Bispectral EEG (BSEEG) quantifying neuro-inflammation in mice induced by systemic inflammation: A potential mouse model of delirium

The Pathophysiology and Biomarkers of Delirium

Delirium is a major disturbance in the mental state characterized by fluctuations in arousal, deficits in attention, distorted perception, and disruptions in memory and cognitive processing. Delirium affects approximately 18% to 25% of hospital inpatients, with even higher rates observed during critical illness. To develop therapies to shorten the duration and limit the adverse effects of delirium, it is important to understand the mechanisms underlying its presentation. Neuroimaging modalities such as magnetic resonance imaging (MRI), positron emission tomography, functional MRI, and near-infrared spectroscopy point to global atrophy, white matter changes, and disruptions in cerebral blood flow, oxygenation, metabolism, and connectivity as key correlates of delirium pathogenesis. Electroencephalography demonstrates generalized slowing of normal background activity, with pathologic decreases in variability of oscillatory patterns and disruptions in functional connectivity among specific brain regions. Elevated serum biomarkers of inflammation, including interleukin-6, C-reactive protein, and S100B, suggest a role of dysregulated inflammatory processes and cellular metabolism, particularly in perioperative and sepsis-related delirium. Emerging animal models that can mimic delirium-like clinical states will reveal further insights into delirium pathophysiology. The combination of clinical and basic science methods of exploring delirium shows great promise in elucidating its underlying mechanisms and revealing potential therapeutic targets.

Discovery of novel protective agents for infection-related delirium through bispectral electroencephalography

Delirium is a multifactorial medical condition of waxing and waning impairment across various domains of mental functioning over time. Importantly, delirium is also one of the greatest risk factors for prolonged hospitalization, morbidity, and mortality. Studying this important condition is challenging due to the difficulty in both objective diagnosis in patients and validation of laboratory models. As a result, there is a lack of protective treatments for delirium. Our recent studies report the efficacy of bispectral electroencephalography (BSEEG) in diagnosing delirium in patients and predicting patient outcomes, advancing the concept that this simple measure could represent an additional vital sign for patients. Here, we applied BSEEG to characterize and validate a novel lipopolysaccharide (LPS) mouse model of infection-related delirium. We then applied this model to evaluate the protective efficacy of three putative therapeutic agents: the conventional antipsychotic medication haloperidol, the neuroprotective compound P7C3-A20, and the antibiotic minocycline. Aged mice were more susceptible than young mice to LPS-induced aberration in BSEEG, reminiscent of the greater vulnerability of older adults to delirium. In both young and old mice, P7C3-A20 and minocycline administration prevented LPS-induced BSEEG abnormality. By contrast, haloperidol did not. P7C3-A20 and minocycline have been shown to limit different aspects of LPS toxicity, and our data offers proof of principle that these agents might help protect patients from developing infection-related delirium. Thus, utilization of BSEEG in a mouse model for infection-related delirium can identify putative therapeutic agents for applications in patient clinical trials.

The Bispectral Electroencephalography Method Quantifies Postoperative Delirium-Like States in Young and Aged Male Mice After Head-Mount Implantation Surgery

Delirium, a syndrome characterized by an acute change in attention, awareness, and cognition, is commonly observed in older adults, although there are few quantitative monitoring methods in the clinical setting. We developed a bispectral electroencephalography (BSEEG) method capable of detecting delirium and can quantify the severity of delirium using a novel algorithm. Preclinical application of this novel BSEEG method can capture a delirium-like state in mice following lipopolysaccharide administration. However, its application to postoperative delirium (POD) has not yet been validated in animal experiments. This study aimed to create a POD model in mice with the BSEEG method by monitoring BSEEG scores following EEG head-mount implantation surgery and throughout the recovery. We compared the BSEEG scores of C57BL/6J young (2-3 months old) with aged (18-19 months old) male mice for quantitative evaluation of POD-like states. Postoperatively, both groups displayed increased BSEEG scores and a loss of regular diurnal changes in BSEEG scores. In young mice, BSEEG scores and regular diurnal changes recovered relatively quickly to baseline by postoperative day (PO-Day) 3. Conversely, aged mice exhibited prolonged increases in postoperative BSEEG scores and it reached steady states only after PO-Day 8. This study suggests that the BSEEG method can be utilized as a quantitative measure of POD and assess the effect of aging on recovery from POD in the preclinical model.

