Extra temporal involvement in herpes simplex encephalitis

Ictal vomiting as an unusual presentation of herpes simplex encephalitis - Pathophysiological and therapeutic perspectives

Introduction

Herpes Simplex Encephalitis (HSE) is a formidable neurological infection that is often challenging to diagnose owing to its diverse clinical manifestations. This case report details the clinical odyssey of a sixty-year-old female with diabetes, hypothyroidism, and hypertension, who presented with fever, vomiting, and evolving neurological symptoms.

Case Presentation

The patient's initial admission failed to yield a diagnosis, and her condition worsened, marked by behavioral changes, cognitive decline, and focal seizures. Neuroimaging revealed characteristic findings, confirming non-hemorrhagic herpetic encephalitis. Despite antiviral and antiepileptic therapy, persistent vomiting prompted further investigations, uncovering infrequent right temporal sharp waves on EEG, leading to a diagnosis of "ictus emiticus."

Conclusion

This case of Herpes Simplex Encephalitis (HSE) underscores the diverse clinical spectrum and challenges in management. The patient's atypical presentation underscores the importance of considering HSE in patients with fever and unexplained persistent vomiting for early diagnosis and better prognosis.Diagnostic tools (neuroimaging, cerebrospinal fluid analysis, and electroencephalography) confirmed HSE involvement in the right temporal lobe, emphasizing the strong association between HSV encephalitis and seizures, which can be explained by various mechanisms.Timely antiviral therapy and tailored antiepileptic strategies led to gradual clinical improvement, showcasing the potential of valproate beyond antiepileptic use.This case prompts further exploration into HSE's pathophysiology and treatment. It emphasizes individualized patient care and vigilance for potential post-resolution sequelae, contributing to our evolving understanding of HSE.

Neuropsychological and Structural Neuroimaging Outcomes in LGI1-Limbic Encephalitis: A Case Study

OBJECTIVE

Anti-leucine-rich glioma-inactivated 1 limbic encephalitis (LGI1-LE) is a rare autoimmune condition that affects the structural integrity and functioning of the brain's limbic system. Little is known about its impact on long-term neuropsychological functioning and the structural integrity of the medial temporal lobe. Here we examined the long-term neuropsychological and neuroanatomical outcomes of a 68-year-old male who acquired LGI1-LE.

METHODS

Our case patient underwent standardized neuropsychological testing at two time points. Volumetric analyses of T1-weighted images were undertaken at four separate time points and qualitatively compared with a group of age-matched healthy controls.

RESULTS

At the time of initial assessment, our case study exhibited focal impairments in verbal and visual episodic memory and these impairments continued to persist after undergoing a course of immunotherapy. Furthermore, in reference to an age-matched healthy control group, over the course of 11 months, volumetric brain imaging analyses revealed that areas of the medial temporal lobe including specific hippocampal subfields (e.g., CA1 and dentate gyrus) underwent a subacute period of volumetric enlargement followed by a chronic period of volumetric reduction in the same regions.

CONCLUSIONS

In patients with persisting neurocognitive deficits, LGI1-LE may produce chronic volume loss in specific areas of the medial temporal lobe; however, this appears to follow a subacute period of volume enlargement possibly driven by neuro-inflammatory processes.

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.

Pharmacovigilance during treatment of multiple sclerosis: early recognition of CNS complications

An increasing number of highly effective disease-modifying therapies for people with multiple sclerosis (MS) have recently gained marketing approval. While the beneficial effects of these drugs in terms of clinical and imaging outcome measures is welcomed, these therapeutics are associated with substance-specific or group-specific adverse events that include severe and fatal complications. These adverse events comprise both infectious and non-infectious complications that can occur within, or outside of the central nervous system (CNS). Awareness and risk assessment strategies thus require interdisciplinary management, and robust clinical and paraclinical surveillance strategies. In this review, we discuss the current role of MRI in safety monitoring during pharmacovigilance of patients treated with (selective) immune suppressive therapies for MS. MRI, particularly brain MRI, has a pivotal role in the early diagnosis of CNS complications that potentially are severely debilitating and may even be lethal. Early recognition of such CNS complications may improve functional outcome and survival, and thus knowledge on MRI features of treatment-associated complications is of paramount importance to MS clinicians, but also of relevance to general neurologists and radiologists.

