.1–4 Nervous system involvement is more commonly seen with serotypes 2 and 3.4 To our knowledge, only three other articles reporting abnormal brain MRI findings in dengue have been written.2–4
Management of viral encephalitis involves airway maintenance, hydration, anti-epileptics and mannitol for increased intracranial pressure. Use of corticosteroids is controversial and not considered safe.4 At the time of writing, there exists no antiviral drug or vaccine for dengue.1,5 Imaging differentials the radiologist may consider in patients coming from endemic areas include Japanese encephalitis, West Nile virus, herpes simplex virus, rabies, chikungunya and Nipah virus.4
Fig. 2. (a) T2/FLAIR (fluid-attenuated inversion recovery) axial image showing a hyperintense midbrain. (b) T2/FLAIR sagittal image showing hyperintense thalami and pons.
2
© 2014 The Royal Australian and New Zealand College of Radiologists
Rare case of acute dengue encephalitis
Fig. 3. (a) Diffusion-weighted MR image showing hyperintense thalami and cerebellum. (b) Thalami and cerebellum were hypointense on the apparent diffusion coefficient map, suggestive of diffusion restriction.
Fig. 4. Postcontrast axial T1-weighted images showed patchy enhancement of (a) thalami and (b) pons, with ependymal enhancement suggestive of ventriculitis.
Table 1. Differentiation between encephalopathy and encephalitis
Fever Headache Focal neurological deficits Seizures Blood analysis Cerebrospinal fluid analysis MRI
© 2014 The Royal Australian and New Zealand College of Radiologists
Encephalopathy
Encephalitis
Uncommon Uncommon Uncommon Generalised Leucocytosis uncommon Pleocytosis uncommon Usually normal
Common Common Common Generalised/focal Leucocytosis common Pleocytosis common Focal changes present
3
RP Mathew et al.
Fig. 5. Post-treatment follow-up brain MRI. (a) T2-weighted axial, (b) FLAIR (fluid-attenuated inversion recovery) and (c) T2-weighted coronal images showed almost complete resolution of abnormal signal intensities, albeit with mild persistence in the left hemipons.
Conclusion In the past few years, dengue virus has been found to show features of neurotropism. In patients diagnosed with dengue, dengue encephalitis should be considered among the differentials of encephalopathy. Neuroimaging and CSF analysis must be carried out in such cases. With early detection and adequate treatment, it is possible to reverse the pathological changes revealed on neuroimaging, as proven in our case.
References 1. Varatharaj A. Encephalitis in the clinical spectrum of dengue infection. Neurol India 2010; 58: 585–91.
4
2. Wasay M, Channa R, Jumani M, Shabbir G, Azeemuddin M, Zafar A. Encephalitis and myelitis associated with dengue viral infection clinical and neuroimaging features. Clin Neurol Neurosurg 2008; 110: 635–40. 3. Rao S, Kumar M, Ghosh S, Gadpayle AK. A rare case of dengue encephalitis. BMJ Case Rep 2013. doi:10.1136/bcr-2012-008229. 4. Acharya S, Shukla S, Thakre R, Kothari N, Mahajan SN. Dengue encephalitis – a rare entity. IOSR-JDMS 2013; 5: 40–2. 5. Wan SW, Lin CF, Wang S et al. Current progress in dengue vaccines. J Biomed Sci 2013; 20: 37. doi:10.1186/1423-0127-20-37.
© 2014 The Royal Australian and New Zealand College of Radiologists
