Perioperative Delirium and Mild Cognitive Impairment

The Role of Stress Hyperglycemia on Delirium Onset

Delirium is an acute neuropsychiatric syndrome that recognizes one or more underlying causal medical conditions. Stress hyperglycemia usually refers to transient hyperglycemia associated with stress conditions such as stroke, myocardial infarction, and major surgery. Both delirium and stress hyperglycemia share common pathways, such as activation of inflammation. Stress hyperglycemia has been associated with negative outcomes, and recent studies suggested that there is an increased risk of delirium onset in patients with stress hyperglycemia. The purpose of this review is to illustrate the relationship between stress hyperglycemia and delirium. Initially, we illustrate the role of diabetes on delirium onset, summarize the criteria used for the diagnosis of stress hyperglycemia, discuss the impact of stress hyperglycemia on outcome, and focus on the evidence about the relationship between stress hyperglycemia and delirium.

Early postoperative neurocognitive complications in elderly patients: comparing those with and without preexisting mild cognitive impairment- a prospective study

BACKGROUND

As societies age, increasing numbers of older adults undergo surgeries with anesthesia. Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) frequently occur in older surgical patients. Most of these patients already have preoperative mild cognitive impairment (MCI). However, the correlation between MCI and POD remains unclear. This study aimed to determine the incidence of POD in elderly patients with and without preexisting MCI.

METHODS

A prospective study enrolled patients aged 60 years and above scheduled for major surgeries between December 2017 and April 2022. Preoperative MCI was determined by a Montreal Cognitive Assessment (MoCA) score between 18 and 24. POD was diagnosed using criteria from the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). POCD was characterized by a MoCA score reduction of 2 or more points from the preoperative score. The primary outcome was the incidence of POD within the first 72 h postoperatively. Secondary outcomes encompassed other postoperative complications, including POCD.

RESULTS

The study comprised 223 elderly patients with MCI and 56 without MCI. The incidence of POD was 16.6% in the MCI group and 14.3% in the non-MCI group (P = 0.839). POCD occurred in 24.3% of MCI patients and 50% of non-MCI patients (P = 0.001). There were no significant differences in other postoperative complications between the groups. Postoperatively, the MCI group notably declined in visuospatial, attention, and orientation domains, while the non-MCI group declined in all domains except delayed recall.

CONCLUSIONS

The incidence of POD was similar in the MCI and non-MCI groups. However, the non-MCI group demonstrated a higher incidence of POCD than the MCI group. This was identified by a reduction in postoperative MoCA scores for the visuospatial, naming, attention, language, abstraction, and orientation domains. These findings underscore the importance of postoperative cognitive assessments for both elderly patients with preexisting MCI and those with previously intact cognitive functions.

TRIAL REGISTRATION

This trial was retrospectively registered in the Thai Clinical Trials Registry on 15/01/2019 (registration number: TCTR20190115001).

The possible role of gut microbiota dysbiosis in the pathophysiology of delirium in older persons

Delirium is a clinical syndrome characterized by an acute change in attention, awareness and cognition with fluctuating course, frequently observed in older patients during hospitalization for acute medical illness or after surgery. Its pathogenesis is multifactorial and still not completely understood, but there is general consensus on the fact that it results from the interaction between an underlying predisposition, such as neurodegenerative diseases, and an acute stressor acting as a trigger, such as infection or anesthesia. Alterations in brain insulin sensitivity and metabolic function, increased blood-brain barrier permeability, neurotransmitter imbalances, abnormal microglial activation and neuroinflammation have all been involved in the pathophysiology of delirium. Interestingly, all these mechanisms can be regulated by the gut microbiota, as demonstrated in experimental studies investigating the microbiota-gut-brain axis in dementia. Aging is also associated with profound changes in gut microbiota composition and functions, which can influence several aspects of disease pathophysiology in the host. This review provides an overview of the emerging evidence linking age-related gut microbiota dysbiosis with delirium, opening new perspectives for the microbiota as a possible target of interventions aimed at delirium prevention and treatment.

Screening for Mild Cognitive Impairment in the Preoperative Setting: A Narrative Review

