Pharmacological perioperative brain neuroprotection: a qualitative review of randomized clinical trials

Effects of mid‑gestational sevoflurane and magnesium sulfate on maternal oxidative stress, inflammation and fetal brain histopathology

Models of inflammation, oxidative stress, hyperoxia and hypoxia have demonstrated that magnesium sulfate (MgSO4), a commonly used drug in obstetrics, has neuroprotective potential. In the present study, the effects of MgSO4 treatment on inflammation, oxidative stress and fetal brain histopathology were evaluated in an experimental rat model following sevoflurane (Sv) exposure during the mid-gestational period. Rats were randomly divided into groups: C (control; no injections or anesthesia), Sv (exposure to 2.5% Sv for 2 h), MgSO4 (administered 270 mg/kg MgSO4 intraperitoneally) and Sv + MgSO4 (Sv administered 30 min after MgSO4 injection). Inflammatory and oxidative stress markers were measured in the serum and neurotoxicity was investigated histopathologically in fetal brain tissue. Short-term mid-gestational exposure to a 1.1 minimum alveolar concentration of Sv did not significantly increase the levels of any of the measured biochemical markers, except for TNF-α. Histopathological evaluations demonstrated no findings suggestive of pathological apoptosis, neuroinflammation or oxidative stress-induced cell damage. MgSO4 injection prior to anesthesia caused no significant differences in biochemical or histopathological marker levels compared to the C and Sv groups. The present study indicated that short-term exposure to Sv could potentially be considered a harmless external stimulus to the fetal brain.

A Comprehensive Review on the Role of Melatonin's Anesthetic Applications in Pediatric Care

Anesthesia is critical to pediatric care, ensuring the safety and comfort of children undergoing medical procedures. With a growing interest in alternative anesthetic agents, melatonin has emerged as a promising candidate due to its sedative, analgesic, anti-inflammatory, and neuroprotective properties. This comprehensive review explores the potential applications of melatonin in pediatric anesthesia. We delve into the pharmacological characteristics of melatonin, its anesthetic properties, and its clinical applications in pediatric care, including preoperative sedation, adjunct to general anesthesia, postoperative pain management, and prevention of emergence delirium. Additionally, we discuss the safety profile of melatonin, potential adverse effects, and comparative analysis with traditional anesthetics. Finally, we highlight future research directions to provide insights into melatonin's role in pediatric anesthesia and its implications for clinical practice.

Comprehensive Perioperative Approach to Complex Spine Deformity Management

OBJECTIVE

Study perioperative strategies for optimizing neuroprotection in complex spine deformity correction surgery.

METHODS

We report the case of a patient with severe lumbar dextroscoliosis, thoracolumbar junction hyperkyphosis with a 40-degree Cobb angle levoconvex scoliosis who underwent spinal deformity correction with loss of neuromonitoring during surgery. We performed a literature review on perioperative management of complex spine deformity.

RESULTS

A 50-year-old man presented with lumbar pain and right L4 radiculopathy. Surgical intervention for deformity correction and decompression was indicated with T4-L4 posterior instrumentation L2/L3 and L3/L4 transforaminal lumbar interbody fusion. Surgery was aborted due to the loss of neuromonitoring. Postsurgery, the patient had left sensory deficit and the neurocritical care team clinically suspected and deduced the anatomic location of the spinal cord compression. Magnetic resonance imaging confirmed a T10-T11 hyperintensity suggestive of cord ischemia due to osteophyte compressing the spinal cord. The patient underwent a second corrective surgery with no intraoperative events and has no long-term neurological sequela.

CONCLUSIONS

This case illustrates that a comprehensive perioperative approach and individualized risk factor assessment is useful in complex spine deformity surgery. Further research is needed to determine how this individualized comprehensive approach can lead to intraoperative and postoperative countermeasures that improved spine surgery outcomes.

LEVEL OF EVIDENCE

Level V.

Protective Effects of Remimazolam on Cerebral Ischemia/Reperfusion Injury in Rats by Inhibiting of NLRP3 Inflammasome-Dependent Pyroptosis

INTRODUCTION

Remimazolam is a novel benzodiazepine γ-aminobutyric acid A (GABAa) receptor agonist used for sedation and the induction as well as maintenance of general anesthesia. Previous research proved that anesthetic agents acting on GABAa receptor, such as thiopentone, propofol and midazolam, have protective actions for cerebral ischemia/reperfusion (I/R) injury. We here probed into remimazolam for its protective effect and potential mechanism of action against cerebral I/R injury.

MATERIAL AND METHODS

A rat model of middle cerebral artery occlusion (MCAO) with focal transient cerebral I/R injury was established and was given tail vein injection of gradient remimazolam (5, 10, 20 mg/kg) after 2 h of ischemia. Following 24 h of reperfusion, neurological function, brain infarct volume, morphology of cerebral cortical neurons, and expressions of corticocerebral NLRP3, ASC, caspase-1, GSDMD, IL-1β and IL-18 were evaluated.

RESULTS

The results showed that remimazolam could effectively improve the neurological dysfunction, reduce the infarct volume and alleviate the damage of cortical neurons after I/R injury. Notably, the expression of NLRP3 inflammasome pathway was down-regulated, suggesting that remimazolam exerted protective actions on I/R injury by suppressing pyroptosis with decreased expression and release of inflammatory factors, and the involvement of the NLRP3 inflammasome pathway might be the core during that process. Overall, our results indicate that NLRP3 inflammation is a promising target.

CONCLUSION

Based on this mechanism, remimazolam may be one of the ideal anesthetic drugs for patients with ischemic stroke.

Optimal brain protection in aortic arch surgery

There is considerable debate with regard to the optimal cerebral protection strategy during aortic arch surgery. There are three contemporary techniques in use which include straight deep hypothermic circulatory arrest (DHCA), DHCA with retrograde cerebral perfusion (DHCA + RCP), and moderate hypothermic circulatory arrest with antegrade cerebral perfusion (MHCA + ACP). Appropriate application of these methods ensures appropriate cerebral, myocardial, and visceral protection. Each of these techniques has benefits and drawbacks and ensuring coordinated circulation management strategy is critical to safe performance of aortic arch surgery. In this report, we will review various cannulation strategies, review logistics of hypothermia, and review the relevant literature to outline the strengths and weaknesses of these various cerebral protection strategies.

