Streptococcus bovis infection of the central nervous system in adults: Report of 4 cases and literature review

OBJECTIVES

To describe the clinical features, history and association with intestinal disease in central nervous system (CNS) S. bovis infections.

METHODS

Four cases of S. bovis CNS infections from our institution are presented. Additionally a systematic literature review of articles published between 1975 and 2021 in PubMed/MEDLINE was conducted.

RESULTS

52 studies with 65 cases were found; five were excluded because of incomplete data. In total 64 cases were analyzed including our four cases: 55 with meningitis and 9 with intracranial focal infections. Both infections were frequently associated with underlying conditions (70.3%) such as immunosuppression (32.8%) or cancer (10.9%). In 23 cases a biotype was identified, with biotype II being the most frequent (69.6%) and S. pasteurianus the most common within this subgroup. Intestinal diseases were found in 60.9% of cases, most commonly neoplasms (41.0%) and Strongyloides infestation (30.8%). Overall mortality was 17.1%, with a higher rate in focal infection (44.4% vs 12.7%; p=0.001).

CONCLUSIONS

CNS infections due to S. bovis are infrequent and the most common clinical form is meningitis. Compared with focal infections, meningitis had a more acute course, was less associated with endocarditis and had a lower mortality. Immunosuppression and intestinal disease were frequent in both infections.

Single-Cell RNA Sequencing Reveals the Diversity of the Immunological Landscape following Central Nervous System Infection by a Murine Coronavirus

Intracranial (i.c.) infection of susceptible C57BL/6 mice with the neurotropic JHM strain of mouse hepatitis virus (JHMV) (a member of the Coronaviridae family) results in acute encephalomyelitis and viral persistence associated with an immune-mediated demyelinating disease. The present study was undertaken to better understand the molecular pathways evoked during innate and adaptive immune responses as well as the chronic demyelinating stage of disease in response to JHMV infection of the central nervous system (CNS). Using single-cell RNA sequencing analysis (scRNAseq) on flow-sorted CD45-positive (CD45+) cells enriched from brains and spinal cords of experimental mice, we demonstrate the heterogeneity of the immune response as determined by the presence of unique molecular signatures and pathways involved in effective antiviral host defense. Furthermore, we identify potential genes involved in contributing to demyelination as well as remyelination being expressed by both microglia and macrophages. Collectively, these findings emphasize the diversity of the immune responses and molecular networks at defined stages following viral infection of the CNS.IMPORTANCE Understanding the immunological mechanisms contributing to both host defense and disease following viral infection of the CNS is of critical importance given the increasing number of viruses that are capable of infecting and replicating within the nervous system. With this in mind, the present study was undertaken to evaluate the molecular signatures of immune cells within the CNS at defined times following infection with a neuroadapted murine coronavirus using scRNAseq. This approach has revealed that the immunological landscape is diverse, with numerous immune cell subsets expressing distinct mRNA expression profiles that are, in part, dictated by the stage of infection. In addition, these findings reveal new insight into cellular pathways contributing to control of viral replication as well as to neurologic disease.

Molecular and Histologic Diagnosis of Central Nervous System Infections

Infections of the central nervous system cause significant morbidity and mortality in immunocompetent and immunocompromised individuals. A wide variety of microorganisms can cause infections, including bacteria, mycobacteria, fungi, viruses, and parasites. Although less invasive testing is preferred, surgical biopsy may be necessary to collect diagnostic tissue. Histologic findings, including special stains and immunohistochemistry, can provide a morphologic diagnosis in many cases, which can be further classified by molecular testing. Correlation of molecular, culture, and other laboratory results with histologic findings is essential for an accurate diagnosis, and to minimize false positives from microbial contamination.

Prevalence and Risk Factors of White Matter Lesions in Tibetan Patients Without Acute Stroke

Background and Purpose—

Studies on the prevalence and risk factors of white matter lesions (WMLs) in Tibetans living at high altitudes are scarce. We conducted this study to determine the prevalence and risks of WMLs in Tibetan patients without or with nonacute stroke.

Methods—

We undertook a retrospective analysis of medical records of patients treated at the People’s Hospital of Tibetan Autonomous Region and identified a total of 301 Tibetan patients without acute stroke. WML severity was graded by the Fazekas Scale. We assessed the overall and age-specific prevalence of WMLs and analyzed associations between WMLs and related factors with univariate and multivariate methods.

Results—

Of the 301 patients, 87 (28.9%) had peripheral vertigo, 83 (27.3%) had primary headache, 52 (17.3%) had a history of stroke, 36 (12.0%) had an anxiety disorder, 29 (9.6%) had epilepsy, 12 (4.0%) had infections of the central nervous system, and 3 (1.0%) had undetermined diseases. WMLs were present in 245 (81.4%) patients, and 54 (17.9%) were younger than 40 years. Univariate analysis showed that age, history of cerebral infarction, hypertension, the thickness of the common carotid artery intima, and plaque within the intracarotid artery were related risks for WMLs. Ordered logistic analysis showed that age, history of cerebral ischemic stroke, hypertension, male sex, and atrial fibrillation were associated with WML severity.

Conclusions—

Risk factors for WMLs appear similar for Tibetans residing at high altitudes and individuals living in the plains. Further investigations are needed to determine whether Tibetans residing at high altitudes have a higher burden of WMLs than inhabitants of the plains.

Mass spectrometry-based proteomic techniques to identify cerebrospinal fluid biomarkers for diagnosing suspected central nervous system infections. A systematic review

OBJECTIVES

Central nervous system (CNS) infections account for considerable death and disability every year. An urgent research priority is scaling up diagnostic capacity, and introduction of point-of-care tests. We set out to assess current evidence for the application of mass spectrometry (MS) peptide sequencing in identification of diagnostic biomarkers for CNS infections.

METHODS

We performed a systematic review (PROSPEROCRD42018104257) using PRISMA guidelines on use of MS to identify cerebrospinal fluid (CSF) biomarkers for diagnosing CNS infections. We searched PubMed, Embase, Web of Science, and Cochrane for articles published from 1 January 2000 to 1 February 2019, and contacted experts. Inclusion criteria involved primary research except case reports, on the diagnosis of infectious diseases except HIV, applying MS to human CSF samples, and English language.

RESULTS

4,620 papers were identified, of which 11 were included, largely confined to pre-clinical biomarker discovery, and eight (73%) published in the last five years. 6 studies performed further work termed verification or validation. In 2 of these studies, it was possible to extract data on sensitivity and specificity of the biomarkers detected by ELISA, ranging from 89-94% and 58-92% respectively.

CONCLUSIONS

The findings demonstrate feasibility and potential of the methods in a variety of infectious diseases, but emphasise the need for strong interdisciplinary collaborations to ensure appropriate study design and biomarker validation.

