The neurological complications of sepsis

Clinical image of sepsis-associated encephalopathy midst E. coli urosepsis: Emergency department database study

Background

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, which, if untreated, leads to multi-organ failure. One of the severe possible complications is sepsis associated encephalopathy (SAE), a neurological dysfunction occurring secondary to a severe inflammatory response. It manifests as acute cognitive dysfunction and sudden-onset dysfunctions in mental state. Uropathogenic Escherichia coli is the most common pathogen causing bacteremia, responsible for 80% of uncomplicated outpatient urinary tract infections and 40% of nosocomial infections. The study aimed to assess the difference in the severity and the course of urosepsis caused by E. coli in patients with and without septic encephalopathy.

Materials and methods

This study presents a retrospective analysis of the population of urosepsis patients admitted to the Emergency Department between September 2019 and June 2022. Inflammatory parameters, urinalysis and blood cultures were performed, along with a clinical evaluation of sepsis severity and encephalopathy. The patients were then stratified into SAE and non-SAE groups based on neurological manifestations and compared according to the collected data.

Results

A total of 199 septic patients were included in the study. E. coli-induced urosepsis was diagnosed in 84 patients. In this group, SAE was diagnosed in 31 (36.9%) patients (33.3% in males, 40.5% females). Patients with SAE were found to be hypotensive (p < 0,005), with a higher respiratory rate (p < 0,017) resulting in a higher mortality rate (p = 0.002) compared to non-SAE septic patients. The APACHE II score was an independent risk factor associated with a higher mortality rate. Biochemical parameters between the groups did not show any statistical importance related to the severity of urosepsis.

Conclusions

The severity of urosepsis and risk of SAE development increase according to the clinical condition and underlying comorbidities. Urosepsis patients with SAE are at a higher risk of death. Patients should undergo more careful screening for the presence of SAE on admission, and more intense monitoring and treatment should be provided for patients with SAE. This study indicates the need to develop projects aiming to further investigate neuroprotective interventions in sepsis.

Illness Weakness, Polyneuropathy and Myopathy: Diagnosis, treatment, and long-term outcomes

BACKGROUND

Severe weakness associated with critical illness (CIW) is common. This narrative review summarizes the latest scientific insights and proposes a guide for clinicians to optimize the diagnosis and management of the CIW during the various stages of the disease from the ICU to the community stage.

MAIN BODY

CIW arises as diffuse, symmetrical weakness after ICU admission, which is an important differentiating factor from other diseases causing non-symmetrical muscle weakness or paralysis. In patients with adequate cognitive function, CIW can be easily diagnosed at the bedside using manual muscle testing, which should be routinely conducted until ICU discharge. In patients with delirium or coma or those with prolonged, severe weakness, specific neurophysiological investigations and, in selected cases, muscle biopsy are recommended. With these exams, CIW can be differentiated into critical illness polyneuropathy or myopathy, which often coexist. On the general ward, CIW is seen in patients with prolonged previous ICU treatment, or in those developing a new sepsis. Respiratory muscle weakness can cause neuromuscular respiratory failure, which needs prompt recognition and rapid treatment to avoid life-threatening situations. Active rehabilitation should be reassessed and tailored to the new patient's condition to reduce the risk of disease progression. CIW is associated with long-term physical, cognitive and mental impairments, which emphasizes the need for a multidisciplinary model of care. Follow-up clinics for patients surviving critical illness may serve this purpose by providing direct clinical support to patients, managing referrals to other specialists and general practitioners, and serving as a platform for research to describe the natural history of post-intensive care syndrome and to identify new therapeutic interventions. This surveillance should include an assessment of the activities of daily living, mood, and functional mobility. Finally, nutritional status should be longitudinally assessed in all ICU survivors and incorporated into a patient-centered nutritional approach guided by a dietician.

CONCLUSIONS

Early ICU mobilization combined with the best evidence-based ICU practices can effectively reduce short-term weakness. Multi-professional collaborations are needed to guarantee a multi-dimensional evaluation and unitary community care programs for survivors of critical illnesses.

Extracellular proteins as potential biomarkers in Sepsis-related cerebral injury

Background

Sepsis can cause brain damage known as septic encephalopathy (SAE), which is linked to higher mortality and poorer outcomes. Objective clinical markers for SAE diagnosis and prognosis are lacking. This study aimed to identify biomarkers of SAE by investigating genes and extracellular proteins involved in sepsis-induced brain injury.

Methods

Extracellular protein differentially expressed genes (EP-DEGs) from sepsis patients' brain tissue (GSE135838) were obtained from Gene Expression Omnibus (GEO) and evaluated by protein annotation database. The function and pathways of EP-DEGs were examined using GO and KEGG. Protein-protein interaction (PPI) networks were built and crucial EP-DEGs were screened using STRING, Cytoscape, MCODE, and Cytohubba. The diagnostic and prognostic accuracy of key EP-DEGs was assessed in 31 sepsis patients' blood samples and a rat cecal ligation and puncture (CLP)-induced sepsis model. Cognitive and spatial memory impairment was evaluated 7-11 days post-CLP using behavioral tests. Blood and cerebrospinal fluid from 26 rats (SHAM n=14, CLP n=12) were collected 6 days after CLP to analyze key EP-DEGs.

Results

Thirty-one EP-DEGs from DEGs were examined. Bone marrow leukocytes, neutrophil movement, leukocyte migration, and reactions to molecules with bacterial origin were all enhanced in EP-DEGs. In comparison to the sham-operated group, sepsis rats had higher levels of MMP8 and S100A8 proteins in their venous blood (both p<0.05) and cerebrospinal fluid (p=0.0506, p<0.0001, respectively). Four important extracellular proteins, MMP8, CSF3, IL-6, and S100A8, were identified in clinical peripheral blood samples. MMP8 and S100A8 levels in the peripheral blood of sepsis patients were higher in SAE than in non-SAE. In comparison to MMP8, S100A8 had a higher area under the curve (AUC: 0.962, p<0.05) and a higher sensitivity and specificity (80% and 100%, respectively) than MMP8 (AUC: 0.790, p<0.05). High levels of S100A8 strongly correlated with 28-day mortality and the Glasgow Coma Scale (GCS) scores.

Conclusion

The extracellular proteins MMP8, CSF3, IL-6, and S100A8 may be crucial in the pathophysiology of SAE. S100A8 and MMP8 are possible biomarkers for SAE's onset and progression. This research may help to clarify the pathogenesis of SAE and improve the diagnosis and prognosis of the disease.

Neurologic Complications of Critical Medical Illness

OBJECTIVE

This article reviews the neurologic complications encountered in patients admitted to non-neurologic intensive care units, outlines various scenarios in which a neurologic consultation can add to the diagnosis or management of a critically ill patient, and provides advice on the best diagnostic approach in the evaluation of these patients.

LATEST DEVELOPMENTS

Increasing recognition of neurologic complications and their adverse impact on long-term outcomes has led to increased neurology involvement in non-neurologic intensive care units. The COVID-19 pandemic has highlighted the importance of having a structured clinical approach to neurologic complications of critical illness as well as the critical care management of patients with chronic neurologic disabilities.

ESSENTIAL POINTS

Critical illness is often accompanied by neurologic complications. Neurologists need to be aware of the unique needs of critically ill patients, especially the nuances of the neurologic examination, challenges in diagnostic testing, and neuropharmacologic aspects of commonly used medications.

HMGB1 mediates synaptic loss and cognitive impairment in an animal model of sepsis-associated encephalopathy

BACKGROUND

Microglial activation-mediated neuroinflammation is one of the essential pathogenic mechanisms of sepsis-associated encephalopathy (SAE). Mounting evidence suggests that high mobility group box-1 protein (HMGB1) plays a pivotal role in neuroinflammation and SAE, yet the mechanism by which HMGB1 induces cognitive impairment in SAE remains unclear. Therefore, this study aimed to investigate the mechanism of HMGB1 underlying cognitive impairment in SAE.

METHODS

An SAE model was established by cecal ligation and puncture (CLP); animals in the sham group underwent cecum exposure alone without ligation and perforation. Mice in the inflachromene (ICM) group were continuously injected with ICM intraperitoneally at a daily dose of 10 mg/kg for 9 days starting 1 h before the CLP operation. The open field, novel object recognition, and Y maze tests were performed on days 14-18 after surgery to assess locomotor activity and cognitive function. HMGB1 secretion, the state of microglia, and neuronal activity were measured by immunofluorescence. Golgi staining was performed to detect changes in neuronal morphology and dendritic spine density. In vitro electrophysiology was performed to detect changes in long-term potentiation (LTP) in the CA1 of the hippocampus. In vivo electrophysiology was performed to detect the changes in neural oscillation of the hippocampus.

