Chronic Granulomatous Herpes Simplex Encephalitis in Children

The immunobiology of herpes simplex virus encephalitis and post-viral autoimmunity

Herpes simplex virus encephalitis (HSE) is the leading cause of non-epidemic encephalitis in the developed world and, despite antiviral therapy, mortality and morbidity is high. The emergence of post-HSE autoimmune encephalitis reveals a new immunological paradigm in autoantibody-mediated disease. A reductionist evaluation of the immunobiological mechanisms in HSE is crucial to dissect the origins of post-viral autoimmunity and supply rational approaches to the selection of immunotherapeutics. Herein, we review the latest evidence behind the phenotypic progression and underlying immunobiology of HSE including the cytokine/chemokine environment, the role of pathogen-recognition receptors, T- and B-cell immunity and relevant inborn errors of immunity. Second, we provide a contemporary review of published patients with post-HSE autoimmune encephalitis from a combined cohort of 110 patients. Third, we integrate novel mechanisms of autoimmunization in deep cervical lymph nodes to explore hypotheses around post-HSE autoimmune encephalitis and challenge these against mechanisms of molecular mimicry and others. Finally, we explore translational concepts where neuroglial surface autoantibodies have been observed with other neuroinfectious diseases and those that generate brain damage including traumatic brain injury, ischaemic stroke and neurodegenerative disease. Overall, the clinical and immunological landscape of HSE is an important and evolving field, from which precision immunotherapeutics could soon emerge.

Herpes simplex virus type 2 encephalitis in a child with chronic progressive white matter lesions: A case report

RATIONALE

This case is a rare manifestation of central nervous system infection of Herpes simplex virus (HSV)-2. Due to few studies in China, it provides a pathological basis for further diagnosis and treatment of HSV-2.

PATIENT CONCERNS

We describe a patient with HSV-2 virus infection who was diagnosed with HSV-2 encephalitis in a Chinese patient.

DIAGNOSIS

Based on brain biopsy and pathological findings, the patient was diagnosed with HSV-2 encephalitis.

INTERVENTIONS

Hormone and antiviral therapy were given.

OUTCOME

The patient eventually died.

LESSONS

The diagnosis and differential diagnosis of the disease is very difficult. Its differential diagnosis include cerebrovascular disease, bacteria or fungi and other viral infection of the brain.

Granulomatous Herpetic Encephalitis A Possible Role for Inflammasomes

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.

Microglia in antiviral immunity of the brain and spinal cord

Viral infections of the central nervous system (CNS) are a significant cause of neurological impairment and mortality worldwide. As tissue resident macrophages, microglia are critical initial responders to CNS viral infection. Microglia seem to coordinate brain-wide antiviral responses of both brain resident cells and infiltrating immune cells. This review discusses how microglia may promote this antiviral response at a molecular level, from potential mechanisms of virus recognition to downstream cytokine responses and interaction with antiviral T cells. Recent advancements in genetic tools to specifically target microglia in vivo promise to further our understanding about the precise mechanistic role of microglia in CNS infection.

Clinical, neuropathological, and immunological short- and long-term feature of a mouse model mimicking human herpes virus encephalitis

Herpes simplex encephalitis (HSE) is one of the most serious diseases of the nervous system in humans. However, its pathogenesis is still only poorly understood. Although several mouse models of predominantly herpes simplex virus 1 (HSV-1) infections mimic different crucial aspects of HSE, central questions remain unanswered. They comprise the specific temporofrontal tropism, viral spread within the central nervous system (CNS), as well as potential molecular and immunological barriers that drive virus into latency while only rarely resulting in severe HSE. We have recently proposed an alternative mouse model by using a pseudorabies virus (PrV) mutant that more faithfully represents the striking features of human HSE: temporofrontal meningoencephalitis with few severely, but generally only moderately to subclinically affected mice as well as characteristic behavioral abnormalities. Here, we characterized this animal model using 6- to 8-week-old female CD-1 mice in more detail. Long-term investigation over 6 months consistently revealed a biphasic course of infection accompanied by recurring clinical signs including behavioral alterations and mainly mild meningoencephalitis restricted to the temporal and frontal lobes. By histopathological and immunological analyses, we followed the kinetics and spatial distribution of inflammatory lesions as well as the underlying cytokine expression in the CNS over 21 days within the acute phase of infection. Affecting the temporal lobes, the inflammatory infiltrate was composed of lymphocytes and macrophages showing a predominantly lymphocytic shift 15 days after infection. A strong increase was observed in cytokines CXCL10, CCL2, CCL5, and CXCL1 recruiting inflammatory cells to the CNS. Unlike the majority of infected mice, strongly affected animals demonstrated extensive temporal lobe edema, which is typically present in severe human HSE cases. In summary, these results support the validity of our animal model for in-depth investigation of HSE pathogenesis.