Research advancements in the neurological presentation of flaviviruses

Owing to the large-scale epidemic of Zika virus disease and its association with microcephaly, properties that allow flaviviruses to cause nervous system diseases are an important area of investigation. At present, although potential pathogenic mechanisms of flaviviruses in the nervous system have been examined, they have not been completely elucidated. In this paper, we review the possible mechanisms of blood-brain barrier penetration, the pathological effects on neurons, and the association between virus mutations and neurotoxicity. A hypothesis on neurotoxicity caused by the Zika virus is presented. Clarifying the mechanisms of virulence of flaviviruses will be helpful in finding better antiviral drugs and optimizing the treatment of symptoms.

Mycobacteria employ two different mechanisms to cross the blood-brain barrier

Central nervous system (CNS) infection by Mycobacterium tuberculosis is one of the most devastating complications of tuberculosis, in particular in early childhood. In order to induce CNS infection, M. tuberculosis needs to cross specialised barriers protecting the brain. How M. tuberculosis crosses the blood-brain barrier (BBB) and enters the CNS is not well understood. Here, we use transparent zebrafish larvae and the closely related pathogen Mycobacterium marinum to answer this question. We show that in the early stages of development, mycobacteria rapidly infect brain tissue, either as free mycobacteria or within circulating macrophages. After the formation of a functionally intact BBB, the infiltration of brain tissue by infected macrophages is delayed, but not blocked, suggesting that crossing the BBB via phagocytic cells is one of the mechanisms used by mycobacteria to invade the CNS. Interestingly, depletion of phagocytic cells did not prevent M. marinum from infecting the brain tissue, indicating that free mycobacteria can independently cause brain infection. Detailed analysis showed that mycobacteria are able to cause vasculitis by extracellular outgrowth in the smaller blood vessels and by infecting endothelial cells. Importantly, we could show that this second mechanism is an active process that depends on an intact ESX-1 secretion system, which extends the role of ESX-1 secretion beyond the macrophage infection cycle.

Viral Determinants of Virulence in Tick-Borne Flaviviruses

Tick-borne flaviviruses have a global distribution and cause significant human disease, including encephalitis and hemorrhagic fever, and often result in neurologic sequelae. There are two distinct properties that determine the neuropathogenesis of a virus. The ability to invade the central nervous system (CNS) is referred to as the neuroinvasiveness of the agent, while the ability to infect and damage cells within the CNS is referred to as its neurovirulence. Examination of laboratory variants, cDNA clones, natural isolates with varying pathogenicity, and virally encoded immune evasion strategies have contributed extensively to our understanding of these properties. Here we will review the major viral determinants of virulence that contribute to pathogenesis and influence both neuroinvasiveness and neurovirulence properties of tick-borne flaviviruses, focusing particularly on the envelope protein (E), nonstructural protein 5 (NS5), and the 3′ untranslated region (UTR).

Neurobrucellosis: diagnostic and clinical management of an atypical case

Brucellosis is the most common zoonosis in the world and it is caused by ingestion of foods contaminated by Brucella spp. that is able to avoid the immune system and can involve every organ system. The bacteria may affect the Central Nervous System (CNS) directly or using phagocytic cells with the way of the "Trojan Horse Model". Meningitis is the most common form of neuro-brucellosis (NB) but other neurological manifestation, with variable onset, such as severe encephalic involvement, neuropathy, vascular damage, radiculitis and hydrocephalus might happened. NB may manifest itself with an acute or chronic onset and could be the only manifestation of the infection or appearance during the systemic disease. Frequently the diagnosis might be very difficult and the clinical characteristics and the microbiological demonstration in the blood and in the CSF are necessary. The prognosis of brucella meningitis is generally better than other forms of chronic meningitis except for encephalitis or spinal cord involvement. The treatment is based on the combination of two or three antibiotics to achieve normalization of the cerebrospinal fluid parameters otherwise relapse are relatively frequent. We describe an atypical case of brucellar meningitis with many stroke-like signs, think as recurrent cerebrovascular events and treated with antithrombotic therapy, but without meningeal syndrome.

Reprint of-Differential diagnosis: Trepanation

Trepanation is the scraping, cutting, or drilling of an opening (or openings) into the neurocranium. World surveys reveal that a number of ancient cultures experimented with cranial surgery, and that in some areas these practices continued into modern times. Archaeological discoveries of possible trepanations continue to be made, often from geographic areas or time periods from which the practice was not previously known. Unfortunately, most of these reports describe single crania with healed defects interpreted as trepanations. When evaluating a possible trepanation in a skull that lacks medical history or comes from an archaeological context where there is no other evidence that such operations were performed, a thorough differential diagnosis is essential. Identification of unhealed trepanations is a relatively straightforward exercise, since tool marks provide direct evidence of surgical intervention. A confident diagnosis is more difficult in healed defects of the skull, where the mechanism that produced an opening may be obscured by bone remodeling. There are many possible causes of defects of the skull vault, including congenital and developmental anomalies, trauma, infection, neoplasm, and taphonomic damage. For this reason, a careful differential diagnosis is essential for identifying surgical intervention and distinguishing it from cranial defects caused by other mechanisms.

Central nervous system infections in the absence of cerebrospinal fluid pleocytosis

Previous multicenter/multinational studies were evaluated to determine the frequency of the absence of cerebrospinal fluid pleocytosis in patients with central nervous system infections, as well as the clinical impact of this condition. It was found that 18% of neurosyphilis, 7.9% of herpetic meningoencephalitis, 3% of tuberculous meningitis, 1.7% of Brucella meningitis, and 0.2% of pneumococcal meningitis cases did not display cerebrospinal fluid pleocytosis. Most patients were not immunosuppressed. Patients without pleocytosis had a high rate of unfavorable outcomes and thus this condition should not be underestimated.

Emerging Zika Virus Infection: A Rapidly Evolving Situation

Zika virus is a mosquito-borne flavivirus, firstly identified in Uganda and responsible for sporadic human cases in Africa and Asia until recently, when large outbreak occurred in Pacific Ocean and the Americas. Since the main vectors during its spread outside of Africa have been Ae. albopictus and Ae. aegypti mosquitoes, which are widely distributed all over the world, there is urgent need for a coordinated response for prevention and spread of ZIKV epidemics.Despite clinical manifestation of Zika virus infection are usually mild and self limiting, there are reports suggesting, during the recent epidemic, an association of ZIKV infection with severe consequences, including fetal/newborn microcephaly, due to vertical in utero transmission, autoimmune-neurological presentations including cranial nerve dysfunction, and Guillain-Barré Syndrome in adults. The primary mode of transmission of Zika virus between humans is through the bite of an infected female mosquito of the Aedes genus, but also sexual and blood transfusion transmission may occur. Moreover, a case of non-sexual spread from one person to another has been described, indicating that we still have more to learn about Zika transmission.Biological basis for pathogenetic effects are under investigation. Laboratory diagnosis is challenging since, so far, there are no "gold standard" diagnostic tools, and the low and short viremia in the acute phase, and together with the high cross-reactivity among the members of flavivirus genus are the most challenging aspects to be overcome.