Seizures and epilepsy secondary to viral infection in the central nervous system

Viral infection in the central nervous system (CNS) is a common cause of seizures and epilepsy. Acute symptomatic seizures can occur in the context of almost all types of acute CNS viral infection. However, late unprovoked seizures and epilepsy may not be frequent after viral infection of the CNS. The incidence of seizures and epilepsy after CNS viral infection is mainly dependent on the brain region of infection. It remains to be determined whether treatment of CNS viral infection using antiepileptic drugs (AEDs) can prevent seizures and subsequent epilepsy in patients, particularly with regard to the timing, drug choice and dosage, and duration of AEDs. The postoperative outcome of seizures in patients with intractable epilepsy caused by viral encephalitis primarily depends on the epileptogenic zone. In addition, neuroinflammation is known to be widely involved in the generation of seizures during CNS viral infection, and the effects of anti-inflammatory therapies in preventing seizures and epilepsy secondary to CNS viral infection require further studies. In this review, we discuss the incidence, mechanisms, clinical management and prognosis of seizures and epilepsy secondary to CNS viral infection, and summarize common CNS viral infections that cause seizures and epilepsy.

An improved animal model for herpesvirus encephalitis in humans

Herpesviral encephalitis caused by Herpes Simplex Virus 1 (HSV-1) is one of the most devastating diseases in humans. Patients present with fever, mental status changes or seizures and when untreated, sequelae can be fatal. Herpes Simplex Encephalitis (HSE) is characterized by mainly unilateral necrotizing inflammation effacing the frontal and mesiotemporal lobes with rare involvement of the brainstem. HSV-1 is hypothesized to invade the CNS via the trigeminal or olfactory nerve, but viral tropism and the exact route of infection remain unclear. Several mouse models for HSE have been developed, but they mimic natural infection only inadequately. The porcine alphaherpesvirus Pseudorabies virus (PrV) is closely related to HSV-1 and Varicella Zoster Virus (VZV). While pigs can control productive infection, it is lethal in other susceptible animals associated with severe pruritus leading to automutilation. Here, we describe the first mutant PrV establishing productive infection in mice that the animals are able to control. After intranasal inoculation with a PrV mutant lacking tegument protein pUL21 and pUS3 kinase activity (PrV-ΔUL21/US3Δkin), nearly all mice survived despite extensive infection of the central nervous system. Neuroinvasion mainly occurred along the trigeminal pathway. Whereas trigeminal first and second order neurons and autonomic ganglia were positive early after intranasal infection, PrV-specific antigen was mainly detectable in the frontal, mesiotemporal and parietal lobes at later times, accompanied by a long lasting lymphohistiocytic meningoencephalitis. Despite this extensive infection, mice showed only mild to moderate clinical signs, developed alopecic skin lesions, or remained asymptomatic. Interestingly, most mice exhibited abnormalities in behavior and activity levels including slow movements, akinesia and stargazing. In summary, clinical signs, distribution of viral antigen and inflammatory pattern show striking analogies to human encephalitis caused by HSV-1 or VZV not observed in other animal models of disease.

In developed countries, more than 50% of humans are seropositive for the neurotropic Herpes Simplex Virus 1 (HSV-1) and two to four million cases of Herpes simplex encephalitis (HSE) are reported per year worldwide. Primary infection with HSV-1 takes place via the skin or the oral mucosa followed by intraaxonal retrograde spread to sensory ganglia of the peripheral nervous system where HSV-1 usually establishes latency. Further spread to the central nervous system results in HSE, a necrotizing encephalitis effacing predominantly the temporal and frontal lobes of the brain. Mice infected with HSV-1 develop encephalitis, but do not show the typical lesions and exhibit high mortality rates. Here we demonstrate that mice infected with a mutant pseudorabies virus lacking the tegument protein pUL21 and an active viral kinase pUS3 were able to survive the productive infection but developed lymphohistiocytic encephalitis with viral antigen distribution, inflammation and associated behavioral changes comparable to HSE in humans. These striking analogies offer new perspectives to study herpesviral encephalitis in a suitable animal model.

