Usefulness of various MRI sequences in the diagnosis of viral encephalitis

Rapidly progressive locked-in syndrome secondary to atypical herpes simplex virus-1 rhombencephalitis in an immunocompromised individual

HSV-1 encephalitis (HSE) is the most common cause of fatal sporadic encephalitis in the United States. HSE in adults is most commonly due to the reactivation of HSV in the central nervous system (CNS) which results in CNS necrosis leading to neurological compromise. The most common symptoms include altered mentation, fever, seizures, and focal neurological deficits. HSE most commonly involves damage to the temporal lobes however can rarely involve other CNS structures such as the brainstem and cerebellum. Immunocompromised status may increase the risk of atypical HSE. HSE involvement of the brainstem, particularly the pons, most commonly cause neuro-ocular and neuro-bulbar deficits. Rarely can HSV brainstem encephalitis cause quadriplegia or locked-in syndrome. We present a case of HSV-1 rhombencephalitis complicated by locked-in syndrome in a patient with CLL.

Radiological Features of Herpetic Encephalitis in Children

BACKGROUND

Nonspecific clinical manifestations and unclear radiological features may delay treatment initiation in pediatric patients with Herpes simplex encephalitis (HSE). The aim of this study is to analyze the clinical and radiological features of the disease.

METHODS

Clinical, laboratory, and magnetic resonance imaging (MRI) data were obtained retrospectively from a group of 37 hospitalized pediatric patients older than two months and with a polymerase chain reaction-confirmed HSE diagnosis. Clinical severity (i.e., mechanical ventilatory support) and outcome at discharge (i.e., pediatric modified Rankin Scale [ped-mRS]) were also assessed.

RESULTS

Median age was 14 months (interquartile range: 10-36). All patients survived, 15 (41%) had complete recovery (i.e., ped-mRS = 0), and 10 (27%) had significant residual disability at discharge (i.e., ped-mRS ≥3). Brain MRI was obtained in 31 patients. T2-hyperintense lesions were usually bilateral (28, 90%) and multifocal (30, 97%). Hemorrhage and mass effect were observed in 13 (42%) and 15 (48%) patients, respectively. Parenchymal lesions involved the temporal lobes (94%), insula (90%), parietal lobes (84%), and frontal lobes (61%). Occipital lesions were rare. In multivariable binary logistic regression models the presence of altered consciousness was associated with mechanical ventilation (odds ratio [OR] = 8.2, Nagelkerke R2 = 0.22), whereas the involvement of the occipital lobes (OR = 7.8) and the administration of vasopressors (OR = 12.1) were independent predictors of poor outcome (Nagelkerke R2 = 0.41).

CONCLUSIONS

Brain MRI is useful for diagnosis and outcome assessment in pediatric HSE. Radiological patterns with common frontotemporal involvement overlap adults, but multifocal and parietal lobe abnormalities are observed as well.

EBV-associated CNS infection in an immunocompetent adult: A case report and literature review

EBV infections rarely cause CNS involvement. For young adult patients with suspected CNS infection, bacterial and other common viral infections should be excluded first and treated empirically until proven otherwise. Challenges in diagnosing EBV-associated CNS infection, emphasizing the role of CSF PCR in confirming the diagnosis.

Takotsubo cardiomyopathy associated with Herpes simplex encephalitis: A case report and literature review

Takotsubo cardiomyopathy (TCM) is a stress-induced cardiomyopathy characterized by transient left ventricular dysfunction. It can be triggered by various central nervous system pathologies including status epilepticus (SE) and N-methyl-d-aspartate receptor (NMDAr) encephalitis. Herpex simplex encephalitis (HSE) is a life-threatening, sporadic, encephalitis associated with focal or global cerebral dysfunction caused by herpes simplex viruses type 1(HSV-1), or less commonly, type 2(HSV-2). While approximately 20% of patients with HSE develop NMDAr antibodies, not all manifest with encephalitis clinically. We present here a 77-year-old woman admitted with HSV-1 encephalitis who presented with acute encephalopathy and seizure-like activity. Continuous EEG monitoring (cEEG) showed periodic lateralized epileptiform discharges (PLEDs) involving the left parietotemporal region but no evidence of electrographic seizures. Her early hospital course was complicated by TCM which subsequently resolved on repeat TTE. She demonstrated initial neurological improvement. However, five weeks later her mental status declined. Again, no seizures were appreciated on cEEG. Unfortunately, repeat studies including lumbar puncture and magnetic resonance imaging (MRI) of the brain were consistent with NMDAr encephalitis. She was treated with immunosuppression and immunomodulation therapies. To our knowledge we report the first case of TCM secondary to HSE without comorbid status epilepticus. However, further studies are needed to better understand the correlation between, and underlying pathophysiology of HSE and TCM, as well as any potential association with this presentation and subsequent development of NMDAr encephalitis.

Herpes simplex encephalitis in a patient abusing morphine: a case report from Nepal

Herpes simplex encephalitis results from either primary infection with the herpes simplex virus (HSV) or reactivation of latent HSV residing within the nuclei of sensory neurons. Opioid's administration is known to reactivate HSV infection.

Case presentation

We report a 46-year-old male who was in a rehabilitation center for 17 days for abusing morphine for 2 years.

Discussion

Chronic morphine use weakens immune system thereby, making body prone for development of infection. Opioids may reactivate HSV infection because of their immunosuppressive function.

Conclusion

Herpes simplex encephalitis is a potentially fatal condition but can be treated with early diagnosis and intervention.