Effective Suckling C57BL/6, Kunming, and BALB/c Mouse Models with Remarkable Neurological Manifestation for Zika Virus Infection

Since 2015, 84 countries and territories reported evidence of vector-borne Zika Virus (ZIKV) transmission. The World Health Organization (WHO) declared that ZIKV and associated consequences especially the neurological autoimmune disorder Guillain–Barré syndrome (GBS) and microcephaly will remain a significant enduring public health challenge requiring intense action. We apply a standardization of the multi-subcutaneous dorsal inoculation method to systematically summarize clinical neurological manifestation, viral distribution, and tissue damage during the progress of viremia and systemic spread in suckling mouse models. We found that C57BL/6 and Kunming mice (KM) both showed remarkable and uniform neurologic manifestations. C57BL/6 owned the highest susceptibility and pathogenicity to the nervous system, referred to as movement disorders, with 100% incidence, while KM was an economic model for a Chinese study characterized by lower limb weakness with 62% morbidity. Slight yellow extraocular exudates were observed in BALB/c, suggesting the association with similar ocular findings to those of clinical cases. The virus distribution and pathological changes in the sera, brains, livers, kidneys, spleens, and testes during disease progression had strong regularity and uniformity, demonstrating the effectiveness and plasticity of the animal models. The successful establishment of these animal models will be conducive to expound the pathogenic mechanism of GBS.

CROI 2016: Neurologic Complications of HIV Infection

The brain remains a major target for HIV infection and a site of potential complications for HIV-infected individuals. Emerging data presented at the 2016 Conference on Retroviruses and Opportunistic Infections suggest that during the early stages of infection, activated CD4+ cells may traffic the virus into the central nervous system (CNS). HIV is detectable in cells and tissues of the CNS in some individuals despite suppressive antiretroviral treatment. A potential source of cerebrospinal fluid HIV escape may be compartmentalized HIV replication within macrophage lineage cells. Virally infected cells can traffic out of the CNS and may have the potential to reseed the systemic compartment. Additional modifiers of HIV-associated neurocognitive disorder (HAND) were identified, including female sex and hepatic dysfunction. Large epidemiologic studies reported an elevated risk of stroke among HIV-infected individuals, related to traditional vascular risk factors, history of recreational drug use, and HIV measures (lower CD4+ cell nadir and higher viral load). Brain imaging may provide a noninvasive means for detecting early changes in the brain associated with HIV infection and may assist in prognosis of HAND. Some potential adjunctive therapies to standard antiretroviral therapy for HIV-infected individuals were considered.

Infections, inflammation and epilepsy

Epilepsy is the tendency to have unprovoked epileptic seizures. Anything causing structural or functional derangement of brain physiology may lead to seizures, and different conditions may express themselves solely by recurrent seizures and thus be labelled "epilepsy." Worldwide, epilepsy is the most common serious neurological condition. The range of risk factors for the development of epilepsy varies with age and geographic location. Congenital, developmental and genetic conditions are mostly associated with the development of epilepsy in childhood, adolescence and early adulthood. Head trauma, infections of the central nervous system (CNS) and tumours may occur at any age and may lead to the development of epilepsy. Infections of the CNS are a major risk factor for epilepsy. The reported risk of unprovoked seizures in population-based cohorts of survivors of CNS infections from developed countries is between 6.8 and 8.3 %, and is much higher in resource-poor countries. In this review, the various viral, bacterial, fungal and parasitic infectious diseases of the CNS which result in seizures and epilepsy are discussed. The pathogenesis of epilepsy due to brain infections, as well as the role of experimental models to study mechanisms of epileptogenesis induced by infectious agents, is reviewed. The sterile (non-infectious) inflammatory response that occurs following brain insults is also discussed, as well as its overlap with inflammation due to infections, and the potential role in epileptogenesis. Furthermore, autoimmune encephalitis as a cause of seizures is reviewed. Potential strategies to prevent epilepsy resulting from brain infections and non-infectious inflammation are also considered.

Fighting the Monster: Applying the Host Damage Framework to Human Central Nervous System Infections

The host damage-response framework states that microbial pathogenesis is a product of microbial virulence factors and collateral damage from host immune responses. Immune-mediated host damage is particularly important within the size-restricted central nervous system (CNS), where immune responses may exacerbate cerebral edema and neurological damage, leading to coma and death. In this review, we compare human host and therapeutic responses in representative nonviral generalized CNS infections that induce archetypal host damage responses: cryptococcal menigoencephalitis and tuberculous meningitis in HIV-infected and non-HIV-infected patients, pneumococcal meningitis, and cerebral malaria. Consideration of the underlying patterns of host responses provides critical insights into host damage and may suggest tailored adjunctive therapeutics to improve disease outcome.

Magnetic Resonance Imaging of Pediatric Neurologic Emergencies

Although computed tomography is often the first line of imaging in the emergency setting, magnetic resonance imaging (MRI) is of increasing importance in the evaluation of central nervous system emergencies in the pediatric population. As such, it is necessary to understand the indications for which MRI may be necessary. This article reviews the unique pathophysiologic entities affecting the pediatric population and the associated MRI findings. Specifically, utility of emergent MRI and characteristic appearances of traumatic brain injury, traumatic spinal injury, nonaccidental trauma, arterial ischemic stroke, cerebral sinovenous thrombosis, stroke mimics, and central nervous system infections are described.

Intraventricular granulomatous mass associated with Mycobacterium haemophilum: A rare central nervous system manifestation in a patient with human immunodeficiency virus infection

We report a rare case of Mycobacterium haemophilum presenting as an intraventricular granulomatous mass with loculated hydrocephalus and seizures in a patient with human immunodeficiency virus. M. haemophilum, a slow-growing mycobacteria, causes localized and disseminated disease among immunocompromised hosts. Central nervous system infection with M. haemophilum is extremely rare. Preoperative laboratory testing of our patient for tuberculosis, toxoplasmosis, sarcoidosis and histoplasmosis were negative. Surgical resection of the mass revealed a caseating granuloma that stained positive for acid-fast bacillus suggesting possible tuberculoma. Despite negative testing for tuberculosis, a polymerase chain reaction analysis was ultimately performed from the resected mass which revealed M. haemophilum. To our knowledge, this is the first case of M. haemophilum presenting as an intraventricular mass. We review the clinical manifestations of this pathogen and discuss the medical and surgical management.

