Is this viral encephalitis? - A pictorial review of common and uncommon viral CNS infections.

Transcription

1 Is this viral encephalitis? - A pictorial review of common and uncommon viral CNS infections. Poster No.: C-2478 Congress: ECR 2018 Type: Educational Exhibit Authors: H. C. Chadaga, S. Patwari, N. Perothayil ; BANGALORE, KA/ IN, Bangalore/IN Keywords: CNS, Neuroradiology brain, MR, Diagnostic procedure, Infection DOI: /ecr2018/C-2478 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 52

2 Learning objectives The purpose of this educational exhibit is to: To enumerate various viral pathogens infecting brain. To revisit the imaging spectrum and MRI features of viral encephalitis. Page 2 of 52

3 Background Viruses, unlike bacteria, lack motility and are essentially obligate intracellular parasites that, for replication, must invade the living cells. It can gain access via bodily fluids-saliva, blood, semen, urine, feces, and mucosal secretionsto infect the central nervous system (CNS). Some viruses specifically seek the brain, spinal cord, and other nervous tissue (neurotropic), while others cause indiscriminate collateral damage in these structures. Of the 61 known viral families, there are 15 (comprising more than 100 (1) different viruses) that can cause CNS infections. These infections can range from asymptomatic initial manifestations to fatal viremia; from acute manifestations to smouldering disease; and from ubiquitous with worldwide prevalence to those that are localized to small regions. Fig. 1: Viral encephalitis - Common etiologies References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN Page 3 of 52

4 Fig. 2: Brain regions effected by viruses References: Page 4 of 52

5 Fig. 3: Possible etiologic agents of encephalitis based on age References: The Management of Encephalitis: Clinical Practice Guidelines by the Infectious Diseases Society of America The inflammatory response of the body, which is variable in intensity, to (2) the virus is the core of pathophysiologic changes in CNS viral infections. Neuroimaging can document the extent of the inflammatory changes, but these are rarely specific enough to suggest a single entity. Some infections have certain characteristic imaging features that aid in prioritizing diagnostic considerations. However, the single most valuable tool in establishing diagnosis of the specific viral CNS infection is CSF analysis to identify the antibodies or the remnants of viral DNA/RNA through polymerase chain reaction (PCR) assays. Early identification aids in prompt treatment which is usually only supportive care including anti-oedema and anti-seizure medications. Specific antiviral therapy for herpes simplex is available- IV acyclovir is recognized as the primary pharmaceutical agent, with improved mortality after initiation of therapy. Ganciclovir combined with foscarnet has been used in the treatment of patients infected with HIV. Page 5 of 52

6 Images for this section: Fig. 1: Viral encephalitis - Common etiologies RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 6 of 52

7 Fig. 2: Brain regions effected by viruses Page 7 of 52

8 Fig. 3: Possible etiologic agents of encephalitis based on age The Management of Encephalitis: Clinical Practice Guidelines by the Infectious Diseases Society of America Page 8 of 52

9 Findings and procedure details The pattern of involvement varies among the various family and sub-groups of viruses. MRI with IV gadolinium contrast is the imaging modality of choice. Magnetic resonance imaging with T1 and T2 weighted imaging, fluid attenuation inversion recovery (FLAIR), diffusion weighted imaging (DWI) and post contrast T1 and FLAIR sequences are commonly used. Usually FLAIR hyperintesities are seen in viral encephalitis with varying distribution and type of involvement according to the different viruses. Here we present the typical and atypical imaging features of the viral encephalitis cases encountered in our hospital. 1. Human Herpes virus: These include DNA viruses: a. # viruses are represented by herpes simplex virus (HSV) type 1 (HSV-1), type 2 (HSV-2), B virus, and varicellazoster virus. b. # viruses include cytomegaloviruses, HHV-6, and HHV-7, while # viruses include Epstein-Barr virus and HHV-8 (3). Mode of spread: Haematogenous or Neuronal transmission. A. HSV-1 and HSV-2: Main source of spread: Direct contact with virally infected bodily secretions onto disrupted skin, conjunctiva, or mucosa of the oropharynx (more common with HSV-1) or genitalia (more common with HSV-2). Clinical Features: Though uncommon, it is the most common sporadic fatal encephalitis, with majority of the (4) cases reported in children and adolescents. The clinical presentation in older children and adults is nonspecific. Altered sensorium, fever, and headache (the classic clinical triad for encephalitis) are present in virtually all patients, and seizures (66% of cases) are also common. Aphasia, anosmia, and temporal lobe seizures are common clinical manifestations of temporal lobe involvement seen in HSE (5). Neonatal HSE shows several distinctions from the "classic" features of HSE. It is related to HSV-2 infection acquired at vaginal delivery. It is likely blood borne and Page 9 of 52