Sequelae and Animal Modeling of Encephalitic Alphavirus Infections

Eastern (EEEV), Venezuelan (VEEV), and western equine encephalitis viruses (WEEV) are members of the genus Alphavirus, family Togaviridae. Typically spread by mosquitoes, EEEV, VEEV, and WEEV induce febrile illness that may develop into more severe encephalitic disease, resulting in myriad severe neurologic sequelae for which there are no vaccines or therapeutics. Here, we summarize the clinical neurologic findings and sequelae induced by these three encephalitic viruses and describe the various animal models available to study them. We emphasize the crucial need for the development of advanced animal modeling combined with the use of telemetry, behavioral testing, and neuroimaging to facilitate a detailed mechanistic understanding of these encephalitic signs and sequelae. Through the use of these systems, much-needed therapeutics and vaccines can be developed.

Increased volume of cerebral oedema is associated with risk of acute seizure activity and adverse neurological outcomes in encephalitis - regional and volumetric analysis in a multi-centre cohort

BACKGROUND

Seizures can occur unpredictably in patients with acute encephalitis syndrome (AES), and many suffer from poor long-term neurological sequelae. Establishing factors associated with acute seizures risk and poor outcomes could support clinical care. We aimed to conduct regional and volumetric analysis of cerebral oedema on magnetic resonance imaging (MRI) in patients with AES. We assessed the relationship of brain oedema with acute seizure activity and long-term neurological outcome.

METHODS

In a multi-centre cohort study, adults and children presenting with an AES were recruited in the UK. The clinical and brain MRI data were retrospectively reviewed. The outcomes variables were inpatient acute seizure activity and neurological disability at six-months post-discharge. A poor outcome was defined as a Glasgow outcome score (GOS) of 1-3. We quantified regional brain oedema on MRI through stereological examination of T2-weighted images using established methodology by independent and blinded assessors. Clinical and neuroimaging variables were analysed by multivariate logistic regression to assess for correlation with acute seizure activity and outcome.

RESULTS

The study cohort comprised 69 patients (mean age 31.8 years; 53.6% female), of whom 41 (59.4%) had acute seizures as inpatients. A higher Glasgow coma scale (GCS) score on admission was a negative predictor of seizures (OR 0.61 [0.46-0.83], p = 0.001). Even correcting for GCS on admission, the presence of cortical oedema was a significant risk factor for acute seizure activity (OR 5.48 [1.62-18.51], p = 0.006) and greater volume of cerebral oedema in these cortical structures increased the risk of acute seizures (OR 1.90 [1.12-3.21], p = 0.017). At six-month post-discharge, 21 (30.4%) had a poor neurological outcome. Herpes simplex virus encephalitis was associated with higher risk of poor outcomes in univariate analysis (OR 3.92 [1.08-14.20], p = 0.038). When controlling for aetiology, increased volume of cerebral oedema was an independent risk factor for adverse neurological outcome at 6 months (OR 1.73 [1.06-2.83], p = 0.027).

CONCLUSIONS

Both the presence and degree of cerebral oedema on MRIs of patients with AES may help identify patients at risk of acute seizure activity and subsequent long-term morbidity.

Herpes Simplex Encephalitis: Detection, Management, and Outcomes

The pathophysiology of herpes simplex encephalitis (HSE) is incompletely understood and proposed to be secondary to the retrograde transport of the herpes simplex virus type 1 (HSV-1) via the trigeminal and/or olfactory nerves to the central nervous system (CNS). In this case report, we present a 68-year-old female who presents to our emergency department after a fall. Upon initial admission, her neurological examination was benign, and a computer tomography (CT) scan of her brain showed a subdural hematoma for which she was treated conservatively. Day 4 of her hospitalization marked a rapid decline in her course of illness, beginning with confusion and hallucinations, progressing to subclinical seizures, and culminating in irreversible brain damage and palliative extubation on day 16 of hospitalization. This case report discusses our insight into the challenges of early diagnosis and treatment of herpes encephalitis and their impact on improving patient outcomes.

Herpes simplex virus-1 encephalitis secondary to whole brain radiation therapy for metastatic renal cell carcinoma

Herpes simplex virus-1 (HSV-1) infection is the most common cause of encephalitis. This virus commonly lays dormant in neural ganglia, specifically the trigeminal ganglia, following retrograde axonal transport from the site of infection. States of immunosuppression can activate the virus to cause active infection. There are several causes of immunosuppression that can cause viral reactivation. Sporadic case reports have demonstrated HSV-1 encephalitis following brain radiotherapy, although no clear relationship between this treatment and HSV-1 encephalitis has been elucidated. HSV1 encephalitis that arises during immunocompromized states has an atypical presentation for encephalitis, potentially obfuscating the diagnosis and delaying subsequent treatment. The main diagnostic criteria, including CSF analysis, brain imaging, and clinical presentation, all commonly present atypically during states of immunosuppression. For these reasons, it is imperative for physicians to be aware of this rare sequelae in appropriate populations, such as patients undergoing brain radiotherapy. We present a case of an atypical presentation of HSV-1 encephalitis in a patient who recently completed radiotherapy for brain metastases secondary to renal cell carcinoma.

A systematic review of brain imaging findings in neurological infection with Japanese encephalitis virus compared with Dengue virus

OBJECTIVES

Japanese encephalitis virus (JEV) and dengue virus (DENV) represent important causes of encephalitis in Asia. Brain imaging may provide diagnostic clues about the etiology of infectious encephalitis. We performed a systematic review of brain imaging findings in Japanese encephalitis (JE) and DENV neurological infection (dengue) to identify characteristic lesions.

METHODOLOGY

Five databases were searched. We included all study types and imaging techniques. Laboratory methods were categorized using diagnostic confidence levels. Imaging data were synthesized, and focal findings are presented as proportions for JE and dengue and for subgroups based on diagnostic confidence.

