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Objective: Herpes simplex virus encephalitis (HSVE) is associated with significant morbidity and mortality. Here, we present the occurrence of HSVE in a 36-year-old immunocompetent patient following craniotomy for a traumatic acute subdural hematoma (ASDH)., Methods: Imaging after four days of progressive headache following a fall with head-strike demonstrated a 1 cm thick left holohemispheric ASDH with significant cerebral compression, edema, and 8 mm of left-to-right midline shift, and an emergent craniotomy and ASDH evacuation were performed, with additional treatment needed for reaccumulation. Postoperatively, the patient developed a worsening leukocytosis, became febrile, and was hypotensive requiring vasopressor support., Results: Despite empiric antibiotics, the patient remained persistently febrile with significant leukocytosis. Repeat head CT showed a new left insular hypodensity and a subsequent viral encephalitis panel was positive for HSV-1. The patient was then started on intravenous acyclovir, with progressive neurological exam improvement. Of note, the patient was noted to have a positive serum HSV-1 IgG antibody titer, indicative of prior infection., Conclusions: Given the known systemic immunosuppression in brain injury and the high prevalence of HSV seropositivity, clinicians should consider the possibility of HSVE from HSV reactivation in TBI patients with persistent fever, leukocytosis, and/or neurological deficits without an obvious etiology.

Background: Herpes simplex virus encephalitis (HSE) frequently triggers secondary anti-N-methyl-D-aspartate receptor encephalitis (NMDARE), but markers predicting the occurrence of this entity (HSE-NMDARE) are lacking., Methods: We conducted a retrospective description of patients with HSE-NMDARE diagnosed between July 2014 and August 2022 and compared them to both patients with regular forms of HSE and NMDARE., Results: Among the 375 patients with NMDARE, 13 HSE-NMDARE were included. The median age was 19 years (0.5-73), 4/13 (31%) were children < 4 years old, and 7/13 (54%) were male. The median time between HSE and NMDARE onset was 30 days (21-46). During NMDARE, symptoms differed from HSE, including increased behavioral changes (92% vs 23%, p = 0.008), movements disorders (62% vs 0%, p = 0.013), and dysautonomia (54% vs 0%, p = 0.041). Compared to 21 patients with regular HSE, patients with HSE-NMDARE more often achieved severity-associated criteria on initial MRIs, with extensive lesions (11/11, 100% vs 10/21, 48%, p = 0.005) and bilateral diffusion-weighted imaging sequence abnormalities (9/10, 90% vs 6/21, 29%, p = 0.002). Compared to 198 patients with regular NMDARE, patients with HSE-NMDARE were more frequently males (7/13, 54% vs 43/198, 22%; p = 0.015) and children < 4 (4/13, 31% vs 14/198, 7%; p = 0.016), with a worse 12-month mRS (2[1-6] vs 1[0-6], p = 0.023)., Conclusions: Herein, patients with HSE-NMDARE have a poorer long-term prognosis than patients with regular NMDARE. We report a greater rate of severity-associated criteria on initial MRIs for HSE-NMDARE compared to regular HSE, which may help identify patients with higher risk of HSE-NMDARE., (© 2024. The Author(s).)

Herpes simplex virus (HSV) infections necessitate careful management of urinary dysfunction and retention, which are underestimated conditions. Here, we present a rare case of HSV encephalomyeloradiculitis in a 76-year-old man, whose initial symptoms included urinary dysfunction and retention that alone lasted for approximately 1 week. Unlike in meningoencephalitis, high fever and headache were absent; however, the patient subsequently developed cauda equina syndrome and consciousness disturbance. Gadolinium-enhanced spinal MRI suggested enhanced cauda equina at the L2/3 level. Upon admission, he was treated for meningoencephalitis with acyclovir and steroid pulse therapy. Subsequent cerebrospinal fluid analysis result was positive for HSV DNA. A ‍brain MRI conducted 1 week after admission displayed high-intensity lesions in the white matter of the right temporal lobe, confirming HSV encephalomyeloradiculitis. These treatments were highly effective and gradually improved the patient's condition. He was discharged 1 month after hospitalization, and the urinary catheter was removed 2 weeks later. HSV infections can cause life-threatening encephalomyeloradiculitis. Therefore, both neurologists and urologists must pay attention to their occurrence and characteristics in clinical settings.

A 78-year-old man was admitted to the hospital with a 4-day history of fever and confusion. Physical examination revealed oral dryness and decreased skin turgor. Blood tests showed hyponatremia (121.5 ‍mEq/l), and cerebrospinal fluid examination revealed positivity for herpes simplex virus 1 (HSV-1) via polymerase chain reaction. He was diagnosed with herpes simplex encephalitis and initiated acyclovir treatment. The hyponatremia was diagnosed as cerebral salt wasting syndrome (CSWS) and treated with hypertonic saline infusion and fludrocortisone. The cerebrospinal fluid HSV-1 DNA became negative, and the serum sodium levels normalized. Hyponatremia complicated with encephalitis is often caused by the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), whereas CSWS is rare, mostly observed in tuberculous meningitis. Differentiating between the SIADH and CSWS is important as they require distinct therapeutic strategies.

Background: Cognitive disorders usually develop slowly over years and are mainly caused by untreatable neurodegenerative disorders. Rapidly progressive cognitive disorders should raise suspicion of an underlying and treatable psychiatric, internal or neurological condition. Timely recognition of these conditions is important., Case: We present the case of a 68-year old man, presenting on the emergency department with a history of progressive cognitive impairment since several weeks. Cerebral MRI showed T2-hyperintensities in the left hippocampal, mesotemporal and insular regions; lesser so in the right mesotemporal region. After initial treatment for herpesencephalitis and autoimmune encephalitis, we diagnosed neurolues and started treatment with benzylpenicillin., Conclusion: It may be difficult to diagnose neurolues because the vast variety of clinical symptoms and radiological signs. This case shows that neurolues should be considered in a patient with rapidly progressive cognitive disorders and that neurolues can mimic a herpesencephalitis or an autoimmune encephalitis. Timely recognition is important to prevent irreversible damage.