Anti-α4 antibody treatment blocks virus traffic to the brain and gut early, and stabilizes CNS injury late in infection

Four SIV-infected monkeys with high plasma virus and CNS injury were treated with an anti-α4 blocking antibody (natalizumab) once a week for three weeks beginning on 28 days post-infection (late). Infection in the brain and gut were quantified, and neuronal injury in the CNS was assessed by MR spectroscopy, and compared to controls with AIDS and SIV encephalitis. Treatment resulted in stabilization of ongoing neuronal injury (NAA/Cr by 1H MRS), and decreased numbers of monocytes/macrophages and productive infection (SIV p28⁺, RNA⁺) in brain and gut. Antibody treatment of six SIV infected monkeys at the time of infection (early) for 3 weeks blocked monocyte/macrophage traffic and infection in the CNS, and significantly decreased leukocyte traffic and infection in the gut. SIV – RNA and p28 was absent in the CNS and the gut. SIV DNA was undetectable in brains of five of six early treated macaques, but proviral DNA in guts of treated and control animals was equivalent. Early treated animals had low-to-no plasma LPS and sCD163. These results support the notion that monocyte/macrophage traffic late in infection drives neuronal injury and maintains CNS viral reservoirs and lesions. Leukocyte traffic early in infection seeds the CNS with virus and contributes to productive infection in the gut. Leukocyte traffic early contributes to gut pathology, bacterial translocation, and activation of innate immunity.

To determine whether ongoing cell traffic is required for SIV-associated tissue damage, we blocked monocyte and T lymphocyte traffic to the brain and gut during a) ongoing infection or, b) at the time of infection. When animals were treated at four weeks post infection (late), once significant neuronal injury and accumulation of infected macrophages had already occurred, neuronal injury was stabilized, and CNS infection and the number of CNS lesions decreased. In the gut, there were significantly fewer productively infected cells and decreased inflammatory macrophages post treatment. Treatment at the time of infection (early) blocked infection of the CNS (SIV –DNA, RNA, or protein) and macrophage accumulation. In the gut, treatment at the time of infection blocked productive infection (SIV –RNA and protein) but not SIV –DNA. Interestingly, with treatment at the time of infection, there was no evidence of microbial translocation or elevated sCD163 in plasma, demonstrating that leukocyte traffic early plays a role in damage to gut tissues. Overall, these data point to the role of monocyte traffic and possibly lymphocytes to the CNS and leukocyte traffic to the gut to establish and maintain viral reservoirs. They underscore the role of monocyte/macrophage traffic and accumulation in the CNS for neuronal injury and maintenance of CNS lesions.

Magnetic resonance imaging in fungal infections of the brain

An invasive fungal infection is a rare disease that can occur in otherwise healthy individuals. Fungi themselves are universal, and they are overall harmless organisms that cause at most a self-limiting disease in the general population. Immunocompromised individuals, whether iatrogenically, genetically, or acquired, present a group who are especially susceptible to a life-threatening disease from a normally innocuous pathogen. Fungi are normally inhaled and are cleared by pulmonary defense mechanisms in immunocompetent hosts. Invasion begins when these mechanisms fail in depressed immunity. Through bypassing of the pulmonary immune system, fungi can spread hematogenously. Fungal infections of the central nervous system are the most common extrapulmonary manifestation after fungal inhalation. Other risk factors of fungemia include prolonged indwelling catheters, maxillofacial infections, uncontrolled diabetes mellitus, systemic antibiotics, implanted neurosurgical devices, and intravenous drug abuse. Thus, other than direct inoculation via surgical complications or open trauma, central nervous system fungal infections are almost never primary.

Association between cerebrospinal fluid S100B protein and neuronal damage in patients with central nervous system infections

PURPOSE

S100B protein is widely used as a measure of glial activity or damage in several brain conditions. Central nervous system (CNS) infections can cause neurological sequelae because of parenchyma invasion. It is difficult to predict further neuronal damage in the CNS infection. The present study is aimed to evaluate the role of the cerebrospinal fluid (CSF) S100B protein as an indicator of neuronal damage in CNS infection.

MATERIALS AND METHODS

We measured the concentration of CSF S100B protein in 62 patients with a CNS infection using an Enzyme-Linked Immunosorbent Assay. The patients with CNS infections were classified as having no neuronal damage (CNS-N) or as having neuronal damage (CNS+N) according to the presence of neurological change or structural lesions on brain MRI.

RESULTS

The CSF S100B protein level of the CNS+N group (n=22, 0.235 μg/L, 0.10-2.18) was significantly higher than that of the CNS-N group (n=40, 0.087 μg/L, 0.06-0.12) and control group (n=40, 0.109 μg/L, 0.07-0.14, p<0.01). Using an arbitrary cut off value, S100B-positive CSF was detected in 2.5% of the CNS-N group and in 50% of the CNS+N group (p<0.05).

CONCLUSION

These findings suggest that increased S100B protein levels in the CSF may be associated with the neuronal damage following CNS infections.

Proton magnetic resonance spectroscopy in the evaluation of infiltration zone of cerebral alveolar echinococcosis

BACKGROUND

Cerebral alveolar echinococcosis (CAE) grows infiltratively like a malignant tumor, causing great harm to the human body. It is possible to display mass lesions of CAE using various imaging systems, but regarding the infiltrating proliferation active regions, it is difficult to evaluate its actual range using conventional magnetic resonance imaging (cMRI). This research focused on proton magnetic resonance spectroscopy ((1)HMRS) techniques to find the mass and infiltration zone of CAE. We explored the marginal zone (MZ) of CAE nearly close to the actual infiltrating scope, to provide reliable images for clinical purposes, to overcome shortcomings of cMRI, to formulate beneficial clinical surgical plans and assess prognosis.

METHODS

Between September 2005 and May 2011, 15 patients who were suffering from CAE (36 effective lesions altogether) were examined by (1)HMRS at the first affiliated hospital of Xinjiang Medical University. Multi-voxel (1)HMRS was acquired with a 1.5T MRI scanner. Concentrations and the ratios of the metabolites of CAE were calculated. Furthermore, changes in the concentrations of the metabolites containing N-acetyl-aspartic-acid (NAA), choline (Cho), creatine (Cr), lipids and lactate (Lip + Lac) and the ratios of Cho/Cr, NAA/Cr, (Lip + Lac) /Cr were compared in the substantial region, 0 - 10 mm MZ, and 11 - 20 mm MZ of the infiltration zone, as well as the corresponding contralateral part of the normal brain parenchyma area (control group).

RESULTS

In this study, the ratios of Cho/Cr in the substantial region, 0 - 10 mm MZ of infiltration zone and the control group were 1.78 ± 0.70, 1.90 ± 0.54, and 0.78 ± 0.15, respectively; the ratios of NAA/Cr were 1.60 ± 0.20, 1.80 ± 0.42, 2.24 ± 0.86, respectively; the ratios of (Lip + Lac)/Cr were 25.69 ± 13.84, 25.18 ± 16.03, and 0.61 ± 0.15, respectively. From the control group, 11 - 20 mm MZ to 0 - 10 mm MZ and the substantial region of CAE, the concentrations of the metabolites showed that NAA and Cho decreased gradually and markedly. But (Lip + Lac) increased gradually and markedly. The ratios of Cho/Cr and NAA/Cr, (Lip + Lac)/Cr were statistically significant (P < 0.0083) between the substantial region and the control group, as well as between the 0 - 10 mm MZ and the control group. The ratios of Cho/Cr and NAA/Cr, (Lip + Lac)/Cr displayed no statistically significant differences (P > 0.0083) between the substantial region and the 0 - 10 mm MZ.