Surgical outcomes in patients with epilepsy after viral encephalitis: contribution of SEEG study

Background

Nowadays, few surgery analysis has been reported in cases of epilepsy after viral encephalitis(VE). Herein, this study was to evaluate the efficacy of surgery and capability of stereoelectroencephalography (SEEG) in the definition of the epileptogenic zone (EZ) after VE, and also to explore the relationship between the SEEG features and the surgical outcomes.

Methods

We retrospectively analyzed 10 surgically treated patients that identified to suffer from epilepsy secondary to VE using SEEG, and investigated the SEEG features associated with surgical outcomes in these patients. Besides visual analysis, we used the epileptogenicity index (EI), a semi-quantitative and supplementary tool to evaluate the validity of SEEG in the context of VE.

Results

Among the 10 operated patients, 3 of them became completely seizure-free. The patients who got totally seizure free or significant improvement, the seizure onset was located either in the antero-mesial temporal structures or focal gyrus; patients who got worthwhile improvement or no improvement, the seizure started from multiple brain lobes. The number of electrodes classified as epileptogenic visually involved were closely correlated with EI positive onses.Anatomic areas defined and shown as EZ on MRI by visual assessment were also defined as epileptogenic by the EI in these cases.

Conclusion

Apart from exploring the surgical outcome related to epilepsy after VE, we also bring insight into the relationship between the SEEG features and surgical outcome with the application of the supplementary methods.

Multimodal management of severe herpes simplex virus encephalitis: A case report and literature review

BACKGROUND

Herpes simplex encephalitis (HSE) is the most frequent sporadic encephalitis in the world. In severe cases of HSE, the pathology usually progresses with an increase in intracranial pressure secondary to cerebral edema and/or hemorrhagic necrosis. Currently no high-power studies exist regarding the management of severe HSE and most of the papers reported in the literature are case reports. Decompressive craniectomy, effective in some cases of pharmaco-resistant intracranial hypertension (ICH) resulting from other causes, may be suggested in severe HSE, with several good results reported in the literature.

CASE DESCRIPTION

The case of a 26-year-old man with severe HSE and a subsequent ICH is reported. In dealing with an ICH rebellious to conservative treatment, it was decided to perform a right decompressive hemicraniectomy, associated with a right temporal polectomy. The postoperative evolution was satisfactory, with normal neuropsychological tests and a Glasgow Outcome Scale of 1.

CONCLUSION

Although herpes simplex encephalitis is sometimes devastatingly complicated by intracranial hypertension, its management lacks consensus and reliable data in the literature remains scarce. Surgical as well as conservative treatment, used together in a multimodal approach, may hold the key to a greater control of intracranial pressure, thus resulting in a better outcome. In this multimodal management, the window of opportunity where surgery may be considered is small, and must be discussed further and more precisely in future articles.

Herpes Simplex Encephalitis of the Parietal Lobe: A Rare Presentation

A 69-year-old female with a history of breast cancer and hypertension presented with a rare case of herpes simplex encephalitis (HSE) isolated to her left parietal lobe. The patient's first biopsy was negative for herpes simplex virus (HSV) I/II antigens, but less than two weeks later, the patient tested positive on repeat biopsy. This initial failure to detect the virus and the similarities between HSE and symptoms of intracranial hemorrhage (ICH) suggests repeat testing for HSV in the presence of ICH. Due to the frequency of patients with extra temporal HSE, a diagnosis of HSE should be more readily considered, particularly when a patient may not be improving and a concrete diagnosis has not been solidified.

Herpes simplex encephalitis as a complication of neurosurgical procedures: report of 3 cases and review of the literature

BACKGROUND

Herpes simplex virus (HSV) is the most common identified cause of focal encephalitis worldwide. However, postoperative HSV encephalitis (HSVE) is a rare complication of neurosurgical procedures and a significant clinical challenge

METHOD

We describe 3 cases of postoperative HSVE and review all published reports. A total of 23 cases were identified.