Sinus arrest and inappropriate sinus bradycardia are sinus node dysfunction (SND), which cause loss of consciousness. Cardiac pacing is recommended in patients with symptoms, such as syncope or dizziness. Several conditions can induce these arrhythmias; however, whether or not intracranial infectious diseases, such as herpes simplex encephalitis (HSE), can cause secondary SND is unclear. We encountered a patient with sinus arrest and transient sinus bradycardia associated with HSE. Since cardiac pause was never monitored and the bradycardia improved after HSE treatment, HSE was suspected to be the cause of SND. Although the underlying mechanisms have not yet been completely elucidated, HSE may cause secondary SND.

Introduction: Identifying coronavirus disease 2019 (COVID-19)-related encephalitis without clear etiological evidence is clinically challenging. The distinctions between this condition and other prevalent encephalitis types remain unknown. Therefore, we aimed to explore the similarities and differences in the clinical characteristics of COVID-19-related encephalitis and other encephalitis types., Methods: Adult patients with encephalitis admitted to the neurology department at Xuanwu Hospital were enrolled and categorized into the following six groups based on the results of metagenomic next-generation sequencing and autoimmune antibody detection in cerebrospinal fluid (CSF): COVID-19-related encephalitis (n = 36), herpes simplex virus type 1 encephalitis (HSV-1 encephalitis; n = 28), human herpesvirus 3 encephalitis (HHV-3 encephalitis; n = 10), NMDAR-antibody encephalitis (n = 18), LGI1-antibody encephalitis (n = 12), and GABAB-antibody encephalitis (n = 8)., Results: The predominant characteristics of COVID-19-related encephalitis include a low incidence of seizures (38.9%), cognitive defects (30.6%), and meningeal irritation signs (8.3%). Compared with HSV-1 and HHV-3 encephalitis, COVID-19-related encephalitis exhibited lower white blood cell count (2.5 count/mm 3 ), protein (32.2 mg/dL), and immunoglobulin M, G, and A levels (0.09, 3.2, and 0.46 mg/dL, respectively) in the CSF tests. Abnormal imaging findings were present in only 36.1% of COVID-19-related encephalitis cases, mostly showing diffuse inflammation scattered in various parts, which differed from HSV-1 encephalitis. Additionally, COVID-19-related encephalitis exhibited significant differences in clinical symptoms and CSF white blood cell counts compared with NMDAR-antibody encephalitis; however, it showed limited differences compared with LGI1-antibody and GABAB-antibody encephalitis., Discussion: COVID-19-related encephalitis and herpes virus or autoimmune encephalitis differ clinically. Symptoms and auxiliary examinations can be used as distinguishing tools., (© 2024. The Author(s).)

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 R 2  = 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 R 2  = 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., Competing Interests: Declaration of competing interest Thai Son Pham, Federico Montini, Hoang Nhat Pham, Minh-Thu Nguyen Tran, and Tien Huy Nguyen report no disclosures. Laura Cacciaguerra received speaker and consultant honoraria from ACCMED, Biomedia, Roche, BMS Celgene, and Sanofi and travel support for conferences by Merck Serono. Massimo Filippi is Editor-in-Chief of the Journal of Neurology, is Associate Editor of Human Brain Mapping, Neurological Sciences, and is Associate Editor of Radiology. He received compensation for consulting services from Alexion, Almirall, Biogen, Merck, Novartis, Roche, and Sanofi; for speaking activities from Bayer, Biogen, Celgene, Chiesi Italia SpA, Eli Lilly, Genzyme, Janssen, Merck-Serono, Neopharmed Gentili, Novartis, Novo Nordisk, Roche, Sanofi, Takeda, and TEVA; for participation in Advisory Boards for Alexion, Biogen, Bristol-Myers Squibb, Merck, Novartis, Roche, Sanofi, Sanofi-Aventis, Sanofi-Genzyme, and Takeda; and for scientific direction of educational events for Biogen, Merck, Roche, Celgene, Bristol-Myers Squibb, Lilly, Novartis, and Sanofi-Genzyme; he receives research support from Biogen Idec, Merck-Serono, Novartis, Roche, Italian Ministry of Health, Fondazione Italiana Sclerosi Multipla, and ARiSLA (Fondazione Italiana di Ricerca per la SLA)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

We report a baby with neonatal herpes simplex virus (HSV) encephalitis concurrent with Rrhesus (Rh) incompatibility. He was delivered by a Ggravida 2 mother with a history of miscarriage in her previous pregnancy at a gestation age of 4 months. She had Bblood group 0 and Rrhesus negative. The baby was noticed to have jaundice on day one1 of life accompanied by generalised petechiae on the face and upper chest. A full blood picture revealed severe anaemia and severe thrombocytopaenia and HSV 1/2 IgM was positive. MRI of the brain showed multiple extensive haemorrhagic lesions on the frontal-temporal regions., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Herpes simplex virus (HSV) infection triggered n-methyl-D-aspartate (NMDA) encephalitis can lead to varied neuropsychiatric manifestations, including movement disorders and manic symptoms. HSV is known to affect the same brain regions as in secondary mania., Method: We present a 35-year-old female diagnosed with recurrent depressive disorder (RDD) who developed NMDA encephalitis triggered by HSV infection., Result: HSV-triggered NMDA encephalitis led to a manic switch in a woman with RDD on antidepressants, along with the new onset of dyskinetic movements., Conclusion: A neurological insult predisposed our patient to the variable effects of antidepressant drugs., (© 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

An 85-year-old woman was diagnosed with coronavirus disease 2019 (COVID-19). The patient was treated with dexamethasone, and the infection was cured. She later developed a low-grade fever and fell unconscious. Positivity for herpes simplex virus deoxyribonucleic acid polymerase chain reaction (HSV-DNA PCR) was detected in the cerebrospinal fluid, so she was diagnosed with HSV encephalitis. The patient was treated with antiviral drugs and recovered from the HSV encephalitis. This case suggests that, in patients with COVID-19 and disorders of consciousness, the possibility of HSV encephalitis should be considered along with COVID-19 encephalitis.

