A systematic review of postoperative cognitive decline following open and endovascular aortic aneurysm surgery

Canadian Stroke Best Practice Recommendations: Vascular cognitive impairment, 7th edition practice guidelines update, 2024

The Canadian Stroke Best Practice Recommendations (CSPR) 7th edition includes this new module on the diagnosis and management of vascular cognitive impairment (VCI) with or without neurodegenerative disease. An expert writing group and people with VCI lived experience (PWLE) reviewed current evidence. Existing recommendations were reviewed and revised, and new recommendations added. Sections include definitions, signs and symptoms, screening, assessment, diagnosis, pharmacological and non-pharmacological management, secondary prevention, rehabilitation, and end-of-life care. PWLE were actively involved in all aspects of the development, ensuring their experiences are integrated. A unique VCI journey map, developed by PWLE, is included, and helped to motivate and anchor the recommendations. We encourage it to be displayed across healthcare settings to raise awareness and support persons with VCI. These VCI CSBPRs emphasize the need for integrated multidisciplinary care across the continuum. Evidence for the diagnosis and management of VCI continues to emerge and gaps in knowledge should drive future research. HIGHLIGHTS: This Canadian Stroke Best Practice Recommendations module focuses specifically on VCI using a structured framework and validated methodology. A comprehensive set of evidence-based recommendations is presented that addresses the continuum from symptom onset to diagnosis, management, and end of life. The recommendations consider individuals who experience VCI because of stroke or because of other vascular pathologies such as atrial fibrillation or heart failure. A journey map of an individual's experience with VCI has been developed by individuals with lived experience. It is a valuable guide to inform educational content, approaches to caring for individuals and families with VCI, and systems planning.

Postoperative Cognitive Decline in Patients Undergoing Major Gynecologic Oncology Surgery: A Pilot Prospective Study

OBJECTIVES

Postoperative cognitive decline (POCD) is characterised by deficits in attention, memory, executive function, and information processing that persist beyond the early postoperative period. Its incidence ranges from 10%-25% after noncardiac surgery. Limited literature exists on POCD after gynecologic oncology surgery. Our primary objective was to identify the incidence of POCD among patients 55 years or older undergoing major gynecologic oncology surgery.

METHODS

This mixed-methods, prospective, observational cohort study followed patients 55 years or older who underwent surgery for gynecologic malignancies between February and July 2022. Semi-structured interviews and the Mini-Mental State Exam (MMSE) were administered before surgery as well as 1 and 3 months after. Assessments were delivered virtually and in-person in the context of the COVID-19 pandemic. POCD was defined as ≥2-point decline from baseline MMSE score.

RESULTS

Twenty-four patients participated; 19 completed the 1-month follow-up, and 15 completed the 3-month follow-up. The average age was 64 (range: 56-90). The mean preoperative MMSE score was 16.6 out of 17 (virtual) and 12.9 out of 13 (in-person). Two patients had a 1-point decline in their 1-month MMSE score; both recovered by 3 months. One patient had a 1-point decline in their 3-month MMSE score. Semi-structured interviews revealed common themes of "brain fog" at the 1-month follow-up and mild, persistent attention and word-finding deficits at 3 months postoperatively.

CONCLUSIONS

This study's qualitative component captured subtle subjective findings suggestive of potential POCD. Larger studies are required, and a more extensive neuropsychological test battery may be required to elicit subtle findings not clearly reflected by MMSE scores.

"Brain Fog" After COVID-19 Infection: How the Field of Neuropsychology Can Help Clear the Air

The chapter explores the role of neuropsychology in understanding brain fog as a subjective complaint in the context of COVID-19. It discusses the historical and medical significance of the term "brain fog" and its psychological and neurological aspects. The chapter identifies the cognitive domains commonly affected by brain fog, such as attention, executive function, memory, and language. Additionally, it emphasizes the impact of societal changes during the COVID-19 pandemic on the general population as a crucial backdrop for understanding the issue. The chapter also highlights the important role of clinical and research neuropsychologists in gaining clarity on grouped data and individual patients' cognitive and emotional difficulties after COVID-19 infection. It discusses indications for neuropsychological rehabilitation and therapy and describes typical therapy phases and methods, including new approaches like telemedicine, virtual reality, and mobile app-based rehabilitation and self-tracking. The chapter underscores that experiences of brain fog can vary among COVID-19 patients and may change over time. It provides clinicians and interested parties with an in-depth understanding of brain fog and its manifestations, concomitant subtypes, and concrete strategies for addressing it. The chapter emphasizes the critical role of neuropsychology in scientifically examining brain fog and advocating for personalized approaches to cognitive rehabilitation.