RESULTS

CLP-induced cognitive impairment was accompanied by increased HMGB1 secretion and microglial activation. The phagocytic capacity of microglia was enhanced, resulting in aberrant pruning of excitatory synapses in the hippocampus. The loss of excitatory synapses reduced neuronal activity, impaired LTP, and decreased theta oscillation in the hippocampus. Inhibiting HMGB1 secretion by ICM treatment reversed these changes.

CONCLUSIONS

HMGB1 induces microglial activation, aberrant synaptic pruning, and neuron dysfunction in an animal model of SAE, leading to cognitive impairment. These results suggest that HMGB1 might be a target for SAE treatment.

β-patchoulene alleviates cognitive dysfunction in a mouse model of sepsis associated encephalopathy by inhibition of microglia activation through Sirt1/Nrf2 signaling pathway

BACKGROUND

Sepsis associated encephalopathy (SAE) is a common but poorly understood complication during sepsis. Currently, there are no preventive or therapeutic agents available for this neurological disorder. The present study was designed to determine the potential protective effects of β-patchoulene (β-PAE) in a mouse model of SAE and explore the putative mechanisms underpinning the beneficial effects.

MATERIALS AND METHODS

SAE was induced in C57BL/6 mice by cecal ligation and puncture(CLP). Mice were administrated with β-PAE or saline by intra-cerebral ventricle(i.c.v) injection immediately after CLP surgery. The inhibitory avoidance tests and open field tests were performed at 24h, 48h and 7days after procedures. Cytokines expression, oxidative parameters, microglia polarization and apoptosis in the brain tissue were assessed. Sirt1, Nrf2, HO-1and cleaved-caspase3 expression in hippocampus was determined by western-blotting. Further, serum cytokines expression and spleen lymphocytes apoptosis were evaluated, and survival study was performed.

RESULTS

Septic mice suffered severe cognitive decline following CLP as evidenced by decreased memory latency time and lower frequency of line crossing in the behavioral tests. A high dose of β-PAE(1mg/kg) improved the cognitive impairment in SAE mice, which was accompanied by reduced cytokines expression and oxidative stress. Immunofluorescence assay showed that β-PAE inhibited the expression of Iba-1 and iNOS in microglia. The mechanistic study indicated that β-PAE could promote the nuclear expression of Sirt1/Nrf2 and enhance cytoplasmic HO-1 expression. Furthermore, i.c.v administration of β-PAE decreased the expression of serum cytokines and apoptosis in the spleen, thus leading to an improved 7-day survival of septic mice. Finally, blockade of Nrf2 activation with ML385 largely mitigated the protective effects of β-PAE on the cognitive function, neuroinflammation and survival in SAE mice.

CONCLUSION

In this study, we found that β-PAE significantly altered sepsis induced neuroinflammation and microglia activation, thus reversed the cognitive decline and improved the peripheral immune function. The neuroprotective effects were possibly mediated by the activation of Sirt1/Nrf2/HO-1 pathway. β-PAE might serve as a promising therapeutic agent for SAE prevention and treatment.

What Exactly Makes Age a Risk Factor for an Unfavorable Outcome after Mitral Valve Surgery?

Objective: Age has an undeniable impact on perioperative mortality. However, it is not necessarily a predictor of frailty per se, as older patients have different outcomes. To verify specific conditions underlying frailty, we examined demographics, comorbidities, frequency, and distribution of postoperative complications influencing outcomes in a challenging cohort of patients undergoing mitral valve surgery. Methods: The study enrolled 1627 patients who underwent mitral valve surgery. Patients younger than 40 years who had been diagnosed with endocarditis were excluded. Patients were divided into three groups with ages ranging from 40−59 (n = 319), 60−74 (n = 795), and >75 years (n = 513). Baseline, comorbidities, postoperative complications, and mortality were recorded. Results: The older the patients were, the more frequently they suffered from pre- and postoperative renal insufficiency (p < 0.001). The likelihood of postoperative renal failure requiring dialysis was significantly higher with pre-existing renal failure. There was a significant association between postoperative renal insufficiency and the development of postoperative pleural or pericardial effusion (p < 0.001, p = 0.016). A significant decrease in BMI was observed in patients >75 years of age compared to the 60−74 years group (27.3 vs. 28.2 kg/m2, p = 0.007). The development of critical illnesses such as myopathy and neuropathy (CIP/CIM) was age-dependent and increased significantly with age (p = 0.04). Hospitalization duration and mortality also increased significantly with age (p = 0.013, p < 0.001). Conclusions: It appears that elderly patients with advanced renal failure have a significantly higher risk of mortality, postoperative renal failure, need for dialysis, and possibly the development of pleural and pericardial effusions in mitral valve surgery. In addition, more frequent CIP/CIM with concomitant decrease in BMI in the most advanced age group indicate sarcopenia and thus an additional feature of frailty besides renal failure.

Management of Polyneuromyopathy in a Critically Ill Patient with a Left Ventricular Assist Device

Critical illness polyneuromyopathy after cardiac surgery is often unrecognized and is a rarely reported clinical condition. It is characterized by more proximal than distal symmetrical flaccid muscle weakness and difficulty in weaning from a respirator. When done in a timely manner, rehabilitation prevents early complications and reduces the length of hospitalization. Rehabilitation leads to better motor outcome, improves short-term and long-term functionality, and results in a better quality of life.

Sepsis and the brain: a review for acute and general physicians

Sepsis-associated encephalopathy (SAE) describes acute cognitive dysfunction secondary to systemic or peripheral infection occurring outside of the central nervous system (CNS). Symptoms can range from mild confusion to coma and may precede the clinical signs of sepsis. Recognition that SAE is a potential differential diagnosis in patients presenting with delirium is important, as SAE is a diagnosis of exclusion. Physicians should also be aware that severe SAE is associated with a high mortality. Although mortality is often secondary to multiorgan failure rather than neurological sequelae, long-term cognitive and psychological morbidities have been reported in sepsis survivors. Early treatment (which can include prompt identification and source control of the infection) and good supportive care might improve cognitive outcomes. Future work should aim to improve understanding of both acute and chronic SAE with a focus on therapeutic interventions and improving patient outcomes.

In vivo Detection of Macromolecule Free Radicals in Mouse Sepsis-Associated Encephalopathy Using a New MRI and Immunospin Trapping Strategy

Introduction

Free radicals in oxidative stress are known to play a pathogenic role in sepsis. A major clinical challenge associated with sepsis is sepsis-associated encephalopathy (SAE). The rapid increase of free radicals in the brain promotes SAE progression. Here, macromolecule free radicals in the mouse brain were uniquely detected by immunospin trapping (IST) and magnetic resonance imaging (MRI).

Methods

The new strategy uses spin trapping agent DEPMPO-biotin to capture macromolecule free radicals in lesions and form biotin-DEPMPO-radical adducts. Then, a targeting MRI probe, avidin-BSA@Gd-ESIO, was used to detect the radical adducts through the highly specific binding of avidin and biotin. The avidin-BSA@Gd-ESIO probe was synthesized and systematically characterized. The detection capability of the new strategy was evaluated in vitro and in vivo using a confocal microscope and a 7T MRI, respectively.

Results

In reactive oxygen species (ROS)–induced microglial cells, the accumulation of the avidin-BSA@Gd-ESIO probe in the DEPMPO-biotin-treated group was significantly higher than that of control groups. In vivo MRI T1 signal intensities were significantly higher within the hippocampus, striatum, and medial cortex of the brain in mice with a mild or severe degree of sepsis compared with the sham control group. Histological analysis validated that the distribution of the avidin-BSA@Gd-ESIO probe in brain tissue slices was consistent with the MRI images. The fluorescence signals of ROS and avidin-BSA@Gd-ESIO probe were overlapped and visualized using immunofluorescent staining. By evaluating the T1 signal changes over time in different areas of the brain, we estimated the optimal MRI detection time to be 30 minutes after the probe administration.

Discussion

This method can be applied specifically to assess the level of macromolecular free radicals in vivo in a simple and stable manner, providing a pathway for a more comprehensive understanding of the role of free radicals in SAE.

Unusual sensory-motor neuropathies in post-COVID-19 patients admitted in rehabilitation hospitals: a case-series

BACKGROUND

Several neurological complications occurred in SARS-CoV-2 disease (COVID-19), mainly related to inflammatory and vascular disorders. The involvement of the peripheral nervous system (PNS) has been mostly reported as Guillain-Barré Syndrome, while focal peripheral neuropathies have been rarely described.