PRINCIPAL FINDINGS

Thalamic lesions were the most reported magnetic resonance imaging finding in both diseases but appeared to occur more often in JE (74% in 23 studies) than dengue (29.4% in 58 studies). In cases diagnosed with antigen or nucleic acid tests, thalamic lesions were reported frequently in both JE (76.5% in 17 studies) and dengue (65.2% in 23 studies).

SIGNIFICANCE

The results suggest that thalamic lesions frequently occur in both JE and dengue encephalitis. No radiological findings were found to be pathognomonic of either disease. Although brain imaging may support a diagnosis, laboratory confirmation with highly specific tests remains crucial.

Changing spectrum of acute encephalitis syndrome in India and a syndromic approach

Acute encephalitis syndrome (AES) refers to an acute onset of fever and clinical neurological manifestation that includes mental confusion, disorientation, delirium, or coma, which may occur because of infectious or non-infectious causes. Cerebrospinal fluid (CSF) pleocytosis generally favors infectious etiology, and a normal CSF favors an encephalopathy or non-infectious AES. Among the infectious AES, viral, bacterial, rickettsial, fungal, and parasitic causes are the commonest. Geographical and seasonal clustering and other epidemiological characteristics are important in clinical decision making. Clinical markers like eschar, skin rash, myalgia, hepatosplenomegaly, thrombocytopenia, liver and kidney dysfunction, elevated serum CK, fronto-temporal or thalamic involvement on MRI, and anterior horn cell involvement are invaluable clues for the etiological diagnosis. Categorizing the AES cases into neurologic [Herpes simplex encephalitis (HSE), Japanese encephalitis (JE), and West Nile encephalitis (WNE)] and systemic (scrub typhus, malaria, dengue, and Chikungunya) helps in rational utilization of diagnostic and management resources. In neurological AES, cranial CT/MRI revealing frontotemporal lesion is consistent with HSE, and thalamic and basal ganglia lesions are consistent with JE. Cerebrospinal fluid nucleic acid detection test or IgM antibody for JE and HSE are confirmatory. Presence of frontotemporal involvement on MRI indicates acyclovir treatment pending virological confirmation. In systemic AES, CT/MRI, PCR for HSE and JE, and acyclovir therapy may not be useful, rather treatable etiologies such as malaria, scrub typhus, and leptospirosis should be looked for. If smear or antigen for malaria is positive, should receive antimalarial, if negative doxycycline and ceftriaxone should be started pending serological confirmation of scrub typhus, leptospira, or dengue. A syndromic approach of AES based on the prevalent infection in a geographical region may be developed, which may be cost-effective.

Case of fatal eastern equine encephalitis

Eastern Equine Encephalitis (EEE) is a rare and very serious arbovirus that is transmitted to humans through the bite of infected mosquitoes. When symptomatic, patients with this condition are typically seriously ill and the fatality rate is high. We present a fatal case of EEE that exhibited classic symptoms and findings. Included are high quality MRI images that show the classic radiographic findings of this infection. In addition to confirmatory laboratory findings, the case report includes pathologic specimens from brain tissue obtained at autopsy. Perhaps due to climate change and human encroachment on mosquito habitat, there is a westward spread of EEE in the United States.

Association between cytomegalovirus infection, reduced gray matter volume, and resting-state functional hypoconnectivity in major depressive disorder: a replication and extension

Human cytomegalovirus (HCMV) is a neurotropic herpes virus known to cause neuropathology in patients with impaired immunity. Previously, we reported a reduction in the gray matter volume (GMV) of several brain regions in two independent samples of participants who were seropositive for HCMV (HCMV+) compared to matched participants who were seronegative for HCMV (HCMV-). In addition to an independent replication of the GMV findings, this study aimed to examine whether HCMV+ was associated with differences in resting-state functional connectivity (rsfMRI-FC). After balancing on 11 clinical/demographic variables using inverse probability of treatment weighting (IPTW), GMV and rsfMRI-FC were obtained from 99 participants with major depressive disorder (MDD) who were classified into 42 HCMV+ and 57 HCMV- individuals. Relative to the HCMV- group, the HCMV+ group showed a significant reduction of GMV in nine cortical regions. Volume reduction in the right lateral orbitofrontal cortex (standardized beta coefficient (SBC) = -0.32, [95%CI, -0.62 to -0.02]) and the left pars orbitalis (SBC = -0.34, [95%CI, -0.63 to -0.05]) in the HCMV+ group was also observed in the previous study. Regardless of the parcellation method or analytical approach, relative to the HCMV- group, the HCMV+ group showed hypoconnectivity between the hubs of the sensorimotor network (bilateral postcentral gyrus) and the hubs of the salience network (bilateral insula) with effect sizes ranging from SBC = -0.57 to -0.99. These findings support the hypothesis that a positive HCMV serostatus is associated with altered connectivity of regions that are important for stress and affective processing and further supports a possible etiological role of HCMV in depression.

Encephalitis and Brain Abscess

PURPOSE OF REVIEW

This article reviews infections of the brain parenchyma and includes an overview of the epidemiology, pathogenesis, diagnostic approach, and management of infectious encephalitis and brain abscess.

RECENT FINDINGS

The epidemiology of infectious encephalitis and brain abscess has changed in recent years. Vaccination has reduced the incidence of certain viruses associated with encephalitis, while a decrease in fulminant otogenic infections has led to fewer brain abscesses associated with otitis media. However, changes in climate and human population density and distribution have enabled the emergence of newer pathogens and expanded the geographic range of others, and greater adoption of intensive immunosuppressive regimens for autoimmune conditions has increased the risk of opportunistic infections of the brain. The widespread use of early neuroimaging, along with improved diagnostic methodologies for pathogen detection, newer antimicrobial therapies with better brain penetration, and less invasive neurosurgical techniques, has resulted in better outcomes for patients with infectious encephalitis and brain abscess. Novel technologies including metagenomic next-generation sequencing are increasingly being applied to these conditions in an effort to improve diagnosis. Nevertheless, both infectious encephalitis and brain abscess continue to be associated with substantial mortality.