10 commonly causes multiorgan disseminated disease, including ophthalmic and cutaneous manifestations (6). Imaging Features: Abnormal MR imaging findings are seen within the temporal lobe, especially in the inferomedial region and insular cortex with sparing of the basal ganglia. Parenchymal enhancement, often in a patchy or gyriform pattern, is seen in contrastenhanced MR imaging several days after the onset of disease. In neonatal HSE, diffuse encephalitis and in the chronic stage of disease, diffuse encephalomalacia is seen. Page 10 of 52

11 Fig. 4: HSV encephalitis. 23 year old female with fever since 5 days and altered sensorium since 1 day. MR imaging demonstrates patchy areas of FLAIR/T2 (A,B) asymmetrical hyperintensities in bilateral hippocampus(right>left), right lateral temporal lobe, right occipital lobe. These areas shows restriction on diffusion (C) with most of the lesions showing blooming on GRE (D) in right hippocampus. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN B. Cytomegalovirus: Main source of spread: Via bodily fluids, including breast milk, and solid organ transplantation. Page 11 of 52

12 Imaging Features: MR imaging in immunocompromised individuals include non-specific volume loss in the cerebral and cerebellar hemispheres and regions of periventricular T2 hyperintensity and restricted diffusion at MR imaging and associated contrast enhancement correlating with ventriculoencephalitis. Ring-enhancing nodular masses with surrounding edema, and meningeal enhancement may also be seen at MR imaging Fig. 5: CMV ventriculitis. 35 year male known retroviral positive presenting with headache, vomiting. Multiplanar MR imaging demonstrates dilated ventricles with high signal on T2 and DWI is seen lining the ependymal surface of the lateral ventricles, which also demonstrates enhancement- findings suggestive of moderate hydrocephalus with ventriculitis. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN C. EPSTEIN-BARR VIRUS Page 12 of 52

13 Epstein-Barr virus (EBV) accounts for 5% of all encephalitis in children. About 20% of patients with primary EBV infection will have systemic complications, with neurologic involvement seen in about 5%. The clinical outcome varies from complete recovery to death. The pattern of CNS involvement seen on imaging has prognostic value, as prognosis is worse when there is brain stem involvement Imaging features CT will show non-specific areas of decreased attenuation, but this finding has a low sensitivity. MRI shows bilateral and symmetric increased T2-weighted signal in the caudate nuclei, putamina (as the virus has special tropism for the basal ganglia), and thalami, and may also involve the cortex. Involvement of the white matter, brainstem and splenium is possible, but rare. Fig. 6: EBV encephalitis. Axial FLAIR images show cortical swelling with hyperintensity in bilateral medial temporal, left posterior temporal and occipital lobes. Mild hyperintensity can also be seen in bilateral basal ganglia, which is rarely seen in HSV encephalitis. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN Page 13 of 52

14 2. Arbovirus: Infections related to arthropod-borne viruses (arbovirus) are common during the summer, due to peak in the mosquito breeding. A. Japanese Encephalitis Virus: It is a single-stranded RNA flavivirus that is transmitted through a zoonotic cycle between culicine mosquitoes, pigs, and water birds with the humans as accidental dead-end host, manifesting as serious life-threatening encephalitis. Clinical Features: Seizures, focal neurologic deficits, and parkinsonian features are seen in both children and adults, but children are more likely to have dystonia and poor outcome at 6 months. About one-third of the survivors have severe neuropsychiatric sequelae. Infection during the first and second trimesters is associated with fetal demise. Imaging Features: Asymmetrical T2 hyperintense, T1 hypointense lesions involving the bilateral thalami is characteristic (seen in 90% of the patients). Other areas of involvement include medulla and multifocal areas of necrosis in the thalamus, substantia nigra, basal ganglia, and hippocampi. Isolated substantia nigra involvement can also be seen in japanese encephalitis (Fig.8) Page 14 of 52