Exploring the Pathophysiology of Delirium: An Overview of Biomarker Studies, Animal Models, and Tissue-Engineered Models

Delirium is an acute brain disorder associated with disorganized thinking, difficulty focusing, and confusion that commonly follows major surgery, severe infection, and illness. Older patients are at high risk for developing delirium during hospitalization, which may contribute to increased morbidity, longer hospitalization, and increased risk of institutionalization following discharge. The pathophysiology underlying delirium remains poorly studied. This review delves into the findings from biomarker studies and animal models, and highlights the potential for tissue-engineered models of the brain in studying this condition. The aim is to bring together the existing knowledge in the field and provide insight into the future direction of delirium research.

Live and Recorded Music Interventions to Reduce Postoperative Pain: Protocol for a Nonrandomized Controlled Trial

BACKGROUND

Postoperative patients who were previously engaged in the live musical intervention Meaningful Music in Healthcare reported significantly reduced perception of pain than patients without the intervention. This encouraging finding indicates a potential for postsurgical musical interventions to have a place in standard care as therapeutic pain relief. However, live music is logistically complex in hospital settings, and previous studies have reported the more cost-effective recorded music to serve as a similar pain-reducing function in postsurgical patients. Moreover, little is known about the potential underlying physiological mechanisms that may be responsible for the reduced pain perceived by patients after the live music intervention.

OBJECTIVE

The primary objective is to see whether a live music intervention can significantly lower perceived postoperative pain compared to a recorded music intervention and do-nothing control. The secondary objective is to explore the neuroinflammatory underpinnings of postoperative pain and the potential role of a music intervention in mitigating neuroinflammation.

METHODS

This intervention study will compare subjective postsurgical pain ratings among 3 groups: live music intervention, recorded music intervention, and standard care control. The design will take the form of an on-off nonrandomized controlled trial. Adult patients undergoing elective surgery will be invited to participate. The intervention is a daily music session of up to 30 minutes for a maximum of 5 days. The live music intervention group is visited by professional musicians once a day for 15 minutes and will be asked to interact. The recorded music active control intervention group receives 15 minutes of preselected music over headphones. The do-nothing group receives typical postsurgical care that does not include music.

RESULTS

At study completion, we will have an empirical indication of whether live music or recorded music has a significant impact on postoperative perceived pain. We hypothesize that the live music intervention will have more impact than recorded music but that both will reduce the perceived pain more than care-as-usual. We will moreover have the preliminary evidence of the physiological underpinnings responsible for reducing the perceived pain during a music intervention, from which hypotheses for future research may be derived.

CONCLUSIONS

Live music can provide relief from pain experienced by patients recovering from surgery; however, it is not known to what degree live music improves the patients' pain experience than the logistically simpler alternative of recorded music. Upon completion, this study will be able to statistically compare live versus recorded music. This study will moreover be able to provide insight into the neurophysiological mechanisms involved in reduced pain perception as a result of postoperative music listening.

TRIAL REGISTRATION

The Netherlands Central Commission on Human Research NL76900.042.21; https://www.toetsingonline.nl/to/ccmo_search.nsf/fABRpop?readform&unids=F2CA4A88E6040A45C1258791001AEA44.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/40034.

Altered EEG, disrupted hippocampal long-term potentiation and neurobehavioral deficits implicate a delirium-like state in a mouse model of sepsis

Sepsis and systemic inflammation are often accompanied by severe encephalopathy, sleep disruption and delirium that strongly correlate with poor clinical outcomes including long-term cognitive deficits. The cardinal manifestations of delirium are fluctuating altered mental status and inattention, identified in critically ill patients by interactive bedside assessment. The lack of analogous assessments in mouse models or clear biomarkers is a challenge to preclinical studies of delirium. In this study, we utilized concurrent measures of telemetric EEG recordings and neurobehavioral tasks in mice to characterize inattention and persistent cognitive deficits following polymicrobial sepsis. During the 24-hour critical illness period for the mice, slow-wave EEG dominance, sleep disruption, and hypersensitivity to auditory stimuli in neurobehavioral tasks resembled clinical observations in delirious patients in which alterations in similar outcome measurements, although measured differently in mice and humans, are reported. Mice were tested for nest building ability 7 days after sepsis induction, when sickness behaviors and spontaneous activity had returned to baseline. Animals that showed persistent deficits determined by poor nest building at 7 days also exhibited molecular changes in hippocampal long-term potentiation compared to mice that returned to baseline cognitive performance. Together, these behavioral and electrophysiological biomarkers offer a robust mouse model with which to further probe molecular pathways underlying brain and behavioral changes during and after acute illness such as sepsis.