SUMMARY

Infectious encephalitis and brain abscess can present as neurologic emergencies and require rapid assessment, thorough and appropriate diagnostic testing, and early initiation of empiric therapies directed against infectious agents. Close clinical follow-up, proper interpretation of diagnostic results, and appropriate tailoring of therapeutic agents are essential to optimizing outcomes. Diagnosis and management of parenchymal brain infections are complex and often best achieved with a multidisciplinary care team involving neurologists, neurosurgeons, neuroradiologists, infectious disease physicians, and pathologists.

MRI Spectrum of Japanese Encephalitis in Northeast India: A Cross-Sectional Study

Objective  Japanese encephalitis (JE) is an arthropod-borne flavivirus infection having high mortality and morbidity. This study was performed to evaluate the conventional magnetic resonance imaging (MRI) findings in JE and to find out any difference between pediatric and adult JE.

Materials and Methods  This retrospective study was performed on serologically positive 54 JE patients presented to a tertiary care hospital with acute encephalitic symptoms between April 2016 and October 2019. Relevant neurological examination, cerebrospinal fluid analysis, and MRI scan of the brain were performed.

Results  Fifty-four JE patients ( n = 31 males and n = 23 females) having 32 pediatric and 22 adult JE were included in the study sample. Group 1 JE ( n = 16) patients had encephalitic symptoms with duration less than 15 days up to the day of MRI scan and group 2 JE ( n = 38) had symptoms more than 15 days. Group 1 JE had mean apparent diffusion coefficient (ADC) value of 0.563 ± 0.109 (standard deviation [SD]) × 10 ^–3 mm ² /sec and group 2 JE had 1.095 ± 0.206 (SD) × 10 ^–3 mm ² /sec. The mean ADC value of pediatric JE was 0.907 ± 0.336 (SD) × 10 ^–3 mm ² /sec and adult JE was 0.982 ± 0.253 (SD) × 10 ^–3 mm ² /sec.

Conclusion  The majority of the JE patient shows abnormal signal alterations in bilateral thalami and substantia nigra. Diffusion-weighted imaging with ADC mapping helps in evaluating the stage of the JE. No statistical significance of the various conventional MRI findings was found between the pediatric JE and adult JE.

Case Report: Epstein-Barr Virus Encephalitis Complicated With Brain Stem Hemorrhage in an Immune-Competent Adult

Encephalitis caused by Epstein-Barr virus infection is uncommon, but most patients have a good outcome after symptomatic treatment. The infiltration of mononuclear cells in blood vessels and necrosis resulting from the immune response to Epstein-Barr virus infection in a very small number of patients seem to be the main cause of death. We describe a fatal case of Epstein-Barr virus encephalitis diagnosed by next-generation sequencing in an immune-competent adult but progressed to brainstem hemorrhage.

Case Report: Japanese Encephalitis Associated with Chorioretinitis after Short-Term Travel to Bali, Indonesia

Japanese encephalitis (JE) virus is a mosquito-borne flavivirus endemic throughout Asia. Incidence in non-endemic countries is rare, with an estimate of less than one case per one million travelers. Most human JE infections are asymptomatic or cause a mild, nonspecific febrile illness. Neurological involvement, if present, is usually severe and associated with high mortality or ongoing neurological sequelae in survivors. Ocular manifestations are rare with JE, but uveitis has been described to be associated with other flavivirus infections, including West Nile virus. We report the first probable case of JE chorioretinitis acquired by a 45-year-old Australian traveler to Bali. This case highlights the importance of a detailed ocular examination when there is clinical suspicion of JE.

Intraventricular hemorrhage as clinical presentation of herpes simplex virus encephalitis. A case report and review of the literature

OBJECTIVE

Herpes simplex virus encephalitis (HSVE) represents the most common cause of sporadic encephalitis in humans. The development of intracerebral hematomas is rare and late during the course of HSVE. To report a case of a patient with HSVE who initially presented a diffuse intracranial hemorrhage with predominant intraventricular bleeding.

CASE REPORT

A 66-year-old man was admitted to the Emergency Department with acute headache. Antecedents: alcohol consumption and ethylic hepatopathy. The brain computed tomography showed acute tetraventricular hemorrhage and hydrocephalus. The blood analysis showed pancytopenia and alteration of all hepatic parameters. After external drainage of cerebrospinal fluid the patient presented a worsening of headache, disorientation, mild left hemiparesis, neck stiffness and temperature of 37.6 °C. The cerebrospinal fluid was hemorrhagic, with 3 lymphocytes/mm3, 60 mg/dL of proteins and PCR positive for Herpes simplex virus type 1. The patient improved with intravenous acyclovir, however he experienced several medical complications which caused his dead.

DISCUSSION

The patient presented an atypical cerebral bleeding related to HSVE because the development of hematoma was early and the topography of hemorrhage was basically intraventricular. Probably, both atypical characteristics were related to thrombocytopenia and severe coagulation disorder. This case expands the spectrum of cerebrovascular disorders associated with HSVE.

Primary Categorizing and Masking Cerebral Small Vessel Disease Based on "Deep Learning System"

Objective

To supply the attending doctor’s diagnosis of the persisting of cerebral small vessel disease and speed up their work effectively, we developed a “deep learning system (DLS)” for cerebral small vessel disease predication. The reliability and the disease area segmentation accuracy, of the proposed DLS, was also investigated.