Subacute Herpes Simplex Type 1 Encephalitis: Case Report With Literature Review

INTRODUCTION

The typical herpes simplex viral encephalitis (HSVE) course is an acute illness, less commonly it may present as a chronic course, mainly in children, and rarely may it be subacute. Subacute HSVE is rarely described in the literature being reported 4 times only.

CASE REPORT

We here report 2 cases of subacute HSV1 encephalitis diagnosed based on cerebrospinal fluid polymerase chain reaction and magnetic resonance imaging findings and review the literature trying to find any specific clinical, laboratory, radiologic diagnostic or prognostic criteria regarding this subacute form of HSVE.

CONCLUSION

There is subacute form of HSVE and should be suspected with any subacute febrile illness with nonspecific cognitive impairment even in the absence of focal neurological symptoms and in cases with rapidly progressive dementia. This form has similar radiologic finding and good response to acyclovir but carry even better prognosis than that the acute HSVE.

Management and results of epilepsy surgery associated with acyclovir prophylaxis in four pediatric patients with drug-resistant epilepsy due to herpetic encephalitis and review of the literature

PURPOSE

Herpes simplex virus encephalitis (HSE) is the most common cause of sporadic viral encephalitis in children and is responsible for epilepsy in approximately half of patients. In addition to medical treatment, epilepsy surgery may be offered to drug-resistant patients but carries a high risk of relapse of herpetic encephalitis. We are reporting our series of patients operated on between 2000 and 2019 with the systematic administration of acyclovir (ACV).

RESULTS

Four pediatric patients aged 4.5-12.8 years with drug-resistant epilepsy post-HSE underwent a tailored focal resection following invasive recordings (three patients) and a complete callosotomy (one patient). The total number of the surgical procedures for the four patients was eight, and a systematic administration of ACV as a prophylactic treatment of herpetic encephalitis relapse was done at each step. No patients had a relapse and the ACV was well-tolerated in all the cases. Following surgery two patients are seizure free, the patient who underwent callosotomy is Engel 3 and the fourth patient, in whom a large epileptic zone has contraindicated a second surgery, is Engel 4.

CONCLUSIONS

Our series demonstrated the dramatic efficacy of systematic ACV prophylaxis during all cranial surgeries. Moreover, our results on epilepsy, together with those of the literature, encourage more consideration regarding epilepsy surgery in this specific etiology. All types of surgical procedures (curative or palliative) can be offered to the patients, but in the case of focal surgery, due to the poor anatomical limits, invasive recordings are highly recommended.

An Adult Case of Herpes Simplex Virus-associated Granulomatous Encephalitis

Brain granuloma occurs under certain conditions. Herpes simplex virus (HSV) causes granulomatous encephalitis in children; however, it has been rarely reported in adults. A 74-year-old man with a history of herpes simplex encephalitis suffered recurrent seizures. Brain magnetic resonance imaging revealed a mass lesion and resection was performed. A polymerase chain reaction using a brain biopsy specimen was positive for HSV DNA; thus, the patient was diagnosed with HSV-associated granulomatous encephalitis. After administering acyclovir, the patient showed improvement. HSV can cause granulomatous encephalitis in adults, and acyclovir can be used for its treatment.