Prophylactic Effects of Sub-anesthesia Ketamine on Cognitive Decline, Neuroinflammation, and Oxidative Stress in Elderly Mice

Cognitive dysfunction is a very common postoperative complication. The study aimed at investigating the effects of ketamine on the cognition of elderly mice after anesthesia and surgery (AS). We reported that AS impaired the cognition of elderly mice, while ketamine helped to maintain the cognitive function. Ketamine decreased the levels of TNF-α, IL-6, IL-1β and the expression of p-TAU, S100B in hippocampal induced by AS. In addition, AS triggered severe oxidative stress in hippocampal, while ketamine inhibited it. Oxidative stress induced autophagy of hippocampal neurons via inhibiting PI3K/AKT/mTOR pathway. Ketamine could activate PI3K pathway and inhibit autophagy in hippocampal, thus maintain the loss of hippocampal neurons. The study suggested that ketamine inhibited the neuroinflammation and oxidative stress, reduced the autophagy of hippocampal neurons via PI3K/AKT/mTOR pathway. It may provide novel methods for the protection of cognitive function in elderly during perioperative period.

The surgical management of intraoperative intracranial internal carotid artery injury in open skull base surgery-a systematic review

Intraoperative internal carotid artery (ICA) injury during open skull base surgery is a catastrophic complication. Multiple techniques and management strategies have been reported for endoscopic skull base surgery; however, the literature on managing this complication in open skull base surgery is limited. To perform a systematic review and give an overview of the different techniques described to manage this complication intraoperatively, a systematic review was conducted in PubMed, Ovid Medline, Ovid Embase and Scopus for literature published until July 2021. Titles and abstracts were screened. Studies meeting prespecified inclusion criteria were reviewed in full. PRISMA guidelines were strictly adhered to. Out of 4492 articles, only 12 articles could be included, reflecting an underreporting of open skull base ICA injuries. Multiple techniques can be used depending on the location and size of the injury as well as the surgeon's experience. Described techniques include the following: a primary repair via a micro-suture or nonpenetrating clips; wrapping or plugging; coating; occlusion of the parent artery with or without a bypass; packing with further endovascular management. A treatment algorithm is proposed.

Brain Herniation and Intracranial Hypertension

This article introduces the basic concepts of intracranial physiology and pressure dynamics. It also includes discussion of signs and symptoms and examination and radiographic findings of patients with acute cerebral herniation as a result of increased as well as decreased intracranial pressure. Current best practices regarding medical and surgical treatments and approaches to management of intracranial hypertension as well as future directions are reviewed. Lastly, there is discussion of some of the implications of critical medical illness (sepsis, liver failure, and renal failure) and treatments thereof on causation or worsening of cerebral edema, intracranial hypertension, and cerebral herniation.

Intranasal Insulin Administration to Prevent Delayed Neurocognitive Recovery and Postoperative Neurocognitive Disorder: A Narrative Review

Delayed neurocognitive recovery and postoperative neurocognitive disorders are major complications of surgery, hospitalization, and anesthesia that are receiving increasing attention. Their incidence is reported to be 10–80% after cardiac surgery and 10–26% after non-cardiac surgery. Some of the risk factors include advanced age, level of education, history of diabetes mellitus, malnutrition, perioperative hyperglycemia, depth of anesthesia, blood pressure fluctuation during surgery, chronic respiratory diseases, etc. Scientific evidence suggests a causal association between anesthesia and delayed neurocognitive recovery or postoperative neurocognitive disorders, and various pathophysiological mechanisms have been proposed: mitochondrial dysfunction, neuroinflammation, increase in tau protein phosphorylation, accumulation of amyloid-β protein, etc. Insulin receptors in the central nervous system have a non-metabolic role and act through a neuromodulator-like action, while an interaction between anesthetics and central nervous system insulin receptors might contribute to anesthesia-induced delayed neurocognitive recovery or postoperative neurocognitive disorders. Acute or chronic intranasal insulin administration, which has no influence on the blood glucose concentration, appears to improve working memory, verbal fluency, attention, recognition of objects, etc., in animal models, cognitively healthy humans, and memory-impaired patients by restoring the insulin receptor signaling pathway, attenuating anesthesia-induced tau protein hyperphosphorylation, etc. The aim of this review is to report preclinical and clinical evidence of the implication of intranasal insulin for preventing changes in the brain molecular pattern and/or neurobehavioral impairment, which influence anesthesia-induced delayed neurocognitive recovery or postoperative neurocognitive disorders.

The Effect of Intraoperative Magnesium Sulphate Infusion on Emergence Agitation after Ambulatory Ophthalmic Surgery in Children

This study investigated whether intraoperative infusion of magnesium sulphate reduces the incidence of emergence agitation (EA) in paediatric patients who undergo ambulatory ophthalmic surgery using the Paediatric Anaesthesia Emergence Delirium (PAED) scale. Ninety-two paediatric patients who were scheduled for elective ophthalmic surgery were randomly allocated to two groups: control or magnesium. In the magnesium group, patients received an initial intravenous loading dose of 30 mg/kg of 10% solution of magnesium sulphate over 10 min and then a continuous infusion of 10 mg/kg×h during the surgery. In the control group, an equal volume of 0.9% isotonic saline was administered in the same way as in the magnesium group. The PAED scale was assessed at 15-min intervals until the PAED score reached below 10 at the postanaesthetic care unit. EA was defined as a PAED score of 10 or higher. Of the 86 patients recruited, 44 and 42 were allocated to the control and magnesium groups, respectively. The incidence of EA was 77.3% in the control group and 57.1% in the magnesium group (odds ratio, 0.392; 95% confidence interval, 0.154 to 0.997; p = 0.046). The intraoperative infusion of magnesium sulphate significantly reduced the incidence of EA.

Effect of perioperative intravenous lidocaine on the incidence of short-term cognitive function after noncardiac surgery: A meta-analysis based on randomized controlled trials

OBJECTIVES

Postoperative cognitive dysfunction is a debilitating postoperative complication. The perioperative neuroprotective effect of lidocaine has conflicting results.

METHODS

In this qualitative review of randomized controlled clinical trials on the perioperative use of lidocaine, we report the effects of intravenous lidocaine on brain function after noncardiac surgery. Studies were identified from PubMed, MEDLINE, and Cochrane Central Register.

RESULTS

Of the 453 retrieved studies, 4 randomized trials were included. No significant association between the use of lidocaine postoperative cognitive states was found (risk ratio 0.67; 95% CI -0.02 to 1.36; I² 89%; p = .06).

CONCLUSIONS

Current evidence cannot suggest that perioperative intravenous use of lidocaine has pharmacological brain neuroprotection after noncardiac surgery. All the included studies were small-scale research, and the total number of participants was small; the results should be interpreted with caution.

Does electroencephalographic burst suppression still play a role in the perioperative setting?

With the widespread use of electroencephalogram [EEG] monitoring during surgery or in the Intensive Care Unit [ICU], clinicians can sometimes face the pattern of burst suppression [BS]. The BS pattern corresponds to the continuous quasi-periodic alternation between high-voltage slow waves [the bursts] and periods of low voltage or even isoelectricity of the EEG signal [the suppression] and is extremely rare outside ICU and the operative room. BS can be secondary to increased anesthetic depth or a marker of cerebral damage, as a therapeutic endpoint [i.e., refractory status epilepticus or refractory intracranial hypertension]. In this review, we report the neurophysiological features of BS to better define its role during intraoperative and critical care settings.