CASE REPORT

We report the cases of ten patients hospitalized in Rehabilitation Units after COVID-19, who presented severe focal motor involvement. Electrophysiological investigations revealed focal sensory-motor neuropathies, atypical for many aspects: bilaterality, location and contemporary involvement of different nervous districts. We speculate that their pathogenesis is possibly related to prolonged abnormal postures maintained during hospitalization in Intensive Care Unit, virus neurotropism and thrombotic vascular damage involving vasa nervorum.

CLINICAL REHABILITATION IMPACT

Motor neuropathies could induce severe disability and their early recognition in post COVID-19 patients is of primary importance for a specific rehabilitation treatment.

Imbalanced Subthreshold Currents Following Sepsis and Chemotherapy: A Shared Mechanism Offering a New Therapeutic Target?

Both sepsis and treatment of cancer with chemotherapy are known to cause neurologic dysfunction. The primary defects seen in both groups of patients are neuropathy and encephalopathy; the underlying mechanisms are poorly understood. Analysis of preclinical models of these disparate conditions reveal similar defects in ion channel function contributing to peripheral neuropathy. The defects in ion channel function extend to the central nervous system where lower motoneurons are affected. In motoneurons the defect involves ion channels responsible for subthreshold currents that convert steady depolarization into repetitive firing. The inability to correctly translate depolarization into steady, repetitive firing has profound effects on motor function, and could be an important contributor to weakness and fatigue experienced by both groups of patients. The possibility that disruption of function, either instead of, or in addition to neurodegeneration, may underlie weakness and fatigue leads to a novel approach to therapy. Activation of serotonin (5HT) receptors in a rat model of sepsis restores the normal balance of subthreshold currents and normal motoneuron firing. If an imbalance of subthreshold currents also occurs in other central nervous system neurons, it could contribute to encephalopathy. We hypothesize that pharmacologically restoring the proper balance of subthreshold currents might provide effective therapy for both neuropathy and encephalopathy in patients recovering from sepsis or treatment with chemotherapy.

Rapid and persistent decrease in brain tissue oxygenation in ovine gram-negative sepsis

The changes in brain perfusion and oxygenation in critical illness, which are thought to contribute to brain dysfunction, are unclear due to the lack of methods to measure these variables. We have developed a technique to chronically measure cerebral tissue perfusion and oxygen tension in unanesthetized sheep. Using this technique, we have determined the changes in cerebral perfusion and Po₂ during the development of ovine sepsis. In adult Merino ewes, fiber-optic probes were implanted in the brain, renal cortex, and renal medulla to measure tissue perfusion, oxygen tension (Po₂), and temperature, and flow probes were implanted on the pulmonary and renal arteries. Conscious sheep were infused with live Escherichia coli for 24 h, which induced hyperdynamic sepsis; mean arterial pressure decreased (from 85.2 ± 5.6 to 71.5 ± 8.7 mmHg), while cardiac output (from 4.12 ± 0.70 to 6.15 ± 1.26 L/min) and total peripheral conductance (from 48.9 ± 8.5 to 86.8 ± 11.5 mL/min/mmHg) increased (n = 8, all P < 0.001) and arterial Po₂ decreased (from 104 ± 8 to 83 ± 10 mmHg; P < 0.01). Cerebral perfusion tended to decrease acutely, although this did not reach significance, but there was a significant and sustained decrease in cerebral tissue Po₂ (from 32.2 ± 10.1 to 18.8 ± 11.7 mmHg) after 3 h and to 22.8 ± 5.2 mmHg after 24 h of sepsis (P < 0.02). Sepsis induced large reductions in both renal medullary perfusion and Po₂ but had no effect in the renal cortex. In ovine sepsis, there is an early decrease in cerebral Po₂ that is maintained for 24 h despite minimal changes in cerebral perfusion. Cerebral hypoxia may be one of the factors causing sepsis-induced malaise and lethargy.

MiR-195-5p represses inflammation, apoptosis, oxidative stress, and endoplasmic reticulum stress in sepsis-induced myocardial injury by targeting activating transcription factor 6

Myocardial injury (MI) is a common complication of sepsis. MicroRNAs (miRNAs) have been suggested as potential biomarkers of MI; however, their mechanisms in sepsis-induced MI remain unclear. A sepsis rat model was constructed by use of cecal ligation and puncture (CLP). The levels of miR-195-5p and activating transcription factor 6 (ATF6) expression were determined by quantitative reverse-transcription polymerase chain reaction, and cytokine levels were detected by ELISA. The levels of oxidative stress (OS)-related indicators and endoplasmic reticulum stress (ERS)-related proteins were examined, and the regulatory effect of miR-195-5p on ATF6 was determined by using the luciferase reporter assay. Our results showed that miR-195-5p expression was downregulated and ATF6 expression was upregulated in lipopolysaccharide-induced cardiomyocytes and mice with CLP-induced sepsis. We also found that miR-195-5p could markedly attenuate the inflammation, apoptosis, OS, and ERS associated with sepsis-induced MI. Additionally, we verified that miR-195-5p could relieve sepsis-induced MI by targeting ATF6. This study identified potential targets for treating MI after sepsis.

Longitudinal Assessment of Health and Quality of Life of COVID-19 Patients Requiring Intensive Care-An Observational Study

Long-term health consequences in survivors of severe COVID-19 remain unclear. Eighteen COVID-19 patients admitted to the intensive care unit at the University Hospital Rechts der Isar, Munich, Germany, between 14 March and 23 June 2020, were prospectively followed-up at a median of 36, 75.5, 122 and 222 days after discharge. The health-related quality of life (HrQoL) (36-item Short Form Health Survey and St. George’s Respiratory Questionnaire, SGRQ), cardiopulmonary function, laboratory parameters and chest imaging were assessed longitudinally. The HrQoL assessment revealed a reduced physical functioning, as well as increased SGRQ impact and symptoms scores that all improved over time but remained markedly impaired compared to the reference groups. The median radiological severity scores significantly declined; persistent abnormalities were found in 33.3% of the patients on follow-up. A reduced diffusion capacity was the most common abnormal pulmonary function parameter. The length of hospitalization correlated with role limitations due to physical problems, the SGRQ symptom and the impact score. In conclusion, in survivors of severe COVID-19, the pulmonary function and symptoms improve over time, but impairments in their physical function and diffusion capacity can persist over months. Longer follow-up studies with larger cohorts will be necessary to comprehensively characterize long-term sequelae upon severe COVID-19 and to identify patients at risk.

Heterogeneity in the Number of Astrocytes in the Central Nervous System after Peritonitis

Sepsis remains a major medical emergency that describes the body's systemic immune response to an infectious process and can lead to end-stage organ dysfunction and death. Clinical studies have introduced the concept of sepsis associated encephalopathy, which seems to have a plethora of cellular and molecular triggers starting from systemic inflammatory cytokines, blood-brain barrier (BBB) rupture, microscopic brain injury, altered cerebral circulation, neurotransmission, or even metabolic dysfunction. The purpose of our study is to reproduce the sepsis model previously described using the cecal ligature and puncture (CLP), and to take a closer look to the acute modifications that occur on cellular level when it comes to the brain-blood-barrier of the mice with systemic inflammation. After a rapid systemic response to peritonitis, we show a heterogeneity in astrocytic response within different cortical structures; hippocampus having the longest change in the number of GFAP+cells, while no difference was seen in the number of cortical astrocytes. With even more increasing roles of astrocytes in different pathologies, the relation between sepsis and astrocytes could prove a valuable in discovering new therapy in sepsis.

Emerging benefits and drawbacks of α2 -adrenoceptor agonists in the management of sepsis and critical illness

Agonists of α₂ -adrenoceptors are increasingly being used for the provision of comfort, sedation and the management of delirium in critically ill patients, with and without sepsis. In this context, increased sympathetic and inflammatory activity are common pathophysiological features linked to multi-organ dysfunction, particularly in patients with sepsis or those undergoing cardiac surgery requiring cardiopulmonary bypass. Experimental and clinical studies support the notion that the α₂ -adrenoceptor agonists, dexmedetomidine and clonidine, mitigate sympathetic and inflammatory overactivity in sepsis and cardiac surgery requiring cardiopulmonary bypass. These effects can protect vital organs, including the cardiovascular system, kidneys, heart and brain. We review the pharmacodynamic mechanisms by which α₂ -adrenoceptor agonists might mitigate multi-organ dysfunction arising from pathophysiological conditions associated with excessive inflammatory and adrenergic stress in experimental studies. We also outline recent clinical trials that have examined the use of dexmedetomidine in critically ill patients with and without sepsis and in patients undergoing cardiac surgery.