The impact of circulatory arrest with selective antegrade cerebral perfusion on brain functional connectivity and postoperative cognitive function

Aortic surgery is one of the most challenging types of surgeries, which is possibly related to cognitive sequelae. We aimed to investigate the changes in resting-state functional connectivity (rsFC) associated with intraoperative circulatory arrest (CA) in aortic surgery, exploring the relationship between the altered connectivity and postoperative cognitive functions. Thirty-eight patients participated in this study (14 with CA, 24 without). Functional magnetic resonance imaging was scanned on the fifth day after surgery or after the resolution of delirium if it was developed. We assessed the differences in the development of postoperative cognitive changes and rsFC between patients with and without CA. The occurrence of postoperative delirium and postoperative cognitive dysfunction was not significantly different between the patients with and without the application of CA. However, patients with CA showed increased in posterior cingulate cortex-based connectivity with the right superior temporal gyrus, right precuneus, and right hippocampus, and medial prefrontal cortex-based connectivity with the dorsolateral prefrontal cortex. The application of moderate hypothermic CA with unilateral antegrade cerebral perfusion is unlikely to affect aspects of postoperative cognitive changes, whereas it may lead to increased rsFC of the default mode network at a subclinical level following acute brain insults.

Dysfunction of EAAT3 Aggravates LPS-Induced Post-Operative Cognitive Dysfunction

Numerous results have revealed an association between inhibited function of excitatory amino acid transporter 3 (EAAT3) and several neurodegenerative diseases. This was also corroborated by our previous studies which showed that the EAAT3 function was intimately linked to learning and memory. With this premise, we examined the role of EAAT3 in post-operative cognitive dysfunction (POCD) and explored the potential benefit of riluzole in countering POCD in the present study. We first established a recombinant adeno-associated-viral (rAAV)-mediated shRNA to knockdown SLC1A1/EAAT3 expression in the hippocampus of adult male mice. The mice then received an intracerebroventricular microinjection of 2 μg lipopolysaccharide (LPS) to construct the POCD model. In addition, for old male mice, 4 mg/kg of riluzole was intraperitoneally injected for three consecutive days, with the last injection administered 2 h before the LPS microinjection. Cognitive function was assessed using the Morris water maze 24 h following the LPS microinjection. Animal behavioral tests, as well as pathological and biochemical assays, were performed to clarify the role of EAAT3 function in POCD and evaluate the effect of activating the EAAT3 function by riluzole. In the present study, we established a mouse model with hippocampal SLC1A1/EAAT3 knockdown and found that hippocampal SLC1A1/EAAT3 knockdown aggravated LPS-induced learning and memory deficits in adult male mice. Meanwhile, LPS significantly inhibited the expression of EAAT3 membrane protein and the phosphorylation level of GluA1 protein in the hippocampus of adult male mice. Moreover, riluzole pretreatment significantly increased the expression of hippocampal EAAT3 membrane protein and also ameliorated LPS-induced cognitive impairment in elderly male mice. Taken together, our results demonstrated that the dysfunction of EAAT3 is an important risk factor for POCD susceptibility and therefore, it may become a promising target for POCD treatment.

Edaravone attenuates sustained pial arteriolar vasoconstriction independently of the endothelial function after unclamping of an abdominal aorta in rabbits

Background

Cerebral blood flow (CBF) has direct impacts on the neuronal function and neurocognitive disorder. Oxidative stress from abdominal aortic surgery is important in the pathophysiology of CBF impairment. We investigated whether oxidative damage from abdominal aortic surgery is associated with reduced CBF and whether vascular endothelial dysfunction modifies these associations.

Methods

Rabbit closed cranial window preparation was used to measure changes in the pial arteriolar diameter after unclamping following abdominal aortic cross-clamping with an intravenous free radical scavenger, edaravone (control group, n=6; edaravone 10 μg/kg/min, n=6; 100 μg/kg/min, n=6). The pial vasodilatory responses to the topical application of acetylcholine (ACh) into the cranial window were investigated before abdominal aortic cross-clamping and after unclamping with the intravenous administration of edaravone (control group, n=6; edaravone 100 μg/kg/min, n=6).

