Neuro-intensive care of patients with acute CNS infections

Treadmill Exercise Decreases Inflammation Via Modulating IL-6 Expression in the Rat Model of Middle Cerebral Artery Occlusion

BACKGROUND

Long-term bed rest in neurointensive care (NIC) patients leads to skeletal muscle atrophy and cognitive dysfunction, which seriously affects the physical fitness and final prognosis of critically ill patients. Exercise therapy plays an increasingly important role in the treatment and rehabilitation of patients with sarcopenia. However, the therapeutic effect and mechanism of exercise therapy for patients with neurological impairment remain unclear.

METHODS

Serum samples of NIC patients before and after exercise therapy and normal people were collected to detect interleukin-6 (IL-6) and interleukin-1β levels by enzyme-linked immunosorbent assay (ELISA). Middle cerebral artery occlusion (MCAO) was used for the construction of a rat model. The Morris water maze test, exploration test, and open-field test were used to assess neurological function in rats. Western blot and quantitative real-time polymerase chain reaction were performed to evaluate the activation of IL-6/adenosine-monophosphate-activated protein kinase (AMPK) signaling.

RESULTS

Exercise therapy attenuated IL-6 expression in NIC patients. Exercise therapy alleviated cognitive dysfunctions and decreased IL-6 expression in MCAO rats. Exercise therapy alleviated gastrocnemius muscle injury in rats after MCAO by modulating IL-6/AMPK signaling.

CONCLUSIONS

Treadmill exercise decreases inflammation in MCAO rats via modulating IL-6/AMPK signaling.

Factors associated with mortality in intracranial infection patients admitted to pediatric intensive care unit: A retrospective cohort study

Background

Intracranial infection is a major cause of emergency and death in children. To assist clinical decision-making in patient management, we conducted a study about factors associated with mortality. This study aimed to evaluate factors associated with mortality in pediatric patients with intracranial infection.

Methods

We performed a cohort retrospective study in our tertiary hospital to evaluate the outcomes of patients admitted to the pediatric intensive care unit (PICU) from 2014 to 2018. The Chi-square test was performed to determine the significance of the predictor, and p < 0.05 was considered to indicate a statistically significant result. We used multivariate logistic regression to determine relative risk (RR) with 95% confidence interval (CI).

Results

We recruited 112 patients who were admitted to the PICU of our tertiary hospital. A total of 38.4% were diagnosed with encephalitis, 9.8% meningitis and 51.8% meningoencephalitis. Of the 112 patients who met the inclusion criteria, 28 (25%) patients died in the PICU. The need of mechanical ventilation support variable had a statistically significant association with mortality (RR 22.76; 95% CI: 3.88–51.45).

Conclusion

Recognition of conditions that exacerbate intracranial infection in children needs to be done as early as possible. Moreover, the need of mechanical ventilation support in the PICU needs more attention.

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Intracranial infection is a major cause of emergency and death in children.

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Recognition of conditions that exacerbate intracranial infection.

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The need of mechanical ventilation support in the pediatric intensive care unit.

The Prospect of Nanoparticle Systems for Modulating Immune Cell Polarization During Central Nervous System Infection

The blood-brain barrier (BBB) selectively restricts the entry of molecules from peripheral circulation into the central nervous system (CNS) parenchyma. Despite this protective barrier, bacteria and other pathogens can still invade the CNS, often as a consequence of immune deficiencies or complications following neurosurgical procedures. These infections are difficult to treat since many bacteria, such as Staphylococcus aureus, encode a repertoire of virulence factors, can acquire antibiotic resistance, and form biofilm. Additionally, pathogens can leverage virulence factor production to polarize host immune cells towards an anti-inflammatory phenotype, leading to chronic infection. The difficulty of pathogen clearance is magnified by the fact that antibiotics and other treatments cannot easily penetrate the BBB, which requires extended regimens to achieve therapeutic concentrations. Nanoparticle systems are rapidly emerging as a promising platform to treat a range of CNS disorders. Nanoparticles have several advantages, as they can be engineered to cross the BBB with specific functionality to increase cellular and molecular targeting, have controlled release of therapeutic agents, and superior bioavailability and circulation compared to traditional therapies. Within the CNS environment, therapeutic actions are not limited to directly targeting the pathogen, but can also be tailored to modulate immune cell activation to promote infection resolution. This perspective highlights the factors leading to infection persistence in the CNS and discusses how novel nanoparticle therapies can be engineered to provide enhanced treatment, specifically through modulation of immune cell polarization.