The Use of Electroencephalography in Patients with Sepsis: a Review of The Literature

Sepsis-associated encephalopathy (SAE) is the term used to define brain dysfunction related to infections that are principally located outside the central nervous system (CNS). A number of published studies report that electroencephalography (EEG) has been used in the evaluation of patients with sepsis, alone or usually in combination, to evoked potentials and neuroimaging. This was in an effort to assess if EEG can be a tool in the diagnosis and monitoring of the neurological status in sepsis patients. Although there is no specific test for the diagnosis and prognosis of sepsis related encephalopathy, our literature review suggests that EEG has a role in the assessment of this clinical entity. Due to its low cost and simplicity in its performance, EEG could be a potential aid in the assessment of sepsis neurological complications even in the early, subclinical stages of the syndrome. The aim of this review is to summarize the published literature regarding the application and utility of electroencephalography in adult patients with sepsis.

Neurological associations of COVID-19

BACKGROUND

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is of a scale not seen since the 1918 influenza pandemic. Although the predominant clinical presentation is with respiratory disease, neurological manifestations are being recognised increasingly. On the basis of knowledge of other coronaviruses, especially those that caused the severe acute respiratory syndrome and Middle East respiratory syndrome epidemics, cases of CNS and peripheral nervous system disease caused by SARS-CoV-2 might be expected to be rare.

RECENT DEVELOPMENTS

A growing number of case reports and series describe a wide array of neurological manifestations in 901 patients, but many have insufficient detail, reflecting the challenge of studying such patients. Encephalopathy has been reported for 93 patients in total, including 16 (7%) of 214 hospitalised patients with COVID-19 in Wuhan, China, and 40 (69%) of 58 patients in intensive care with COVID-19 in France. Encephalitis has been described in eight patients to date, and Guillain-Barré syndrome in 19 patients. SARS-CoV-2 has been detected in the CSF of some patients. Anosmia and ageusia are common, and can occur in the absence of other clinical features. Unexpectedly, acute cerebrovascular disease is also emerging as an important complication, with cohort studies reporting stroke in 2-6% of patients hospitalised with COVID-19. So far, 96 patients with stroke have been described, who frequently had vascular events in the context of a pro-inflammatory hypercoagulable state with elevated C-reactive protein, D-dimer, and ferritin. WHERE NEXT?: Careful clinical, diagnostic, and epidemiological studies are needed to help define the manifestations and burden of neurological disease caused by SARS-CoV-2. Precise case definitions must be used to distinguish non-specific complications of severe disease (eg, hypoxic encephalopathy and critical care neuropathy) from those caused directly or indirectly by the virus, including infectious, para-infectious, and post-infectious encephalitis, hypercoagulable states leading to stroke, and acute neuropathies such as Guillain-Barré syndrome. Recognition of neurological disease associated with SARS-CoV-2 in patients whose respiratory infection is mild or asymptomatic might prove challenging, especially if the primary COVID-19 illness occurred weeks earlier. The proportion of infections leading to neurological disease will probably remain small. However, these patients might be left with severe neurological sequelae. With so many people infected, the overall number of neurological patients, and their associated health burden and social and economic costs might be large. Health-care planners and policy makers must prepare for this eventuality, while the many ongoing studies investigating neurological associations increase our knowledge base.

Sepsis-Associated Brain Dysfunction: A Review of Current Literature

Sepsis-associated brain dysfunction (SABD) may be the most common type of encephalopathy in critically ill patients. SABD develops in up to 70% of septic patients and represents the most frequent organ insufficiency associated with sepsis. It presents with a plethora of acute neurological features and may have several serious long-term psychiatric consequences. SABD might cause various pathological changes in the brain through numerous mechanisms. Clinical neurological examination is the basic screening method for SABD, although it may be challenging in subjects receiving with opioids and sedative agents. As electrographic seizures and periodic discharges might be present in 20% of septic patients, screening with electroencephalography (EEG) might be useful. Several imaging techniques have been suggested for non-invasive assessment of structure and function of the brain in SABD patients; however, their usefulness is rather limited. Although several experimental therapies have been postulated, at the moment, no specific treatment exists. Clinicians should focus on preventive measures and optimal management of sepsis. This review discusses epidemiology, clinical presentation, pathology, pathophysiology, diagnosis, management, and prevention of SABD.

Poldip2 mediates blood-brain barrier disruption in a model of sepsis-associated encephalopathy

Background

Sepsis-associated encephalopathy (SAE), a diffuse cerebral dysfunction in the absence of direct CNS infection, is associated with increased rates of mortality and morbidity in patients with sepsis. Increased cytokine production and disruption of the blood-brain barrier (BBB) are implicated in the pathogenesis of SAE. The induction of pro-inflammatory mediators is driven, in part, by activation of NF-κΒ. Lipopolysaccharide (LPS), an endotoxin produced by gram-negative bacteria, potently activates NF-κΒ and its downstream targets, including cyclooxygenase-2 (Cox-2). Cox-2 catalyzes prostaglandin synthesis and in the brain prostaglandin, E2 is capable of inducing endothelial permeability. Depletion of polymerase δ-interacting protein 2 (Poldip2) has previously been reported to attenuate BBB disruption, possibly via regulation of NF-κΒ, in response to ischemic stroke. Here we investigated Poldip2 as a novel regulator of NF-κΒ/cyclooxygenase-2 signaling in an LPS model of SAE.

Methods

Intraperitoneal injections of LPS (18 mg/kg) were used to induce BBB disruption in Poldip2^+/+ and Poldip2^+/− mice. Changes in cerebral vascular permeability and the effect of meloxicam, a selective Cox-2 inhibitor, were assessed by Evans blue dye extravasation. Cerebral cortices of Poldip2^+/+ and Poldip2^+/− mice were further evaluated by immunoblotting and ELISA. To investigate the role of endothelial Poldip2, immunofluorescence microscopy and immunoblotting were performed to study the effect of siPoldip2 on LPS-mediated NF-κΒ subunit p65 translocation and Cox-2 induction in rat brain microvascular endothelial cells. Finally, FITC-dextran transwell assay was used to assess the effect of siPoldip2 on LPS-induced endothelial permeability.

Results

Heterozygous deletion of Poldip2 conferred protection against LPS-induced BBB permeability. Alterations in Poldip2^+/+ BBB integrity were preceded by induction of Poldip2, p65, and Cox-2, which was not observed in Poldip2^+/− mice. Consistent with these findings, prostaglandin E2 levels were significantly elevated in Poldip2^+/+ cerebral cortices compared to Poldip2^+/− cortices. Treatment with meloxicam attenuated LPS-induced BBB permeability in Poldip2^+/+ mice, while having no significant effect in Poldip2^+/− mice. Moreover, silencing of Poldip2 in vitro blocked LPS-induced p65 nuclear translocation, Cox-2 expression, and endothelial permeability.

Conclusions

These data suggest Poldip2 mediates LPS-induced BBB disruption by regulating NF-κΒ subunit p65 activation and Cox-2 and prostaglandin E2 induction. Consequently, targeted inhibition of Poldip2 may provide clinical benefit in the prevention of sepsis-induced BBB disruption.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1575-4) contains supplementary material, which is available to authorized users.

Blockade of IL-17A/IL-17R Pathway Protected Mice from Sepsis-Associated Encephalopathy by Inhibition of Microglia Activation

Sepsis-associated encephalopathy (SAE) is a poorly understood condition that leads to long-term cognitive impairment and increased mortality in survivors. Recent research revealed that IL-17A/IL-17R might serve as a checkpoint in microglia-mediated neuroinflammation. The present study was designed to determine the specific role of IL-17A-mediated microglia activation in the development of SAE. A mouse model of SAE was induced by cecal ligation and puncture (CLP), and behavior performance was evaluated by the inhibitory avoidance test and the open field test. Cytokine expression and microglia activation in brain tissue were determined at 6 h, 12 h, 24 h, 48 h, and day 7 post surgery. Further, septic mice were intracerebral ventricle- (i.c.v.-) injected with recombinant IL-17A, anti-IL-17A ab, anti-IL-17R ab, or isotype controls to evaluate the potential effects of IL-17A/IL-17R blockade in the prevention of SAE. Septic peritonitis induced significant impairment of learning memory and exploratory activity, which was associated with a higher expression of IL-17A, IL-1β, and TNF-α in the brain homogenate. Fluorescence intensity of Iba-1 and IL-17R in the hippocampus was significantly increased following CLP. Treatment with recombinant IL-17A enhanced the neuroinflammation and microglia activation in CLP mice. On the contrary, neutralizing anti-IL-17A or anti-IL-17R antibodies mitigated the CNS inflammation and microglia activation, thus alleviating the cognitive dysfunction. Furthermore, as compared to the sham control, microglia cultured from CLP mice produced significantly higher levels of cytokines and expressed with higher fluorescence intensity of Iba-1 in response to IL-17A or LPS. Pretreatment with anti-IL-17R ab suppressed the Iba-1 expression and cytokine production in microglia stimulated by IL-17A. In conclusion, blockade of the IL-17A/IL-17R pathway inhibited microglia activation and neuroinflammation, thereby partially reversing sepsis-induced cognitive impairment. The present study suggested that the IL-17A/IL-17R signaling pathway had an important, nonredundant role in the development of SAE.