A rare suspected case of chronic nodular granulomatous herpes simplex encephalitis in an adult

Herpes simplex encephalitis is the most common sporadic viral encephalitis in the western world, HSV-1 (herpes simplex virus) being the mostly commonly implicated serotype. The disease is usually monophasic, although patients may relapse weeks, months or years after initial infection. This chronic granulomatous inflammatory process is almost exclusively described in children and rarely forms discrete enhancing parenchymal nodules. We present the clinical and radiological features of an unusual case of chronic nodular granulomatous herpes encephalitis with enhancing “mass-like” nodules in an adult. To the author’s knowledge, this is the first reported case of macroscopic “mass-like” nodular granuloma formation in an adult.

Epilepsy surgery for epileptic encephalopathy as a sequela of herpes simplex encephalitis: case report

Herpes simplex virus (HSV) encephalitis can manifest with different clinical presentations, including acute monophasic illness and biphasic chronic granulomatous HSV encephalitis. Chronic encephalitis is much less common, and very rare late relapses are associated with intractable epilepsy and progressive neurological deficits with or without evidence of HSV in the cerebrospinal fluid. The authors report on an 8-year-old girl with a history of treated HSV-1 encephalitis when she was 13 months of age and focal epilepsy when she was 2 years old. Although free of clinical seizures, when she was 5, she experienced behavioral and academic dysfunction, which was later attributed to electrographic focal seizures and worsening electroencephalography (EEG) findings with electrical status epilepticus during slow-wave sleep (ESES). Following a right temporal lobectomy, chronic granulomatous encephalitis was diagnosed. The patient's clinical course improved with the resolution of seizures and EEG abnormalities.

Chronic herpes simplex type-1 encephalitis with intractable epilepsy in an immunosuppressed patient

BACKGROUND

Chronic herpes simplex virus type-1 encephalitis (HSE-1) is uncommon. Past reports focused on its association with prior documented acute infection. Here, we describe a patient with increasingly intractable epilepsy from chronic HSE-1 reactivation without history of acute central nervous system infection.

CASE PRESENTATION

A 49-year-old liver transplant patient with 4-year history of epilepsy after initiation of cyclosporine developed increasingly frequent seizures over 3 months. Serial brain magnetic resonance imaging showed left temporoparietal cortical edema that gradually improved despite clinical decline. Herpes simplex virus type-1 (HSV-1) DNA was detected in cerebrospinal fluid by polymerase chain reaction. Cerebrospinal fluid HSV-1&2 IgM was negative. Seizures were controlled after acyclovir treatment, and the patient remained seizure free at 1-year follow-up.

CONCLUSION

Chronic HSE is a cause of intractable epilepsy, can occur without a recognized preceding acute phase, and the clinical course of infection may not directly correlate with neuroimaging changes.

Granulomatous herpes simplex encephalitis in an infant with multicystic encephalopathy: a distinct clinicopathologic entity?

BACKGROUND

Herpes simplex virus encephalitis can manifest as a range of clinical presentations including classic adult, neonatal, and biphasic chronic-granulomatous herpes encephalitis.

METHOD

We report an infant with granulomatous herpes simplex virus type 2 encephalitis with a subacute course and multicystic encephalopathy.

CASE

A 2-month-old girl presented with lethargy and hypothermia. Computed tomography scan of the head showed multicystic encephalopathy and calcifications. Cerebrospinal fluid analysis by polymerase chain reaction testing for herpes simplex virus 1 and 2, enterovirus, and cytomegalovirus was negative. Normal cerebrospinal fluid interferon-α levels argued against Aicardi-Goutières syndrome. The patient died 2 weeks after presentation. At autopsy, multicystic encephalopathy was confirmed with bilateral gliosis, granulomatous inflammation with multinucleated giant cells, and calcifications. Bilateral healing necrotizing retinitis suggested a viral etiology, but retina and brain were free of viral inclusions and immunohistochemically negative for herpes simplex virus-2 and cytomegalovirus. However, polymerase chain reaction analysis showed herpes simplex virus-2 DNA in four cerebral paraffin blocks. Subsequent repeat testing of the initial cerebrospinal fluid sample using a different polymerase chain reaction assay was weakly positive for herpes simplex virus-2 DNA.