Temperature management in acute brain injury: A systematic review of clinical evidence

Temperature alterations in neurocritical care settings are common and have a striking effect on brain metabolism leading to or exacerbating neuronal injury. Hyperthermia worsens acute brain injury (ABI) patients outcome. However conclusive evidence linking control of temperature to improved outcome is still lacking. This review article report an update -results from clinical studies published between March 2006 and March 2020- on the relationship between hyperthermia or Target Temperature Management and functional outcome or mortality in ABI patients.

MATERIALS AND METHODS

A systematic search of articles in PubMed and EMBASE database was accomplished. Only complete studies, published in English in peer-reviewed journals were included.

RESULTS

A total of 63 articles into 5 subchapters are presented: acute ischemic stroke (17), subarachnoid hemorrhage (14), brain trauma (14), intracranial hemorrhage (8), and mixed acute brain injury (10). This evidence confirm and extend the negative impact of hyperthermia in ABI patients on worse functional outcome and higher mortality. In particular "early hyperthermia" in AIS patients seems to have a protective role have as promoting factor of clot lysis but no conclusive evidence is available. Normothermic TTM seems to have a positive effect on TBI patients in a reduced mortality rate compared to hypothermic TTM.

CONCLUSIONS

Hyperthermia in ABI patients is associated with worse functional outcome and higher mortality. The use of normothermic TTM has an established indication only in TBI; further studies are needed to define the role and the indications of normothermic TTM in ABI patients.

Exogenous GM1 Ganglioside Attenuates Ketamine-Induced Neurocognitive Impairment in the Developing Rat Brain

BACKGROUND

A prolonged exposure to ketamine triggers significant neurodegeneration and long-term neurocognitive deficits in the developing brain. Monosialotetrahexosylganglioside (GM1) can limit the neuronal damage from necrosis and apoptosis in neurodegenerative conditions. We aimed to assess whether GM1 can prevent ketamine-induced developmental neurotoxicity.

METHODS

Postnatal day 7 (P7) rat pups received 5 doses of intraperitoneal ketamine (20 mg/kg per dose) at 90-minute intervals for 6 hours. Cognitive functions, determined by using Morris water maze (MWM) including escape latency (at P32-36) and platform crossing (at P37), were compared among the ketamine-exposed pups treated with or without exogenous GM1 (30 mg/kg; n = 12/group). The effect of GM1 on apoptosis in hippocampus was determined by terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling (TUNEL) staining and activated caspase 3 measurement. The hippocampal expression of brain-derived neurotrophic factor (BDNF), along with the phosphorylation of protein kinase B (AKT) and extracellular signal-related kinases 1 and 2 (ERK1/2), was detected by western blotting (n = 6/group). Anti-BDNF antibody (2 μg per rat) administered before GM1 treatment was applied to determine the neuroprotective mechanisms of GM1.

RESULTS

The rats receiving ketamine exposure experinced cognitive impairment in MWM test compared to the control rats, indicated by prolonged escape latency at P34 (P = .006), P35 (P = .002), and P36 (P = .005). However, in GM1-pretreated rats, ketamine exposure did not induce prolonged escape latency. The exogenous GM1 increased the platform-crossing times at P37 (3.00 ± 2.22 times vs 5.40 ± 1.53 times, mean ± standard deviation; P = .041) and reduced the hippocampal TUNEL-positive cells and cleaved-caspase 3 expression in ketamine-exposed young rats. Ketamine decreased BDNF expression and phosphorylation of AKT and ERK in the hippocampus, whereas exogenous GM1 blocked these ketamine-caused effects. However, for the ketamine-exposed rat pups receiving exogenous GM1, compared to immunoglobulin Y (IgY) isotype control, the BDNF-neutralizing antibody treatment counteracted the exogenous GM1-induced improvement of the escape latency at P36 (41.32 ± 12.37 seconds vs 25.14 ± 8.97 seconds, mean ± standard deviation; P = .036), platform-crossing times at P37 (2.16 ± 1.12 times vs 3.92 ± 1.97 times, mean ± standard deviation; P < .036), apoptotic activity, as well as AKT and ERK1/2 phosphorylation in the hippocampus of ketamine-challenged young rats.

CONCLUSIONS

Our data suggest that the exogenous GM1 acts on BDNF signaling pathway to ameliorate the cognitive impairment and hippocampal apoptosis induced by ketamine in young rats. Our study may indicate a potential use of GM1 in preventing the cognitive deficits induced by ketamine in the young per se.

A Review of Nonanesthetic Uses of Ketamine

Ketamine, a nonselective NMDA receptor antagonist, is used widely in medicine as an anesthetic agent. However, ketamine's mechanisms of action lead to widespread physiological effects, some of which are now coming to the forefront of research for the treatment of diverse medical disorders. This paper aims at reviewing recent data on key nonanesthetic uses of ketamine in the current literature. MEDLINE, CINAHL, and Google Scholar databases were queried to find articles related to ketamine in the treatment of depression, pain syndromes including acute pain, chronic pain, and headache, neurologic applications including neuroprotection and seizures, and alcohol and substance use disorders. It can be concluded that ketamine has a potential role in the treatment of all of these conditions. However, research in this area is still in its early stages, and larger studies are required to evaluate ketamine's efficacy for nonanesthetic purposes in the general population.

Emergence agitation: current knowledge and unresolved questions

Emergence agitation (EA), also referred to as emergence delirium, can have clinically significant consequences. The mechanism of EA remains unclear. The proposed risk factors of EA include age, male sex, type of surgery, emergency operation, use of inhalational anesthetics with low blood-gas partition coefficients, long duration of surgery, anticholinergics, premedication with benzodiazepines, voiding urgency, postoperative pain, and the presence of invasive devices. If preoperative or intraoperative objective monitoring could predict the occurrence of agitation during emergence, this would help to reduce its adverse consequences. Several tools are available for assessing EA. However, there are no standardized clinical research practice guidelines and its incidence varies considerably with the assessment tool or definition used. Total intravenous anesthesia, propofol, μ-opioid agonists, N-methyl-D-aspartate receptor antagonists, nefopam, α2-adrenoreceptor agonists, regional analgesia, multimodal analgesia, parent-present induction, and preoperative education for surgery may help in preventing of EA. However, it is difficult to identify patients at high risk and apply preventive measures in various clinical situations. The risk factors and outcomes of preventive strategies vary with the methodologies of studies and patients assessed.This review discusses important outcomes of research on EA and directions for future research.

Intravenous parecoxib for early postoperative cognitive dysfunction in elderly patients: evidence from a meta-analysis

BACKGROUND

Inflammation plays a key role in the etiology and pathology of postoperative cognitive dysfunction (POCD). Cyclooxygenase (COX)-2 inhibitor parecoxib is used for the treatment of acute pain due to its potent anti-inflammatory and analgesic effects. Herein, we evaluated the efficacy and safety of parecoxib on early POCD in geriatric patients.