Herpes simplex virus (HSV) encephalitis is a common cause of severe and potentially fatal encephalitis. Autoimmune post-herpes simplex encephalitis (AIPHSE) affects a percentage of patients who developed herpes simplex encephalitis (HSE) and is characterized by the onset of new neurological/psychiatric symptoms and/or worsening of deficits acquired during the herpes infection within a predictable time frame. It is caused by a mechanism not related to HSV, but by autoimmune conditions, and is susceptible to treatment with immunomodulators. Here we describe the case of a 5-year-old boy with AIPHSE who required first- and second-line immunomodulatory treatment, with an adequate course and remission of symptoms., (Sociedad Argentina de Pediatría.)

Patients with herpes simplex virus (HSV) encephalitis (HSE) often develop neuronal autoantibody-associated encephalitis (AE) post-infection. Risk factors of AE are unknown. We tested the hypotheses that predisposition for AE post-HSE may be involved, including genetic variants at specific loci, human leucocyte (HLA) haplotypes, or the blood innate immune response against HSV, including type I interferon (IFN) immunity. Patients of all ages with HSE diagnosed between 1 January 2014 and 31 December 2021 were included in one of two cohorts depending on whether the recruitment was at HSE onset (Spanish Cohort A) or by the time of new neurological manifestations (international Cohort B). Patients were assessed for the type of neurological syndromes; HLA haplotypes; blood type I-IFN signature [RNA quantification of 6 or 28 IFN-response genes (IRG)] and toll-like receptor (TLR3)-type I IFN-related gene mutations. Overall, 190 patients (52% male) were recruited, 93 in Cohort A and 97 in Cohort B. Thirty-nine (42%) patients from Cohort A developed neuronal autoantibodies, and 21 (54%) of them developed AE. Three syndromes (choreoathetosis, anti-NMDAR-like encephalitis and behavioural-psychiatric) showed a high (≥95% cases) association with neuronal autoantibodies. Patients who developed AE post-HSE were less likely to carry the allele HLA-A*02 (4/21, 19%) than those who did not develop AE (42/65, 65%, P = 0.0003) or the Spanish general population (2005/4335, 46%, P = 0.0145). Blood IFN signatures using 6 or 28 IRG were positive in 19/21 (91%) and 18/21 (86%) patients at HSE onset, and rapidly decreased during follow-up. At Day 21 after HSE onset, patients who later developed AE had higher median IFN signature compared with those who did not develop AE [median Zs-6-IRG 1.4 (0.6; 2.0) versus 0.2 (-0.4; 0.8), P = 0.03]. However, a very high median Zs-6-IRG (>4) or persistently increased IFN signature associated with uncontrolled viral infection. Whole exome sequencing showed that the percentage of TLR3-IFN-related mutations in patients who developed AE was not different from those who did not develop AE [3/37 (8%) versus 2/57 (4%), P = 0.379]. Multivariate logistic regression showed that a moderate increase of the blood IFN signature at Day 21 (median Zs-6-IRG >1.5 but <4) was the most important predictor of AE post-HSE [odds ratio 34.8, interquartile ratio (1.7-691.9)]. Altogether, these findings show that most AE post-HSE manifest with three distinct syndromes, and HLA-A*02, but not TLR3-IFN-related mutations, confer protection from developing AE. In addition to neuronal autoantibodies, the blood IFN signature in the context of HSE may be potentially useful for the diagnosis and monitoring of HSE complications., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objectives: We examined the temporal changes of the CSF proteome in patients with herpes simplex encephalitis (HSE) during the course of the disease, in relation to anti-N-methyl-D-aspartate receptor (NMDAR) serostatus, corticosteroid treatment, brain MRI and neurocognitive performance., Methods: Patients were retrospectively included from a previous prospective trial with a pre-specified CSF sampling protocol. Mass spectrometry data of the CSF proteome were processed using pathway analysis., Results: We included 48 patients (110 CSF samples). Samples were grouped based on time of collection relative to hospital admission - T1: ≤ 9 d, T2: 13-28 d, T3: ≥ 68 d. At T1, a strong multi-pathway response was seen including acute phase response, antimicrobial pattern recognition, glycolysis and gluconeogenesis. At T2, most pathways activated at T1 were no longer significantly different from T3. After correction for multiplicity and considering the effect size threshold, 6 proteins were significantly less abundant in anti-NMDAR seropositive patients compared to seronegative: procathepsin H, heparin cofactor 2, complement factor I, protein AMBP, apolipoprotein A1 and polymeric immunoglobulin receptor. No significant differences in individual protein levels were found in relation to corticosteroid treatment, size of brain MRI lesion or neurocognitive performance., Conclusions: We show a temporal change in the CSF proteome in HSE patients during the course of the disease. This study provides insight into quantitative and qualitative aspects of the dynamic pathophysiology and pathway activation patterns in HSE and prompts for future studies on the role of apolipoprotein A1 in HSE, which has previously been associated with NMDAR encephalitis.