Medullary abscess: a rare clinical presentation

Brain abscesses represent areas of localised infection of the brain parenchyma. Those confined to the brainstem are rare and usually fatal if untreated. Streptococcus intermedius is a common causative organism of brain abscesses and is associated with significant morbidity. We describe a case report of medullary abscess secondary to dental infection in a 68-year-old patient. The patient presented with headaches and flu-like symptoms progressing to left hemiparesis and reduced consciousness/bulbar function. The patient underwent emergency posterior fossa craniectomy and drainage with subsequent medical management with antibiotics. Prompt diagnosis, early surgical intervention and maximal therapy with antibiotics alongside extensive rehabilitation are all vital to ensure good neurological outcome. It is imperative for medical practitioners to consider the diagnosis of brain abscess in patients presenting with rapid onset neurological deterioration. Such cases require early neurological imaging with involvement of tertiary neurosurgery services.

Iatrogenic cerebral abscess leading to resolution of severe delusional disorder

A cerebral abscess (focal infection of brain parenchyma) carries a high mortality and morbidity. Iatrogenic cerebral abscesses are less common and make up 10% of all cases. The presence of a cerebral abscess can rarely improve a patient's prognosis and quality of life, however this case illustrates an abscess and its treatment following a prolonged course of antibiotics leading to resolution of a severe psychotic disorder. This is a case report of a 32-year-old female inpatient at a psychiatric hospital with a long-standing history of congenital hydrocephalus, cerebral palsy and organic delusional disorder who developed an iatrogenic cerebral abscess after insertion of an implantable intracranial pressure monitoring device. After receiving treatment of 6 weeks of intravenous meropenem the patient's mental condition rapidly improved, she became stable and euthymic and was discharged home. The patient has since had no delusions or hallucinations and is living independently at home.

Gamma Interferon Alters Junctional Integrity via Rho Kinase, Resulting in Blood-Brain Barrier Leakage in Experimental Viral Encephalitis

Blood-brain barrier (BBB) breakdown is a hallmark of many diseases of the central nervous system (CNS). Loss of BBB integrity in CNS diseases such as viral encephalitis results in the loss of nutrient/oxygen delivery, rapid infiltration of immune cells, and brain swelling that can exacerbate neuronal injury. Despite this, the cellular and molecular mechanisms that underlie BBB breakdown in viral encephalitis are incompletely understood. We undertook a comprehensive analysis of the cellular and molecular signaling events that induce BBB breakdown in an experimental model of virus-induced encephalitis in which neonatal mice are infected with reovirus (serotype 3 strain Abney). We show that BBB leakage during reovirus infection correlates with morphological changes in the vasculature, reductions in pericytes (BBB supporting cells), and disorganization of vascular junctions. Pathway analysis on RNA sequencing from brain endothelial cells identified the activation of interferon (IFN) signaling within the brain vasculature following reovirus infection. Our in vitro and in vivo studies show that type II IFN mediated by IFN-γ, a well known antiviral signal, is a major contributor to BBB leakage during reovirus infection. We show that IFN-γ reduces barrier properties in cultured brain endothelial cells through Rho kinase (ROCK)-mediated cytoskeletal contractions, resulting in junctional disorganization and cell-cell separations. In vivo neutralization of IFN-γ during reovirus infection significantly improved BBB integrity, pericyte coverage, attenuated vascular ROCK activity, and junctional disorganization. Our work supports a model in which IFN-γ acts directly on the brain endothelium to induce BBB breakdown through a mechanism involving ROCK-induced junctional disorganization.IMPORTANCE In an experimental viral encephalitis mouse model in which mice are infected with reovirus, we show that IFN-γ induces blood-brain barrier leakage. We show that IFN-γ promotes Rho kinase activity, resulting in actin cytoskeletal contractions in the brain endothelium that lead to vascular junctional disorganization and cell-cell separations. These studies now provide insight into a previously unknown mechanism for how blood-brain barrier breakdown occurs in viral encephalitis and implicates IFN-γ-Rho kinase activity as major contributor to this phenomenon. By identifying this mechanism of blood-brain barrier breakdown, we now provide potential therapeutic targets in treating patients with viral causes of encephalitis with the hope of limiting damage to the central nervous system.