Cognitive impairment predisposes patients to the development of delirium and postoperative cognitive dysfunction. In particular, in older patients, the adverse sequelae of cognitive decline in the perioperative period may contribute to adverse outcomes after surgical procedures. Subtle signs of cognitive impairment are often not previously diagnosed. Therefore, the aim of this review is to describe the available cognitive screeners suitable for preoperative screening and their psychometric properties for identifying mild cognitive impairment, as preoperative workup may improve perioperative care for patients at risk for postoperative cognitive dysfunction. Electronic systematic and snowball searches of PubMed, PsycInfo, ClinicalKey, and ScienceDirect were conducted for the period 2015-2020. Major inclusion criteria for articles included those that discussed a screener that included the cognitive domain 'memory', that had a duration time of less than 15 min, and that reported sensitivity and specificity to detect mild cognitive impairment. Studies about informant-based screeners were excluded. We provided an overview of the characteristics of the cognitive screener, such as interrater and test-retest reliability correlations, sensitivity and specificity for mild cognitive impairment and cognitive impairment, and duration of the screener and cutoff points. Of the 4775 identified titles, 3222 were excluded from further analysis because they were published prior to 2015. One thousand four hundred and forty-eight titles did not fulfill the inclusion criteria. All abstracts of 52 studies on 45 screeners were examined of which 10 met the inclusion criteria. For these 10 screeners, a further snowball search was performed to obtain related studies, resulting in 20 articles. Screeners included in this review were the Mini-Cog, MoCA, O3DY, AD8, SAGE, SLUMS, TICS(-M), QMCI, MMSE2, and Mini-ACE. The sensitivity and specificity range to detect MCI in an older population is the highest for the MoCA, with a sensitivity range of 81-93% and a specificity range of 74-89%. The MoCA, with the highest combination of sensitivity and specificity, is a feasible and valid routine screening of pre-surgical cognitive function. This warrants further implementation and validation studies in surgical pathways with a large proportion of older patients.

A health care record review of early mobility activities after fragility hip fracture: Utilizing the French systematic method to inform future interventions

BACKGROUND

A fragility hip fracture is a serious injury in older adults. After experiencing a fracture, a large percentage of patients do not regain their pre-fracture level of mobility. There are several international guidelines recommending early mobility after surgery. We do not know the usage of these early mobility recommendations by health care providers within our institution. An evidence-to-practice gap occurs when there is a failure to implement best practices. Utilization of a systematic method allows for a strategic approach to assessment of an evidence-to-practice gap. There were two aims of this project: a) to describe early mobility activities undertaken on one post surgical unit and, b) to identify if there is an evidence-to-practice gap.

METHODS

At a large tertiary centre in Toronto, Ontario, medical records from one calendar year were abstracted for older adults (≥65 years of age) recovering from fragility hip fracture repair. Data were collected regarding demographics, co-morbidities, surgery type, post-operative mobility activities, and any post-operative complications. Primary outcomes were: evidence of early mobility activities and a comparison to Health Quality Ontario recommendations for fragility hip fracture care.

RESULTS

Between 11% and 50% of patients were not participating in early mobility activities. By postoperative day five only two patients had walked over 50 m. Those with low pre-fracture functional ability and a cognitive impairment consistently experienced lower rates of participation compared to patients with high pre-fracture functional ability and no cognitive impairment. Chi-square tests and regression analysis did not reveal any significant associations with variables.

CONCLUSIONS

There was very limited participation in early mobility activities after surgery. The study was unable to identify any significant relationships between several variables that may impact participation. This chart review identified the processes that have been sustained and highlights potential areas for future interventions.

Exposure to surgery under general anaesthesia and brain magnetic resonance imaging changes in older adults

BACKGROUND

Preclinical studies suggest that exposure to general anaesthesia (GA) could cause neurodegeneration consistent with Alzheimer's disease (AD) pathology. Brain magnetic resonance imaging (MRI) is useful to study structural brain changes. We tested the hypothesis that exposure to surgery with GA (surgery/GA) is associated with greater cortical thinning and increased frequency of white matter lesions.

METHODS

This is a cross-sectional analysis of 70-91-yr-old participants enrolled in the Mayo Clinic Study of Aging who had baseline MRI. The thickness of selected cortical regions, the volume of white matter hyperintensities, and the frequency of cortical infarctions were compared in participants who were and were not exposed to surgery/GA within 20 yr before the first MRI obtained after enrolment.

RESULTS

Of 1410 participants with MRI scans, 932 were exposed to surgery/GA before scanning. In adjusted analyses, cortical thickness in regions vulnerable to AD was significantly less in those exposed to surgery/GA in the prior 20 yr (difference -0.023 mm, [95% confidence interval (CI) -0.041 to -0.005], P=0.014). Those with surgery in the prior 20 yr were more likely to have 'abnormal thickness' compared with those without surgery (odds ratio=1.45, [95% CI 1.10-1.90], P=0.009). Exposure was not associated with white matter hyperintensities or the presence of brain infarcts.

CONCLUSIONS

This study suggests that exposure of older adults to surgical anaesthesia is associated with thinning in cortical regions implicated in AD. The pathogenesis and mechanisms driving these neurodegenerative changes, and the potential clinical significance of these findings, require further study.

Recent Preoperative Concussion and Postoperative Complications: A Retrospective Matched-cohort Study

BACKGROUND

Physiological alterations during the perianesthetic period may contribute to secondary neurocognitive injury after a concussion.

METHODS

Patients exposed to concussion and who received an anesthetic within 90 days were matched to unexposed patients without concussion. Intraoperative and postoperative events were compared. Subgroup analyses assessed relationships among patients with a concussion in the prior 30, 31 to 60, and 61 to 90 days and their respective unexposed matches. To facilitate identification of potential targets for further investigation, statistical comparisons are reported before, as well as after, correction for multiple comparisons.