Methods

A deep learning model based on the convolutional neural network was designed and trained on 1,010 DWI b1000 images from 1010 patients diagnosed with segmentation of subcortical infarction, 359 T2^∗ images from 359 patients diagnosed with segmentation of cerebral microbleed, as well as 824 T1-weighted and T2-FLAIR images from 824 patients diagnosed with segmentation of lacune and WMH. Dicw accuracy, recall, and f1-score were calculated to evaluate the proposed deep learning model. Finally, we also compared the DLS prediction capability with that of 6 doctors with 3 to 18 years’ clinical experience (8 ± 6 years).

Results

The results support that an appropriately trained DLS can achieve a high-level dice accuracy, 0.598 in the training section over all these four classifications on 30 patients (0.576 for young neuroradiologists), validation accuracy is 0.496 in lacune, 0.666 in WMH, 0.728 in subcortical infarction, and 0.503 in cerebral microbleeds. It is comparable to attending doctor with a few years of experience, regardless of whether the emphasis is placed on the segmentation or detection of lesions with less time-spending compared with manual analysis, about 4.4 s/case, which is dramatically less than doctors about 634 s/case.

Conclusion

The results of our comparison lend support to the case that an appropriately trained DLS can be trusted to the same extent as one would trust an attending doctor with a few years of experience, regardless of whether the emphasis is placed on the segmentation or detection of lesions.

Immunomodulatory Strategies in Herpes Simplex Virus Encephalitis

Herpes simplex virus 1 (HSV-1) can be responsible for life-threatening HSV encephalitis (HSE). The mortality rate of patients with HSE who do not receive antiviral treatment is 70%, with most survivors suffering from permanent neurological sequelae. The use of intravenous acyclovir together with improved diagnostic technologies such as PCR and magnetic resonance imaging has resulted in a reduction in the mortality rate to close to 20%. However, 70% of surviving patients still do not recover complete neurological functions. Thus, there is an urgent need to develop more effective treatments for a better clinical outcome. It is well recognized that cerebral damage resulting from HSE is caused by viral replication together with an overzealous inflammatory response. Both of these processes constitute potential targets for the development of innovative therapies against HSE. In this review, we discuss recent progress in therapy that may be used to ameliorate the outcome of patients with HSE, with a particular emphasis on immunomodulatory agents. Ideally, the administration of adjunctive immunomodulatory drugs should be initiated during the rise of the inflammatory response, and its duration should be limited in time to reduce undesired effects. This critical time frame should be optimized by the identification of reliable biomarkers of inflammation.

Clinical features and surgical treatment of epilepsy after viral encephalitis

Encephalitis is an acute inflammatory process of the brain parenchyma, which is often caused by viral infection. It is an vital cause of acute symptomatic seizures and subsequent epilepsy. The incidence of unprovoked and recurrent seizures after previous infections of the central nervous system is high and accounts for 1%~5% of the cases of epilepsy. Viral encephalitis (VE) is directly caused by viral infection. The occurrence of seizures after VE is associated with poor prognosis. In survivors of VE, among other neurological sequelae, the risk of developing epilepsy is increased 10-fold. The risk of severe neurological sequelae after VE is particularly high in very young children. Studies on seizure occurrence, possible underlying mechanisms, clinical characteristics, and clinical treatment (especially surgical treatment) of VE have yielded only limited detailed data. We reviewed the most recent literature on the clinical features and surgical treatment of post-VE epilepsy.

Role of 3D Pseudocontinuous Arterial Spin-Labeling Perfusion in the Diagnosis and Follow-Up in Patients with Herpes Simplex Encephalitis

BACKGROUND AND PURPOSE

Early diagnosis and treatment of herpes simplex encephalitis are crucial to reduce morbidity and mortality. Our aim was to investigate the role of 3D pseudocontinuous arterial spin-labeling in herpes simplex encephalitis.

MATERIALS AND METHODS

From 2014 to 2019, seventeen consecutive patients with herpes simplex encephalitis and 15 healthy volunteers were recruited in the study. Conventional MR imaging and 3D pseudocontinuous arterial spin-labeling were performed in all subjects. According to the disease duration, the lesions were classified into 3 groups, including acute, subacute, and chronic stages, respectively. Clinical, neuroradiologic, and follow-up features were studied. The normalized lesion/normal tissue CBF values of lesions at different stages were measured and compared with those in the control group, respectively.

RESULTS

Compared with the control group, herpes simplex encephalitis demonstrated hyperperfusion in 11 acute cases and 6 subacute cases and hypoperfusion in 6 chronic cases. The mean normalized lesion/normal tissue CBF values of the lesions were 2.68 ± 0.54 in the acute stage, 2.42 ± 0.52 in the subacute stage, and 0.87 ± 0.30 in the chronic stage, respectively. The mean normalized lesion/normal tissue CBF values of acute and subacute lesions were significantly higher than those of the control group (1.33 ± 0.08; P < .001, respectively), while the mean normalized lesion/normal tissue CBF values of chronic lesions were lower than those of the control group (P < .05). Gradual perfusion reduction on serial 3D pseudocontinuous arterial spin-labeling was observed in herpes simplex encephalitis after effective therapy.

CONCLUSIONS

Conventional MR imaging remains most helpful in the diagnosis of herpes simplex encephalitis, while 3D pseudocontinuous arterial spin-labeling could be an adjunctive technique by providing dynamic CBF features at different stages in herpes simplex encephalitis.