OBJECTIVE

This study was performed to evaluate the efficacy and safety of parecoxib for early postoperative cognitive dysfunction (POCD) in elderly patients.

METHODS

Comprehensive literature search based on six electronic databases was applied to retrieve all related randomized controlled trials (RCTs). Two independent reviewers screened each article for eligibility according to the predetermined inclusion criteria. The Cochrane's Tool was applied to evaluate the methodological quality of included studies. RevMan 5.3 was used to conduct meta-analysis.

RESULTS

Eight RCTs comprising a total of 1106 subjects prepared for orthopedic surgical operation were selected. All the identified RCTs were conducted in China. The methodological qualities of included studies were judged to be medium to high. The integrated data showed that perioperative intravenous parecoxib could remarkably reduce the incidence of POCD with improved Mini-Mental State Examination (MMSE) score. Parecoxib could significantly reduce the concentrations of interleukin-6, but results regarding the changes in tumor necrosis factor-alpha, C-reactive protein, and S100β levels remained inconsistent.

CONCLUSION

Perioperative parecoxib administration is effective in reducing the incidence of POCD and improving the MMSE score compared with control. However, the beneficial effect of parecoxib has been tested only in the Chinese population. Future RCTs in western countries with larger-scale and more comprehensive neurological tests are needed.

Perioperative Heart-Brain Axis Protection in Obese Surgical Patients: The Nutrigenomic Approach

The number of obese patients undergoing cardiac and noncardiac surgery is rapidly increasing because they are more prone to concomitant diseases, such as diabetes, thrombosis, sleep-disordered breathing, cardiovascular and cerebrovascular disorders. Even if guidelines are already available to manage anesthesia and surgery of obese patients, the assessment of the perioperative morbidity and mortality from heart and brain disorders in morbidly obese surgical patients will be challenging in the next years. The present review will recapitulate the new mechanisms underlying the Heart-brain Axis (HBA) vulnerability during the perioperative period in healthy and morbidly obese patients. Finally, we will describe the nutrigenomics approach, an emerging noninvasive dietary tool, to maintain a healthy body weight and to minimize the HBA propensity to injury in obese individuals undergoing all types of surgery by personalized intake of plant compounds that may regulate the switch from health to disease in an epigenetic manner. Our review provides current insights into the mechanisms underlying HBA response in obese surgical patients and how they are modulated by epigenetically active food constituents.

Edaravone at high concentrations attenuates cognitive dysfunctions induced by abdominal surgery under general anesthesia in aged mice

Postoperative cognitive dysfunction (POCD) is a common neurological disease affecting the elderly patients after surgery. Unfortunately, no effective treatment for this disease has been discovered. Edaravone, a clinical-used free radical scavenger, at 3 mg/kg has been reported to prevent neuroinflammation induced by the combination of surgery and lipopolysaccharide in adult rodents. However, we found that edaravone at such low concentration could not inhibit POCD in aged mice. Instead, edaravone at 33.2 mg/kg significantly prevented recognition and spatial cognitive dysfunctions in 14 month aged mice after abdominal surgery under general anesthesia with isoflurane. Furthermore, edaravone significantly prevented the increase of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) induced by abdominal surgery in aged mice. Edaravone could also decrease glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule-1 (Iba-1) positive areas in the hippocampal regions of surgery mice, suggesting that edaravone might inhibit surgery-induced over-activation of microglia and astrocytes. Moreover, edaravone substantially increased the expression of PSD-95 and pSer9-glycogen synthase kinase-3β (pSer9-GSK3β) as demonstrated by Western blotting assay. Furthermore, the activity of acetylcholinesterase (AChE) is decreased in the mice in edaravone group. All these results suggested that edaravone at high concentrations could inhibit surgery-induced cognitive impairments in aged animals, possibly via the attenuation of neuroinflammation, the increase of synaptic proteins, and the elevation of cholinergic transmission, providing a further support that edaravone might be developed as a treatment of POCD.

High‑fat treatment prevents postoperative cognitive dysfunction in a hyperlipidemia model by protecting the blood‑brain barrier via Mfsd2a‑related signaling

Damage to the blood-brain barrier (BBB) resulting from systemic inflammation caused by surgical trauma is associated with cognitive dysfunction, and individuals with hyperlipidemia are more sensitive to such impairment. The present study was designed to ascertain whether dexmedetomidine (Dex) treatment could reduce the incidence of cognitive dysfunction following surgery in a hyperlipidemia model. Hyperlipidemia was induced in Sprague-Dawley rats (male, 6–7 months old) by consuming a high-fat diet, and rats were divided into three groups (n=10 each) and underwent: exploratory laparotomy to introduce surgical trauma (surgery group), laparotomy and Dex treatment (surgery+Dex group), or sham surgery (sham group). Learning, memory and exploration behavior were assessed using the Morris water maze. Concentrations of tumor necrosis factor (TNF)-α and interleukin (IL)-1β, were determined by enzyme-linked immunosorbent assay. BBB permeability was assessed by Evans blue staining. Relative major facilitator superfamily domain-containing protein 2 (Mfsd2a) mRNA expression was determined by quantitative PCR. In the Morris water maze test, the time and distance ratio for the surgery group was significantly lower than those of the sham and surgery+Dex groups (P<0.05). In addition, the TNF-α concentrations in the sham and surgery+Dex groups were lower than that in the surgery group (P<0.05 on days 1 and 3). Evans Blue staining was increased in the surgery group on day 1 (P<0.01). Mfsd2a mRNA expression was higher in the sham and surgery+Dex groups compared with that noted in the surgery group (P<0.05). In conclusion, Dex treatment decreased the incidence of cognitive dysfunction following surgical trauma in a hyperlipidemia rat model. We demonstrated that Dex stabilized BBB integrity through increased Mfsd2a gene expression.

Anesthetic management of endovascular treatment for acute ischemic stroke: Influences on outcome and complications

Background and objectives

The emerging use of endovascular therapies for acute ischemic stroke, like intra-arterial thrombectomy, compels a better understanding of the anesthetic management required and its impact in global outcomes. This article reviews the available data on the anesthetic management of endovascular treatment, comparing general anesthesia with conscious sedation, the most used modalities, in terms of anesthetic induction and procedure duration, patient mobility, occlusion location, hemodynamic parameters, outcome and safety; it also focuses on the state-of-the-art on physiologic and pharmacologic neuroprotection.

Contents

Most of the evidence on this topic is retrospective and contradictory, with only three small randomized studies to date. Conscious sedation was frequently associated with better outcomes, but the prospective evidence declared that it has no advantage over general anesthesia concerning that issue. Conscious sedation is at least as safe as general anesthesia for the endovascular treatment of acute ischemic stroke, with equivalent mortality and fewer complications like pneumonia, hypotension or extubation difficulties. It has, however, a higher frequency of patient agitation and movement, which is the main cause for conversion to general anesthesia.