A randomized controlled trial into the effects of probiotics on electroencephalography in preschoolers with autism

LAY ABSTRACT

This study investigates the effects of a probiotic on preschoolers' brain electrical activity with autism spectrum disorder. Autism is a disorder with an increasing prevalence characterized by an enormous individual, family, and social cost. Although the etiology of autism spectrum disorder is unknown, an interaction between genetic and environmental factors is implicated, converging in altered brain synaptogenesis and, therefore, connectivity. Besides deepening the knowledge on the resting brain electrical activity that characterizes this disorder, this study allows analyzing the positive central effects of a 6-month therapy with a probiotic through a randomized, double-blind placebo-controlled study and the correlations between electroencephalography activity and biochemical and clinical parameters. In subjects treated with probiotics, we observed a decrease of power in frontopolar regions in beta and gamma bands, and increased coherence in the same bands together with a shift in frontal asymmetry, which suggests a modification toward a typical brain activity. Electroencephalography measures were significantly correlated with clinical and biochemical measures. These findings support the importance of further investigations on probiotics' benefits in autism spectrum disorder to better elucidate mechanistic links between probiotics supplementation and changes in brain activity.

IκB kinase inhibition remodeled connexins, pannexin-1, and excitatory amino-acid transporters expressions to promote neuroprotection of galantamine and morphine

Inflammatory pathway and disruption in glutamate homeostasis join at the level of the glia, resulting in various neurological disorders. In vitro studies have provided evidence that membrane proteins connexions (Cxs) are involved in glutamate release, meanwhile, excitatory amino-acid transporters (EAATs) are crucial for glutamate reuptake (clearance). Moreover, pannexin-1 (Panx-1) activation is more detrimental to neurons. Their expression patterns during inflammation and the impacts of IκB kinase (IKK) inhibition, morphine, and galantamine on the inflammatory-associated glutamate imbalance remain elusive. To investigate this, rats were injected with saline or lipopolysaccharide. Thereafter, vehicles, morphine, galantamine, and BAY-117082 were administered in different groups of animals. Subsequently, electroencephalography, enzyme-linked immunosorbent assay, western blot, and histopathological examinations were carried out and various indicators of inflammation and glutamate level were determined. Parallel analysis of Cxs, Panx-1, and EAAts in the brain was performed. Our findings strengthen the concept that unregulated expressions of Cxs, Panx-1, and EAATs contribute to glutamate accumulation and neuronal cell loss. Nuclear factor-kB (NF-κB) pathway can significantly contribute to glutamate homeostasis via modulating Cxs, Panx-1, and EAATs expressions. BAY-117082, via inhibition of IkK, promoted the anti-inflammatory effects of morphine as well as galantamine. We concluded that NF-κB is an important component of reshaping the expressions of Cxs, panx-1, and EAATs and the development of glutamate-induced neuronal degeneration.

(R)-Ketamine attenuates LPS-induced endotoxin-derived delirium through inhibition of neuroinflammation

RATIONALE

(R)-Ketamine produced beneficial effects in a variety of models of inflammatory diseases, including low dose of bacterial lipopolysaccharide (LPS) (0.5-1.0 mg/kg)-induced endotoxemia. LPS-treated mice have been used as animal model of delirium.

OBJECTIVES

We investigated the effects of (R)-ketamine in neuroinflammation and cognitive impairment in rodents after administration of high dose of LPS.

METHODS

LPS (5 mg/kg) or saline was administered intraperitoneally (i.p.) to mice. (R)-Ketamine (10 mg/kg) was administrated i.p. 24 h before and/or 10 min after LPS injection.

RESULTS

LPS (5.0 mg/kg) caused a remarkable splenomegaly and increased plasma levels of pro-inflammatory cytokines [i.e., interleukin (IL-6), IL-17A, and interferon (IFN)-γ]. There were positive correlations between spleen weight and plasma cytokines levels. Furthermore, LPS led to increased levels of pro-inflammatory cytokines in the prefrontal cortex (PFC) and hippocampus. Moreover, LPS impaired the natural and learned behaviors, as demonstrated by a decrease in the number of mice's entries and duration in the novel arm in the Y maze test and an increase in the latency of mice to eat the food in the buried food test. Interestingly, the treatment with (R)-ketamine (twice 24 h before and 10 min after LPS injection) significantly attenuated LPS-induced splenomegaly, central and systemic inflammation, and cognitive impairment.

CONCLUSION

Our results highlighted the importance of combined prophylactic and therapeutic use of (R)-ketamine in the attenuation of LPS-induced systemic inflammation, neuroinflammation, and cognitive impairment in mice. It is likely that (R)-ketamine could be a prophylactic drug for delirium.