15 Fig. 7: Japanese encephalitis. T2/FLAIR hyperintensities seen in bilateral thalami and substantia nigra with ares of diffusion restriction. Associated right frontal neurocysticercosis(ncc) with perifocal edema can be noted. NCC and JE co-infection can be attributed to common epidemiologic and socio-demographic factors. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN Page 15 of 52

16 Fig. 8: Isolated substantia nigra involvement in JE. 13 year old with fever, seizures and poor GCS. Axial T2/FLAIR images showing symmetrical hyperintensity in bilateral substantia nigra. CSF ELISA was positive for Japanese encephalitis. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN B. Dengue Virus: Clinical Features: It manifest as break bone fever, which is a severe but self-limiting influenza-like illness. The more severe manifestation include the dengue haemorrhagic fever, which may progress to dengue shock syndrome and death if untreated. Imaging Features: MRI demonstrates diffuse cerebral oedema with bilateral symmetrical FLAIR and T2 hyperintensities in thalami, globus pallidus, temporal lobe, hippocampi, pons, and medulla with heterogenous or peripheral enhancement on contrast administration. Few of these areas may demonstrate diffusion restriction and petechial hemorrhages. Page 16 of 52

17 Fig. 9: Dengue encephalitis. 4 year old child with fever since 4 days,1 episode of seizure, altered sensorium. MR imaging demonstrates bilateral symmetrical T2/ FLAIR hyperintensity (A,B) and T1 hypointensity (C) in thalamus, posterior limb of internal capsules. The corresponding areas demonstrate restricted diffusion (D,E) with blooming (F)seen in bilateral thalamus suggestive of haemorrhage. Serology was positive for Dengue. Imaging differential for this appearance could be Acute necrotising encephalitis of childhood. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN C. St Louis Encephalitis virus: It is a subtype of West Nile encephalitis, which is enzootic with birds as a common reservoir and Culex mosquitos as vectors. Clinical Features: Most infections are subclinical, while about 20% manifest with features of a mild febrile illness and less than 1% of cases present with encephalitis (or less commonly, aseptic meningitis) which is more prevalent in adults older than 50 years. Page 17 of 52

18 Imaging Features: Non-specific imaging findings include: Areas of restricted diffusion without or with associated FLAIR or T2 signal hyperintensity may occur. Cerebellar and brainstem involvement is seen with selective involvement of the substantia nigra.in indian subcontinent, isolated substantia nigra involvement can be seen in japanese encephalitis (Fig.8) Fig. 10: St.Louis encephalitis on follow up. 39 year old with extrapyramidal symptoms. Axial T2 images(a,c) showing symmetrical hyperintensity in bilateral substantia nigra. No haemoorhage on GRE (B) and no abnormal enhancement (D). Page 18 of 52

19 References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 3. Rabies Virus: After inoculation from usually a dog, bat, or other wild terrestrial animal, the incubation period varies from 5 days to more than 6 months. Clinical Features: In the classic (encephalitic) form, clinical features include prominent mental status changes fluctuating between excessive agitation and depression with hydrophobia. Imaging Features: Pituitary and infundibular T2 signal intensity changes and enhancement at MR imaging correlates with the hypothalamic-pituitary axis dysfunction. MR imaging features include non-enhancing, ill-defined, mildly hyperintense T2 signal intensity changes in the brainstem, hippocampi, hypothalamus, white matter (both deep and subcortical), and gray matter (both deep and cortical). Fig. 11: Rabies encephalitis. 45 year old with acute onset of altered consciousness and drowsiness, with history of dog bite to face 1 month back. MRI brain reveals' symmetrical T2 hyperintensities (A) in basal ganglia, brainstem and cerebellum. The lesions in basal ganglia and brainstem demonstrate diffusion restriction (B). The findings suggestive of Rabies encephalitis. Page 19 of 52