Conclusions

General anesthesia and conscious sedation are both safe alternatives for anesthetic management of patients submitted to endovascular thrombectomy. No anesthetic management is universally recommended and hopefully the ongoing randomized clinical trials will shed some light on the best approach; meanwhile, the choice of anesthesia should be based on the patient's individual characteristics. Regarding neuroprotection, hemodynamic stability is currently the most important strategy, as no pharmacological method has been proven effective in humans.

Intraoperative magnesium sulphate decreases agitation and pain in patients undergoing functional endoscopic surgery: A randomised double-blind study

BACKGROUND

Postoperative agitation is harmful for the patient as it may be associated with removal of catheters, nasal packs, oxygen masks and self-injury, and pose a danger to operating theatre staff.

OBJECTIVE

The current study investigated the potential role of magnesium sulphate in treatment of postoperative agitation following functional endoscopic sinus surgery.

DESIGN

A randomised, double-blinded, placebo-controlled trial.

SETTING

ENT operating room, Menofia University Hospitals, Egypt.

PATIENTS

A total of 312 adult patients (171 men and 141 women) were enrolled in the study. Eighteen patients (10 men and eight women) were excluded; data from 294 patients were analysed. Inclusion criteria were age between 20 and 60 years, American Society of Anesthesiologists' physical status 1 or 2 scheduled for functional endoscopic sinus surgery. Exclusion criteria were hypertension, cardiac ischaemia, cerebrovascular insufficiency, neuromuscular diseases, pregnancy, prolonged treatment with calcium-channel blockers, diabetic neuropathy or a known allergy to magnesium compounds.

INTERVENTIONS

Patients were allocated randomly to either the magnesium group (a magnesium infusion of 30 mg kg in the first hour followed by 9 mg kg h until the end of the surgical procedure) or the control group (0.9% saline at the same volume and rate). Hypotensive anaesthesia was induced by nitroglycerine 5 to 20 μg kg min. In the postanaesthetic care unit (PACU), patients were assessed for agitation and pain using the Richmond agitation-sedation scale and numerical rating scale, respectively.

PRIMARY OUTCOME

The incidence and severity of agitation measured 5 min after admission to the PACU.

RESULTS

Magnesium reduced postoperative agitation at time 0 (P = 0.009) and 5, 10, 15 and 30 min after PACU admission (P < 0.0001) as well as total agitation score [3 (0 to 6) versus 9 (0 to 12), P < 0.0001]. Magnesium also reduced pain [4.5 (4 to 5) versus 6 (5 to 6.25), P < 0.0001] and length of PACU stay (88 ± 23 versus 111 ± 31 min, P < 0.0001). The magnesium group consumed less pethidine in PACU compared with the control group (43 ± 15 and 59 ± 19 mg, respectively, P < 0.0001). The intraoperative end-tidal CO2 tension was comparable between groups (4.7 ± 0.7 versus 4.8 ± 1.2 kPa).

CONCLUSION

Intraoperative infusion of magnesium in patients undergoing endoscopic sinus surgery reduced postoperative agitation, pethidine consumption and pain assessed in the PACU. It also decreased the length of stay in PACU compared with the control group.

TRIAL REGISTRATION

The current study was registered according to WHO and ICMJE standards on 7 January 2014, under registration number PACTR 201402000737691.

[Anesthetic management of endovascular treatment for acute ischemic stroke: Influences on outcome and complications]

BACKGROUND AND OBJECTIVES

The emerging use of endovascular therapies for acute ischemic stroke, like intra-arterial thrombectomy, compels a better understanding of the anesthetic management required and its impact in global outcomes. This article reviews the available data on the anesthetic management of endovascular treatment, comparing general anesthesia with conscious sedation, the most used modalities, in terms of anesthetic induction and procedure duration, patient mobility, occlusion location, hemodynamic parameters, outcome and safety; it also focuses on the state-of-the-art on physiologic and pharmacologic neuroprotection.

CONTENTS

Most of the evidence on this topic is retrospective and contradictory, with only three small randomized studies to date. Conscious sedation was frequently associated with better outcomes, but the prospective evidence declared that it has no advantage over general anesthesia concerning that issue. Conscious sedation is at least as safe as general anesthesia for the endovascular treatment of acute ischemic stroke, with equivalent mortality and fewer complications like pneumonia, hypotension or extubation difficulties. It has, however, a higher frequency of patient agitation and movement, which is the main cause for conversion to general anesthesia.

CONCLUSIONS

General anesthesia and conscious sedation are both safe alternatives for anesthetic management of patients submitted to endovascular thrombectomy. No anesthetic management is universally recommended and hopefully the ongoing randomized clinical trials will shed some light on the best approach; meanwhile, the choice of anesthesia should be based on the patient's individual characteristics. Regarding neuroprotection, hemodynamic stability is currently the most important strategy, as no pharmacological method has been proven effective in humans.

Perioperative cognitive protection

There is significant evidence that many older surgical patients experience at least a transient decrease in cognitive function. Although there is still equipoise regarding the degree, duration, and mechanism of cognitive dysfunction, there is a concurrent need to provide best-practice clinical evidence. The two major cognitive disorders seen after surgery are postoperative delirium and postoperative cognitive dysfunction. Delirium is a public health problem; millions of dollars are spent annually on delirium-related medical resource use and prolonged hospital stays. Postoperative cognitive dysfunction is a research construct that historically signifies decline in performance on a neuropsychiatric test or group of tests and begins days to weeks after surgery. This review focuses on the current state of information gathered by several interdisciplinary stakeholder groups. Although there is still a need for high-level evidence to guide clinical practice, there is an emerging literature that can guide practitioners.

Perioperative hyperglycemia and neurocognitive outcome after surgery: a systematic review

INTRODUCTION

Preliminary evidence suggest a possible relationship between perioperative hyperglycemia, postoperative delirium (POD) or cognitive dysfunction (POCD). We aim to present the available clinical evidence related to chronic (i.e. diabetes mellitus) or acute perioperative hyperglycemia as risk factors for POD/POCD.

EVIDENCE ACQUISITION

A literature search of EMBASE (via Ovid, 1974-present) online medical database and MEDLINE (via PubMed or Ovid, 1946-present) was performed. All types of clinical studies including randomized controlled trials, prospective, as well as retrospective cohort studies were screened. Clinical studies that reported original information on the relationship between diabetes mellitus (DM) and/or acute perioperative abnormal glucose levels and POD or POCD were selected. Reviews and editorials (i.e. articles not presenting original preclinical or clinical research) were excluded and case-reports were not considered for analysis.