Evaluation of point-of-care thumb-size bispectral electroencephalography device to quantify delirium severity and predict mortality

BACKGROUND

We have developed the bispectral electroencephalography (BSEEG) method for detection of delirium and prediction of poor outcomes.

AIMS

To improve the BSEEG method by introducing a new EEG device.

METHOD

In a prospective cohort study, EEG data were obtained and BSEEG scores were calculated. BSEEG scores were filtered on the basis of standard deviation (s.d.) values to exclude signals with high noise. Both non-filtered and s.d.-filtered BSEEG scores were analysed. BSEEG scores were compared with the results of three delirium screening scales: the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU), the Delirium Rating Scale-Revised-98 (DRS) and the Delirium Observation Screening Scale (DOSS). Additionally, the 365-day mortalities and the length of stay (LOS) in the hospital were analysed.

RESULTS

We enrolled 279 elderly participants and obtained 620 BSEEG recordings; 142 participants were categorised as BSEEG-positive, reflecting slower EEG activity. BSEEG scores were higher in the CAM-ICU-positive group than in the CAM-ICU-negative group. There were significant correlations between BSEEG scores and scores on the DRS and the DOSS. The mortality rate of the BSEEG-positive group was significantly higher than that of the BSEEG-negative group. The LOS of the BSEEG-positive group was longer compared with that of the BSEEG-negative group. BSEEG scores after s.d. filtering showed stronger correlations with delirium screening scores and more significant prediction of mortality.

CONCLUSIONS

We confirmed the usefulness of the BSEEG method for detection of delirium and of delirium severity, and prediction of patient outcomes with a new EEG device.

Mortality among patients with sepsis associated with a bispectral electroencephalography (BSEEG) score

We have previously developed a bispectral electroencephalography (BSEEG) device, which was shown to be effective in detecting delirium and predicting patient outcomes. In this study we aimed to apply the BSEEG approach for a sepsis. This was a retrospective cohort study conducted at a single center. Sepsis-positive cases were identified based on retrospective chart review. EEG raw data and calculated BSEEG scores were obtained in the previous studies. The relationship between BSEEG scores and sepsis was analyzed, as well as the relationship among sepsis, BSEEG score, and mortality. Data were analyzed from 628 patients. The BSEEG score from the first encounter (1st BSEEG) showed a significant difference between patients with and without sepsis (p = 0.0062), although AUC was very small indicating that it is not suitable for detection purpose. Sepsis patients with high BSEEG scores showed the highest mortality, and non-sepsis patients with low BSEEG scores showed the lowest mortality. Mortality of non-sepsis patients with high BSEEG scores was as bad as that of sepsis patients with low BSEEG scores. Even adjusting for age, gender, comorbidity, and sepsis status, BSEEG remained a significant predictor of mortality (p = 0.008). These data are demonstrating its usefulness as a potential tool for identification of patients at high risk and management of sepsis.

Mortality prediction by bispectral electroencephalography among 502 patients: its role in dementia

Complications of delirium and dementia increase mortality; however, it is difficult to diagnose delirium accurately, especially among dementia patients. The bispectral electroencephalography score can detect delirium and predict mortality in elderly patients. We aimed to develop an efficient and reliable bispectral electroencephalography device for high-throughput screening. We also hypothesized that bispectral electroencephalography score can predict mortality among dementia patients. A prospective cohort study was conducted between January 2016 and December 2018 to measure bispectral electroencephalography from elderly patients and correlate with outcomes. A total of 502 elderly (55 years old or older) patients with and without dementia were enrolled. For a replication of the utility of bispectral electroencephalography, mortalities between bispectral electroencephalography-positive and bispectral electroencephalography-negative group were compared. In addition, patients with and without dementia status were added to examine the utility of bispectral electroencephalography among dementia patients. The mortality within 180 days in the bispectral electroencephalography-positive group was higher than that of the bispectral electroencephalography-negative group in both the replication and the total cohorts. Mortality of those in the bispectral electroencephalography-positive group showed a dose-dependent increase in both cohorts. When the dementia patients showed bispectral electroencephalography positive, their mortality was significantly higher than those with dementia but who were bispectral electroencephalography-negative. Mortality within 30 days in the bispectral electroencephalography-positive group was significantly higher than that of the bispectral electroencephalography-negative group. The utility of the bispectral electroencephalography to predict mortality among large sample of 502 elderly patients was shown. The bispectral electroencephalography score can predict mortality among elderly patients in general, and even among dementia patients, as soon as 30 days.