This report describes a case in which diplopia was developed as a finding of postinfectious anti- N -methyl- d -aspartate receptor encephalitis. Infectious encephalitis, especially herpes simplex virus, is essential as it is one of the triggers of autoimmune encephalitis. Even if the cases present unexpected clinical findings, we should be vigilant in terms of autoimmune processes, such as diplopia seen in our case., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Herpes Simplex Virus-1 (HSV-1) is a neurotropic DNA virus with neural latency and stereotypic viral encephalitis. It has been reported to conceal underlying glioblastoma (GBM) due to similar radiographic imaging and clinical presentation. Limited data exist on the co-occurrence of GBM and HSV-1. To better describe the pathophysiology of HSV-1 superinfections in GBM, we performed a comprehensive review of GBM cases with superimposed HSV-1., Methods: A comprehensive literature search of six electronic databases with apriori search criteria was performed to identify eligible cases of GBM with HSV-1. Relevant clinic-radiographic data were collected, Kaplan-Meier estimates, Fisher's exact test, and logistic regression analyses were used., Results: We identified 20 cases of HSE in GBM with an overall survival (OS) of 8.0 months. The median age of presentation was 63 years (range: 24-78 years) and the median interval between GBM or HSE diagnosis was 2 months (range: 0.05-25 months). HSE diagnosis before GBM diagnosis was a predictor for improved survival (HR: 0.06; 95% CI: [0.01-0.54]; p < 0.01). There is a significant reduction in OS in patients with concomitant HSE and GBM compared to the cancer genome atlas (TCGA) cohort (median OS: 8 months vs. 14.2 months; p < 0.05). Finally, HSV does not directly infect GBM cells but indirectly activates a local immune response in the tumor microenvironment., Conclusions: Superimposed HSE in GBM may contribute to a significant reduction in OS compared to uninfected controls, potentially activating proto-oncogenes during active infection and latency. Preoperative HSE may induce an antiviral immune response, which may serve as a positive prognostic factor. Prompt antiviral treatment upon co-occurrence is necessary., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Objectives: To identify the prevalence of herpes simplex encephalitis (HSE), factors influencing the duration of empirical acyclovir and frequency of acute kidney injury (AKI) in children with acute encephalitis syndrome (AES)., Design: Prospective observational study., Setting: Pediatric Emergency Department and PICU of a tertiary hospital in Northern India., Patients: All consecutive, eligible children between 1 month and 12 years old presenting with AES, defined as altered consciousness for greater than 24 hours (including lethargy, irritability, or a change in personality) and two or more of the following signs: 1) fever (temperature ≥ 38°C) during the current illness, 2) seizures or focal neurological signs, 3) cerebrospinal fluid (CSF) pleocytosis, 4) electroencephalogram, and/or 5) neuroimaging suggesting encephalitis, who received at least one dose of acyclovir., Interventions: None., Measurements and Main Results: Of the 101 children screened, 83 were enrolled. The median (interquartile range [IQR]) age was 3 years (1-6 yr). Thirty-one children (37.3%) were diagnosed with AES, of which four were labeled as probable HSE (three based on MRI brain, one based on serology). Scrub typhus, dengue, Japanese encephalitis, and mumps were the other infective causes. The median (IQR) duration of acyclovir therapy was 72 hours (24-264 hr); 21 children (25.3%) received acyclovir for less than 24 hours and 11 (13.3%) for greater than or equal to 14 days. New-onset AKI was seen in 18 children (21.7%) but was mostly transient. Death ( n = 8, 9.6%) and discontinuation of care due to futility or other reasons ( n = 15, 18%) were noted in 23 children (28%). Factors associated with duration of acyclovir greater than 7 days, on univariable analysis, were lower modified Glasgow Coma Score at admission, requirement of invasive ventilation, invasive intracranial pressure monitoring, and CSF pleocytosis (5-500 cells). On multivariable analysis, only CSF pleocytosis of 5-500 cells was associated with duration of acyclovir greater than 7 days., Conclusions: Given the low prevalence of HSE, and the risk of AKI, this study sensitizes the need to review our practice on initiation and stopping of empirical acyclovir in children with acute encephalitis., Competing Interests: Dr. Sankhyan disclosed that he is the site principal investigator (PI) for a funded international multicentric trial on treatment of tuberculous meningitis in children (Short intensive treatment for children with tuberculous meningitis, the “SURE trial”), which is being coordinated by the University College London and is an investigator-initiated academic trial. He is also the site PI for a pharmaceutical-sponsored (PTC United States) trial on Ataluren in Duchenne muscular dystrophy. The remaining authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2023 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.)

Background: We reported on a case involving an older patient with HSV-1 encephalitis who simultaneously experienced the onset of peripheral nerve symptoms associated with the presence of anti-GM3 immunoglobulin G (IgG)., Case Presentation: A 77-year-old male was admitted to hospital with high fever, weakness of both lower limbs, and an unstable gait. A CSF test revealed a strikingly increased protein level (1,002 mg/L, normative values: 150-450 mg/L) and MRI revealed hyper-signal lesions in the right temporal lobe, right hippocampus, right insula, and right cingulate gyrus. The CSF was positive for HSV PCR (HSV-1,17870). In addition, the serum samples were positive for CASPR2 antibodies (antibody titer: 1/10) and anti-GM3 immunoglobulin G (IgG) (+). The patient was diagnosed with HSV-1-induced peripheral nerve symptoms that were associated with encephalitis and the presence of anti-GM3 IgG and anti-CASPR2 antibodies. The patient had received included intravenous immunoglobulin, intravenous acyclovir, and corticosteroids therapy. At the one-year follow-up examination, he had regained the necessary skills associated with daily life., Conclusions: Herpes simplex virus infection often induces encephalitis, and reaction to the virus may trigger an autoimmune response. Early diagnosis and treatment can avoid the progression of the disease to include autoimmune encephalitis., (© 2023. The Author(s).)