Results

The aortic unclamping-induced vasoconstriction was significantly attenuated under the continuous infusion of edaravone at 100 μg/kg/min. The topical application of ACh after unclamping did not produce any changes in pial arteriolar responses in comparison to before aortic cross-clamping in the control or edaravone groups. The changes in the response to topical ACh after unclamping in the saline and edaravone groups did not differ to a statistically significant extent.

Conclusions

Free radicals during abdominal aortic surgery might have contracted cerebral blood vessels independently of the endothelial function in rabbits. The suppression of free radicals attenuated sustained pial arteriolar vasoconstriction after aortic unclamping. Thus, the free radical scavenger might have some brain protective effect that maintains the CBF independently of the endothelial function.

Low-dose Sevoflurane Attenuates Cardiopulmonary Bypass (CPB)- induced Postoperative Cognitive Dysfunction (POCD) by Regulating Hippocampus Apoptosis via PI3K/AKT Pathway

BACKGROUND

Cardiopulmonary bypass (CPB) caused postoperative cognitive dysfunction (POCD) was characterized by hippocampus apoptosis, which seriously limited the therapeutic efficacy and utilization of CPB in clinic. Recent data indicated that sevoflurane anesthesia might alleviate CPB-induced POCD, however, the underlying mechanisms are still unclear.

METHODS

In the present study, the in vivo CPB-POCD models were established by using aged Sprague-Dawley (SD) male rats and the in vitro hypoxia/reoxygenation (H/R) models were inducted by using the primary hippocampus neuron (PHN) cells.

RESULTS

The results showed that CPB impaired cognitive functions and induced hippocampus apoptosis in rat models, which were alleviated by pre-treating rats with low-dose sevoflurane. In addition, the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) signal pathway was inactivated in the hippocampus tissues of CPB-POCD rats, which were rescued by low-dose sevoflurane treatment. Of note, the PI3K/AKT inhibitor (LY294002) abrogated the protective effects of low-dose sevoflurane on CPB-POCD rats. Consistently, the in vitro results showed that H/R treatment induced cell apoptosis and inhibited cell viability in PHN cells, which were attenuated by low-dose sevoflurane. Similarly, LY294002 abrogated the inhibiting effects of low-dose sevoflurane on H/R-induced PHN cell death.

CONCLUSION

Taken together, low-dose sevoflurane attenuated CPB-induced POCD by inhibiting hippocampus apoptosis through activating PI3K/AKT signal pathway.

Randomized clinical trial of intraoperative dexmedetomidine to prevent delirium in the elderly undergoing major non-cardiac surgery

Background

Delirium is common in elderly patients after surgery and is associated with poor outcomes. This study aimed to investigate the impact of intraoperative dexmedetomidine on the incidence of delirium in elderly patients undergoing major surgery.

Methods

This was a randomized double-blind placebo-controlled trial. Elderly patients (aged 60 years or more) scheduled to undergo major non-cardiac surgery were randomized into two groups. Patients in the intervention group received a loading dose of dexmedetomidine 0·6 μg/kg 10 min before induction of anaesthesia followed by a continuous infusion (0·5 μg per kg per h) until 1 h before the end of surgery. Patients in the control group received volume-matched normal saline in the same schedule. The primary outcome was the incidence of delirium during the first 5 days after surgery. Delirium was assessed with the Confusion Assessment Method (CAM) for non-ventilated patients and CAM for the Intensive Care Unit for ventilated patients.

Results

In total, 309 patients who received dexmedetomidine and 310 control patients were included in the intention-to-treat analysis. The incidence of delirium within 5 days of surgery was lower with dexmedetomidine treatment: 5·5 per cent (17 of 309) versus 10·3 per cent (32 of 310) in the control group (relative risk (RR) 0·53, 95 per cent c.i. 0·30 to 0·94; P = 0·026). The overall incidence of complications at 30 days was also lower after dexmedetomidine (19·4 per cent (60 of 309) versus 26·1 per cent (81 of 310) for controls; RR 0·74, 0·55 to 0·99, P = 0·047).