Electroencephalographic Abnormalities in Sepsis Patients in Correlation to the Calculated Prognostic Scores: A Case Series

Objective

To evaluate the electroencephalographic (EEG) findings and correlate EEG findings with inflammatory biomarkers and the sepsis prognostic scores SOFA, SAPS II and APACHE II in patients who present in the Emergency Department with sepsis without clinical central nervous system involvement.

Methods

The study included seventeen patients (< 70 years old) with sepsis without central nervous system involvement presenting in the Emergency Department of the University Hospital of Patras, Greece. All patients underwent neurologic examination and EEG analysis on admission to the hospital and were treated according to the international guideline protocols for sepsis.

Results

Six of seventeen sepsis patients had mild or moderate EEG abnormalities. We did not find any significant correlation between EEG abnormalities and inflammatory biomarkers (CRP, WBC) or commonly used prognostic sepsis scores.

Conclusions

EEG could serve as a useful tool to identify brain alterations at an early stage in sepsis, before clinical sings of encephalopathy can be detected. However, the presence of EEG abnormalities does not correlate with sepsis severity as measured by the commonly used prognostic sepsis scores SOFA, APACHE II or SAPS II. Because this was a small single center observational study, large multi-center studies are warranted to confirm these findings.

Sevoflurane attenuates systemic inflammation compared with propofol, but does not modulate neuro-inflammation: A laboratory rat study

BACKGROUND

Septic encephalopathy is believed to be a result of neuro-inflammation possibly triggered by endotoxins, such as lipopolysaccharides (LPS). Modulation of the immune system is a property of volatile anaesthetics.

OBJECTIVE

We aimed to investigate the systemic and cerebral inflammatory response in a LPS-induced sepsis model in rats. We compared two different sedation strategies, intravenous propofol and the volatile anaesthetic sevoflurane, with the hypothesis that the latter may attenuate neuro-inflammatory processes.

DESIGN

Laboratory rat study.

SETTING

Basic research laboratories at the University Hospital Zurich and University Zurich Irchel between August 2014 and June 2016.

PATIENTS

A total of 32 adult male Wistar rats.

INTERVENTIONS

After tracheotomy and mechanical ventilation, the anaesthetised rats were monitored before sepsis was induced by using intravenous LPS or phosphate-buffered saline as control. Rats were sedated with propofol (10 mg kg h) or sevoflurane (2 vol%) continuously for 12 h.

MAIN OUTCOME MEASURES

Systemic inflammatory markers such as cytokine-induced neutrophil chemo-attractant protein 1, monocyte chemo-tactic protein-1 and IL-6 were determined. The same cytokines were measured in brain tissue. Cellular response in the brain was assessed by defining neutrophil accumulation with myeloperoxidase and also activation of microglia with ionised calcium-binding adaptor molecule-1 and astrocytes with glial fibrillary acidic protein. Finally, brain injury was determined.

RESULTS

Animals were haemodynamically stable in both sedation groups treated with LPS. Blood cytokine peak values were lower in the sevoflurane-LPS compared with propofol-LPS animals. In brain tissue of LPS animals, chemoattractant protein-1 was the only significantly increased cytokine (P = 0.003), however with no significance between propofol and sevoflurane. After LPS challenge, cerebral accumulation of neutrophils was observed. Microglia activation was pronounced in the hippocampus of animals treated with LPS (P = 0.006). LPS induced prominent astrogliosis (P < 0.001). There was no significant difference in microglia or astrocyte activation or apoptosis in the brain between sevoflurane and propofol.

CONCLUSION

We have shown that systemic attenuation of inflammation by the volatile anaesthetic sevoflurane did not translate into attenuated neuro-inflammation in this LPS-induced inflammation model.

TRIAL REGISTRATION

Animal approval No. 134/2014, Veterinäramt Zürich.

Fluid Resuscitation in Septic Patients Improves Systolic but not Diastolic Middle Cerebral Artery Flow Velocity

To investigate the effects of fluid resuscitation on cerebral hemodynamics in sepsis, the following set of transcranial Doppler (TCD) parameters was used: maximal change in flow velocity (FV) during stroke onset (acc), maximal FV during first (sys1) or second (sys2) phase of systole and mean diastolic FV (dias@560). We aim to evaluate changes in cerebral hemodynamics that result from (i) sepsis and (ii) adequate fluid resuscitation in critically ill septic patients. In the majority of 16 septic patients sys2 was initially absent but reappeared during the period of fluid resuscitation; whereas sys2 absence was never seen in healthy controls. Second, adequate fluid resuscitation resulted in a significant increase of the systolic FV components (acc, sys1, sys2 and systolic blood pressure); whereas the diastolic components (dias@560 and diastolic blood pressure) remained unchanged. Sys2 absence and reappearance in sepsis suggests that TCD could become a non-invasive alternative for hemodynamic monitoring.

Impact of Critical Illness Polyneuromyopathy in Rehabilitation: A Prospective Observational Study

BACKGROUND

Critical illness polyneuromyopathy (CIPNM) increasingly is recognized as a source of disability in patients requiring intensive care unit (ICU) admission. The prevalence and impact of CIPNM on patients in the rehabilitation setting has not been established.

OBJECTIVES

To determine the proportion of at-risk rehabilitation inpatients with evidence of CIPNM and the functional sequelae of this disorder.

DESIGN

Prospective observational study.

SETTING

Tertiary academic rehabilitation hospital.

PATIENTS

Rehabilitation inpatients with a history of ICU admission for at least 72 hours.

METHODS

Electrodiagnostic studies were performed to evaluate for axonal neuropathy and/or myopathy in at least one upper and one lower limb.

MAIN OUTCOME MEASUREMENTS

The primary outcome was prevalence of CIPNM. Secondary outcomes included Functional Independence Measure (FIM) scores, rehabilitation length of stay (RLOS), and discharge disposition.

RESULTS

A total of 33 participants were enrolled; 70% had evidence of CIPNM. Admission FIM score, discharge FIM, FIM gain, and FIM efficiency were 64.1, 89.9, 25.5, and 0.31 in those with CIPNM versus 78.4, 94.6, 16.1, and 0.33 in those without CIPNM, respectively. Average RLOS was 123 days versus 76 days and discharge to home was 57% versus 90% in the CIPNM and non-CIPNM groups, respectively.

CONCLUSIONS

CIPNM is very common in rehabilitation inpatients with a history of ICU admission. It was associated with a lower functional status at rehabilitation admission, but functional improvement was at a similar rate to those without CIPNM. Longer RLOS stay may be required to achieve the same functional level.

LEVEL OF EVIDENCE

III.

No Awakening in Supratentorial Intracerebral Hemorrhage Is Potentially Caused by Sepsis-Associated Encephalopathy

BACKGROUND Acute supratentorial intracerebral hemorrhage (sICH) with secondary sepsis is increasing in frequency. We investigated whether no awakening (NA) after sICH with coma is potentially caused by sepsis-associated encephalopathy (SAE). MATERIAL AND METHODS A case-control study of 147 recruited sICH cases with NA and 198 sICH controls with subsequent awakening (SA) was performed at 2 centers in China. All patients underwent brain computed tomography (CT) scans on admission. The odds ratio (OR) of NA was calculated using logistic regression. RESULTS During the study period, 56.5% (83/147) of the patients with sICH with coma and NA had SAE, and 10% (20/198) with sICH with coma and SA had SAE; this difference between the 2 groups was significant (p<0.000). The sICH patients with coma and NA exhibited a longer median time from onset to coma (2.0 days vs. 0.5 days), more frequent confirmed infection (98.0% vs. 24.2%), and a higher Sequential Organ Failure Assessment (SOFA) score (6.3±1.5 vs. 3.4±0.8). These patients also exhibited lower hematoma volume (28.0±18.8 vs. 38.3±24), a lower initial National Institutes of Health Stroke Scale score (19.5±6.6 vs. 30.3±6.8), more frequent brain midline shift (59.2% vs. 27.8%), more frequent diffuse cerebral swelling (64.6% vs. 16.0%), and higher 30-day mortality (54.4% vs. 0.0%) than the patients who did awaken. Logistic multivariable regression analyses revealed that only a higher SOFA score (OR, 1.4; 95% CI, 1.079-1.767; p=0.010) and SAE (OR, 4.0; 95% CI, 1.359-6.775; p=0.001) were associated with NA events in patients with sICH. CONCLUSIONS NA in sICH patients with coma is potentially caused by secondary SAE.