DISCUSSION

Clinical heterogeneity represents a diagnostic challenge in the postoperative setting. Cerebral magnetic resonance imaging showed typical findings in a minority of patients only, whereas HSV-specific polymerase chain reaction on the cerebrospinal fluid proved to be a valuable test. The postoperative viral pathophysiology remains a subject of debate. The rate of adverse outcome is high and early antiviral treatment seems to be a strong predictor of clinical outcome.

CONCLUSION

We recommend early empirical treatment for any patient presenting with post-neurosurgical lymphocytic meningo-encephalitis, and prophylactic antiviral treatment for patients with a history of previous HSVE who will undergo a neurosurgical procedure.

[Herpes simplex encephalitis initially presented with parietal cortex lesions mimicking acute ischemic stroke: A case report]

A 73-year-old woman was admitted to our hospital due to a decreased conscious level and a high fever. Six days before her admission, she felt transient numbness in her right lower limb. Brain MRI taken by her local doctor revealed only right parietal cortex lesions. She was diagnosed with transient ischemic attack and started on anti-platelet therapy. One day before her admission, she became drowsy, and left-side weakness developed. She was admitted to a community hospital for treating stroke. On the next day, she was referred to our hospital because of a high fever. Our brain MRI showed new lesions in her right temporal lobe. She had no stroke risk factors, and embolic sources were not detected. Cerebrospinal fluid analysis detected herpes simplex virus DNA. She was diagnosed with herpes simplex encephalitis (HSE). HSE is common encephalitis which develops fever, headache and alteration in mental status. It often involves temporal lobe, but extratemporal lesions alone are not uncommon. Diffusion-weighted images (DWI) of brain are of importance to differentiate HSE from stroke. When it is questionable to diagnose with stroke for patients with cerebral cortex lesions, they must be monitored with close observation. There is the possibility of initial presentation of HSE in that situation even if patients have no typical symptoms.

HSV Encephalitis with Normal CSF - A Case Report with Review of Literature

Herpes simplex virus encephalitis (HSVE) is one of the most potentially fatal infectious disease that should be detected as early as possible. The combination of clinical history and examination, brain computed tomography or magnetic resonance imaging (MRI) and lumbar puncture have been used to establish a diagnosis. The authors present a case of HSVE with normal CSF analysis, but typical MRI findings consistent with HSE and CSF PCR positive for Herpes simplex virus1 DNA, who responded to Acyclovir therapy with complete recovery.

An unusual presentation of herpes simplex encephalitis with negative PCR

A 74-year-old man presented with acute right-sided hemiparesis and epilepsia partialis continua in association with fever and confusion. Initial workup revealed possible cerebritis in the left medial frontal lobe without involvement of the temporal lobes. Cerebrospinal fluid (CSF) analysis revealed minimal lymphocytic pleocytosis but negative real-time herpes simplex virus (HSV) PCR. Acyclovir was discontinued on day 5 due to a negative infectious workup and clinical improvement. On day 9 his condition deteriorated and he was transferred to a higher level of acuity for advanced supportive care. Worsening encephalopathy and refractory status epilepticus ensued despite medical care. Repeat CSF analysis showed mild lymphocytic pleocytosis with negative real-time HSV PCR. Brain MRI revealed progression of cortical enhancement. Immunosuppressive therapy and plasma exchange were attempted without clinical response. On day 24, another lumbar puncture showed only mild lymphocytic pleocytosis. Brain MRI showed involvement of the right medial temporal lobe. Subsequently, acyclovir was resumed. The HSV-1 PCR result was positive on day 30. Unfortunately, the patient expired.

Use of clinical and neuroimaging characteristics to distinguish temporal lobe herpes simplex encephalitis from its mimics

BACKGROUND

We describe the spectrum of etiologies associated with temporal lobe (TL) encephalitis and identify clinical and radiologic features that distinguish herpes simplex encephalitis (HSE) from its mimics.