Rationale: Recurrent herpes simplex encephalitis (HSE) can easily induce autoimmune encephalitis (AE). However, there are few reports of anti-contactin-associated protein-2 (CASPR2)-related encephalitis, especially with positive anti-aquaporin 4 (AQP4) antibodies., Patient Concerns: A 14-year-old boy was admitted to the Department of Neurology of the First Affiliated Hospital of Kunming Medical University for "headache, dizziness, and fever for four days" with positive anti-CASPR2 and anti-AQP4 antibodies in the cerebrospinal fluid., Diagnoses: Cranial MRI showed lesions in the right hippocampus, amygdala, and insular lobe, with local sulcus enhancement in the right insular, temporal, and frontal lobes. The fluid-attenuated inversion recovery was significantly enhanced. Human herpes virus type I was detected by cerebrospinal fluid metagenomic testing. The patient was diagnosed with AE secondary to HSE, with positive anti-CASPR2 and anti-AQP4 antibodies., Interventions: After 2 weeks of immunoglobulin and methylprednisolone immunomodulatory therapy, acyclovir antivirus, mannitol dehydration, reducing intracranial pressure, and other symptomatic support therapy., Outcomes: The patient's symptoms significantly improved, with no complaints of discomfort, and he was discharged for observation. The patient was followed up a month after discharge and had no complaints of discomfort., Lessons: CASPR2 and anti-aquaporin-4 antibody-positive AE have not been reported to be positive. This case will raise awareness of CASPR2 and anti-aquaporin-4 antibody-positive AE secondary to HSE, strengthen diagnostic capacities, and provide advice to treat it., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: To describe the clinical and radiological characteristics of anti-metabotropic glutamate receptor 5 (mGluR5) encephalitis., Methods: We reviewed the clinical data of five patients with anti-mGluR5 encephalitis, and performed a literature review., Results: The five cases included a 52-year-old man who developed a biphasic course of anti-mGluR5 encephalitis after herpes simplex encephalitis, a 22-year-old woman who showed bilateral basal ganglia lesions on brain magnetic resonance imaging (MRI), and a 36-year-old man with mixed aphasia and generalized tonic-clonic seizures, a 51-year-old man presented with personality changes, hallucinations, delusions, sleeping disorders and a 58-year-old man with short-term memory deficits and absence seizures.. There are 16 reported cases of anti-mGluR5 encephalitis worldwide. Of all 21 patients, with a median onset age of 35 years old, the main neurological symptoms were cognitive impairment (85.7%, 18/21), psychiatric or behavior problems (76.2%, 16/21), seizures (57.1%, 12/21), sleeping disorders (52.4%, 11/21), different degrees of decreased consciousness (42.9%, 9/21), and movement disorders (23.8%, 5/21). Brain MRI was normal in 11 of 21 patients. Lesions of the limbic lobes were presented in 5 patients, while involvement of other extralimbic regions was also reported. Seven of 21 (33.3%) cases were combined with tumors. Elevated white blood cell counts or specific oligoclonal IgG bands in the cerebrospinal fluid were found in 18 of 21 patients, with marked improvements observed after immunotherapy., Discussion: Patients with anti-mGluR5 encephalitis typically present with diffuse, rather than purely limbic, encephalitis. Anti-mGluR5 encephalitis can be triggered by herpes simplex encephalitis. The risk of a combined tumor may be reduced in anti-mGluR5 encephalitis patients., (© 2023 The Authors. Brain and Behavior published by Wiley Periodicals LLC.)

Background: Herpes simplex encephalitis (HSE) is associated with severe mortality and morbidity. Its incidence is estimated at 1:250 000, and the typical symptomatology of acute disease including headaches, mental state disturbances, confusion, sleepiness, and seizures. The chronic phase of the disease is occasionally characterized by epilepsy and neurological deficits., Study Rationale: The present retrospective single-center study aims to identify risk factors for predicting the development of epilepsy (epileptogenesis) following HSE., Methods: Medical records were screened for patients older than 18 years, hospitalized between January 2005 and September 2019 with a diagnosis of "encephalitis" and "herpes simplex virus, HSV" infection. HSE diagnosis was based on an analysis of the cerebrospinal fluid with positive HSV testing results., Results: Twenty-three patients fit our inclusion criteria: fever and behavioral changes, followed by seizures, were reported in 58.3 % of patients. On follow-up (59.7 ± 38.8 months), eight patients (34.8 %) developed epilepsy. Pathological imaging and EEG were correlated with acute symptomatic seizures (ASS). ASS was associated with an 8-fold risk increase to develop post-encephalitis epilepsy (PE). PE was associated with younger age but not with CSF results, imaging, or EEG., Conclusion: Our retrospective single-center study on PE, following HSE, shows that younger age and ASS were associated with PE. Brain imaging, CSF analysis, and EEG were not associated with the development of epilepsy following HSE., Competing Interests: Conflicts of Interest None of the authors has any conflict of interest to disclose., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background and Objectives: Anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) is the most common form of autoimmune encephalitis in children and adults. Although our understanding of the disease mechanisms has progressed, little is known about estimating patient outcomes. Therefore, the NEOS (anti- N MDAR E ncephalitis O ne-Year Functional S tatus) score was introduced as a tool to predict disease progression in NMDARE. Developed in a mixed-age cohort, it currently remains unclear whether NEOS can be optimized for pediatric NMDARE., Methods: This retrospective observational study aimed to validate NEOS in a large pediatric-only cohort of 59 patients (median age of 8 years). We reconstructed the original score, adapted it, evaluated additional variables, and assessed its predictive power (median follow-up of 20 months). Generalized linear regression models were used to examine predictability of binary outcomes based on the modified Rankin Scale (mRS). In addition, neuropsychological test results were investigated as alternative cognitive outcome., Results: The NEOS score reliably predicted poor clinical outcome (mRS ≥3) in children in the first year after diagnosis ( p = 0.0014) and beyond ( p = 0.036, 16 months after diagnosis). A score adapted to the pediatric cohort by adjusting the cutoffs of the 5 NEOS components did not improve predictive power. In addition to these 5 variables, further patient characteristics such as the " Herpes simplex virus encephalitis (HSE) status" and "age at disease onset" influenced predictability and could potentially be useful to define risk groups. NEOS also predicted cognitive outcome with higher scores associated with deficits of executive function ( p = 0.048) and memory ( p = 0.043)., Discussion: Our data support the applicability of the NEOS score in children with NMDARE. Although not yet validated in prospective studies, NEOS also predicted cognitive impairment in our cohort. Consequently, the score could help identify patients at risk of poor overall clinical outcome and poor cognitive outcome and thus aid in selecting not only optimized initial therapies for these patients but also cognitive rehabilitation to improve long-term outcomes., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Herpes simplex virus (HSV) type 1 is a frequent pathogen causing infectious encephalitis (HSVE). Early treatment with intravenous acyclovir has led to a significant decrease in mortality. However, especially in children, deterioration during or after HSVE may occur without any evidence of HSV reactivation or improvement following repeated antiviral therapy. Here, we report 15 patients (age range 3 months to 15 years) who suffered from autoimmune encephalitis with autoantibodies to NMDAR1 following Herpes encephalitis, presenting with movement abnormalities (young children) or neuropsychiatric symptoms (older children) as major complaints, respectively. The diagnosis was based on positive cerebrospinal fluid (CSF) and/or serum anti-NMDAR-antibodies with two children showing only positive CSF antibody findings. The time lag between first symptoms and diagnosis of autoimmune encephalitis was significantly longer than between first symptoms and diagnosis of HSVE ( p <0.01). All patients improved during immunosuppressive treatment, during which plasmapheresis or rituximab treatments were applied in 11 patients, irrespective of their age. Despite immunotherapy, no patients relapsed with HSVE. Early diagnosis and treatment of autoimmune encephalitis after HSVE may be associated with a better outcome so that high clinical awareness and routine testing for anti-NMDAR-antibodies after HSVE seems advisable. If autoimmune encephalitis is suspected, antibody testing should also be performed on CSF if negative in serum., Competing Interests: None declared., (Thieme. All rights reserved.)