Secreted Frizzled-Related Protein 2 and Inflammation-Induced Skeletal Muscle Atrophy

OBJECTIVE

In sepsis, the disease course of critically ill patients is often complicated by muscle failure leading to ICU-acquired weakness. The myokine transforming growth factor-β1 increases during inflammation and mediates muscle atrophy in vivo. We observed that the transforming growth factor-β1 inhibitor, secreted frizzled-related protein 2, was down-regulated in skeletal muscle of ICU-acquired weakness patients. We hypothesized that secreted frizzled-related protein 2 reduction enhances transforming growth factor-β1-mediated effects and investigated the interrelationship between transforming growth factor-β1 and secreted frizzled-related protein 2 in inflammation-induced atrophy.

DESIGN

Observational study and prospective animal trial.

SETTING

Two ICUs and research laboratory.

PATIENTS/SUBJECTS

Twenty-six critically ill patients with Sequential Organ Failure Assessment scores greater than or equal to 8 underwent a skeletal muscle biopsy from the vastus lateralis at median day 5 in ICU. Four patients undergoing elective orthopedic surgery served as controls. To search for signaling pathways enriched in muscle of ICU-acquired weakness patients, a gene set enrichment analysis of our recently published gene expression profiles was performed. Quantitative reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemistry were used to analyze secreted frizzled-related protein 2 expression and protein content. A mouse model of inflammation-induced skeletal muscle atrophy due to polymicrobial sepsis and cultured myocytes were used for mechanistic analyses.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Gene set enrichment analysis uncovered transforming growth factor-β1 signaling activation in vastus lateralis from ICU-acquired weakness patients. Muscular secreted frizzled-related protein 2 expression was reduced after 5 days in ICU. Likewise, muscular secreted frizzled-related protein 2 expression was decreased early and continuously in mice with inflammation-induced atrophy. In muscle, secreted frizzled-related protein 2 was predominantly contained in fast twitch/type II myofibers. Secreted frizzled-related protein 2 physically interacted and colocalized with transforming growth factor-β1 through its cysteine-rich domain. Finally, secreted frizzled-related protein 2 prevented transforming growth factor-β1-induced atrophy in C2C12 myotubes.

CONCLUSIONS

Muscular secreted frizzled-related protein 2 is down-regulated in ICU-acquired weakness patients and mice with inflammation-induced muscle atrophy. Decreased secreted frizzled-related protein 2 possibly establishes a positive feedback loop enhancing transforming growth factor-β1-mediated atrophic effects in inflammation-induced atrophy.

Neurologic complications of sepsis

Over the past decades, the incidence of sepsis and resultant neurologic sequelae has increased, both in industrialized and low- or middle-income countries, by approximately 5% per year. Up to 300 patients per 100 000 population per year are reported to suffer from sepsis, severe sepsis, and septic shock. Mortality is up to 30%, depending on the precision of diagnostic criteria. The increasing incidence of sepsis is partially explained by demographic changes in society, with aging, increasing numbers of immunocompromised patients, dissemination of multiresistant pathogens, and greater availability of supportive medical care in both industrialized and middle-income countries. This results in more septic patients being admitted to intensive care units. Septic encephalopathy is a manifestation especially of severe sepsis and septic shock where the neurologist plays a crucial role in diagnosis and management. It is well known that timely treatment of sepsis improves outcome and that septic encephalopathy may precede other signs and symptoms. Particularly in the elderly and immunocompromised patient, the brain may be the first organ to show signs of failure. The neurologist diagnosing early septic encephalopathy may therefore contribute to the optimal management of septic patients. The brain is not only an organ failing in sepsis (a "sepsis victim" - as with other organs), but it also overwhelmingly influences all inflammatory processes on a variety of pathophysiologic levels, thus contributing to the initiation and propagation of septic processes. Therefore, the best possible pathophysiologic understanding of septic encephalopathy is essential for its management, and the earliest possible therapy is crucial to prevent the evolution of septic encephalopathy, brain failure, and poor prognosis.

Perspectives on aetiology, pathophysiology and management of shock in African children

Paediatric shock is still a common emergency of public health importance with an estimated 400,000–500,000 reported cases annually. Mortality due to paediatric shock has varied over the years. Data in 1980s show that mortality rates due to septic shock in children were over 50%; but by the end of the year 2000 data indicated that though a marked decline in mortality rates had been achieved, it had stagnated at about 20%. Descriptions of paediatric shock reveal the lack of a common definition and there are important gaps in evidence-based management in different settings. In well-resourced healthcare systems with well-functioning intensive care facilities, the widespread implementation of shock management guidelines based on the Paediatric Advanced Life Support and European Paediatric Advanced Life Support courses have reduced mortality. In resource limited settings with diverse infectious causative agents, the Emergency Triage Assessment and Treatment (ETAT) approach is more pragmatic, but its impact remains circumscribed to centres where ETAT has been implemented and sustained. Advocacy for common management pathways irrespective of underlying cause have been suggested. However, in sub Saharan Africa, the diversity of underlying causative organisms and patient phenotypes may limit a single approach to shock management.

Data from a large fluid trial (the FEAST trial) in East Africa have provided vital insight to shock management. In this trial febrile children with clinical features of impaired perfusion were studied. Rapid infusion of fluid boluses, irrespective of whether the fluid was colloid or crystalloid, when compared to maintenance fluids alone had an increased risk of mortality at 48 h. All study participants were promptly managed for underlying conditions and comorbidity such as malaria, bacteraemia, severe anaemia, meningitis, pneumonia, convulsions, hypoglycaemia and others. The overall low mortality in the trial suggests the potential contribution of ETAT, the improved standard of care and supportive treatment across the subgroups in the trial. Strengthening systems that enable rapid identification of shock, prompt treatment of children with correct antimicrobials and supportive care such as oxygen administration and blood transfusion may contribute to better survival outcomes in resources limited settings.

Neuronal Circuits Modulate Antigen Flow Through Lymph Nodes

When pathogens and toxins breech the epithelial barrier, antigens are transported by the lymphatic system to lymph nodes. In previously immunized animals, antigens become trapped in the draining lymph nodes, but the underlying mechanism that controls antigen restriction is poorly understood. Here we describe the role of neurons in sensing and restricting antigen flow in lymph nodes. The antigen keyhole-limpet hemocyanin (KLH) injected into the mouse hind paw flows from the popliteal lymph node to the sciatic lymph node, continuing through the upper lymphatics to reach the systemic circulation. Re-exposure to KLH in previously immunized mice leads to decreased flow from the popliteal to the sciatic lymph node as compared with naïve mice. Administering bupivacaine into the lymph node region restores antigen flow in immunized animals. In contrast, neural activation using magnetic stimulation significantly decreases antigen trafficking in naïve animals as compared with sham controls. Ablating Na_V1.8 + sensory neurons significantly reduces antigen restriction in immunized mice. Genetic deletion of FcγRI/FcεRI also reverses the antigen restriction. Colocalization of PGP9.5-expressing neurons, FcγRI receptors and labeled antigen occurs at the antigen challenge site. Together, these studies reveal that neuronal circuits modulate antigen trafficking through a pathway that requires Na_V1.8 and FcγR.

Neurologic Complications in the Intensive Care Unit

Complications involving the central and peripheral nervous system are frequently encountered in critically ill patients. All components of the neuraxis can be involved including the brain, spinal cord, peripheral nerves, neuromuscular junction, and muscles. Neurologic complications adversely impact outcome and length of stay. These complications can be related to underlying critical illness, pre-existing comorbid conditions, and commonly used and life-saving procedures and medications. Familiarity with the myriad neurologic complications that occur in the intensive care unit can facilitate their timely recognition and treatment. Additionally, awareness of treatment-related neurologic complications may inform decision-making, mitigate risk, and improve outcomes.

Risk factors for nosocomial nontraumatic coma: sepsis and respiratory failure

Background

Coma’s are a major cause of clinical deterioration or death. Identification of risks that predispose to coma are important in managing patients; however, the risk factors for nosocomial nontraumatic coma (NNC) are not well known. Our aim was to investigate the risk factors in patients with NNC.