Streptococcus intermedius posterior fossa abscess after a minor dental procedure in an immunocompetent woman

A 52-year-old woman with no relevant previous medical history was diagnosticated of an infratentorial bulky cerebellar mass. The mass showed restricted diffusion on MR images, which was consistent with cerebellar abscess. The patient had undergone a minor dental procedure three weeks before. Microbiological analysis after surgical evacuation of the mass confirmed the presence of Streptococcus intermedius.

Infectious causes and outcomes in patients presenting with cerebral spinal fluid pleocytosis

To evaluate the infectious etiologies, clinical features, and outcomes of patients with CNS infections at a tertiary care center. Patients that present with a pleocytosis in the cerebral spinal fluid (CSF), defined as a CSF WBC count > 5 cells/mm³, from July 2015 to June 2016 at a tertiary care hospital were analyzed for this report. Data from patients with confirmed (n = 43) and presumed (n = 51) CNS infections were analyzed. CNS infection was the leading known cause of CSF pleocytosis (n = 43, 18% of all patients with a pleocytosis in the CSF), and HSV-2 was identified as the leading causative pathogen (n = 10) followed by varicella zoster virus (n = 5). Fifty-three percent of patients with a pleocytosis in the CSF did not receive a diagnosis. In the patients that did not receive a diagnosis, CNS infection was presumed to be the cause in 51 patients (21% of patients with CSF pleocytosis). The mean time to diagnosis for patients with confirmed CNS infection was 16 days, but time to diagnosis was highly variable depending on the causative pathogen. There was a significant overlap in CSF parameters and peripheral white blood cell counts in patients diagnosed with a viral, bacterial, or fungal infection. Neuroimaging changes were present in only 44% of CNS infections. The overall mortality was 7% for CNS infections, and 17% of patients with a CNS infection had a severe neurologic deficit at presentation while only 3% had a severe deficit at the last neurologic assessment. This study provides new insights into the infectious causes of disease in a cohort of patients with pleocytosis in the CSF. The study provides new insights into the time to diagnosis and outcomes in patients that present with pleocytosis in the CSF.

Defining diagnostic approaches and outcomes in patients with inflammatory CSF: A retrospective cohort study

OBJECTIVE

Define the etiologies, clinical features, time to diagnosis, and outcomes of patients that present with cerebral spinal fluid (CSF) pleocytosis.

PATIENTS AND METHODS

This is retrospective cohort study of patients with CSF pleocytosis, defined as WBC count >5 cells/mm³ in the CSF, from July 2015 to June 2016 at a large tertiary care hospital. The proportion of patients within specific diagnostic categories were analyzed for differences in diagnostic testing and outcomes.