EVIDENCE SYNTHESIS

Our search resulted in 2356 papers for screening, from which we selected 29 studies that met our inclusion criteria. DM was investigated in 24 observational papers, acute perioperative hyperglycemia in six observational studies and two randomized controlled trials examined the effect of perioperative glucose lowering on POD/POCD. Diabetes was associated with POD or POCD in 18/24 observational studies and 6/6 of the included observational studies found that perioperative hyperglycemia was associated with POD/POCD, independent of diabetes. The two randomized controlled trials had a different trial design and reported conflicting results.

CONCLUSIONS

According to the available evidence, DM and acute perioperative hyperglycemia may be associated with an increased risk for POD/POCD. These conclusions are based mostly on observational studies and deserve more and dedicated research. This systematic review may direct the design of future studies.

[The efficacy of prevention of postoperative cognitive dysfunction in cardiac surgeries with the use of the cerebrolysin]

AIM

To assess the efficacy of postoperative cytoprotection with cerebrolysin in cardiac surgeries without using cardiopulmonary bypass and to analyze the changes in the blood circulation in the postoperative period in groups with- and without cerebrolysin preconditioning.

MATERIAL AND METHODS

Thirty-eight patients, who underwent coronary and mammaro-coronary bypass grafting without using cardiopulmonary bypass, were included in the study. Fifteen patients received cerebrolysin before surgery.

RESULTS AND CONCLUSION

Cerebrolysin improved cognitive test scores. Positive changes on anxiety and depression scales were observed as well. In the group of patients treated with cerebrolysin, quantitative parameters of the cerebral blood flow were in stable condition, with a slight increase on the 10th day after surgery, which may indicate increasing stress resistance of cells of the central nervous system after appropriate pharmacological protection.

Lidocaine dose-response effect on postoperative cognitive deficit: meta-analysis and meta-regression

INTRODUCTION

The true influence of the perioperative intravenous lidocaine on the development of postoperative cognitive deficit (POCD) in coronary artery bypass grafting (CABG) remains controversial. The principal aim is to undertake a meta-regression to determine whether moderator variables mediate the relationship between lidocaine and POCD. Areas covered: We searched the Web of Science, PubMed database, Scopus and the Cochrane Library database (up to June 2017) and systematically reviewed a list of retrieved articles. Our final review includes only randomized controlled trials (RCTs) that compared infusion of lidocaine and placebo during cardiopulmonary bypass (CPB). Mantel-Haenszel risk ratio (MH RR) and corresponding 95% confidence interval (CI) was used to report the overall effect and meta-regression analysis. A total of 688 patients in five RCTs were included. POCD occurred in 34% of all cases. Perioperative lidocaine reduces POCD (MH RR 0.702 (95% CI: 0.541-0.909). Younger age, male gender, longer CPB and higher concentration of lidocaine significantly mediate the relationship between lidocaine and POCD in favour of the neuroprotective effect of lidocaine. Expert commentary: The neuroprotective effect of lidocaine on POCD is consistent in spite of longer CPB time. A higher concentration of lidocaine strengthened the neuroprotective effect of lidocaine.

Neuroprotective Anesthesia Regimen and Intensive Management for Pediatric Cardiac Surgery with Cardiopulmonary Bypass: a Review and Initial Experience

This article describes our proposal for routine anesthesia, intraoperative medical management, cerebral and physiological monitoring during pediatric cardiac surgery with cardiopulmonary bypass that intend to provide appropriate anesthesia (analgesia, hypnosis), neuroprotection, adequate cerebral and systemic oxygen supply, and preventing against drugs neurotoxicity. A concise retrospective data is presented.

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

Spine Surgery and Blood Loss: Systematic Review of Clinical Evidence

Spine surgery has been growing rapidly as a neurosurgical operation, with an increase of 220% over a 15-year period. Intraoperative blood transfusion is a major outcome determinant of spine procedures. Various approaches, including pharmacologic and nonpharmacologic therapies, have been tested to decrease both intraoperative and postoperative blood loss. The aim of this systematic review is to report clinical evidence on the relationship between intraoperative blood loss (primary outcome) and on transfusion requirements and postoperative complications (secondary outcomes) in patients undergoing spine surgery. A literature search of PubMed database was performed using 5 key words: spine surgery and transfusion; spine surgery and blood loss; spine surgery and blood complications; spine surgery and deep vein thrombosis; and spine surgery and pulmonary embolism. Clinical reports (randomized controlled trials, prospective and retrospective studies, and case reports) were selected. A total of 473 articles were examined; 450 were excluded, and 24 were selected for this systematic review. Selected articles were categorized into 3 subchapters: (1) drugs active on coagulation (12 studies): tranexamic acid, aminocaproic acid, aprotinin, and recombinant activated factor VII; (2) drugs not active on coagulation (5 studies): ketorolac, epoetin alfa, magnesium sulfate, propofol/sevoflurane, and omega-3 and fish oil; (3) nonpharmacologic approaches (7 studies): surgical tips, patient positioning, and general or spinal anesthesia. Several studies have shown a significant reduction in intraoperative bleeding during spine surgery and in the requirement for blood transfusion.

Curcumin attenuates surgery-induced cognitive dysfunction in aged mice

Post-operative cognitive dysfunction (POCD) is associated with elderly patients undergoing surgery. However, pharmacological treatments for POCD are limited. In this study, we found that curcumin, an active compound derived from Curcuma longa, ameliorated the cognitive dysfunction following abdominal surgery in aged mice. Further, curcumin prevented surgery-induced anti-oxidant enzyme activity. Curcumin also increased brain-derived neurotrophic factor (BDNF)-positive area and expression of pAkt in the brain, suggesting that curcumin activated BDNF signaling in aged mice. Furthermore, curcumin neutralized cholinergic dysfunction involving choline acetyltransferase expression induced by surgery. These results strongly suggested that curcumin prevented cognitive impairments via multiple targets, possibly by increasing the activity of anti-oxidant enzymes, activation of BDNF signaling, and neutralization of cholinergic dysfunction, concurrently. Based on these novel findings, curcumin might be a potential agent in POCD prophylaxis and treatment.

Intraoperative care for aortic surgery using circulatory arrest

The total circulatory arrest (CA) is necessary to achieve optimal surgical conditions in certain aortic pathologies, especially in those affecting the ascending aorta and aortic arch. During this procedure it is necessary to protect all the organs of ischemia, especially those of the central nervous system and for this purpose several strategies have been developed. The first and most important protective method is systemic hypothermia. The degree of hypothermia and the route of application have been evolving and currently tend to use moderate hypothermia (MH) (20.1-28 °C) associated with unilateral or bilateral selective cerebral perfusion methods. In this way the neurological results are better, the interval of security is greater and the times of extracorporeal circulation are smaller. Even so, it is necessary to take into account that there is the possibility of ischemia in the lower part of the body, especially of the abdominal viscera and the spinal cord, therefore the time of circulatory stop should be limited and not to exceed 80 minutes. Evidence of possible neurological drug protection is very weak and only mannitol, magnesium, and statins can produce some benefit. Inhalational anesthetics and some intravenous seem to have advantages, but more studies would be needed to test their long-term benefit. Other important parameters to be monitored during these procedures are blood glucose, anemia and coagulation disorders and acid-base balance. The recommended monitoring is common in complex cardiovascular procedures and it is of special importance the neurological monitoring that can be performed with several techniques, although currently the most used are Bispectral Index (BIS) and Near-Infrared Spectroscopy (NIRS). It is also essential to monitor the temperature routinely at the nasopharyngeal and bladder level and it is important to control coagulation with rotational thromboelastometry (ROTEM).