Herpes simplex virus-1 (HSV-1) is a widespread neurotropic virus that can reach the brain and cause a rare but acute herpes simplex encephalitis (HSE) with a high mortality rate. Most patients present with changes in neurological and behavioral status, and survivors suffer long-term neurological sequelae. To date, the pathogenesis leading to brain damage is still not well understood. HSV-1 induced encephalitis in the central nervous system (CNS) in animals are usually very diffuse and progressing rapidly, and mostly fatal, making the analysis difficult. Here, we established a mouse model of HSE via intracerebral inoculation of modified version of neural-attenuated strains of HSV-1 (deletion of ICP34.5 and inserting a strong promoter into the latency-associated transcript region), in which the LMR-αΔpA strain initiated moderate productive infection, leading to strong host immune and inflammatory response characterized by persistent microglia activation. This viral replication activity and prolonged inflammatory response activated signaling pathways in neuronal damage, amyloidosis, Alzheimer's disease, and neurodegeneration, eventually leading to neuronal loss and behavioral changes characterized by hypokinesia. Our study reveals detailed pathogenic processes and persistent inflammatory responses in the CNS and provides a controlled, mild and non-lethal HSE model for studying long-term neuronal injury and increased risk of neurodegenerative diseases due to HSV-1 infection., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2022 The Authors. Publishing services by Elsevier B.V. All rights reserved.)

A 52-year-old male was carried to hospital by ambulance, because of an abrupt abnormal behavior and impaired consciousness. Soon after the arrival, the patient started a generalized seizure. Although the seizure was stopped by Midazolam, amnesia were observed. With meningeal irritation signs, in addition to the clinical course, the patient was thought to develop limbic encephalitis. The cause of the encephalitis was diagnosed as neurosyphilis because of the positive serum and CSF syphilis reactions, and the patient was treated with penicillin G from the first admission day on. Steroid pulse therapy was also conducted, followed by acyclovir since herpes encephalitis could not be ruled out; the brain MRI showed left-side dominant T 2 /FLAIR high intensity lesions in the bilateral temporal lobes and left hippocampus. With the treatment progression, the amnestic syndrome improved and the patient returned to work. Although neurosyphilis is a rare cause of acute onset limbic encephalitis, it is important to keep the possibility of this disease in mind in making a treatment plan.

Background: Encephalitis is an inflammation of the cerebral parenchyma manifested by acute symptoms such as fever, headaches, and other neurological disorders. Its etiology is mostly viral, with herpes simplex virus being a frequent etiological agent in children. The development of neurological sequelae is a serious outcome associated with this infection., Objective: To assess the general prevalence and types of neurological sequelae in children after a case of acute viral encephalitis caused by HSV., Methods: This systematic review and meta-analysis was developed following the PRISMA guidelines. The literature search was carried out in the MEDLINE, Embase, SciELO, LILACS, Cochrane, CINAHL, PsycINFO, and Web of Science databases. Studies were included of children with confirmed HSV infection and that presented a description of neurological sequelae associated with that infection. For the meta-analysis of general prevalence and of the types of neurological sequelae a random effects model was used., Results: Of the 2827 articles chosen in the initial search, nine studies were included in the systematic review and meta-analysis. The general prevalence of neurological sequelae was 50.7% (95% CI 39.2-62.2). The most frequent sequelae were related to mental disability, with a 42.1% prevalence (95% CI 30-55.2); on the other hand, the least frequent sequelae were those related with visual impairment, with a 5.9% prevalence (95% CI 2.2-14.6). The included studies presented regular quality and substantial heterogeneity., Conclusion: Even with antiviral therapy, half of patients will develop some type of disability., (© 2023. The Author(s).)