Methods

A retrospective case–control design was used to compare patients with NNC and a control group of patients without coma in a population-based cohort of 263 participants from the neurological intensive care unit in Shuyang County People’s Hospital of Northern China. Coma was diagnosed by a Glasgow Coma Scale score ≤8. Adjusted odds ratios for patients with NNC were derived from multivariate logistic regression analyses.

Results

A total of 96 subjects had NNC. The prevalence of NNC was 36.5% among the subjects. Among these, 82% had acute cerebrovascular etiology. Most of the NNC usually occurred at day 3 after admission to the neurological intensive care unit. Patients with NNC had higher hospital mortality rates (67.7% vs 3%, P<0.0001) and were more likely to have a central herniation (47.9% vs 0%, P<0.001) or uncal herniation (11.5% vs 0%, P<0.001) than those without NNC. Multiple logistic regression showed that systemic inflammatory response syndrome-positive sepsis (odds ratio =4, 95% confidence interval =1.875−8.567, P<0.001) and acute respiratory failure (odds ratio =3.275, 95% confidence interval =1.014−10.573, P<0.05) were the factors independently associated with a higher risk of NNC.

Conclusion

Systemic inflammatory response syndrome-positive sepsis and acute respiratory failure are independently associated with an increased risk of NNC. This information may be important for patients with NNC.

Neurologic Causes of Acute Respiratory Dysfunction

Many neurologic diseases can cause acute respiratory decompensation, therefore a familiarity with these diseases is critical for any clinician managing patients with respiratory dysfunction. In this article, we review the anatomy of the respiratory system, focusing on the neurologic control of respiration. We discuss general mechanisms by which diseases of the peripheral and central nervous systems can cause acute respiratory dysfunction, and review the neurologic diseases which can adversely affect respiration. Lastly, we discuss the diagnosis and general management of acute respiratory impairment due to neurologic disease.

ICU-Acquired Weakness

Survivorship after critical illness is an increasingly important health-care concern as ICU use continues to increase while ICU mortality is decreasing. Survivors of critical illness experience marked disability and impairments in physical and cognitive function that persist for years after their initial ICU stay. Newfound impairment is associated with increased health-care costs and use, reductions in health-related quality of life, and prolonged unemployment. Weakness, critical illness neuropathy and/or myopathy, and muscle atrophy are common in patients who are critically ill, with up to 80% of patients admitted to the ICU developing some form of neuromuscular dysfunction. ICU-acquired weakness (ICUAW) is associated with longer durations of mechanical ventilation and hospitalization, along with greater functional impairment for survivors. Although there is increasing recognition of ICUAW as a clinical entity, significant knowledge gaps exist concerning identifying patients at high risk for its development and understanding its role in long-term outcomes after critical illness. This review addresses the epidemiologic and pathophysiologic aspects of ICUAW; highlights the diagnostic challenges associated with its diagnosis in patients who are critically ill; and proposes, to our knowledge, a novel strategy for identifying ICUAW.

The Sick and the Weak: Neuropathies/Myopathies in the Critically Ill

Critical illness polyneuropathies (CIP) and myopathies (CIM) are common complications of critical illness. Several weakness syndromes are summarized under the term intensive care unit-acquired weakness (ICUAW). We propose a classification of different ICUAW forms (CIM, CIP, sepsis-induced, steroid-denervation myopathy) and pathophysiological mechanisms from clinical and animal model data. Triggers include sepsis, mechanical ventilation, muscle unloading, steroid treatment, or denervation. Some ICUAW forms require stringent diagnostic features; CIM is marked by membrane hypoexcitability, severe atrophy, preferential myosin loss, ultrastructural alterations, and inadequate autophagy activation while myopathies in pure sepsis do not reproduce marked myosin loss. Reduced membrane excitability results from depolarization and ion channel dysfunction. Mitochondrial dysfunction contributes to energy-dependent processes. Ubiquitin proteasome and calpain activation trigger muscle proteolysis and atrophy while protein synthesis is impaired. Myosin loss is more pronounced than actin loss in CIM. Protein quality control is altered by inadequate autophagy. Ca(2+) dysregulation is present through altered Ca(2+) homeostasis. We highlight clinical hallmarks, trigger factors, and potential mechanisms from human studies and animal models that allow separation of risk factors that may trigger distinct mechanisms contributing to weakness. During critical illness, altered inflammatory (cytokines) and metabolic pathways deteriorate muscle function. ICUAW prevention/treatment is limited, e.g., tight glycemic control, delaying nutrition, and early mobilization. Future challenges include identification of primary/secondary events during the time course of critical illness, the interplay between membrane excitability, bioenergetic failure and differential proteolysis, and finding new therapeutic targets by help of tailored animal models.

Early prediction and outcome of septic encephalopathy in acute stroke patients with nosocomial coma

Background

Septic encephalopathy (SE) is the most common acute encephalopathy in ICU; however, little attention has been focused on risk of SE in the course of acute stroke. Our aim is to investigate the early prediction and outcome of SE in stroke patients with nosocomial coma (NC).

Methods

A retrospective cohort study was conducted in an ICU of the tertiary teaching hospital in China from January 2006 to December 2009. Ninety-four acute stroke patients with NC were grouped according to with or without SE. Risk factors for patients with SE were compared with those without SE by univariate and multivariate analysis.

Results

Of 94 stroke patients with NC, 46 (49%) had NC with SE and 48 (51%) had NC without SE. The onset-to-NC time was significant later in stroke patients with SE than those without SE (P < 0.01). There was a significant difference in body temperature, heart rate, respiratory rate, white blood cell (WBC), systolic blood pressure (SBP), diastolic blood pressure (DBP), systemic inflammatory response syndrome (SIRS), acute respiratory failure, septic shock, hypernatremia, and sequential organ failure assessment (SOFA) score between the SE and non-SE group (P < 0.05). On a repeat head imaging, vasogenic edema (P = 0.023) and subcortical white matter lesions (P = 0.011) were significantly higher in patients with SE than those without SE, while hematoma growth (P = 0.000), infarction progress (P = 0.003), and recurrent subarachnoid hemorrhage (SAH) (P = 0.011) were significantly lower in patients with SE than those without SE. Patients with SE had higher adjusted rates of fever ≥ 39 °C (odds ratio (OR): 2.753; 95% confidence interval (CI): 1.116 - 6.794; P = 0.028) and SIRS ≥ 3 items (OR: 6.459; 95% CI: 2.050 - 20.351; P = 0.001). The 30-day mortality in stroke patients with SE was higher than those without SE (76.1% vs. 45.8%, P = 0.003).

Conclusion

High fever and severe SIRS are two early predictors of stroke patients with SE, and survival rates were worse in stroke patients with SE than those without SE.

Metabolische Störungen

Im folgenden Kapitel werden die verschiedenen metabolischen Störungen betrachtet. Zunächst wird auf die allgemeinen und spezifischen neurologischen Komplikationen bei Organtransplantation eingegangen. Dann geht es um die metabolischen Enzephalopathien: Störungen der Gehirntätigkeit bei angeborenen und erworbenen Stoffwechselerkrankungen im engeren Sinn, Elektrolytstörungen, Hypovitaminosen, zerebrale Folgen einzelner Organdysfunktionen, zerebrale Hypoxien, Endotheliopathien und Mitochondropathien. Anschließend werden das Alkoholdelir und die Wernicke-Enzephalopathie erörtert. Bei zahlreichen akuten Erkrankungen von Gehirn, Rückenmark und peripherem Nervensystem treten typische Störungen vegetativer Systeme auf, deren Erkennung und Therapie insbesondere bei Intensivpatienten eine vitale Bedeutung haben kann: die autonomen Störungen. Bei der zentralen pontinen Myelinolyse kommt es zu einer akuten, vorwiegend fokal-symmetrischen Demyelinisierung im Hirnparenchym. Auch Basalganglienerkrankungen können intensivmedizinisch relevant werden. Und schließlich wird die akute Stressreaktion betrachtet, die aufgrund der vielfältigen metabolischen und endokrinen Veränderungen bei kritischen Erkrankungen entsteht. Gerade das RCVS als neuere Krankheitsentität und wichtige Differenzialdiagnose zur Vaskulitis des ZNS verdient einen eigenen Platz, in diesem Unterkapitel werden ebenfalls verwandte Syndrome wie die hypertensive Enzephalopathie und das PRES abgehandelt.

Clinical neurophysiological assessment of sepsis-associated brain dysfunction: a systematic review

Introduction

Several studies have reported the presence of electroencephalography (EEG) abnormalities or altered evoked potentials (EPs) during sepsis. However, the role of these tests in the diagnosis and prognostic assessment of sepsis-associated encephalopathy remains unclear.