Functional and oxygen-metabolic photoacoustic microscopy of the awake mouse brain

A long-standing challenge in optical neuroimaging has been the assessment of hemodynamics and oxygen metabolism in the awake rodent brain at the microscopic level. Here, we report first-of-a-kind head-restrained photoacoustic microscopy (PAM), which enables simultaneous imaging of the cerebrovascular anatomy, total concentration and oxygen saturation of hemoglobin, and blood flow in awake mice. Combining these hemodynamic measurements allows us to derive two key metabolic parameters-oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO₂). This enabling technology offers the first opportunity to comprehensively and quantitatively characterize the hemodynamic and oxygen-metabolic responses of the mouse brain to isoflurane, a general anesthetic widely used in preclinical research and clinical practice. Side-by-side comparison of the awake and anesthetized brains reveals that isoflurane induces diameter-dependent arterial dilation, elevated blood flow, and reduced OEF in a dose-dependent manner. As a result of the combined effects, CMRO₂ is significantly reduced in the anesthetized brain under both normoxia and hypoxia, which suggests a mechanism for anesthetic neuroprotection. The head-restrained functional and metabolic PAM opens a new avenue for basic and translational research on neurovascular coupling without the strong influence of anesthesia and on the neuroprotective effects of various interventions, including but not limited to volatile anesthetics, against cerebral hypoxia and ischemia.

Monosialoganglioside 1 may alleviate neurotoxicity induced by propofol combined with remifentanil in neural stem cells

Monosialoganglioside 1 (GM1) is the main ganglioside subtype and has neuroprotective properties in the central nervous system. In this study, we aimed to determine whether GM1 alleviates neurotoxicity induced by moderate and high concentrations of propofol combined with remifentanil in the immature central nervous system. Hippocampal neural stem cells were isolated from newborn Sprague-Dawley rats and treated with remifentanil (5, 10, 20 ng/mL) and propofol (1.0, 2.5, 5.0 μg/mL), and/or GM1 (12.5, 25, 50 μg/mL). GM1 reversed combined propofol and remifentanil-induced decreases in the percentage of 5-bromodeoxyuridine(+) cells and also reversed the increase in apoptotic cell percentage during neural stem cell proliferation and differentiation. However, GM1 with combined propofol and remifentanil did not affect β-tubulin(+) or glial fibrillary acidic protein(+) cell percentage during neural stem cell differentiation. In conclusion, we show that GM1 alleviates the damaging effects of propofol combined with remifentanil at moderate and high exposure concentrations in neural stem cells in vitro, and exerts protective effects on the immature central nervous system.

The use of therapeutic magnesium for neuroprotection during global cerebral ischemia associated with cardiac arrest and cardiac surgery in adults: a systematic review

BACKGROUND

Global cerebral ischemia occurs due to reduced blood supply to the brain. This is commonly caused by a cessation of myocardial activity associated with cardiac arrest and cardiac surgery. Survival is not the only important outcome because neurological dysfunction impacts on quality of life, reducing independent living. Magnesium has been identified as a potential neuroprotective agent; however, its role in this context is not yet clear.

OBJECTIVES

The objective of this review was to present the best currently available evidence related to the neuroprotective effects of magnesium during a period of global cerebral ischemia in adults with cardiac arrest or cardiac surgery.

INCLUSION CRITERIA TYPES OF PARTICIPANTS

The current review considered adults aged over 18 years who were at risk of global cerebral ischemia associated with cardiac arrest or cardiac surgery. Studies of patients with existing neurological deficits or under the age of 18 years were excluded from the review.

TYPES OF INTERVENTION(S)/PHENOMENA OF INTEREST

The intervention of interest was magnesium administered in doses of at least of 2 g compared to placebo to adult patients within 24 hours of cardiac arrest or cardiac surgery.

TYPES OF STUDIES

The current review considered experimental designs including randomized controlled trials, non-randomized controlled trials and quasi-experimental designs.

OUTCOMES

The outcome of interest were neurological recovery post-cardiac arrest or cardiac surgery, as measured by objective scales, such as but not limited to, cerebral performance category, brain stem reflexes, Glasgow Coma Score and independent living or dependent living status. To enable assessment of the available data, neuroprotection was examined by breaking down neurological outcomes into three domains - functional neurological outcomes, neurophysiological outcomes and neuropsychological outcomes.

SEARCH STRATEGY

The search strategy aimed to find both published and unpublished studies between January 1980 and August 2014, utilizing the Joanna Briggs Institute (JBI) three-step search strategy. Databases searched included PubMed, Embase, CINAHL, Cochrane Central Register of Controlled Trials, Australian Clinical Trials Register, Australian and New Zealand Clinical Trials Register, Clinical Trials, European Clinical Trials Register and ISRCTN Registry.

METHODOLOGICAL QUALITY

The studies included in this review were of moderate-to-good-quality randomized controlled trials. Studies included measured neurological outcome using functional neurological assessment, neuropsychiatric assessment or neurophysiological assessment.

DATA EXTRACTION

Data were extracted using standardized templates provided by the JBI Meta-analysis of Statistics Assessment and Review Instrument software.

DATA SYNTHESIS

Quantitative data were, where possible, pooled in statistical meta-analysis using Review Manager 5.3 (The Nordic Cochrane Centre, Cochrane; Copenhagen, Denmark). Where statistical pooling was not possible, the findings were presented in narrative form, including tables and figures, to aid in data presentation, where appropriate.

RESULTS

Seven studies with a total of 1164 participants were included in this review. Neurological outcome was categorized into three domains: functional neurological, neurophysiological and neuropsychological outcomes. Meta-analysis of three studies assessing the neuroprotective properties of magnesium administration post cardiac arrest found improved functional neurological outcome (odds ratio 0.44; 95% confidence interval 0.24-0.81).

CONCLUSION

Magnesium may improve functional neurological outcome in patients who suffer global cerebral ischemia associated with cardiac surgery and cardiac arrest. Magnesium does not decrease neuropsychological decline.Further testing of neurological outcomes in the domains of functional outcomes, neurophysiological markers and neuropsychological tests are required to further understanding of the neuroprotective effects of magnesium. Suitable dosing regimens should be investigated prior to introduction into clinical practice. Further research is required to investigate the optimal magnesium dose.