METHODS

We reviewed all adult cases of encephalitis with TL abnormalities on magnetic resonance imaging (MRI) from the California Encephalitis Project. We evaluated the association between specific clinical and MRI characteristics and HSE compared with other causes of TL encephalitis and used multivariate logistic modeling to identify radiologic predictors of HSE.

RESULTS

Of 251 cases of TL encephalitis, 43% had an infectious etiology compared with 16% with a noninfectious etiology. Of infectious etiologies, herpes simplex virus was the most commonly identified agent (n = 60), followed by tuberculosis (n = 8) and varicella zoster virus (n = 7). Of noninfectious etiologies, more than half (n = 21) were due to autoimmune disease. Patients with HSE were older (56.8 vs 50.2 years; P = .012), more likely to be white (53% vs 35%; P = .013), more likely to present acutely (88% vs 64%; P = .001) and with a fever (80% vs 49%; P < .001), and less likely to present with a rash (2% vs 15%; P = .010). In a multivariate model, bilateral TL involvement (odds ratio [OR], 0.38; 95% confidence interval [CI], .18-.79; P = .010) and lesions outside the TL, insula, or cingulate (OR, 0.37; 95% CI, .18-.74; P = .005) were associated with lower odds of HSE.

CONCLUSIONS

In addition to HSE, other infectious and noninfectious etiologies should be considered in the differential diagnosis for TL encephalitis, depending on the presentation. Specific clinical and imaging features may aid in distinguishing HSE from non-HSE causes of TL encephalitis.

Herpes Simplex Virus (HSV-1) Encephalitis Mimicking Glioblastoma: Case Report and Review of the Literature

Glioblastoma multiforme (GBM) often presents as a brain mass with encephalitis. In a patient with GBM, subsequent presentation with new onset encephalitis may be due to another GBM or Herpes simplex virus 1 (HSV-1) encephalitis. We present a case of HSV-1 encephalitis mimicking GBM in a patient with previous GBM.

Insights into pediatric herpes simplex encephalitis from a cohort of 21 children from the California Encephalitis Project, 1998-2011

Twenty-one children with confirmed herpes simplex encephalitis were identified in the California Encephalitis Project.Noteworthy features included 6 (29%) patients with an initial negative herpes simplex virus cerebrospinal fluid polymerase chain reaction test and 13 (62%) patients with extratemporal lobe involvement identified by neuroimaging [corrected]. Eleven cases were <4 years of age, but all 4 fatal cases occurred in adolescents.

A rare sequela of acute disseminated encephalomyelitis

Acute disseminated encephalomyelitis is a demyelinating disease, typically occurring in children following a febrile infection or a vaccination. Primary and secondary immune responses contribute to inflammation and subsequent demyelination, but the exact pathogenesis is still unknown. Diagnosis of acute disseminated encephalomyelitis is strongly suggested by temporal relationship between an infection or an immunization and the onset of neurological symptoms. Biopsy is definitive. In general, the disease is self-limiting and the prognostic outcome is favorable with anti-inflammatory and immunosuppressive agents. Locked-in syndrome describes patients who are awake and conscious but have no means of producing limb, speech, or facial movements. Locked-in syndrome is a rare complication of acute disseminated encephalomyelitis. We present a case of incomplete locked-in syndrome occurring in a 34-year-old male secondary to acute disseminated encephalomyelitis. Our case is unique, as acute disseminated encephalomyelitis occurred in a 34-year-old which was poorly responsive to immunosuppression resulting in severe disability.

Viral encephalitis in the ICU

Viral encephalitis causes an altered level of consciousness, which may be associated with fever, seizures, focal deficits, CSF pleocytosis, and abnormal neuroimaging. Potential pathogens include HSV, VZV, enterovirus, and in some regions, arboviruses. Autoimmune (eg, anti-NMDA receptor) and paraneoplastic encephalitis are responsible for some cases where no pathogen is identified. Indications for ICU admission include coma, status epilepticus and respiratory failure. Timely initiation of anti-viral therapy is crucial while relevant molecular and serological test results are being performed. Supportive care should be directed at the prevention and treatment of cerebral edema and other physiological derangements which may contribute to secondary neurological injury.