Methods

We performed a systematic search for studies evaluating EEG and/or EPs in adult (≥18 years) patients with sepsis-associated encephalopathy. The following outcomes were extracted: a) incidence of EEG/EP abnormalities; b) diagnosis of sepsis-associated delirium or encephalopathy with EEG/EP; c) outcome.

Results

Among 1976 citations, 17 articles met the inclusion criteria. The incidence of EEG abnormalities during sepsis ranged from 12% to 100% for background abnormality and 6% to 12% for presence of triphasic waves. Two studies found that epileptiform discharges and electrographic seizures were more common in critically ill patients with than without sepsis. In one study, EEG background abnormalities were related to the presence and the severity of encephalopathy. Background slowing or suppression and the presence of triphasic waves were also associated with higher mortality. A few studies demonstrated that quantitative EEG analysis and EP could show significant differences in patients with sepsis compared to controls but their association with encephalopathy and outcome was not evaluated.

Conclusions

Abnormalities in EEG and EPs are present in the majority of septic patients. There is some evidence to support EEG use in the detection and prognostication of sepsis-associated encephalopathy, but further clinical investigation is needed to confirm this suggestion.

The E3 ubiquitin ligase TRIM62 and inflammation-induced skeletal muscle atrophy

Introduction

ICU-acquired weakness (ICUAW) complicates the disease course of critically ill patients. Inflammation and acute-phase response occur directly within myocytes and contribute to ICUAW. We observed that tripartite motif–containing 62 (TRIM62), an E3 ubiquitin ligase and modifier of inflammation, is increased in the skeletal muscle of ICUAW patients. We investigated the regulation and function of muscular TRIM62 in critical illness.

Methods

Twenty-six critically ill patients with Sequential Organ Failure Assessment scores ≥8 underwent two skeletal muscle biopsies from the vastus lateralis at median days 5 and 15 in the ICU. Four patients undergoing elective orthopedic surgery served as controls. TRIM62 expression and protein content were analyzed in these biopsies. The kinetics of Trim62, Atrogin1 and MuRF1 expression were determined in the gastrocnemius/plantaris and tibialis anterior muscles from mouse models of inflammation-, denervation- and starvation-induced muscle atrophy to differentiate between these contributors to ICUAW. Cultured myocytes were used for mechanistic analyses.

Results

TRIM62 expression and protein content were increased early and remained elevated in muscles from critically ill patients. In all three animal models, muscular Trim62 expression was early and continuously increased. Trim62 was expressed in myocytes, and its overexpression activated the atrophy-inducing activator protein 1 signal transduction pathway. Knockdown of Trim62 by small interfering RNA inhibited lipopolysaccharide-induced interleukin 6 expression.

Conclusions

TRIM62 is activated in the muscles of critically ill patients. It could play a role in the pathogenesis of ICUAW by activating and maintaining inflammation in myocytes.

Trial registration

Current Controlled Trials ID: ISRCTN77569430 (registered 13 February 2008)

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0545-6) contains supplementary material, which is available to authorized users.

Neuromuscular complications of critical illness

Neuromuscular sequelae are common in the critically ill. Critical illness polyneuropathy and critical illness myopathy are neuromuscular complications of sepsis or iatrogenic complications of treatments required in intensive care. This article discusses the diagnosis, treatment, and prognosis of these disorders based on a literature review. This review found that glycemic control, early mobilization, and judicious use of steroids and neuromuscular blocking agents are the primary approaches to reduce the incidence and severity of neuromuscular complications in affected patients.

Neurologic complications of sepsis

PURPOSE OF REVIEW

This article reviews the current understanding of sepsis, a critical and often fatal illness that results from infection and multiorgan failure and impacts the brain, peripheral nervous system, and muscle.

RECENT FINDINGS

Encephalopathy occurs early in association with sepsis, and its severity correlates with mortality. Neuroimaging in patients with CNS manifestations is typically normal. EEG is nonspecific. EMG is commonly diagnostic, showing a combination of nerve and muscle injury already early in the clinical course. Rapid recognition and correction of reversible causes of encephalopathy and avoidance of risk factors for intensive care unit-acquired weakness may limit sequelae. Major deficiencies in our understanding of the complications of sepsis remain. Studies to improve the recognition and rehabilitation of these patients are imperative in a clinical syndrome affecting countless patients each year.

SUMMARY

The risk of later cognitive and physical disability may be increased after sepsis; therefore, attention to neurologic complications is urgent.

Neuromuscular complications of critical illness

Patients admitted to intensive care units (ICUs) suffer from a wide range of neurological disorders. Some develop within the ICU rendering weakness and difficulty in weaning patients from ventilator support. ICUAW, or ICU acquired weakness, is a broad term that includes several more specific neuromuscular problems. After exclusion of other causes of weakness, ICUAW includes critical illness polyneuropathy (CIP), first described by Charles Bolton, critical illness myopathy (CIM), and disorders of neuromuscular junction transmission. This chapter reviews the clinical, electrophysiological, and pathological features of these conditions and provides clinicians with approaches toward diagnosing and investigating ICUAW.

Inflammation-induced acute phase response in skeletal muscle and critical illness myopathy

Objectives

Systemic inflammation is a major risk factor for critical-illness myopathy (CIM) but its pathogenic role in muscle is uncertain. We observed that interleukin 6 (IL-6) and serum amyloid A1 (SAA1) expression was upregulated in muscle of critically ill patients. To test the relevance of these responses we assessed inflammation and acute-phase response at early and late time points in muscle of patients at risk for CIM.

Design

Prospective observational clinical study and prospective animal trial.

Setting

Two intensive care units (ICU) and research laboratory.

Patients/Subjects

33 patients with Sequential Organ Failure Assessment scores ≥8 on 3 consecutive days within 5 days in ICU were investigated. A subgroup analysis of 12 patients with, and 18 patients without CIM (non-CIM) was performed. Two consecutive biopsies from vastus lateralis were obtained at median days 5 and 15, early and late time points. Controls were 5 healthy subjects undergoing elective orthopedic surgery. A septic mouse model and cultured myoblasts were used for mechanistic analyses.

Measurements and Main Results

Early SAA1 expression was significantly higher in skeletal muscle of CIM compared to non-CIM patients. Immunohistochemistry showed SAA1 accumulations in muscle of CIM patients at the early time point, which resolved later. SAA1 expression was induced by IL-6 and tumor necrosis factor-alpha in human and mouse myocytes in vitro. Inflammation-induced muscular SAA1 accumulation was reproduced in a sepsis mouse model.

Conclusions

Skeletal muscle contributes to general inflammation and acute-phase response in CIM patients. Muscular SAA1 could be important for CIM pathogenesis.

Trial Registration

ISRCTN77569430.

Septic encephalopathy

Every year, more cases of sepsis appear in intensive care units. The most frequent complication of sepsis is septic encephalopathy (SE), which is also the essential determinant of mortality. Despite many years of research, it still is not known at which stage of sepsis the first signs of SE appear; however, it is considered the most frequent form of encephalopathy. Patients have dysfunction of cognitive abilities and consciousness, and sometimes even epileptic seizures. Despite intensive treatment, the effects of SE remain for many years and constitute an important social problem. Numerous studies indicate that changes in the brain involve free radicals, nitric oxide, increased synthesis of inflammatory factors, disturbances in cerebral circulation, microthromboses, and ischemia, which cause considerable neuronal destruction in different areas of the brain. To determine at what point during sepsis the first signs of SE appear, different experimental models are needed to detect the aforementioned changes and to select the proper therapy for this syndrome.

Sepsis Associated Encephalopathy

Sepsis associated encephalopathy (SAE) is a common but poorly understood neurological complication of sepsis. It is characterized by diffuse brain dysfunction secondary to infection elsewhere in the body without overt CNS infection. The pathophysiology of SAE is complex and multifactorial including a number of intertwined mechanisms such as vascular damage, endothelial activation, breakdown of the blood brain barrier, altered brain signaling, brain inflammation, and apoptosis. Clinical presentation of SAE may range from mild symptoms such as malaise and concentration deficits to deep coma. The evaluation of cognitive dysfunction is made difficult by the absence of any specific investigations or biomarkers and the common use of sedation in critically ill patients. SAE thus remains diagnosis of exclusion which can only be made after ruling out other causes of altered mentation in a febrile, critically ill patient by appropriate investigations. In spite of high mortality rate, management of SAE is limited to treatment of the underlying infection and symptomatic treatment for delirium and seizures. It is important to be aware of this condition because SAE may present in early stages of sepsis, even before the diagnostic criteria for sepsis can be met. This review discusses the diagnostic approach to patients with SAE along with its epidemiology, pathophysiology, clinical presentation, and differential diagnosis.