Herpes simplex encephalitis (HSE) is one of the most common sporadic viral encephalitis. Generally, HSE is characterized by a monophasic short course, although in some patients neurological relapses or worsening of deficits can develop some weeks later, when viral therapy has been discontinued and signs and symptoms of the central nervous system (CNS) damage seem to have stabilized. The second HSE stage is generally identified as autoimmune encephalitis after HSE (AEaHSE). Aim of this paper is to discuss which are the present knowledge in this regard. Literature analysis showed that AEaHSE exists, it is more common in younger children and it has different clinical manifestations according to age. All the patients with AEaHSE are positive for one or more neuronal cell-surface and synaptic antibodies, mainly anti-NMDAR antibodies, and the earlier the appearance of the antibodies the greater the risk of AEaHSE development. This means that a careful monitoring of antibody production starting from anti-NMDAR antibodies in all HSE cases could lead to the early identification of AEaHSE and the prompt administration of a potentially effective therapy. Further studies are needed to clarify which are the main pathogenetic mechanisms, whether there are differences in risk of development and clinical course of AEaHSE according to the type of antibody production, why response to immunosuppressive therapy significantly varies and whether administration of steroids to patients with HSE during the first phase of disease can play a role for reducing the risk of AEaHSE development., (Copyright © 2022. Published by Elsevier B.V.)

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., (© 2022. The Author(s).)

Background: Anti-N-methyl-D-aspartate-receptor (anti-NMDA-R) encephalitis is a complex autoimmune neuropsychiatric syndrome. Although initially associated with ovarian teratoma, subsequent studies have demonstrated that anti-NMDA-R encephalitis may occur without an identifiable cause or be triggered by viral infection of the central nervous system such as herpes simplex virus encephalitis (HSVE)., Aim: To present details from a Queensland cohort analysing triggering events in patients with anti-NMDA-R encephalitis in an Australian context., Methodology: The authors identified patients with anti-NMDA-R encephalitis diagnosed and managed through public hospitals in Queensland, Australia, between 2010 and the end of 2019. Data collected included demographics, clinical presentation, investigation results, management and outcome measurements., Results: Thirty-one cases of anti-NMDA-R encephalitis were included in the study. Three cases of anti-NMDA-R encephalitis were triggered by prior HSVE, five cases were associated with ovarian teratoma and 23 cases had no identifiable trigger. There were an additional three cases in which anti-NMDA receptor antibodies were present in the context of other disease states but where the patient did not develop anti-NMDA-R encephalitis. Cases triggered by HSVE or associated with ovarian teratoma experienced a more severe disease course compared to cases with no identifiable trigger. All groups responded to immunosuppressive or immunomodulatory therapy. Analysis of clinical characteristics revealed a complex heterogeneous syndrome with some variability between groups., Conclusion: In this cohort, the number of cases of anti-NMDA-R encephalitis triggered by HSVE is comparable to those triggered by ovarian teratoma. However, the majority of cases of anti-NMDA-R encephalitis had no identifiable trigger or associated disease process., (© 2021 Royal Australasian College of Physicians.)

The long-term response of two infants with anti-N-methyl-D-aspartate receptor (anti-NMDAR) post herpes simplex encephalitis treated with rituximab is reported here. Rituximab may improve the course of the disease and should be considered early as second-line treatment. Data on the long-term effect of rituximab in B cell depletion and immunoglobulins levels in infants are needed., (© 2022. The Author(s), under exclusive licence to Dr. K C Chaudhuri Foundation.)

Autoimmune disorders, such as choreoathetosis and abnormal behavior secondary to herpes simplex encephalitis (HSE), are discussed in this review. These disorders are known to develop without any evidence of HSE relapse, while they respond to immunotherapies such as intravenous corticosteroids. Recent evidence, including a prospective Spanish cohort study of HSE, revealed that autoimmune encephalitis (AE) can be triggered by HSE, which is closely related to several neuronal surface antibodies (NSAs). Anti-N-methyl-D-aspartate encephalitis (NMDARE) is the most common phenotype of AE post-HSE. Moreover, approximately 30% of cases of AE post-HSE are caused by NSAs against undetermined antigens. Thus, patients suspected of having AE post-HSE should be tested for NSAs using comprehensive techniques combining tissue-based and cultured live neuron assays. The primary syndrome of AE post-HSE is age dependent, as demonstrated in non-post-HSE onset NMDARE. Choreoathetosis is the most common symptom in infants and toddlers, while abnormal behavior and psychiatric symptoms are the most common symptoms in adolescents and adults. Regarding the treatment, current knowledge reveals that intensive immunotherapies can be used to treat AE post-HSE and lead to better outcomes although a minority of cases show recovery without immunotherapy administration.

Introduction: Bortezomib is proteasome inhibitor used in multiple myeloma treatment. The reactivation of herpes simplex virus (HSV) and varicella-zoster virus (VZV) during bortezomib-based therapy is a well-known adverse event. Antiviral prophylaxis is mandatory. Nevertheless, reports of herpesviral encephalitis are scarce., Case Report: A 57-year-old multiple myeloma patient who during CyBorD protocol (Bortezomib, cyclophosphamide, and dexamethasone), after a transient suspension of antiviral prophylaxis presented progressive headaches unresponsive to conventional analgesics, asthenia, fever, episodic visual hallucinations, and vesicular lesions in the right supraorbital and frontal region. Herpetic encephalitis was diagnosed after detecting herpes zoster in cerebrospinal fluid., Management & Outcome: The patient was treated with acyclovir 500mg every 6 hours for 21 days, and subsequent valacyclovir prophylaxis achieving an excellent clinical evolution. Anti-myeloma treatment was changed to lenalidomide and dexamethasone achieving a durable complete response. Herpesviral encephalitis is a rare but severe complication associated with the use of Bortezomib, especially when patients did not receive acyclovir prophylaxis. However, a rapid detection based on the clinical suspicion, and the prompt start of treatment, may lead to overcome this adverse event.