Children often present with infantile spasms after herpetic encephalitis

PURPOSE

To determine what epilepsy types occur after herpetic encephalitis and what are the determinant factors for subsequent infantile spasms.

METHODS

We analyzed retrospectively the clinical history of 22 patients, referred to Necker and Saint Vincent de Paul Hospitals (Paris) through the French pediatric epilepsy network from March 1986 to April 2010 and who developed epilepsy some months after herpetic encephalitis. We focused on seizure semiology with video-electroencephalography (EEG) recording, and on neuroradiology and epilepsy follow-up.

KEY FINDINGS

Fourteen patients developed pharmacoresistant spasms, and eight developed focal epilepsy, but none had both. The patients who developed spasms were more frequently younger than 30 months at age of onset of epilepsy and had herpetic encephalitis earlier (mean 10.6 months of age) than those who developed focal epilepsy (mean 59.7 and 39.6 months, respectively). Epilepsy follow-up was similar in both groups (8.5 and 11 years, respectively). We found 26 affected cerebral areas; none alone was related to the development of epileptic spasms.

SIGNIFICANCE

Risk factors to develop epileptic spasms were to have had herpetic encephalitis early (mean 10 months); to be significantly younger at onset of epilepsy (mean 22.1 months); and to have cerebral lesions involving the insula, the hippocampus, and the temporal pole.

Brainstem encephalitis: etiologies, treatment, and predictors of outcome

Brainstem encephalitis (BE) is an uncommon condition. We sought to characterize clinical presentations, etiologies, response to treatment, and predictors of outcome. We performed a retrospective review of non-HIV infected patients diagnosed with BE at Johns Hopkins Hospital (January 1997-April 2010). We characterized clinical and paraclinical features, and used regression models to assess associations with poor outcome. BE was diagnosed in 81 patients. An etiology was identified in 58 of 81 (71.6%) of cases, most of which were confirmed or probable inflammatory/autoimmune conditions. Of the remaining 23 cases in which a specific diagnosis remained undefined, clinical presentation, CSF, neuroimaging studies, and outcomes were similar to the inflammatory/autoimmune group. Brain biopsy identified a specific diagnosis in 7 of 14 patients (50%). Fifteen patients (18.5%) either died or had a poor outcome. In multivariate logistic regression models, a higher CSF protein (per 5 mg/dl, OR = 1.11, 95% CI: 1.03-1.20), a higher CSF glucose (per 5 mg/dl, OR = 1.36, 95% CI: 1.09-1.70), and higher serum glucose (per 5 mg/dl, OR = 1.27, 95% CI: 1.06-1.52) were independently associated with increased odds of poor outcome. Inflammatory and non-infectious conditions accounted for most cases of BE. Higher CSF protein and glucose were independently associated with poor outcome. In immunocompetent patients with BE of undefined etiology despite extensive investigation, a trial of immunosuppressive treatment may be warranted, though deterioration clinically or on magnetic resonance imaging should prompt a brain biopsy.

Herpes simplex encephalitis with occipital localization in an infant: a different route of entry in the brain system?

Herpes simplex encephalitis classically involves the periventricular white matter in infants and the mesial temporal lobes, inferior frontal lobes, and insula in older children and adults. However, the increasing use of polymerase chain reaction to detect viral DNA in the cerebrospinal fluid has allowed the expansion of the spectrum of radiologic findings possibly associated with herpes simplex encephalitis. This study presents a rare case of a previously healthy infant with herpes simplex encephalitis with occipital involvement and permanent visual impairment. Possible pathogenic mechanisms are discussed.