Neuroimaging in Dementia

Although the diagnosis of dementia still is primarily based on clinical criteria, neuroimaging is playing an increasingly important role. This is in large part due to advances in techniques that can assist with discriminating between different syndromes. Magnetic resonance imaging remains at the core of differential diagnosis, with specific patterns of cortical and subcortical changes having diagnostic significance. Recent developments in molecular PET imaging techniques have opened the door for not only antemortem but early, even preclinical, diagnosis of underlying pathology. This is vital, as treatment trials are underway for pharmacological agents with specific molecular targets, and numerous failed trials suggest that earlier treatment is needed. This article provides an overview of classic neuroimaging findings as well as new and cutting-edge research techniques that assist with clinical diagnosis of a range of dementia syndromes, with an emphasis on studies using pathologically proven cases.

Spectrum and outcome of acute infectious encephalitis/encephalopathy in an intensive care unit from India

PURPOSE

To evaluate the spectrum of acute infectious encephalitis/encephalopathy syndrome (AIES) in intensive care unit (ICU) and the predictors of mechanical ventilation (MV) and outcome of these patients.

METHODS

AIES patients diagnosed on the basis of fever, altered sensorium, seizure and cerebrospinal fluid pleocytosis admitted to the neurology ICU were prospectively included. The demographic and clinical details, hematological, biochemical, MRI and etiological findings of the patients were noted. Need of MV, death in hospital and 3-month functional outcome were analyzed.

RESULTS

One hundred sixty-four out of 258 (64%) AIES patients needed ICU admission. Their median age was 35 (2-85) years and 71 (43%) were females. The etiology was viral in 44 (herpes and Japanese encephalitis in 12 each, dengue in 17, mumps, measles and varicella in 1 patient each), non-viral in 64 (scrub typhus in 48, falciparum malaria in 6, leptospira in 3 and bacterial in 7) and undetermined etiology in 56 (34%) patients. Sixty-nine (42%) patients needed MV. On multivariate analysis, Glasgow Coma Scale (GCS) score, Sequential Organ Failure Assessment (SOFA) score and raised intracranial pressure were independent predictors of MV. Forty-three (26%) patients died, and all were in the MV group. Higher SOFA score and untreatable etiology were independent predictors of mortality. At 3-month follow-up, 14% had poor and 86% had good outcome. Low GCS score, focal weakness and status epilepticus independently predicted poor outcome.

CONCLUSION

Twenty-six percent patients with AIES died in ICU, and 86% had good recovery at 3 months. Admission SOFA scores and untreatable etiology predicted mortality.

Herpes Simplex Virus-1 Encephalitis in Adults: Pathophysiology, Diagnosis, and Management

Herpetic infections have plagued humanity for thousands of years, but only recently have advances in antiviral medications and supportive treatments equipped physicians to combat the most severe manifestations of disease. Prompt recognition and treatment can be life-saving in the care of patients with herpes simplex-1 virus encephalitis, the most commonly identified cause of sporadic encephalitis worldwide. Clinicians should be able to recognize the clinical signs and symptoms of the infection and familiarize themselves with a rational diagnostic approach and therapeutic modalities, as early recognition and treatment are key to improving outcomes. Clinicians should also be vigilant for the development of acute complications, including cerebral edema and status epilepticus, as well as chronic complications, including the development of autoimmune encephalitis associated with antibodies to the N-methyl-D-aspartate receptor and other neuronal cell surface and synaptic epitopes. Herein, we review the pathophysiology, differential diagnosis, and clinical and radiological features of herpes simplex virus-1 encephalitis in adults, including a discussion of the most common complications and their treatment. While great progress has been made in the treatment of this life-threatening infection, a majority of patients will not return to their previous neurologic baseline, indicating the need for further research efforts aimed at improving the long-term sequelae.

Dural arteriovenous fistula-induced thalamic dementia: report of 4 cases

Nonhemorrhagic neurological deficits are underrecognized symptoms of intracranial dural arteriovenous fistulas (dAVFs) having cortical venous drainage. These symptoms are the consequence of cortical venous hypertension and portend a clinical course with increased risk of neurological morbidity and mortality. One rarely documented and easily misinterpreted type of nonhemorrhagic neurological deficit is progressive dementia, which can result from venous hypertension in the cortex or in bilateral thalami. The latter, which is due to dAVF drainage into the deep venous system, is the less common of these 2 dementia syndromes. Herein, the authors report 4 cases of dAVF with venous drainage into the vein of Galen causing bithalamic edema and rapidly progressive dementia. Two patients were treated successfully with endovascular embolization, and the other 2 patients were treated successfully with endovascular embolization followed by surgery. The radiographic abnormalities and presenting symptoms rapidly resolved after dAVF obliteration in all 4 cases. Detailed descriptions of these 4 cases are presented along with a critical review of 15 previously reported cases. In our analysis of these 19 published cases, the following were emphasized: 1) the clinical and radiographic differences between dAVF-induced thalamic versus cortical dementia syndromes; 2) the differential diagnosis and necessary radiographic workup for patients presenting with a rapidly progressive thalamic dementia syndrome; 3) the frequency at which delays in diagnosis occurred and potentially dangerous and avoidable diagnostic procedures were used; and 4) the rapidity and completeness of symptom resolution following dAVF treatment.

A prospective study of magnetic resonance imaging patterns of central nervous system infections in pediatric age group and young adults and their clinico-biochemical correlation

Background:

Infections of the central nervous system (CNS) are common and routinely encountered. Our aim was to evaluate the neuroimaging features of the various infections of the CNS so as to differentiate them from tumoral, vascular, and other entities that warrant a different line of therapy.

Aims:

Our aim was to analyze the biochemical and magnetic resonance imaging (MRI) features in CNS infections.

Settings and Design:

This was a longitudinal, prospective study over a period of 1½ years.