Conclusion

Intraoperative dexmedetomidine halved the risk of delirium in the elderly after major non-cardiac surgery. Registration number: ChiCTR-IPR-15007654 (www.chictr.org.cn).

Intestinal dysbacteriosis mediates the reference memory deficit induced by anaesthesia/surgery in aged mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is associated with increased morbidity and mortality and has become a major concern for patients and caregivers. POCD is most common in older patients. Previous studies demonstrated that the gut microbiome affects cognitive function and behaviour, and perioperative factors, including the operation itself, antibiotics, opioids or acid-inducing drugs, affect the gut microbiome. Thus, we hypothesised that intestinal dysbacteriosis caused by anaesthesia/surgery induces POCD.

METHODS

Tibial fracture internal fixation was performed in 18-month-old C57BL/6 mice under isoflurane anaesthesia to establish the POCD model. The Morris water maze was used to measure reference memory after anaesthesia/surgery. High-throughput sequencing of 16S rRNA from faecal samples was used to investigate changes in the abundance of intestinal bacteria after anaesthesia/surgery. To confirm the role of the gut microbiome in POCD, we pretreated mice with compound antibiotics or mixed probiotics (VSL#3). Anaesthesia/surgery impaired reference memory and induced intestinal dysbacteriosis in aged mice.

RESULTS

The 16S rRNA sequencing data revealed 37 genera (18 families) of bacteria that changed in abundance after anaesthesia/surgery. Pretreating mice with compound antibiotics or mixed probiotics (VSL#3) prevented the learning and memory deficits induced by anaesthesia/surgery. We further conducted quantitative real-time polymerase chain reaction (qRT-PCR) of 22 common types of bacteria among the 37 total types to verify the results of bacterial flora changes after anaesthesia/surgery. Numbers of 8 types of bacteria changed after anaesthesia/surgery but returned to normal after treatment with a mix of probiotics.

CONCLUSIONS

Our data suggest that deficits in reference memory induced by anaesthesia/surgery are mediated by intestinal dysbacteriosis.

Effects of acute hypercapnia on cognitive function in patients undergoing bronchoscope intervention

Background

There are multiple studies that have revealed that hypercapnia possessed neuroprotection, the conclusive cognitive impacts of permissive hypercapnia in medicine is still unclear.

Methods

A total of 102 patients registered for this research work had accomplished cognitive tests; with 64 patients possessing moderate hypercapnia all through bronchoscope intervention (BI). Thirty-six patients completed collection of blood specimens. Every patient underwent the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) a day before the surgery (T0), as well as at 7 days (T7). Serum specimens were used to measure levels of S100B, neuron-specific enolase (NSE), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), superoxide dismutase (SOD) prior to the administration of anesthesia (T0), one day (T1) and seven days (T7) after surgery.

Results

In comparison with the preoperative MMSE scores, Group Hypercapnia (Group H) on 7 days after surgery, exhibited a significant increased score (P=0.00). In comparison with the preoperative MoCA scores, Group H on 7 days after surgery exhibited a significant increased score (P=0.00). Meanwhile, the MoCA scores in Group H exhibited considerably higher elevation as compared with that in the Group Control (Group C) (P=0.01). No substantial differences were observed in serum S100B and NSE levels between Group H and Group C (P=0.23, P=0.14). Serum IL-6, TNF-α, SOD and MDA levels shared similarity between two groups.

Conclusions

Mild and moderate hypercapnia augmented cognitive activity with the help of MMSE tests and MoCA tests, whereby the latent reasons were not sure. As suggested by this study, hypercapnia up to 100 mmHg during BI was less likely to affect cognitive function adversely.