The Post-Anaesthesia N-acetylcysteine Cognitive Evaluation (PANACEA) trial: study protocol for a randomised controlled trial

Background

Some degree of cognitive decline after surgery occurs in as many as one quarter of elderly surgical patients, and this decline is associated with increased morbidity and mortality. Cognition may be affected across a range of domains, including memory, psychomotor skills, and executive function. Whilst the exact mechanisms of cognitive change after surgery are not precisely known, oxidative stress and subsequent neuroinflammation have been implicated. N-acetylcysteine (NAC) acts via multiple interrelated mechanisms to influence oxidative homeostasis, neuronal transmission, and inflammation. NAC has been shown to reduce oxidative stress and inflammation in both human and animal models. There is clinical evidence to suggest that NAC may be beneficial in preventing the cognitive decline associated with both acute physiological insults and dementia-related disorders. To date, no trials have examined perioperative NAC as a potential moderator of postoperative cognitive changes in the noncardiac surgery setting.

Methods and design

This is a single-centre, randomised, double-blind, placebo-controlled clinical trial, with a between-group, repeated-measures, longitudinal design. The study will recruit 370 noncardiac surgical patients at the University Hospital Geelong, aged 60 years or older. Participants are randomly assigned to receive either NAC or placebo (1:1 ratio), and groups are stratified by age and surgery type. Participants undergo a series of neuropsychological tests prior to surgery, 7 days, 3 months, and 12 months post surgery. It is hypothesised that the perioperative administration of NAC will reduce the degree of postoperative cognitive changes at early and long-term follow-up, as measured by changes on individual measures of the neurocognitive battery, when compared with placebo. Serum samples are taken on the day of surgery and on day 2 post surgery to quantitate any changes in levels of biomarkers of inflammation and oxidative stress.

Discussion

The PANACEA trial aims to examine the potential efficacy of perioperative NAC to reduce the severity of postoperative cognitive dysfunction in an elderly, noncardiac surgery population. This is an entirely novel approach to the prevention of postoperative cognitive dysfunction and will have high impact and translatable outcomes if NAC is found to be beneficial.

Trial registration

The PANACEA trial has been registered with the Therapeutic Goods Administration, and the Australian New Zealand Clinical Trials Registry: ACTRN12614000411640; registered on 15 April 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1529-4) contains supplementary material, which is available to authorized users.

Atorvastatin enhances kainate-induced gamma oscillations in rat hippocampal slices

Atorvastatin has been shown to affect cognitive functions in rodents and humans. However, the underlying mechanism is not fully understood. Because hippocampal gamma oscillations (γ, 20-80 Hz) are associated with cognitive functions, we studied the effect of atorvastatin on persistent kainate-induced γ oscillation in the CA3 area of rat hippocampal slices. The involvement of NMDA receptors and multiple kinases was tested before and after administration of atorvastatin. Whole-cell current-clamp and voltage-clamp recordings were made from CA3 pyramidal neurons and interneurons before and after atorvastatin application. Atorvastatin increased γ power by ~ 50% in a concentration-dependent manner, without affecting dominant frequency. Whereas atorvastatin did not affect intrinsic properties of both pyramidal neurons and interneurons, it increased the firing frequency of interneurons but not that of pyramidal neurons. Furthermore, whereas atorvastatin did not affect synaptic current amplitude, it increased the frequency of spontaneous inhibitory post-synaptic currents, but did not affect the frequency of spontaneous excitatory post-synaptic currents. The atorvastatin-induced enhancement of γ oscillations was prevented by pretreatment with the PKA inhibitor H89, the ERK inhibitor U0126, or the PI3K inhibitor wortmanin, but not by the NMDA receptor antagonist D-AP5. Taken together, these results demonstrate that atorvastatin enhanced the kainate-induced γ oscillation by increasing interneuron excitability, with an involvement of multiple intracellular kinase pathways. Our study suggests that the classical cholesterol-lowering agent atorvastatin may improve cognitive functions compromised in disease, via the enhancement of hippocampal γ oscillations.

Cerebral protection during neurosurgery and stroke

PURPOSE OF REVIEW

This article reviews the recent evidence on perioperative neuroprotection in patients undergoing brain surgery and in patients with acute stroke.

RECENT FINDINGS

With varying degrees of success, numerous pharmacological and nonpharmacological therapies have been employed to provide neuroprotection for patients during the perioperative period and after acute ischemic stroke (IAS). Recent studies have failed to demonstrate neuroprotective effects of intraoperative remifentanil or propofol use, although hypertonic saline may provide better brain relaxation than mannitol during elective intracranial surgery for tumor. Magnesium sulfate offers no improvement in neurological outcome at 90 days after stroke. Medical management alone may be superior to medical management with interventional therapy for the prevention of death or stroke in unruptured arteriovenous malformations. In patients with IAS with a proximal vessel occlusion, small infarct core, and moderate-to-good collateral circulation, rapid endovascular treatment resulted in improved functional outcomes and reduced mortality. For endovascular clot evacuation after IAS, conscious sedation may be safer than general anaesthesia.

SUMMARY

Recent evidence provides insufficient evidence of neuroprotective strategies to guide clinical management, and more randomized clinical trials are needed to optimize patient care.

The protective effect of hydromorphone to ischemia in rat glial cells

BACKGROUND

Ischemic insults during operation can cause ischemic-reperfusion injuries in brain as well as memory impairments. Total intravenous anesthesia (TIVA) is the preferred anesthetic method in brain surgery, as it utilizes motor evoked potential monitoring. And the use of opioids is common in TIVA. However there are few studies about ischemic protective effect of opioids to glial cells.

METHODS

We used mixed cultures of rat glial cells, which were harvested from the brain of 1-day old rat. We divided the experimental groups according to their hydromorphone conditioning period: (a) pre-culture, (b) per-culture, or (c) pre- and per-culture. We measured the levels of the reactive oxygen species (ROS) induced by tert-butyl hydroperoxide (TBH) using flow cytometry. The ROS levels in the glial cells were also measured after the administration of 100 nM hydromorphone and selective opioid receptor antagonists.

RESULTS

The ROS levels were reduced in the hydromorphone-treated group, as compared to the control group (only TBH treated). There were no differences between pre-conditioned and per-conditioned groups. However, the ROS levels were more reduced in pre- and per-conditioned group compared to pre-conditioned or per-conditioned only groups. Furthermore, selective antagonists for the delta, kappa, or mu opioid receptor partially negated the hydromorphone effect.

CONCLUSION

This study demonstrated that hydromorphone can have additional protective effects on oxidative stress when pre- and per-conditioning is combined. Furthermore we proved that μ, δ, κ opioid receptors participate in protective mechanism of hydromorphone to glial cells.