CONCLUSIONS

There was a pathological spectrum surrounding the infiltration zone of CAE. Multi-voxel 1HMRS has great clinical value for discerning the main lesion and the infiltration zone of CAE.

Intradural extramedullary primary hydatid cyst of the spine: a case report and review of literature

Primary intradural extramedullary hydatid cyst is a rare form of parasitic infection, causing focal neurological signs, commonly observed in sheep-raising areas of the world. We report a rare case of intradural, extramedullary spinal cyst, which we had misdiagnosis in the first surgery, because of rarity of the case. A 55-year-old man presented to our hospital in August 2008. He was admitted to our clinic because of lumbar pain of increasing severity and progressive difficulty with walking and stiffness of both lower limbs, which had lasted for 1 month. On the basis of imaging results, arachnoid cyst of the lumbar spine was diagnosed. Due to rapid progression of the patient's symptoms toward spastic paraplegia, he underwent an emergency surgical decompression procedure. The patient underwent exploratory surgery using a posterior approach. A L1-L2 laminectomy was performed. After opening the dura, an intradural extramedullary cystic mass was determined. The surgical specimen measured 6 × 2 cm and was described as a whitish, pearl-like, semitranslucent, cystic material, which was thought to be parasitic. Surgery has to be followed by albendazole therapy.

The biological basis of injury and neuroprotection in the fetal and neonatal brain

A compromised intrauterine environment that delivers low levels of oxygen and/or nutrients, or is infected or inflammatory, can result in fetal brain injury, abnormal brain development and in cases of chronic compromise, intrauterine growth restriction. Preterm birth can also be associated with injury to the developing brain and affect the normal trajectory of brain growth. This review will focus on the effects that episodes of perinatal hypoxia (acute, chronic, associated with inflammation or as an antecedent of preterm birth) can have on the developing brain. In animal models of these conditions we have found that relatively brief (acute) periods of fetal hypoxemia can have significant effects on the fetal brain, for example death of susceptible neuronal populations (cerebellum, hippocampus, cortex) and cerebral white matter damage. Chronic placental insufficiency which includes fetal hypoxemia, nutrient restriction and altered endocrine status can result in fetal growth restriction and long-term deficits in neural connectivity in addition to altered postnatal function, for example in the auditory and visual systems. Maternal/fetal inflammation can result in fetal brain damage, particularly but not exclusively in the white matter; injury is more pronounced when associated with fetal hypoxemia. In the baboon, in which the normal trajectory of growth is affected by preterm birth, there is a direct correlation between a higher flux in oxygen saturation and a greater extent of neuropathological damage. Currently, the only established therapy for neonatal encephalopathy in full term neonates is moderate hypothermia although this only offers some protection to moderately but not severely affected brains. There is no accepted therapy for injured preterm brains. Consequently the search for more efficacious treatments continues; we discuss neuroprotective agents (erythropoietin, N-acetyl cysteine, melatonin, creatine, neurosteroids) which we have trialed in appropriate animal models. The possibility of combining hypothermia with such agents or growth factors is now being considered. A deeper understanding of causal pathways in brain injury is essential for the development of efficacious strategies for neuroprotection.

Central nervous system infection

This article outlines a practical imaging approach to CNS infection and reviews 5 basic imaging patterns commonly seen: (1) extra-axial lesion, (2) ring-enhancing lesion, (3) temporal lobe lesion, (4) basal ganglia lesion, and (5) white matter abnormality. Opportunistic infections in the setting of HIV are also discussed within the context of these 5 basic imaging patterns. Characteristic imaging features in conjunction with clinical history are also highlighted in order to narrow the differential diagnosis or suggest a specific diagnosis in some cases.

Receptor-independent infection by mutant viruses newly isolated from the neuropathogenic mouse hepatitis virus srr7 detected through a combination of spinoculation and ultraviolet radiation

The mouse hepatitis virus (MHV) has a high mutation rate, leading to various neuropathologies after infection. The srr7 mutant was isolated from the MHV strain cl-2, which induces characteristic spongiform degeneration in the brain. To investigate outcomes of srr7 infection, we re-cloned srr7(H2) from the viral stock srr7(Mix). During this re-cloning, we obtained the mutant viruses, Mu-1, Mu-2, and Br-1 which was isolated from the mice brain infected with srr7(Mix). We examined mutant viruses for infectivity independent of the major MHV receptor (MHVR), because these mutants exhibited high virulence similar to cl-2, which is MHVR-independent. To confirm MHVR-independence in vitro, we used a combination of spinoculation and ultraviolet radiation to detect distinct plaque formation (SpinoPlaque(UV+)) afrer infection of BHK cells, which do not express MHVR. Using this technique, we found that the unique neuropathologies caused by infection with the mutant viruses result from infecting neurons, which do not express MHVR. Infection with the mutant viruses was 100% correlated with SpinoPlaque(UV+) formation. This is in contrast to infection with srr7, which does not from SpinoPlaque(UV+).

Infectious diseases of the nervous system: pathogenesis and worldwide impact

The 2008 Infectious Diseases of the Nervous System: Pathogenesis and World Impact conference was held at the Pasteur Institute of Paris, and was the first worldwide conference on neuroinfections. While viral encephalitis and bacterial meningitis are being actively studied in the developed world, much less attention is paid to the often fatal nervous system infections caused by neurotropic viruses, parasites and mycobacteria that represent important health problems in tropical regions. This meeting fostered worldwide interactions between scientists and stimulated the exchange of the latest research results on these neglected neurotropic pathogens.

Formyl-methionyl-leucyl-phenylalanine-induced dopaminergic neurotoxicity via microglial activation: a mediator between peripheral infection and neurodegeneration?

BACKGROUND

Parkinson disease (PD), a chronic neurodegenerative disease, has been proposed to be a multifactorial disorder resulting from a combination of environmental mechanisms (chemical, infectious, and traumatic), aging, and genetic deficits. Microglial activation is important in the pathogenesis of PD.

OBJECTIVES

We investigated dopaminergic (DA) neurotoxicity and the underlying mechanisms of formyl-methionyl-leucyl-phenylalanine (fMLP), a bacteria-derived peptide, in relation to PD.

METHODS

We measured DA neurotoxicity using a DA uptake assay and immunocytochemical staining (ICC) in primary mesencephalic cultures from rodents. Microglial activation was observed via ICC, flow cytometry, and superoxide measurement.