RESULTS

53% of patients had CSF pleocytosis due to an unknown etiology. The leading known cause of neuroinflammation was CNS infection (n = 43/244, 18%), followed by malignancy (n = 28/244, 11%). Mean time to diagnosis was 125 days in patients with autoimmune neuroinflammation and was 16 days in patients with an infection or malignancy. CSF parameters and peripheral white blood cell counts did not distinguish between categories of disease. The presence of CSF oligoclonal bands or a positive biopsy result most commonly supported a diagnosis of an autoimmune disease or malignancy, respectively. Neuroimaging changes were present in only 44% of infections but were found in 80-90% of other categories of neuroinflammation. Patients presenting with a severe neurologic deficit had 22.29 higher odds of a severe deficit at the last neurologic assessment, and mortality was highest (29%) in patients with malignancy-associated neuroinflammation.

CONCLUSIONS

This study to defines general diagnostic categories of neuroinflammatory disease in patients and provides new insight on the value of specific diagnostic testing, time to diagnosis, and outcomes in these patient populations.

Silicon Foreign Body in the Cerebrum of a Rhesus Macaque (Macaca mulatta)

A male rhesus macaque with a cephalic chamber implant for neurophysiology recording presented with hemiparesis affecting the left thoracic and pelvic limbs at approximately 5 wk after craniotomy surgery. MRI indicated a 1×2-cm ovoid cerebrocortical cystic lesion immediately subjacent to the right hemisphere craniotomy and recording chamber. Transdural aspiration of sterile transudate and resultant decompression resolved the hemiparesis, and follow-up MRI at 1 mo indicated resolution of the lesion. Subsequently, necropsy at study end revealed a cerebrocortical foreign body composed of silicon. The atypically slow cure rate of the lot of silicon used and the unique recording chamber configuration were underlying factors that contributed to the formation of this foreign body. To our knowledge, this report is the first description of iatrogenic intracerebral foreign body in a macaque.

Arbovirus Infections

PURPOSE OF REVIEW

Arbovirus (arthropod-borne virus) infections are increasingly important causes of neurologic disease in the United States through both endemic transmission and travel-associated infections. This article reviews the major arbovirus infections that can cause neurologic disease likely to be encountered in the United States.

RECENT FINDINGS

West Nile virus continues to be an important cause of epidemic encephalitis, while emerging arbovirus infections such as dengue and chikungunya have rapidly expanded their geographic distribution. As emerging arboviruses expand in new geographic regions, neurologic abnormalities are reported in new patient populations.

SUMMARY

Emerging arbovirus infections are increasingly important causes of neurologic disease throughout the world and in the United States. While no US Food and Drug Administration (FDA)-approved therapy is yet available for these infections, prompt recognition and diagnosis from the consulting neurologist will ensure appropriate supportive care for the patient.

Alpha-Synuclein Expression Restricts RNA Viral Infections in the Brain

We have discovered that native, neuronal expression of alpha-synuclein (Asyn) inhibits viral infection, injury, and disease in the central nervous system (CNS). Enveloped RNA viruses, such as West Nile virus (WNV), invade the CNS and cause encephalitis, yet little is known about the innate neuron-specific inhibitors of viral infections in the CNS. Following WNV infection of primary neurons, we found that Asyn protein expression is increased. The infectious titer of WNV and Venezuelan equine encephalitis virus (VEEV) TC83 in the brains of Asyn-knockout mice exhibited a mean increase of 10(4.5) infectious viral particles compared to the titers in wild-type and heterozygote littermates. Asyn-knockout mice also exhibited significantly increased virus-induced mortality compared to Asyn heterozygote or homozygote control mice. Virus-induced Asyn localized to perinuclear, neuronal regions expressing viral envelope protein and the endoplasmic reticulum (ER)-associated trafficking protein Rab1. In Asyn-knockout primary neuronal cultures, the levels of expression of ER signaling pathways, known to support WNV replication, were significantly elevated before and during viral infection compared to those in Asyn-expressing primary neuronal cultures. We propose a model in which virus-induced Asyn localizes to ER-derived membranes, modulates virus-induced ER stress signaling, and inhibits viral replication, growth, and injury in the CNS. These data provide a novel and important functional role for the expression of native alpha-synuclein, a protein that is closely associated with the development of Parkinson's disease.