CONCLUSION

Granulomatous herpes simplex virus encephalitis in infants can present with subacute course and result in multicystic encephalopathy with mineralization and minimal cerebrospinal fluid herpes simplex virus DNA load. Infectious etiologies should be carefully investigated in the differential diagnosis of multicystic encephalopathy with mineralization, in particular if multinucleated giant cells are present.

Chronic granulomatous herpes encephalitis in a child with clinically intractable epilepsy

Most patients with herpes simplex virus Type I encephalitis experience an acute, monophasic illness. Chronic encephalitis is much less common, and few late relapses are associated with intractable seizure disorders. A 10-year-old boy was admitted to our institution for intractable epilepsy as part of an evaluation for epilepsy surgery. His history was significant for herpes meningitis at age 4 months. At that time, he presented to an outside hospital with fever for three days, with acyclovir treatment beginning on day 4 of his 40-day hospital course. He later developed infantile spasms and ultimately a mixed seizure disorder. Video electroencephalogram showed a Lennox-Gastaut-type pattern with frequent right frontotemporal spikes. Imaging studies showed an abnormality in the right frontal operculum. Based on these findings, he underwent a right frontal lobectomy. Neuropathology demonstrated chronic granulomatous inflammation with focal necrosis and mineralizations. Scattered lymphocytes, microglial nodules and nonnecrotizing granulomas were present with multinucleated giant cells. Immunohistochemistry for herpes simplex virus showed focal immunoreactivity. After undergoing acyclovir therapy, he returned to baseline with decreased seizure frequency. This rare form of herpes encephalitis has only been reported in children, but the initial presentation of meningitis and the approximate 10-year-time interval in this case are unusual.

Chronic granulomatous herpes encephalitis: a rare entity posing a diagnostic challenge

Herpesviruses can cause an acute, subacute, or chronic disease state in both immunocompetent and immunocompromised individuals. Herpes simplex virus (HSV) encephalitis is most often an acute monophasic disease process. Rarely, however, it may progress to a chronic state, and more rarely still to a granulomatous encephalitis. Prior studies have suggested that antiviral immunity with Toll-like receptors determines susceptibility to herpesviruses. The authors report the case of a 14-year-old girl with a remote history of treated HSV encephalitis, who had intractable seizures and worsening MR imaging changes that were concerning for either a neoplastic or an inflammatory process. She was found to have granulomatous herpes simplex encephalitis and had a low cytokine response to Toll-like receptor 3 stimulation.

Chronic active herpes simplex type 2 encephalitis in an asymptomatic immunocompetent child

A unique form of chronic, active, granulomatous herpes simplex type 2 encephalitis is described in an asymptomatic, immunocompetent 8-year-old girl who acquired the virus as a neonate. The extensive, bilateral cerebral parenchymal involvement was discovered incidentally. Diagnosis was confirmed by a combination of serial neuroimaging, brain biopsy, and quantitative polymerase chain reaction targeted to DNA sequences in the glycoprotein G gene, allowing differentiation between herpes simplex virus types 1 and 2. The clinical course over a 5-year period, treatment with intermittent intravenous steroids, and daily valacyclovir, diagnostic imaging, and laboratory studies are reviewed in detail. This form of herpes simplex virus type 2 encephalitis hasn't been described previously and is significant because of its prolonged indolent course, absence of neurological findings or suggestive history, and benign behavior in this child, who is now 14 years old. The authors believe this entity can be unsuspected and underdiagnosed in the general pediatric population, especially in those with a prior maternal history of herpes simplex virus type 2 infection.

Asymptomatic self-limiting diffuse white matter lesions in subacute to chronic stage of herpes simplex encephalitis

This study evaluated white matter changes in the subacute and chronic stages of herpes simplex encephalitis (HSE). Subjects comprised 15 patients with HSE. All patients were examined using MRI at onset, and then at seven to ten days, three to five weeks and two to three months after onset. In addition, the six patients who displayed white matter signal abnormalities were examined at six months and <one year after onset. Cell count, protein levels, polymerase chain reaction (PCR) of herpes simplex virus in cerebrospinal fluid (CSF), and exacerbation of neurological symptoms as well as dose of acyclovir were compared between patients with and without white matter abnormalities. Diffuse white matter signal changes were identified at the subacute stage (3-5 weeks after onset) of HSE in six patients (6/15, 40%). No significant relationship was observed between the presence of white matter signal abnormalities and laboratory data, acyclovir dose or clinical symptoms. These signal abnormalities disappeared or improved by two years without any clinical treatment. Diffuse white matter signal abnormalities occur frequently in the subacute stage of HSE. Although the mechanisms underlying these white matter lesions have not been elucidated, subclinical immune-mediated processes may be considered. Repeat MRI studies over a long period are necessary for evaluating the clinical process of patients with HSE.