Pediatric herpes simplex virus encephalitis: a retrospective multicenter experience

Knowledge on pediatric herpes simplex virus encephalitis is limited. Here we summarize 6 neonates and 32 children diagnosed by polymerase chain reaction (n = 37) or serological studies (n = 1), respectively. Diagnosis was difficult, as only 15 patients presented neurologic symptoms. Moreover, cerebrospinal fluid glucose, protein, and leukocytes were normal in 6 patients. Subsequently, all but 2 showed neurologic symptoms. Diffusion-weighted neuroimaging was the most sensitive early imaging method. Despite acyclovir treatment, 8 patients experienced early relapses, showing movement abnormalities, impaired vigilance, and seizures. Diffuse white matter changes, found in 3 of 5 relapse patients on neuroimaging, and a negative cerebrospinal fluid herpes simplex virus polymerase chain reaction suggested inflammatory processes. All relapse patients were again treated with acyclovir, and 3 responded to additional corticosteroid treatment. Whereas outcome after relapses was poor, overall outcome was good. No child died; 14 were asymptomatic at discharge, and neuroimaging remained normal in 7 of 30 patients studied.

Atypical manifestations and poor outcome of herpes simplex encephalitis in the immunocompromised

OBJECTIVE

To characterize clinical features, neuroimaging, and outcomes of herpes simplex encephalitis (HSE) in immunocompromised individuals.

METHODS

We performed a retrospective case control review of patients diagnosed with HSE. Adult patients were dichotomized into immunocompromised (n = 14) and immunocompetent groups (n = 15).

RESULTS

Fewer immunocompromised patients presented with prodromal symptoms and focal deficits. While the majority of CSF profiles in the immunocompromised patients were mononuclear cells predominant, 3 had polymorphonuclear predominance and another 3 had normal profiles. MRI showed widespread cortical involvement, with brainstem or cerebellar involvement in some. Two immunocompromised patients had recurrent HSE. The immunosuppressed state was associated with a decrease in Karnofsky Performance Status Scale (KPSS) score of 23.1 (p = 0.018). Every 1-day delay in initiation of acyclovir was associated with a decrease in KPSS of 10.2 (p = 0.002), and every 10 cell/mm(3) increase of CSF leukocytosis was associated with an increase in KPSS of 0.7 (p = 0.009). Mortality rate was 6 times higher in the immunocompromised patients.

CONCLUSIONS

Immunocompromised states may predispose to HSE with atypical clinical and neuroradiologic features. Immunocompromised individuals with HSE have significantly worse outcomes and mortality. Early diagnosis and treatment is associated with improved outcome. The findings are particularly important in light of the increasing use of potent immunosuppressive and immunomodulatory therapies.

Imaging of central nervous system viral diseases

Viral infections of the central nervous system (CNS) are commonly encountered and there has been continued emergence of new neurotropic viruses which are being frequently recognized. These may present clinically as encephalitis, meningitis, encephalomyelitis, and encephalomyeloradiculitis. The clinical manifestations are usually nonspecific and diagnosis is usually based on the laboratory investigations. Imaging plays a role in its early detection and at times suggests the specific diagnosis that may help in early institution of appropriate therapy. In this review, we summarize the pathology, clinical, and imaging features of the common viral infections that affect the CNS.

Discrepant findings between proton magnetic resonance spectroscopy and magnetic resonance imaging in an immunocompetent patient with herpes simplex virus type 1 encephalitis

The authors report discrepant findings between proton magnetic resonance spectroscopy and conventional magnetic resonance imaging in a 67-y-old woman with herpes simplex virus type 1 encephalitis. The sparse amount of literature on proton magnetic resonance spectroscopy in patients with herpes simplex type 1 encephalitis is discussed.

Temporal and pontine involvement in a case of herpes simplex encephalitis, presenting as kluver bucy syndrome - a case report

Bilateral temporal and frontal lobe involvement is a common characteristic of herpes simplex encephalitis (HSE). Clinical sequelae of herpes simplex encephalitis may manifest sometimes as Kluver Bucy syndrome (KBS). In herpes simplex encephalitis, apart from frontal lobe, extra temporal involvement is rare and uncommon. We report a case of HSE manifesting clinically as KBS with a rare radiological finding of temporal and extratemporal involvement of pons.

Pediatric central nervous system emergencies

This article summarizes current state-of-the-art techniques used in the management of pediatric neurologic emergencies. Solutions to challenges faced by the radiologist, including the selection of an appropriate modality for an individual patient, are discussed. Imaging appearances of specific entities are described with an emphasis on conditions unique to the pediatric population.