20 References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 4. Polyomavirus (JC Virus): It causes asymptomatic primary infection in children and young adults. Its reactivation causes a rare, fatal white matter disease called progressive multifocal leukoencephalopathy (PML) in immunocompromised hosts. Clinical Features: The clinical presentation includes muscle weakness, sensory deficit, hemianopia, cognitive dysfunction, aphasia, and coordination and/or gait difficulties Imaging Features: Multiple T1 hypointense and FLAIR and T2 hyperintense lesions are commonly located in the parieto-occipital and frontal subcortical white matter and cerebellar peduncles. Involvement of the subcortical U-fibres is characteristic. Early involvement of PML can be sometimes observed around perirolandic region. Patchy restricted diffusion at diffusion-weighted imaging has been reported at the periphery of PML lesions. Page 20 of 52

21 Fig. 12: PML. 39 year retroviral positive patient presenting with right upper and lower limb weakness. MRI images demonstrates T2/FLAIR white matter hyperintensities involving the subcortical regions and showing subtle peripheral diffusion restriction suggestive of PML References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN Page 21 of 52

22 Fig. 13: PML. Retroviral positive male presenting with Right upper limb weakness Axial T2/FLAIR images demonstrates Focal hyperintensity seen along left perirolandic fissure and along right precentral gyrus (A,B), diffusion restriction on DWI images (C,D) References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN On the introduction of highly active antiretroviral therapy, HAART, the rapid recovery of the immune status produces PML-immune reconstitution inflammatory syndrome (PMLIRIS)- Seen as edema and transient contrast enhancement on MR images. Lesions with higher maximum ADC ratios before the initiation of HAART is more likely to progress rapidly once the treatment is initiated. Page 22 of 52

23 Fig. 14: PML-IRIS. 42 year retroviral positive who had PML presented with blurred vision, headache and involuntary movement. MRI brain demonstrates abnormal FLAIR (A,B) hyperintense lesions in right frontal lobe, right MCP and cerebellar hemisphere. These lesions demonstrate patchy and peripheral enhancement which on correlating with clinical findings is characteristic of PML-IRIS. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 5. Human Immunodeficiency Virus (HIV): Combination of direct HIV infection and subsequent release of toxins from responding immune-competent cells. Page 23 of 52

24 Clinical Features: The neurologic manifestations frequently include psychomotor slowing, mental status changes, memory problems, and apathy. Imaging Features: Diffuse mild cerebral atrophy affecting mainly deep cortical and white matter lesions as the most common imaging features. Bilateral T2 and FLAIR hyperintensities in white matter is classically symmetric, with sparing of the subcortical U-fibers. These findings are more pronounced after the introduction of HAART. Asymmetric patchy, focal, punctate lesions are less common. MR spectroscopy shows decreased N-acetylaspartate, elevated choline and myo-inositol levels. Fig. 15: HIV Encephalopathy. 36 year male retoviral positive with abnormal behavior and gait disturbance. MRI brain plain demonstrates symmetric periventricular and deep Page 24 of 52

25 white matter T2 hyperintensity with relative sparing of the subcortical white matter and posterior fossa structures suggestive of HIV associated Dementia (HAD). References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 6. Enterovirus: Clinical Features: Most of the patients have a asymptomatic disease which is self-limited. In less than 1% case, neurological symptoms include: cranial nerve palsies, conjugate gaze abnormalities, lethargy which may progress to acute flaccid paralysis, coma and eventually death. Imaging Features: Neuroimaging shows T2 hyperintensity in the cerebellar dentate nuclei and brainstem, sparing corticospinal tracts which shows diffusion restriction. In critical care patients, there may be focal T2 hyperintensity in bilateral ventral horns in the spinal cord. These lesions show T1 hypointensity in the chronic stage. Page 25 of 52

26 Fig. 16: EV 71 encephalitis. 3 year old with fever, headache and altered sensorium. MRI brain demonstrates T2/FLAIR hyperintense lesions in the posterior portion of pons characteristic of Enterovirus encephalitis. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 7. Influenza/ Parainfluenza: The various infections include: 1. Reye syndrome Page 26 of 52

27 2. Acute necrotizing encephalopathy. This is the most common pathogen associated with upper respiratory tract infection, and usually presents as flu-like syndrome. Imaging Features: The common imaging findings include: Diffuse brain edema with symmetric involvement of thalami, brainstem and cerebellum. Milder involvement can present as reversible splenial lesion. Fig. 17: Influenza encephalitis, presenting as transient splenial lesion. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 8. SSPE: It is rare, chronic encephalitis secondary to persistent measles infection. Clinical Features: Page 27 of 52