Purpose: Hyperglycemia can present as many neurological problems, one of them is seizure. Different brain MRI features can be seen in focal seizures associated with nonketotic hyperglycemia that subcortical T2 hypointensity is the only characteristic one. Finding this MRI feature is highly valuable in early diagnosis and treatment., Methods: Our patient was a 60-year-old female, a case of type 2 diabetes mellitus. She was brought to Emergency Room (ER) with focal colonic status epilepticus of right face and arm associated with confusion and drowsiness progressed over 2 weeks prior to admission. At first, acyclovir was started alongside anti-seizure medication with doubt of herpes encephalitis but antiviral was discontinued after normal LP result and characteristic MRI features., Results: Subcortical T2 hypointensity in left temporal and insular lobe was seen on first MRI that was resolved on follow up MRI after she was treated., Conclusion: Epilepsia partialis continua in the setting of non ketotic hyperglycemia should be differentiated from that in herpes encephalitis in a diabetic patient presenting with subacute confusional state and focal status epilepticus considering characteristic MRI finding of subcortical T2 hypointensity.

A 23-year-old woman, who had been suffering from migraine since primary school age, presented with left arm paralysis three days after one such migraine attack. On admission, brain MRI diffusion-weighted imaging (DWI) demonstrated high-signal-intensity lesions in the white matter of the right fronto-parietal lobe, and no abnormal lesions were evident in the limbic system. Although the patient had a fever of 38.7°C, the CSF cell count was not elevated. On the 4‍ th day, the left arm paralysis worsened, with an increase in body temperature to 39.8°C. Brain MRI revealed that the white matter lesions had spread to the right postcentral gyrus and the bilateral insular cortex. Also, MR angiography demonstrated no spasms or dissection of the major vessels. On the 6‍ th day, the CSF cell count was elevated to 54/μl and herpes simplex virus DNA was detected. Acyclovir and steroid pulse therapy ameliorated the symptoms. Cervical artery dissection and reversible cerebral vasoconstriction are well known complications of migraine attack. However, herpes simplex encephalitis should also be considered as a differential diagnosis in patients with a high fever of unknown origin.

Klüver-Bucy syndrome is a rare neurobehavioral disorder caused by a bilateral temporal lobe lesion affecting the hippocampus and amygdala; clinically characterised by hyperorality, hypermetamorphosis, placidity, altered sexual behaviour, eating, disorders and visual impairment, agnosia and amnesia. However, the complete syndrome is rarely seen, and diagnosis does not require all the symptoms to be manifested simultaneously.We describe a patient who developed a complete Klüver-Bucy syndrome secondary to bilateral temporal involvement due to herpetic encephalitis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Herpes simplex virus encephalitis (HSVE) is one of the most common infectious causes of sporadic encephalitis. Coronavirus disease (COVID-19) has been associated with immune dysregulation of the host that might increase the risk of infections like HSVE following SARS-CoV-2 infection. There is paucity of literature on post COVID-19 HSVE. This study was conducted with the aim of analyzing the clinical presentation, brain imaging, and outcome of patients presenting with HSVE within 6 weeks of COVID-19 and providing a comprehensive review on the possible mechanisms of post-COVID-19 HSVE., Methods: This observational study included patients who had laboratory-confirmed HSVE (type 1 or type 2) and a history of COVID-19 within the previous 6 weeks. Patients were followed up for 3 months., Results: Eight patients were included and all of them had type 1 HSVE. The mean latency of onset of neurological symptoms from being diagnosed with COVID-19 is 23.87 days and a majority of the patients have received injectable steroids with a mean duration of 6.5 days. Behavioral abnormality was the commonest neurological presentation and typical brain imaging involved T2 FLAIR hyperintensities of the medial temporal lobes. All patients received intravenous acyclovir 10 mg/kg every eight hourly for atleast 14 days. One patient with concomitant rhinocerebral mucormycosis succumbed while the majority had a complete recovery., Conclusion: Possible immune dysregulation in COVID-19 may increase the susceptibility of HSVE in patients with a history of recent SARS-CoV-2 infection. The clinical manifestations and laboratory findings of HSVE in such patients are similar to typical HSVE., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Association of Physicians. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Post herpes simplex virus (HSV) autoimmune encephalitis has been reported mainly in association with NMDA receptor antibodies, however, never with Caspr2 antibodies., Case Presentation: We report an 82-year old female patient with encephalitis who presented with aphasia, left temporo-mesial hyperintense lesion on MRI, epileptiform discharges on spot electroencephalography, cerebrospinal fluid (CSF) lymphocytic pleocytosis and who showed positive HSV polymerase chain reaction in CSF as well as antibodies against contactin-associated protein-like 2 (Caspr2)., Conclusion: This is the first report of a patient with encephalitis who tested positive for HSV as well as for Caspr2 antibodies., (© 2022. The Author(s).)

Background: Granulomatous herpetic encephalitis is a rare inflammatory complication of acute herpes simplex encephalitis., Methods: We describe 3 cases of granulomatous herpetic encephalitis in children arising between 1 to 10 years after the initial presentation with acute herpes simplex encephalitis. We focus on the clinical course and neuroimaging phenotype with a discussion of possible mechanisms underpinning this entity., Results: The clinical course was highly variable. However, the dominant neuroimaging phenotype in each of our cases was that of confluent gyriform cortical enhancement with predominantly solid foci of enhancement in the subjacent white matter +/- deep gray nuclei. Cerebrospinal fluid was negative for herpes simplex virus DNA in all cases. All 3 cases required brain biopsy to help establish the diagnosis., Conclusions: Increased recognition of granulomatous herpetic encephalitis in children will facilitate earlier diagnosis and treatment. Although the exact role played by the host immune response, genetics, and environment in determining the different outcomes of herpes simplex encephalitis remains to be determined, we postulate a role for inflammasome dysregulation in this entity.