Subjects and Methods:

We studied cerebrospinal fluid (CSF) findings and MRI patterns in 27 patients of 0–20 years age group with clinical features of CNS infections. MRI was performed on MAGNETOM Avanto 18 Channel 1.5 Tesla MR machine by Siemens India Ltd. The MRI protocol consisted of diffusion-weighted and apparent diffusion coefficient imaging, turbo spin echo T2-weighted, spin echo T1-weighted, fluid-attenuated inversion recovery (FLAIR), and gradient-echo in axial, FLAIR in coronal, and T2-weighted in sagittal plane. Contrast-enhanced T1-weighted sequence and MR spectroscopy were done whenever indicated.

Results and Conclusions:

We found that most of the children belong to 1–10 years age group. Fungal infections were uncommon, mean CSF adenosine deaminase values specific for tuberculosis and mean CSF glucose-lowered in pyogenic. Hemorrhagic involvement of thalamus with/without basal ganglia and brainstem involvement may indicate Japanese encephalitis or dengue encephalitis. Diffusion restriction or hemorrhage in not expected in the brainstem afflicted lesions of rabies. Congenital cytomegalovirus can cause cortical malformations. T1 hyperintensities with diffusion restriction may represent viral encephalitis. Lesions of acute disseminated encephalomyelitis (ADEM) may mimic viral encephalitis. Leptomeningeal enhancement is predominant in pyogenic meningitis. Basilar meningitis in the presence of tuberculomas is highly sensitive and specific for tuberculosis.

Neuroimaging in encephalitis: analysis of imaging findings and interobserver agreement

Aim

To assess the role of imaging in the early management of encephalitis and the agreement on findings in a well-defined cohort of suspected encephalitis cases enrolled in the Prospective Aetiological Study of Encephalitis conducted by the Health Protection Agency (now incorporated into Public Health England).

Materials and methods

Eighty-five CT examinations from 68 patients and 101 MRI examinations from 80 patients with suspected encephalitis were independently rated by three neuroradiologists blinded to patient and clinical details. The level of agreement on the interpretation of images was measured using the kappa statistic. The sensitivity, specificity, and negative and positive predictive values of CT and MRI for herpes simplex virus (HSV) encephalitis and acute disseminated encephalomyelitis (ADEM) were estimated.

Results

The kappa value for interobserver agreement on rating the scans as normal or abnormal was good (0.65) for CT and moderate (0.59) for MRI. Agreement for HSV encephalitis was very good for CT (0.87) and MRI (0.82), but only fair for ADEM (0.32 CT; 0.31 MRI). Similarly, the overall sensitivity of imaging for HSV encephalitis was ∼80% for both CT and MRI, whereas for ADEM it was 0% for CT and 20% for MRI. MRI specificity for HSV encephalitis between 3–10 days after symptom onset was 100%.

Conclusion

There is a subjective component to scan interpretation that can have important implications for the clinical management of encephalitis cases. Neuroradiologists were good at diagnosing HSV encephalitis; however, agreement was worse for ADEM and other alternative aetiologies. Findings highlight the importance of a comprehensive and multidisciplinary approach to diagnosing the cause of encephalitis that takes into account individual clinical, microbiological, and radiological features of each patient.

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We assessed the role of imaging in encephalitis.

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We assessed the agreement between raters on scan interpretation.

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Diagnosis for herpes simplex encephalitis (HSE) was good.

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Agreement was worse for ADEM and other alternative aetiologies.

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HSE can be dismissed if MRI normal 72 hours after neurological symptom onset (with negative CSF tests).

Can we differentiate between herpes simplex encephalitis and Japanese encephalitis?

BACKGROUND

Herpes simplex encephalitis (HSE) occurs without regional and seasonal predilections. HSE is important to differentiate from arboviral encephalitis in endemic areas because of therapeutic potential of HSE. This study evaluates clinical features, MRI and laboratory findings which may help in differentiating HSE from Japanese encephalitis (JE).

METHODS

Confirmed patients with JE and HSE in last 10years were included. The presenting clinical symptoms including demographic information, seizure, behavioral abnormality, focal weakness and movement disorders were noted. Cranial MRI was done and location and nature of signal alteration were noted. Electroencephalography (EEG), cerebrospinal fluid (CSF), blood counts and serum chemistry were done. Outcome was measured by modified Rankin Scale (mRS). Death, functional outcome and neurological sequelae were noted at 3, 6 and 12months follow up, and compared between HSE and JE. Outcome was categorized as poor (mRS;>2) and good (mRS≤2).

RESULTS

97 patients with JE and 40 HSE were included. JE patients were younger than HSE and occurred in post monsoon period whereas HSE occurred throughout the year. Seizure (86% vs 40%) and behavioral abnormality (48% vs 10%) were commoner in HSE; whereas movement disorders (76% vs 0%) and focal reflex loss (42% vs 10%) were commoner in JE. CSF findings and laboratory parameters were similar in both the groups. Thalamic involvement in JE and temporal involvement in HSE were specific markers of respective encephalitis. Delta slowing on EEG was more frequent in JE than HSE. 20% JE and 30% HSE died in the hospital, and at 1year follow up JE patients showed better outcome compared to HSE (48% vs 24%). Memory loss (72% vs 22%) was the predominant sequelae in HSE.

CONCLUSION

Seizure and behavioral abnormality are common features in HSE whereas focal reflex loss is commoner in JE. In a patient with acute encephalitis, thalamic lesion suggests JE and temporal lobe involvement HSE. Long term outcome in JE is better compared to HSE.