28 The patients present with gradual but progressive neurological deterioration including seizures, myoclonus, ataxia and behavioural changes. Imaging Features: T2 and FLAIR hyperintensity in bilateral parieto-occipital region involving both grey and white matter is the most common imaging finding. No significant contrast enhancement is seen. Fig. 18: SSPE. 14 years female with history of sudden onset abnormal behavior, upper limb weakness, imbalance. MRI Brain demonstrates abnormal asymmetrical T2/ FLAIR hyperintnsities in bilateral frontal white matter and basal ganglia which turned out to be SSPE. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 9. CJD Page 28 of 52

29 Creutzfeldt-Jakob disease (CJD) is a spongiform encephalopathy that results in a rapidly progressive dementia and other non-specific neurological features and death usually within a year or less from onset. CJD is thought to be mediated via prions, a type of protein, considered infectious in the sense that they can alter the structure of neighbouring proteins. Imaging Features: It classically manifests as T2/FLAIR hyperintensities within the basal ganglia, thalamus (Hockey stick and Pulvinar sign), and cortex (Cortical ribbon sing). These lesions show diffusion restriction on DWI/ADC sequences. Page 29 of 52

30 Fig. 19: CJD. 62 year with gradually progressing weakness of right upper limb. MRI demonstrates bilateral symmetrical diffusion restriction (A,B) and T2/FLAIR hyperintensities (C,D) in basal ganglia region very characteristic of CJD. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN 10. Human Parecho and Rota virus: Page 30 of 52

31 Fig. 22: Comparison of clinical characteristics of white matter injury, rotavirus versus enterovirus and human parechovirus References: Korean J Pediatr Jul; 59(7): Fig. 20: Parechovirus encephalitis. Neonate with seizures DWI images demonstrates extensive and symmetric areas of diffusion restriction involving periventricular white matter, corpus callosum and thalamus which turned out be HPeV infection. Page 31 of 52

32 References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN Fig. 21: Rota viral encephalitis. 5 day old child with seizures. DWI images demonstrates extensive and symmetric areas of diffusion restriction involving periventricular white matter, corpus callosum and thalamus. References: RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral Hospital-Yeshwanthpur - BANGALORE/IN Page 32 of 52

33 Images for this section: Fig. 4: HSV encephalitis. 23 year old female with fever since 5 days and altered sensorium since 1 day. MR imaging demonstrates patchy areas of FLAIR/T2 (A,B) asymmetrical hyperintensities in bilateral hippocampus(right>left), right lateral temporal lobe, right occipital lobe. These areas shows restriction on diffusion (C) with most of the lesions showing blooming on GRE (D) in right hippocampus. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 33 of 52

34 Fig. 5: CMV ventriculitis. 35 year male known retroviral positive presenting with headache, vomiting. Multiplanar MR imaging demonstrates dilated ventricles with high signal on T2 and DWI is seen lining the ependymal surface of the lateral ventricles, which also demonstrates enhancement- findings suggestive of moderate hydrocephalus with ventriculitis. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 34 of 52

35 Fig. 6: EBV encephalitis. Axial FLAIR images show cortical swelling with hyperintensity in bilateral medial temporal, left posterior temporal and occipital lobes. Mild hyperintensity can also be seen in bilateral basal ganglia, which is rarely seen in HSV encephalitis. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 35 of 52

36 Fig. 7: Japanese encephalitis. T2/FLAIR hyperintensities seen in bilateral thalami and substantia nigra with ares of diffusion restriction. Associated right frontal neurocysticercosis(ncc) with perifocal edema can be noted. NCC and JE co-infection can be attributed to common epidemiologic and socio-demographic factors. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 36 of 52

37 Fig. 8: Isolated substantia nigra involvement in JE. 13 year old with fever, seizures and poor GCS. Axial T2/FLAIR images showing symmetrical hyperintensity in bilateral substantia nigra. CSF ELISA was positive for Japanese encephalitis. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 37 of 52