RESULTS

fMLP can cause selective DA neuronal loss at concentrations as low as 10(-13) M. Further, fMLP (10(-13) M) led to a significant reduction in DA uptake capacity in neuron/glia (N/G) cultures, but not in microglia-depleted cultures, indicating an indispensable role of microglia in fMLP-induced neurotoxicity. Using ICC of a specific microglial marker, OX42, we observed morphologic changes in activated microglia after fMLP treatment. Microglial activation after fMLP treatment was confirmed by flow cytometry analysis of major histocompatibility antigen class II expression on a microglia HAPI cell line. Mechanistic studies revealed that fMLP (10(-13) M)-induced increase in the production of extracellular superoxide from microglia is critical in mediating fMLP-elicited neurotoxicity. Pharmacologic inhibition of NADPH oxidase (PHOX) with diphenylene-iodonium or apocynin abolished the DA neurotoxicity of fMLP. N/G cultures from PHOX-deficient (gp91PHOX-/ -) mice were also insensitive to fMLP-induced DA neurotoxicity.

CONCLUSION

fMLP (10(-13) M) induces DA neurotoxicity through activation of microglial PHOX and subsequent production of superoxide, suggesting a role of fMLP in the central nervous system inflammatory process.

Unusual presentation of central nervous system manifestations of Varicella zoster virus vasculopathy in renal transplant recipients

We describe 2 renal transplant recipients with severe but reversible neurological manifestations related to Varicella zoster virus (VZV) cerebral vasculopathy. To the best of our knowledge, this is the first description of cerebral VZV vasculopathy in solid organ transplant recipients. We review the published literature on the clinical presentation, diagnosis and treatment. In solid organ transplant recipients presenting with neurological signs and symptoms, a diagnosis of VZV-associated vasculopathy should be considered.

Characterization of human immunodeficiency virus (HIV)-infected cells in infiltrates associated with CNS opportunistic infections in patients with HIV clade C infection

Infection with human immunodeficiency virus (HIV) clade C is the most common HIV infection worldwide, yet its impact on the nervous system remains largely unknown. Autopsy studies from regions affected by this virus are scarce, and HIV dementia has only rarely been reported from these countries. Most patients who develop neurologic complications die of opportunistic infections. We thus conducted a neuropathologic study from a single institution in India to characterize the HIV-infected cells in the inflammatory infiltrates in a total of 15 cases (5 patients each who died of either CNS toxoplasmosis, tuberculosis, or cryptococcal meningitis). Nearly, all patients had HIV-infected cells in the brain, although these cells were most abundant in patients with toxoplasma encephalitis. Interestingly, none of the patients had any multinucleated giant cells. HIV-infected cells were found in the parenchyma, perivascular regions, and choroid plexus and found infiltrating the parenchyma from the meninges, suggesting multiple portals of entry into the brain. These findings suggest the possibility that patients, even if successfully treated for an opportunistic inflection, may be at high risk of developing HIV encephalitis and subsequent dementia.

[Strokes caused by infection in the tropics]

INTRODUCTION

Almost three out of every four people in the world who suffer a fatal stroke live in developing countries. A number of different tropical diseases may appear in Europe in the coming years as a consequence of the demographic change that is being brought about by migratory flows. We review the main infectious causes of strokes in the tropics.

DEVELOPMENT

There are estimated to be 500 million cases of malaria every year. Cerebral malaria can cause cerebral oedema, diffuse or focal compromise of the subcortical white matter and cortical, cerebellar and pontine infarctions. Chagas disease is an independent risk factor for stroke in South America. At least 20 million people have the chronic form of Chagas disease. The main prognostic factors for Chagas-related stroke are the presence of apical aneurysms, arrhythmia and heart failure. Vascular complications of neurocysticercosis include transient ischemic attacks, ischemic strokes due to angiitis and intracranial haemorrhages. The frequency of cerebral infarction associated with neurocysticercosis varies between 2% and 12%. Gnathostomiasis is a cause of subarachnoid haemorrhage in south-east Asia. Other less common causes of stroke are viral haemorrhagic fevers due to arenavirus and flavivirus.

CONCLUSIONS

Several diseases that are endemic in the tropics can be responsible for up to 10% of the cases of strokes in adults.

An unusual sequelae of an infected persistent dermal sinus tract

CASE REPORT

We present a case of a child born with a birthmark over the lumbar spine, which harbored a pinhole-sized opening. At 6 months of age the child presented with fever of unknown origin. Subsequent lower extremity pain resulted in imaging studies that revealed a spinal mass with extension into the posterior mediastinum. At operation, the child was found to have an infected dermal sinus tract.

DISCUSSION

This case highlights the importance of a thorough examination of the midline craniospinal axis in children with fever of unknown origin. To our knowledge, this is the first reported case of an infected dermal sinus tract with extension into the posterior mediastinum.

Acute isolated sphenoid sinusitis in children

OBJECTIVE

Acute infection of the sphenoid sinus usually affects both pre-adolescent and adolescent subjects and is associated with infections of the other paranasal sinuses. Acute isolated sphenoiditis, though uncommon, is frequently misdiagnosed as symptoms are vague and there are few clinical findings. Indeed, it is not usually diagnosed until the patient develops neurological complications. The aim of this report is to discuss our cases of acute isolated sphenoiditis and compare them with those reported in the International literature.

METHODS

We reviewed our 10-year records of paediatric patients affected by acute isolated sphenoid sinusitis, as confirmed by nasal endoscopy and/or CT scan, and compared them with paediatric cases of sphenoid sinusitis reported in literature. In particular, we focused on clinical findings, associated risk factors, diagnostic approach, and treatment.

RESULTS

As previously stated at the Brussels Consensus Meeting, patients can be separated into two groups on the basis of clinical findings: the first including patients affected by severe acute sphenoiditis presenting fever and headache, and frequently associated with neurological symptoms, with swimming and diving as possible predisposing factors. The second group includes patients with non-severe acute sphenoiditis, mainly associated with headache, allergic rhinitis being a possible predisposing factor.

CONCLUSIONS

Acute isolated sphenoid sinusitis appears to be difficult to diagnose, and there are few reports in peer-reviewed paediatric journals. We wish to alert paediatricians and ENT specialists of the importance of this rare but still potentially devastating disorder.

Altered mental status and a retro-auricular mass

A 29-year-old woman was found lying unconscious in the shower. There was a two-day history of headache and dizziness. In the emergency room, she was initially stuporous (Glasgow Coma Scale 10/15), afebrile, bradycardic and hypertensive. She exhibited roving, conjugate eye movements, left facial paresis (including frontalis), left ptosis, diffuse hypotonia, extensor plantar responses bilaterally and a 1.5 cm warm, fluctuant mass with surrounding erythema behind the left ear (Figure 1). Otoscopy revealed a bulge in the posterior wall of the left external auditory canal.

Mycoplasma pneumoniae central nervous system infections

PURPOSE OF REVIEW

Mycoplasma pneumoniae is associated with a wide range of central nervous system diseases, most importantly with childhood encephalitis. This review summarizes and discusses recent findings in the field of M. pneumoniae central nervous system infections in context with previously published findings, with reference to clinical spectrum, pathogenesis, diagnosis, and treatment.