Bilateral central retinal artery occlusion associated with herpes simplex virus-associated acute retinal necrosis and meningitis: case report and literature review

A 60-year-old woman with a history of recurrent headaches and blurred vision presented with bilateral optic disc edema. Optic neuritis was suspected, and intravenous methylprednisonlone was administered. Her vision declined to hand motions in both eyes, and subsequent evaluation revealed bilateral acute retinal necrosis with bilateral central retinal artery occlusions (CRAO). Aqueous humor polymerase chain reaction analysis was positive for herpes simplex virus (HSV), establishing a diagnosis of HSV-associated bilateral acute retinal necrosis (ARN) and meningitis. CRAO has rarely been reported in association with ARN, and a fulminant course with bilateral CRAO in association with ARN has not been previously reported. This case emphasizes the importance of careful peripheral examination in patients with presumptive optic neuritis, judicious use of systemic corticosteroid in this context, and the retinal vaso-obliterative findings that may be observed in the pathogenesis of ARN.

A study of MRI changes in Wilson disease and its correlation with clinical features and outcome

OBJECTIVE

To evaluate the sensitivity of different MRI sequences in Wilson disease (WD) with neurological manifestations and its correlation with clinical features and outcome.

METHODS

34 WD patients with neurological manifestation with a median age of 14 years were included. Their Mini Mental State Examination (MMSE) score, movement disorders and laboratory findings were noted. Cranial MRI in T1, T2, FLAIR and DW sequences were done. Outcome at 6 months was categorized into improved (>1 grade improvement), static or worsening.

RESULTS

MRI was abnormal in all and revealed involvement of putamen in 29 (85.3%), caudate in 23 (67.6%), brainstem and globus pallidus in 21 (61.8%) each, thalamus in 20 (58.8%), cerebral cortex in 9 (26.5%), subcortical white matter in 8 (23.5%), and cerebellum in 2 (5.9%) patients. The overall sensitivity of T2 and FLAIR was 97.1% each, DWI 38.2% and T1 31.4%. None had contrast enhancement and 4 had reduced ADC value. Choreoathetosis correlated with thalamic, pallidal and putaminal lesions; MMSE with subcortical white mater. MRI load correlated with age, tremor, psychiatric disorder, choreoathetosis, and severity of WD. At 6 months 9 (26.5%) patients improved, 18 (52.9%) remained static and 6 (17.6%) deteriorated.

CONCLUSION

In neurologic WD, putaminal involvement is the commonest; T2 and FLAIR sequences have similar sensitivity and number of MRI lesions correlated with disease severity but not with outcome.

In vivo visualization of encephalitic lesions in herpes simplex virus type 1 (HSV-1) infected mice by magnetic resonance imaging (MRI)

Herpes simplex encephalitis (HSE) is one of the most severe viral infections affecting the temporal lobes of the brain. Despite the improvements in diagnosis and antiviral drug treatment, one third of all patients fail to respond to therapy or subsequently suffer neurological relapse and develop long term neurological damage. Magnetic resonance imaging (MRI) is among the appropriate noninvasive tools for early diagnosis of viral central nervous system (CNS) infections. In this chapter we introduce a mouse model for HSE and describe a MRI protocol to characterize the pathogenesis of HSE over time.

Neuroimaging of rapidly progressive dementias, part 2: prion, inflammatory, neoplastic, and other etiologies

Most dementias begin insidiously, developing slowly and generally occurring in the elderly age group. The so-called rapidly progressive dementias constitute a different, diverse collection of conditions, many of which are reversible or treatable. For this reason, accurate identification and assessment of acute and subacute forms of dementia are critical to effective treatment; neuroimaging aids greatly in narrowing the diagnosis of these conditions. This second installment of a 2-part review of rapidly progressive dementias examines the use of imaging in an assortment of other etiologies in the differential diagnosis, from prion disease and neoplastic-related conditions to rare metabolic and other conditions such as Wernicke encephalopathy. In these clinical conditions, MR imaging has the potential to narrow this broad differential diagnosis and, at times, can definitively aid in the diagnosis of certain conditions on the basis of typical imaging patterns.

Diffusion-weighted imaging in the diagnosis of enterovirus 71 encephalitis

BACKGROUND

In the early phase of viral encephalitis, conventional MRI may appear normal. Diffusion-weighted imaging (DWI) is a sensitive tool for detecting early changes in cellular function in the central nervous system.

PURPOSE

To investigate the usefulness of DWI in the diagnosis of enterovirus 71 (EV71) encephalitis, and to determine whether DWI is superior to conventional MR sequences.

MATERIAL AND METHODS

MRI scans in 26 patients were retrospectively evaluated for distribution of lesions on T1-weighted images (T1WI), T2-weighted images (T2WI), fluid-attenuated inversion recovery (FLAIR), and DWI. Contrast-to-noise ratios (CNRs) were calculated for all regions on each sequence and differences in the four MRI sequences were assessed using CNRs. Apparent diffusion coefficient (ADC) values were measured for all regions to look for true restriction of diffusion.

RESULTS

Fifteen out of 26 cases showed positive findings on MR imaging. The brain stem was involved in 11 patients, cortex and subcortical white matter in four patients. DWI was more sensitive in detecting the abnormalities (89.7%) compared to T2WI (48.7%), FLAIR (41.0%), and T1WI (35.9%), and the positive ratio of DWI was significantly higher compared to other sequences. Furthermore, no significant difference was found between T2WI and FLAIR (P = 0.649). The corresponding mean CNRs were 8.73 ± 2.57, 83.59 ± 29.28, 24.22 ± 6.22, and 132.27 ± 78.32 on T1WI, T2WI, FLAIR, and DWI, respectively. The absolute values of CNRs of lesions on DWI were significantly greater than those on other sequences.

CONCLUSION

DWI appears to be more sensitive in detecting EV71 encephalitis than conventional MRI sequences. This capability may improve the accuracy in diagnosing EV71 encephalitis, especially at the early stage.