IMPORTANCE

Neuroinvasive viruses such as West Nile virus are able to infect neurons and cause severe disease, such as encephalitis, or infection of brain tissue. Following viral infection in the central nervous system, only select neurons are infected, implying that neurons exhibit innate resistance to viral infections. We discovered that native neuronal expression of alpha-synuclein inhibited viral infection in the central nervous system. When the gene for alpha-synuclein was deleted, mice exhibited significantly decreased survival, markedly increased viral growth in the brain, and evidence of increased neuron injury. Virus-induced alpha-synuclein localized to intracellular neuron membranes, and in the absence of alpha-synuclein expression, specific endoplasmic reticulum stress signaling events were significantly increased. We describe a new neuron-specific inhibitor of viral infections in the central nervous system. Given the importance of alpha-synuclein as a cause of Parkinson's disease, these data also ascribe a novel functional role for the native expression of alpha-synuclein in the CNS.

West Nile Virus Population Structure, Injury, and Interferon-Stimulated Gene Expression in the Brain From a Fatal Case of Encephalitis

Background. West Nile virus (WNV) infection in humans can result in severe, acute encephalitis typically involving subcortical gray matter brain regions. West Nile virus replication within specific human brain regions from a human case of acute encephalitis has not been studied.

Methods. We describe a fatal case of WNV encephalitis in which we obtained tissue from specific brain regions at autopsy to evaluate viral-host interactions using next-generation sequencing and immunohistochemistry analysis.

Results. We found that WNV populations in the injured subcortical brain regions exhibited increased amino acid variation and increased expression of specific interferon genes compared with cortical tissues despite similar viral burden.

Conclusions. These observational, patient-based data suggest that neuronal injury and the strength of viral selection pressure may be associated with the level of the innate immune responses. Further studies in human and animal models evaluating the role of innate immune responses on injury patterns and viral selection pressure are needed.

Managing acute central nervous system infections in the UK adult intensive care unit in the wake of UK encephalitis guidelines

The acute central nervous system infections meningitis and encephalitis commonly require management on intensive care units. The clinical features often overlap and in the acute phase-altered consciousness and seizures may also need to be managed. In April 2012, the first UK national guideline for the management of suspected viral encephalitis was published by the British Infection Association and Association of British Neurologists, and other key stakeholders, and included a simple management algorithm. The new guideline results from evidence demonstrating a number of common oversights in the standard management of suspected viral encephalitis in many settings. In combination with British Infection Association meningitis guidelines, evidence-based approaches now exist to facilitate the non-expert managing patients with suspected central nervous system infections. Here we bring together these guidelines and the supporting evidence applicable for intensivists into a single resource.

Imaging in neurologic infections I: bacterial and parasitic diseases

Often presenting as medical emergencies, nervous system infections can be diagnostically challenging. Knowledgeable utilization of neuroimaging modalities and the understanding of characteristic imaging findings facilitate early diagnosis and treatment. In the first part of this two-part review, we address common and unique diagnostic imaging features of bacterial and parasitic nervous system infections.

Multiple brain abscesses in an immunocompetent patient after undergoing professional tooth cleaning

BACKGROUND

Dental disorders and dental treatment are among the variety of causes of brain abscess.

CASE DESCRIPTION

The authors present the case of a patient who developed multiple brain abscesses after undergoing professional tooth cleaning. The results of a diagnostic work-up ruled out an underlying immunodeficiency. After receiving neurosurgical intervention and intensive care treatment by means of local and intravenous antibiotics for 24 days, the patient was transferred to another hospital for rehabilitation. Six months after the treatment, the patient still had moderate residual paresis of the left leg.

PRACTICAL IMPLICATIONS

Although it happens rarely, professional tooth cleaning may be considered a cause of brain abscesses even in otherwise healthy patients.

Neuroinfectious diseases at a European neurological tertiary care center: one-third of patients require treatment in the neurological intensive care unit

BACKGROUND AND PURPOSE

Studies on the impact of infectious diseases affecting the nervous system are sparse.