38 Fig. 9: Dengue encephalitis. 4 year old child with fever since 4 days,1 episode of seizure, altered sensorium. MR imaging demonstrates bilateral symmetrical T2/FLAIR hyperintensity (A,B) and T1 hypointensity (C) in thalamus, posterior limb of internal capsules. The corresponding areas demonstrate restricted diffusion (D,E) with blooming (F)seen in bilateral thalamus suggestive of haemorrhage. Serology was positive for Dengue. Imaging differential for this appearance could be Acute necrotising encephalitis of childhood. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 38 of 52

39 Fig. 10: St.Louis encephalitis on follow up. 39 year old with extrapyramidal symptoms. Axial T2 images(a,c) showing symmetrical hyperintensity in bilateral substantia nigra. No haemoorhage on GRE (B) and no abnormal enhancement (D). RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 39 of 52

40 Fig. 11: Rabies encephalitis. 45 year old with acute onset of altered consciousness and drowsiness, with history of dog bite to face 1 month back. MRI brain reveals' symmetrical T2 hyperintensities (A) in basal ganglia, brainstem and cerebellum. The lesions in basal ganglia and brainstem demonstrate diffusion restriction (B). The findings suggestive of Rabies encephalitis. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 40 of 52

41 Fig. 12: PML. 39 year retroviral positive patient presenting with right upper and lower limb weakness. MRI images demonstrates T2/FLAIR white matter hyperintensities involving the subcortical regions and showing subtle peripheral diffusion restriction suggestive of PML RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 41 of 52

42 Fig. 13: PML. Retroviral positive male presenting with Right upper limb weakness Axial T2/FLAIR images demonstrates Focal hyperintensity seen along left perirolandic fissure and along right precentral gyrus (A,B), diffusion restriction on DWI images (C,D) RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 42 of 52

43 Fig. 14: PML-IRIS. 42 year retroviral positive who had PML presented with blurred vision, headache and involuntary movement. MRI brain demonstrates abnormal FLAIR (A,B) hyperintense lesions in right frontal lobe, right MCP and cerebellar hemisphere. These lesions demonstrate patchy and peripheral enhancement which on correlating with clinical findings is characteristic of PML-IRIS. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 43 of 52

44 Fig. 15: HIV Encephalopathy. 36 year male retoviral positive with abnormal behavior and gait disturbance. MRI brain plain demonstrates symmetric periventricular and deep white matter T2 hyperintensity with relative sparing of the subcortical white matter and posterior fossa structures suggestive of HIV associated Dementia (HAD). RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 44 of 52

45 Fig. 16: EV 71 encephalitis. 3 year old with fever, headache and altered sensorium. MRI brain demonstrates T2/FLAIR hyperintense lesions in the posterior portion of pons characteristic of Enterovirus encephalitis. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 45 of 52

46 Fig. 17: Influenza encephalitis, presenting as transient splenial lesion. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 46 of 52

47 Fig. 18: SSPE. 14 years female with history of sudden onset abnormal behavior, upper limb weakness, imbalance. MRI Brain demonstrates abnormal asymmetrical T2/FLAIR hyperintnsities in bilateral frontal white matter and basal ganglia which turned out to be SSPE. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 47 of 52

48 Fig. 19: CJD. 62 year with gradually progressing weakness of right upper limb. MRI demonstrates bilateral symmetrical diffusion restriction (A,B) and T2/FLAIR hyperintensities (C,D) in basal ganglia region very characteristic of CJD. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 48 of 52

49 Fig. 20: Parechovirus encephalitis. Neonate with seizures DWI images demonstrates extensive and symmetric areas of diffusion restriction involving periventricular white matter, corpus callosum and thalamus which turned out be HPeV infection. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Page 49 of 52

50 Fig. 21: Rota viral encephalitis. 5 day old child with seizures. DWI images demonstrates extensive and symmetric areas of diffusion restriction involving periventricular white matter, corpus callosum and thalamus. RADIOLOGY, Columbia Asia Referral Hospital, Columbia Asia Referral HospitalYeshwanthpur - BANGALORE/IN Fig. 22: Comparison of clinical characteristics of white matter injury, rotavirus versus enterovirus and human parechovirus Korean J Pediatr Jul; 59(7): Page 50 of 52

51 Conclusion Most viral CNS infections have nonspecific imaging manifestations, a few show characteristic patterns of involvement, the knowledge of which can aid in early diagnosis and management. Page 51 of 52

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