RECENT FINDINGS

Further insight into the pathogenesis has been provided by studies on cytokine production and autoantibody formation. Some new manifestations have been described (e.g. Kluver-Bucy syndrome, intracranial hypertension). Anecdotal descriptions on the association of M. pneumoniae with uncommon neurologic diseases remain to be confirmed by additional reports, however, especially when aetiologic diagnosis relied exclusively on serology. New knowledge on treatment options targeting the immune system has been provided by isolated reports. Recent diagnostic advances refer to general methods (polymerase chain reaction, serology), without specific reference to neurologic disease.

SUMMARY

M. pneumoniae must be considered as causative agent of various neurologic diseases. The recent literature shows, however, that the clinical spectrum of M. pneumoniae central nervous system disease is still not well defined. In addition, the main future challenges are the investigation of the pathogenesis of M. pneumoniae central nervous system disease and the establishment of therapeutic approaches.

Diffusion-weighted MR imaging: pediatric clinical applications

We have summarized the diffusion-weighed imaging (DWI) findings in a number of different cerebral disorders. In many cases, DWI with the accompanying apparent diffusion coefficient (ADC) map provides additional useful information to the standard imaging sequences. Pathophysiologic mechanisms resulting in baseline normal ADC values and changes with disease processes are not well understood; therefore, caution should be used when prognosticating the outcome of regions with abnormal ADCs. DWI should be used as an adjunct to routine imaging and interpreted in the context of the routine imaging findings and clinical scenario. As our understanding of ADC mechanisms increases and we begin to incorporate information about tissue organization from diffusion tensor imaging or diffusion spectrum imaging, the role of these methods in clinical diagnosis should continue to increase.

CpG oligodeoxynucleotides protect newborn mice from a lethal challenge with the neurotropic Tacaribe arenavirus

The innate immune system is key to limiting the early spread of most pathogens and directing the development of Ag-specific immunity. Recently, a number of synthetic molecules that activate the innate immune system by stimulating TLRs have been identified. Among them, synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs (CpG ODNs) were shown to activate TLR9-bearing B cells, macrophages, and dendritic cells to induce a strong proinflammatory milieu and a type 1-biased immune response that protects mice from a variety of parasitic, bacterial, and viral infections. Although the protective effect of CpG ODN in adult mice was well established, its effectiveness in neonates, which have lower numbers of dendritic, B, and T cells and tend to favor Th2 responses, was unclear. This study uses the New World arenavirus Tacaribe, a neurotropic pathogen that is lethal in newborn mice, to explore the effectiveness of TLR-mediated innate immune responses. Neonatal BALB/c mice treated with CpG ODN at the time of infection had reduced viral load (p < 0.01) and increased survival (52%, p < 0.001 i.p.; 36%, p < 0.05 intranasally). Protection was achieved in mice treated no later than 3 days postchallenge and appears to be mediated by an increase in Ag-specific Abs (IgG and IgM) and to require inducible NO synthase expression and NO production. To our knowledge, this is the first study assessing the mechanisms by which CpG ODN can protect mice from a neurotropic viral infection.

Role of human brain microvascular endothelial cells during central nervous system infection. Significance of indoleamine 2,3-dioxygenase in antimicrobial defence and immunoregulation

The cerebral endothelium is involved both in regulating the influx of immune cells into the brain and in modifying immunological reactions within the CNS. A number of human pathogens may cause encephalitis or meningitis when this important protective barrier is impaired. We have previously shown that interferon-gamma activated human brain microvascular endothelial cells (HBMEC) restrict the growth of bacteria and parasites. We now provide evidence that HBMEC are also capable of inhibiting viral replication after stimulation with IFN-gamma, an effect further augmented by costimulation with IL-1. This antiviral effect was completely blocked in the presence of L-tryptophan, indicating the induction of the tryptophan degrading enzyme indoleamine 2,3-dioxygenase (IDO) to be responsible for the observed antiviral effect. Apart from exerting antimicrobial effects tryptophan depletetion has also been described as a regulatory mechanism in T cell responses to both allo- and autoantigens. We were able to demonstrate that IDO mediated degradation of L-tryptohan in HBMEC is responsible for a significant reduction in T lymphocyte proliferation. Resupplementation of L-tryptophan and restoration of initial T cell responses demonstrated the central role of this essential amino acid in the reduction of T-cell proliferation. Brain endothelial cells appear to limit microbial expansion in the CNS by local degradation of tryptophan, thus acting in concert with other IDO-positive cell populations on the parenchymal side of the blood-brain barrier such as astrocytes, microglia and neurons. Since all dietary tryptophan must cross the blood-brain barrier, the microvascular endothelial cells may play a key role in restricting tryptophan influx from the bloodstream into the brain. As deleterious effects of brain infections can often be attributed to subsequently invading immune cells, an IDO-mediated reduction of lymphocyte proliferation may be beneficial for preventing collateral brain damage.

[Infectious diseases of brain parenchyma in adults: imaging and differential diagnosis aspects]

Infectious diseases of the central nervous system have often to be considered in differential diagnosis, particularly in immunocompromised persons. Neuroimaging, specifically advanced techniques such as diffusion-weighted MRI and perfusion MRI contribute much to the differentiation of various brain infections and to delineation of brain infections from other, for instance, neoplastic diseases. In this review we present the imaging criteria for the most important brain infections in adults and discuss in detail differential diagnostic aspects.

Virus signaling and apoptosis in the central nervous system infection

Viruses target the central nervous system (CNS) incidentally, due to complications of systemic infection, or specifically, by ascending via the axons of peripheral and cranial nerves. In the CNS, viruses cause acute disease (viz. encephalitis), latent infections or neurodegenerative pathology. Causation of acute disease or immune-mediated pathology, and virus involvement in the etiology of chronic neurodegenerative diseases depends, at least in part, on the ability to commander signaling pathways. Better understanding of these virus-host cell interactions will help identify molecular targets for the development of improved therapeutic strategies.

Neuroimaging of infections

Neuroimaging plays a crucial role in the diagnosis and therapeutic decision making in infectious diseases of the nervous system. The review summarizes imaging findings and recent advances in the diagnosis of pyogenic brain abscess, ventriculitis, viral disease including exotic and emergent viruses, and opportunistic disease. For each condition, the ensuing therapeutic steps are presented. In cases of uncomplicated meningitis, cranial computed tomography (CT) appears to be sufficient for clinical management to exclude acute brain edema, hydrocephalus, and pathology of the base of skull. Magnetic resonance imaging (MRI) is superior in depicting complications like sub-/epidural empyema and vasculitic complications notably on FLAIR (fluid-attenuated inversion recovery)-weighted images. The newer technique of diffusion-weighted imaging (DWI) shows early parenchymal complications of meningitis earlier and with more clarity and is of help in differentiation of pyogenic abscess (PA) from ring enhancing lesions of other etiology. Proton magnetic resonance spectroscopy (PMRS) seems to produce specific peak patterns in cases of abscess. The presence of lactate cytosolic amino acids and absence of choline seems to indicate PA. Also in cases of suspected opportunistic infection due to toxoplasma DWI may be of help in the differentiation from lymphoma, showing no restriction of water diffusion. In patients with herpes simplex and more exotic viruses like West Nile and Murray Valley virus DWI allows earlier lesion detection and therapeutic intervention with virustatic drugs.