METHODS

All patients with neuroinfectious diseases (NIDs) who were treated at our Department of Neurology from 2005 until 2009 were retrospectively analyzed.

RESULTS

Patients with NIDs required treatment at the intensive care unit in 34.8%. The mortality rate of patients with NIDs was significantly higher than that of other inpatients with neurological diseases (5.1% vs. 3.0%, respectively, P = 0.018).

CONCLUSION

In summary, this study shows that patients with NIDs are severely ill and mortality is high.

Fever and neurologic conditions

Neurologic conditions are categorized as either those that cause a change in mental status or those that create a focal finding on physical examination. Neurologic abnormality associated with fever can be caused by a primary neurologic condition or one that does not originate in the central nervous system. Optimal management of such conditions requires high clinical suspicion and a broad differential diagnosis, which facilitates rapid recognition and effective treatment. A thorough history and physical examination are key determinants in accurately diagnosing neurologic conditions associated with fever, often requiring acquisition of collateral information from persons other than the patient.

Specific imaging of inflammation with the 18 kDa translocator protein ligand DPA-714 in animal models of epilepsy and stroke

Inflammation is a pathophysiological hallmark of many diseases of the brain. Specific imaging of cells and molecules that contribute to cerebral inflammation is therefore highly desirable, both for research and in clinical application. The 18 kDa translocator protein (TSPO) has been established as a suitable target for the detection of activated microglia/macrophages. A number of novel TSPO ligands have been developed recently. Here, we evaluated the high affinity TSPO ligand DPA-714 as a marker of brain inflammation in two independent animal models. For the first time, the specificity of radiolabeled DPA-714 for activated microglia/macrophages was studied in a rat model of epilepsy (induced using Kainic acid) and in a mouse model of stroke (transient middle cerebral artery occlusion, tMCAO) using high-resolution autoradiography and immunohistochemistry. Additionally, cold-compound blocking experiments were performed and changes in blood-brain barrier (BBB) permeability were determined. Target-to-background ratios of 2 and 3 were achieved in lesioned vs. unaffected brain tissue in the epilepsy and tMCAO models, respectively. In both models, ligand uptake into the lesion corresponded well with the extent of Ox42- or Iba1-immunoreactive activated microglia/macrophages. In the epilepsy model, ligand uptake was almost completely blocked by pre-injection of DPA-714 and FEDAA1106, another high-affinity TSPO ligand. Ligand uptake was independent of the degree of BBB opening and lesion size in the stroke model. We provide further strong evidence that DPA-714 is a specific ligand to image activated microglia/macrophages in experimental models of brain inflammation.

Brain abscess in a rhesus macaque (Macaca mulatta) with a cephalic implant

We report a case of brain abscess after craniotomy and the placement of a recording chamber for electrophysiologic records in an adult rhesus macaque (Macaca mulatta) enrolled in visual research. Approximately 2 wk after surgery, the macaque presented with nonspecific gastrointestinal signs and showed no evidence of fever, neurologic deficits, increased intracranial pressure, suggestive alterations in the CBC, or abnormal changes in the recording chamber. The macaque responded to symptomatic and antibiotic treatment and showed no behavioral or abnormal clinical signs for 3 wk before collapsing suddenly. The macaque was euthanized, and pathologic evaluation revealed a large brain abscess immediately under the original craniotomy.

Review: apoptotic mechanisms in bacterial infections of the central nervous system

In this article we review the apoptotic mechanisms most frequently encountered in bacterial infections of the central nervous system (CNS). We focus specifically on apoptosis of neural cells (neurons and glia), and provide first an overview of the phenomenon of apoptosis itself and its extrinsic and intrinsic pathways. We then describe apoptosis in the context of infectious diseases and inflammation caused by bacteria, and review its role in the pathogenesis of the most relevant bacterial infections of the CNS.