Central nervous system infections of herpesvirus family

Herpesviruses are one of the most common groups of pathogens causing central nervous system infections in humans. They mostly cause encephalitis, meningitis, or myelitis in immunocompetent and immunocompromised patients. Children, adults, and the elderly can all be affected. Although contrast-enhanced CT is more widely used for diagnosis, contrast-enhanced MR imaging combined with diffusion-weighted imaging is superior to CT in the detection of early changes and the real extent of the disease, and in assessing prognosis and monitoring response to antiviral treatment. More sophisticated techniques, such as MR spectroscopy and perfusion imaging, can aid in the differential diagnosis of herpesvirus infections from other tumoral, demyelinating, and ischemic processes.

The spectrum of herpes simplex encephalitis in children

Clinical and basic science research carried out in recent years into herpes simplex encephalitis (HSE) have shown that the concept of a "classical" picture of HSE in children is now outdated and that our current knowledge of the disease is probably only the tip of an iceberg. Indeed, increasing evidence supports the existence of a wider range of pathophysiological mechanisms, clinical presentations and disease progressions in paediatric HSE. This paper reviews the clinical, biological and radiological data available and redefines the spectrum of HSE in children. Full understanding of the condition should improve the management of suspected cases and decrease the morbidity and the mortality associated with this disease.

Postencephalitic chronic granulomatous disease

This report details the evolution of a case of herpes simplex encephalitis to chronic granuloma in a 13-year old female who, at the age of 8, suffered herpes simplex virus type 1 encephalitis. Eight months later, she developed an intracranial hypertension syndrome with the onset of a new lesion in the necrosed zone of her right temporal lobe, with no viral presence in the cerebrospinal fluid. The histologic characteristics were those of chronic granuloma with multinucleated giant cells and calcifications. Initially treated for neurosarcoidosis, the patient remained steroid-dependent for 4 years and the steroids could only be withdrawn by treatment with Infliximab. This type of evolutive pattern has probably been completely overlooked until now; it can only be accurately diagnosed by biopsy. It was initially mistaken for neurosarcoidosis.

Idiopathic granulomatous encephalitis mimicking malignant brain tumor

Idiopathic granulomatous encephalitis is a rare disorder of unknown etiology, undetermined treatment, and often grave prognosis. This article describes a 4-year-old female who presented with a single focal febrile convulsion followed a few weeks later by right-sided hemiparesis. A huge infiltrative cerebral mass tumor was found which proved to be a granuloma on histologic study. Despite a thorough evaluation, including tissue studies and search for an infectious agent, no etiology could be identified, and the final diagnosis was idiopathic granulomatous encephalitis. Recurrent resections and high-dose steroid treatment failed to control the process, and the patient died of disease 6 months after presentation. Evaluation and treatment of idiopathic granulomatous encephalitis should be aggressive, and the possibility of chemotherapy and perhaps even radiotherapy should be considered if there is no response to steroids.

Chronic herpes simplex virus encephalitis in childhood

Although herpes simplex virus is a major cause of acute encephalitis in childhood, chronic herpes simplex virus encephalitis has only rarely been reported. This report presents a case of chronic herpes simplex virus encephalitis in a 6-year-old female. Diagnosis was based on the detection of herpes simplex virus deoxyribonucleic acid by polymerase chain reaction in combination with the cerebrospinal fluid/serum ratio of herpes simplex virus-specific immunoglobulin G, the presence of herpes simplex virus-specific oligoclonal immunoglobulin G bands in cerebrospinal fluid, and calcifications in the temporal regions found on cerebral computed tomographic scan. Prolonged antiviral therapy was beneficial to later mental development.