Palsy of the rear limbs in Mycobacterium lepraemurium-infected mice results from bone damage and not from nerve involvement

A small but relatively constant proportion (3-5%) of mice chronically infected with Mycobacterium lepraemurium (MLM) develops bilateral paralysis of the rear limbs. The aim of the study was to investigate whether or not the bilateral leg palsy results from nerve involvement. Direct bacterial nerve infection or acute/delayed inflammation might possibly affect the nerves. Therefore, palsied animals were investigated for the presence of: (a) histopathological changes in the leg tissues including nerves, bones and annexes, and (b) serum antibodies to M. lepraemurium and M. leprae lipids, including phenolic glycolipid I from M. leprae. Histopathological study of the palsied legs revealed that the paralysis was not the result of direct involvement of the limb nerves, as neither bacilli nor inflammatory cells were observed in the nerve branches studied. Antibodies to brain lipids and cardiolipin were not detected in the serum of the palsied animals, thus ruling out an immune response to self-lipids as the basis for the paralysis. Although high levels of antibodies to MLM lipids were detected in the serum of palsied animals they were not related to limb paralysis, as the nerves of the palsied legs showed no evidence of inflammatory damage. In fact, nerves showed no evidence of damage. Paralysis resulted from severe damage of the leg bones. Within the bones the bone marrow became replaced by extended bacilli-laden granulomas that frequently eroded the bone wall, altering the normal architecture of the bone and its annexes, namely muscle, tendons and connective tissue. Although this study rules out definitively the infectious or inflammatory damage of nerves in murine leprosy, it opens a new avenue of research into the factors that participate in the involvement or the sparing of nerves in human and murine leprosy, respectively.

Up-regulation of Fas ligand (FasL) in the central nervous system: a mechanism of immune evasion by rabies virus

Following its injection into the hindlimbs of mice, CVS, a highly pathogenic strain of rabies virus, invades the spinal cord and brain resulting in the death of the animal. In contrast, central nervous system (CNS) invasion by PV, a strain of attenuated pathogenicity, is restricted to the spinal cord and mice infected with this virus survive. Lymphocytes display transient migration into the infected CNS in fatal rabies and sustained migration in nonfatal rabies. The transient migration of T cells in fatal rabies is associated with an increase in T-cell apoptosis. We found that the early production of Fas ligand (FasL) mRNAs was up-regulated only in fatal rabies. FasL is produced by several neuronal cells and mainly in infected neurons. In mice lacking FasL (gld), infection with the neuroinvasive rabies virus strain was less severe, and the number of CD3 T cells undergoing apoptosis was smaller than that in normal mice. These data provide strong evidence that fatal rabies virus infection involves the early triggering of FasL production leading to the destruction of migratory T cells by the Fas/FasL apoptosis pathway. This mechanism could be in part responsible for the fact that T cells cannot control neuroinvasive rabies infection. Thus, rabies virus seems to use an immunosubversive strategy that takes advantage of the immune privilege status of the CNS.

Central nervous system infections in cancer patients

With improved therapies, patients with cancer survive longer. However, both the acute complications of intensive therapies and the risks of chronic immunosuppression have led to an increased incidence of central nervous system (CNS) infections. The presentation and course of common infections may be different from those in patients without cancer, and new syndromes related both to the underlying diseases and to their treatment have complicated the differential diagnosis. Noninfectious disorders such as drug treatment complications, vascular lesions, and radiation effects can mimic CNS infections. The major clinical presentations of CNS infections can be divided into meningoencephalitic syndromes and deficits due to focal mass lesions. The range of pathogens can be narrowed by considering the type of immune deficit present. The two groups of patients who most frequently develop CNS infections are those undergoing procedures for primary brain tumors and hematopoietic stem cell transplant recipients. Among several recently recognized syndromes in the latter are infections due to human herpesviruses 6 and 7, West Nile virus, and the immune reconstitution inflammatory syndrome.

A multicenter prospective cohort study of the Strata valve for the management of hydrocephalus in pediatric patients

OBJECT

Previous reports suggest that adjustable valves may improve the survival of cerebrospinal fluid shunts or relieve shunt-related symptoms. To evaluate these claims, the authors conducted a prospective multicenter cohort study of children who underwent placement of Strata valves.

METHODS

Patients undergoing initial shunt placement (Group 1) or shunt revision (Group 2) were treated using Strata valve shunt systems. Valves were adjustable to five performance level settings by using an externally applied magnet. The performance levels were checked using an externally applied hand tool and radiography. Patients were followed for 1 year or until they underwent shunt revision surgery. Between March 2000 and February 2002, 315 patients were enrolled in the study. In Group 1 (201 patients) the common causes of hydrocephalus were myelomeningocele (16%), aqueductal stenosis (14%), and hemorrhage (14%). The overall 1-year shunt survival was 67%. Causes of shunt failure were obstruction (17%), overdrainage (1.5%), loculated ventricles (2%), and infection (10.6%). Patients in Group 2 (114 patients) were older and the causes of hydrocephalus were similar. Among patients in Group 2 the 1-year shunt survival was 71%. There were 256 valve adjustments. Symptoms completely resolved (26%) or improved (37%) after 63% of adjustments. When symptoms improved or resolved, they did so within 24 hours in 89% of adjustments. Hand-tool and radiographic readings of valve settings were the same in 234 (98%) of 238 assessments.

CONCLUSIONS

The 1-year shunt survival for the Strata valve shunt system when used in initial shunt insertion procedures or shunt revisions was similar to those demonstrated for other valves. Symptom relief or improvement following adjustment was observed in 63% of patients. Hand-tool assessment of performance level settings reliably predicted radiographic assessments.

[Residual neurovirulence of the chimera of Langat and Denge-4 flaviviruses in intracerebral infection of monkeys]

The residual neurovirulence of the previously obtained chimeric virus Tp21/DEN4, containing the RNA region encoding the pre M and E structural enzymes, strain Tp21, virus Langat, and the remaining part of the genome from the Denge 4 virus, was studied in experiments with monkeys Cercopithecus aethiops involving the intracerebral administration of the virus. The tick-borne encephalitis virus, strain Absettarov, was used as positive control. A comparative analysis of the experimental and published data showed the chimeric virus to be less virulent by its degree of morphological affection in the CNS zones, its spread into the CNS and by a percentage share of animals with viremia versus the Tp21 parent strain and Elantsev strain of the Langat virus.