Herpes simplex type 1 encephalitis restricted to the brainstem in a pediatric patient

Herpes simplex encephalitis is a potentially fatal infection of central nervous system that typically involves frontal and temporal lobes. Occasionally, it presents an extratemporal involvement and in rarer cases, it is limited to the brainstem. We describe a case of an adolescent who presented with fever, sore throat, and vertigo. Clinical picture evolved to lethargy, tetraparesis, consciousness impairment, and respiratory failure. MRI showed lesions restricted to the brainstem. PCR of CSF was positive for herpes simplex type 1.

Postmortem trucut transnasal brain biopsy in the diagnosis of encephalitis

Diagnosing encephalitis is often difficult with a definitive diagnosis being reached at best in only 40% of cases. This clinical condition is associated with a high morbidity and mortality. A brain biopsy is the gold standard for the diagnosis of this disease. However, this procedure is rarely done, resulting in the cause of death being largely speculative. We propose a simple procedure for postmortem brain biopsy through the transnasal transcribriform route that will possibly be more acceptable to clinicians and relatives alike due to lack of external disfigurement, relative ease of the procedure and economy of time and manpower. This could also prove to be of immense benefit in an epidemic of encephalitis, especially in remote areas.

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.

Herpes simplex encephalitis presenting with exclusively frontal lobe involvement

The authors report a patient with herpes simplex encephalitis who presented with magnetic resonance imaging (MRI) lesions exclusively in the frontal lobes, including the bilateral anterior cingulate gyri. She is making a good recovery after therapy with intravenous acyclovir. A similar presentation with a fatal outcome was previously reported by Rose et al (Neurology 42: 1809-1812, 1992). MRI shows temporal lesions in most patients with herpes simplex encephalitis, whereas occasional patients have normal imaging. A high index of suspicion for the diagnosis of herpes simplex encephalitis should be maintained when a patient presents with fever and brain lesions involving extratemporal limbic system structures.

Neuroimaging of herpesvirus infections in children

Six members of the herpesvirus family cause well-described neurologic disease in children: herpes simplex virus-1 (HSV-1), herpes simplex virus-2 (HSV-2), varicella-zoster (VZV), Epstein-Barr (EBV), cytomegalovirus (CMV), and human herpes virus-6 (HHV-6). When herpesviruses infect the central nervous system (CNS), the clinical presentation is non-specific and often confounding. The clinical urgency is often underscored by progressive neurologic deficits, seizures, or even death, and prompt diagnosis and treatment rely heavily on neuroimaging. This review focuses on the spectrum of cerebral manifestations caused by these viruses, particularly on non-congenital presentations. Recent advances in our understanding of these viruses are discussed, including new polymerase chain reaction techniques that allow parallel detection, which has improved our recognition that the herpesviruses are neurotropic and involve the CNS more often than previously thought. Evolving knowledge has also better elucidated viral neuropathology, particularly the role of VZV vasculitis in the brain, HHV-6 in febrile seizures, and herpesvirus reactivation in immunosuppressed patients. The virology, clinical course, and CNS manifestations of each virus are reviewed, followed by descriptions of neuroimaging findings when these agents infect the brain. Characteristic but often subtle imaging findings are discussed, as well as technical pearls covering appropriate use of MRI and MRI adjuncts to help differentiate viral infection from mimics.

Suspected herpes encephalitis and opercular syndrome in childhood

Herpes simplex encephalitis is the most common form of sporadic viral encephalitis. It may occur at any age, giving rise to a syndrome with a high morbidity and mortality. Its presentation may be atypical, and the initial complementary investigations nonspecific, making early diagnosis difficult and thus worsening its prognosis. This report describes four infants with herpes encephalitis presenting with an opercular syndrome that left significant sequelae after the acute episode. The opercular syndrome is characterized clinically by a disturbance of voluntary control of the facio-linguo-glosso-pharyngeal muscles, affecting speech and swallowing. Recognition of the opercular syndrome as a form of presentation of herpes encephalitis enables early diagnosis to be made in these patients, with the rapid initiation of treatment with acyclovir, improving the clinical course.