Nrdp1 is involved in hippocampus apoptosis in cardiopulmonary bypass-induced cognitive dysfunction via the regulation of ErbB3 protein levels

The cardiopulmonary bypass (CPB) is an important risk factor for the development of postoperative cognitive dysfunction (POCD). The pathological mechanism of the neuro-modulation receptor degradation protein ring finger protein 41 (Nrdp1) in CPB-induced cognitive dysfunction remains unclear. In the present study, aged Sprague-Dawley male rats and CPB treatment were selected to duplicate the POCD model. A hypoxia/reoxygeneration (H/R) model was established to evaluate the effect of Nrdp1 in vitro. Apoptosis in the hippocampus regions were measured using a terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling assay, the viability and apoptosis level of the cells were measured via an MTT assay and flow cytometry, respectively, and the expression levels of Nrdp1, erb-b2 receptor tyrosine kinase 3 (ErbB3), phosphorylated-protein kinase B (p-AKT) and cleaved (c-) caspase-3 were detected using western blot analysis. Then, Nrdp1 was upregulated and downregulated in vitro and in vivo through lentivirus infection to further investigate the effect of Nrdp1 in the rats following CPB. The results revealed that Nrdp1 is associated with hippocampus neuronal apoptosis and POCD following CPB in rats. The overexpression of Nrdp1 altered the cognitive function of the rats which was inhibited by CPB, and additionally inhibited the viability and increased the apoptosis of primary hippocampus neuron cells under H/R treatment. Furthermore, knockdown of Nrdp1 promoted the viability of primary hippocampus neuron cells and decreased the apoptosis of cells under H/R treatment. Further study indicated that Nrdp1 regulates the protein expression of ErbB3, p-AKT, cytochrome c, BCL2-associated X, apoptosis regulator, BCL2, apoptosis regulator and c-caspase-3. The results of the present study suggested that CPB may induce apoptosis in the hippocampus of aged rats. Nrdp1 serves an important role in regulating the apoptosis induced by CPB in vivo and in vitro through regulating ErbB3 and p-AKT protein levels.

Surgery, neuroinflammation and cognitive impairment

Trauma experienced during surgery can contribute to the development of a systemic inflammatory response that can cause multi-organ dysfunction or even failure. Post-surgical neuroinflammation is a documented phenomenon that results in synaptic impairment, neuronal dysfunction and death, and impaired neurogenesis. Various pro-inflammatory cytokines, such as TNFα, maintain a state of chronic neuroinflammation, manifesting as post-operative cognitive dysfunction and post-operative delirium. Furthermore, elderly patients with post-operative cognitive dysfunction or delirium are three times more likely to experience permanent cognitive impairment or dementia. We conducted a narrative review, considering evidence extracted from various databases including Pubmed, MEDLINE and EMBASE, as well as journals and book reference lists. We found that further pre-clinical and well-powered clinical studies are required to delineate the precise pathogenesis of post-operative delirium and cognitive dysfunction. Despite the burden of post-operative neurological sequelae, clinical studies investigating therapeutic agents, such as dexmedetomidine, ibuprofen and statins, have yielded conflicting results. In addition, evidence supporting novel therapeutic avenues, such as nicotinic and HMGB-1 targeting and remote ischaemic pre-conditioning, is limited and necessitates further investigation.

Central cholinergic system mediates working memory deficit induced by anesthesia/surgery in adult mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is consistently associated with increased morbidity and mortality, which has become a major concern of patients and caregivers. Although POCD occurs mainly in aged patients, it happens at any age. Previous studies demonstrated that anesthesia/surgery had no effects on reference memory of adult mice. However, whether it impairs working memory remains unclear. Working memory deficit would result in many deficits of executive function. We hypothesized that anesthesia/surgery impaired the working memory of adult mice and the central cholinergic system was involved.

METHOD

Tibial fracture internal fixation under the anesthesia of isoflurane was performed in two-month-old C57BL/6 mice. Two days later, the spatial reference memory and working memory were measured by a Morris Water Maze (MWM). Donepezil, an inhibitor of acetylcholinesterase (AChE), was administered in another cohort mice for 4 weeks. Then, the working memory was measured by MWM 2 days after anesthesia/surgery. Western blot was used to detect the protein levels of acetylcholine transferase (ChAT), AChE, vesicular acetylcholine transporter (VAChT), and choline transporter (ChT) in the prefrontal cortex (PFC).

RESULTS

We found that anesthesia/surgery had no effects on the reference memory, but it impaired the working memory in adult mice. Meanwhile, we also found that the protein level of ChAT in PFC decreased significantly compared with that in control group. Donepezil pretreatment prevented working memory impairment and the decrease of the protein levels of ChAT induced by anesthesia/surgery.

CONCLUSION

These results suggest that anesthesia/surgery leads to working memory deficits in adult mice and central cholinergic system impairment is involved.