RESULTS

Sixty concussion patients were matched to 176 unexposed patients. Before correction, 28.3% postconcussion versus 14.8% unexposed patients reported postanesthesia care unit pain score≥7 (P=0.02); 16.7% concussion versus 6.5% unexposed patients reported headache within 90 days of anesthesia (P=0.02) and 23.5% of patients who received surgery and anesthesia within 30 days of concussion experienced headache within 90 days of anesthesia compared with 7.1% in the unexposed group (P=0.01). Patients who experienced concussion and had anesthesia between 31 and 60 days after injury had a postanesthesia care unit Richmond Agitation and Sedation Scale score of -1.61±1.29 versus a score of -0.2±0.45 in unexposed patients (P=0.002). After adjusting the P-value threshold for multiple comparisons, the P-value for significance was instead 0.0016 for the overall cohort. Our study revealed no significant associations with application of adjusted significance thresholds.

CONCLUSIONS

There were no differences in intraoperative and postoperative outcomes in patients with recent concussion compared with unexposed patients. Before correction for multiple comparisons, several potential targets for further investigation are identified. Well-powered studies are warranted.

Post-traumatic stress disorder (PTSD) related symptoms following an experience of delirium

AIM

To evaluate the prevalence of symptoms of PTSD and its correlates after 2 weeks of recovery, among patients, who developed delirium.

METHODOLOGY

A prospective study designed was followed, in which subjects diagnosed with delirium were evaluated 2 weeks after resolution of symptoms of delirium, for PTSD symptoms by using Impact of Events Scale-Revised version (IES-R).

RESULTS

59 patients were evaluated for PTSD 2 weeks after resolution of delirium and the total mean IES-R score was 27.81 (SD-11.41). Based on the IES-cut-off scores of the scale, 30.5% of the patients (n = 18) were considered to have substantial symptoms of PTSD, 22% (n = 13) had probable symptoms of PTSD and 15.3% were considered to have partial symptoms of PTSD after resolution of delirium. None of the demographic or clinical factors were associated with development of PTSD. Those with PTSD symptoms had significantly higher prevalence of fluctuation of symptoms, while experiencing delirium and had significantly higher mean scores for the items of motor agitation, attentional deficits, higher total severity score on the Delirium Rating Scale-revised-98 version (DRS-R98) and higher DRS-R-98 total score. Higher severity of delirium as indicated by the total DRS-R98 score and the total DRS-R98 severity score were associated with higher severity of PTSD symptoms. The IES-R total score did not have any significant correlation with duration of illness, duration of delirium or Charlson Co-morbidity index.

CONCLUSIONS

This study suggests that about one-third of patients who develop delirium go on to develop symptoms of PTSD, after recovery from delirium. Development of PTSD symptoms is associated with severity of delirium. Hence, it is important to treat the delirium adequately and provide psychological support to the patients who develop delirium, after recovery from delirium.

Association between baseline cognitive impairment and postoperative delirium in elderly patients undergoing surgery for adult spinal deformity

OBJECTIVE Postoperative delirium is common in elderly patients undergoing spine surgery and is associated with a longer and more costly hospital course, functional decline, postoperative institutionalization, and higher likelihood of death within 6 months of discharge. Preoperative cognitive impairment may be a risk factor for the development of postoperative delirium. The aim of this study was to investigate the relationship between baseline cognitive impairment and postoperative delirium in geriatric patients undergoing surgery for degenerative scoliosis. METHODS Elderly patients 65 years and older undergoing a planned elective spinal surgery for correction of adult degenerative scoliosis were enrolled in this study. Preoperative cognition was assessed using the validated Saint Louis University Mental Status (SLUMS) examination. SLUMS comprises 11 questions, with a maximum score of 30 points. Mild cognitive impairment was defined as a SLUMS score between 21 and 26 points, while severe cognitive impairment was defined as a SLUMS score of ≤ 20 points. Normal cognition was defined as a SLUMS score of ≥ 27 points. Delirium was assessed daily using the Confusion Assessment Method (CAM) and rated as absent or present on the basis of CAM. The incidence of delirium was compared in patients with and without baseline cognitive impairment. RESULTS Twenty-two patients (18%) developed delirium postoperatively. Baseline demographics, including age, sex, comorbidities, and perioperative variables, were similar in patients with and without delirium. The length of in-hospital stay (mean 5.33 days vs 5.48 days) and 30-day hospital readmission rates (12.28% vs 12%) were similar between patients with and without delirium, respectively. Patients with preoperative cognitive impairment (i.e., a lower SLUMS score) had a higher incidence of postoperative delirium. One- and 2-year patient reported outcomes scores were similar in patients with and without delirium. CONCLUSIONS Cognitive impairment is a risk factor for the development of postoperative delirium. Postoperative delirium may be associated with decreased preoperative cognitive reserve. Cognitive impairment assessments should be considered in the preoperative evaluations of elderly patients prior to surgery.