Determinants of cognitive outcome in survivors of out-of-hospital cardiac arrest

Resting state EEG relates to short- and long-term cognitive functioning after cardiac arrest

BACKGROUND

Approximately half of cardiac arrest survivors have persistent cognitive impairment. Guidelines recommend early screening to identify patients at risk for cognitive impairment, but there is no consensus on the best screening method. We aimed to identify quantitative EEG measures relating with short- and long-term cognitive function after cardiac arrest for potential to cognitive outcome prediction.

METHODS

We analyzed data from a prospective longitudinal multicenter cohort study designed to develop a prediction model for cognitive outcome after cardiac arrest. For the current analysis, we used twenty-minute EEG registrations from 80 patients around one week after cardiac arrest. We calculated power spectral density, normalized alpha-to-theta ratio (nATR), peak frequency, and center of gravity (CoG) of this peak frequency. We related these with global cognitive functioning (scores on the Montreal Cognitive Assessment (MoCA)) at one week, three and twelve months follow-up with multivariate mixed effect models, and with performance on standard neuropsychological examination at twelve months using Pearson correlation coefficients.

RESULTS

Each individual EEG parameter related to MoCA at one week (βnATR = 7.36; P < 0.01; βpeak frequency = 1.73, P < 0.01; βCoG = -9.88, P < 0.01). The nATR also related with the MoCA at three months ((βnATR = 2.49; P 0.01). No EEG metrics significantly related to the MoCA score at twelve months. nATR and peak frequency related with memory performance at twelve months. Results were consistent in sensitivity analyses.

CONCLUSION

Early resting-state EEG parameters relate with short-term global cognitive functioning and with memory function at one year after cardiac arrest. Additional predictive values in multimodal prediction models need further study.

Cognitive impairment and psychopathology in sudden out-of-hospital cardiac arrest survivors: Results from the REVIVAL cohort study

AIM

To investigate cognitive impairment and psychopathology in out-of-hospital cardiac arrest (OHCA) survivors using a screening procedure during hospitalisation and examine the evolution of these parameters at three-month follow-up.

METHODS

This multicentre cohort study screened for cognitive impairment using the Montreal Cognitive Assessment (MoCA), for symptoms of anxiety, depression and traumatic distress using the Hospital Anxiety and Depression Scale (HADS) and the Impact of Event Scale-revised (IES-R) during hospitalisation. At three-month follow-up, we evaluated cognitive impairment with a neuropsychological test battery and symptoms of psychopathology were re-assessed using HADS and IES-R. Logistic regression models were applied to examine associations between screening results and outcomes.

RESULTS

This study included 297 OHCA survivors. During hospitalisation, 65% presented with cognitive impairment, 25% reported symptoms of anxiety, 20% symptoms of depression and 21% symptoms of traumatic distress. At follow-up, 53% reported cognitive impairment, 17% symptoms of anxiety, 15% symptoms of depression and 19% symptoms of traumatic distress. Cognitive impairment during hospitalisation was associated with higher odds (OR (95% CI) 2.55 (1.36-4.75), p = .02) of an unfavorable cognitive outcome at follow-up, and symptoms of psychopathology during hospitalisation were associated with higher odds of psychopathology at follow-up across all three symptom groups; anxiety (6.70 (2.40-18.72), p < .001), depression (4.69 (1.69-13.02), p < .001) and traumatic distress (7.07 (2.67-18.73), p < .001).

CONCLUSION

OHCA survivors exhibited both cognitive impairment and symptoms of psychopathology during hospitalisation comparable to previous studies, which were associated with unfavorable mental health outcomes at three-month follow-up.

Chronic Neuroinflammation and Cognitive Decline in Patients with Cardiac Disease: Evidence, Relevance, and Therapeutic Implications

Acute and chronic cardiac disorders predispose to alterations in cognitive performance, ranging from mild cognitive impairment to overt dementia. Although this association is well-established, the factors inducing and accelerating cognitive decline beyond ageing and the intricate causal pathways and multilateral interdependencies involved remain poorly understood. Dysregulated and persistent inflammatory processes have been implicated as potentially causal mediators of the adverse consequences on brain function in patients with cardiac disease. Recent advances in positron emission tomography disclosed an enhanced level of neuroinflammation of cortical and subcortical brain regions as an important correlate of altered cognition in these patients. In preclinical and clinical investigations, the thereby involved domains and cell types of the brain are gradually better characterized. Microglia, resident myeloid cells of the central nervous system, appear to be of particular importance, as they are extremely sensitive to even subtle pathological alterations affecting their complex interplay with neighboring astrocytes, oligodendrocytes, infiltrating myeloid cells, and lymphocytes. Here, we review the current evidence linking cognitive impairment and chronic neuroinflammation in patients with various selected cardiac disorders including the aspect of chronic neuroinflammation as a potentially druggable target.

External validation and insights about the calibration of the return of spontaneous circulation after cardiac arrest (RACA) score

Background

The return of spontaneous circulation (ROSC) after cardiac arrest (RACA) score was developed as a tool to predict ROSC probability (pROSC) based on easily available information and it could be useful to compare the performances of different EMS agencies or the effects of eventual interventions.

We performed an external validation of the RACA score in a cohort of out of hospital cardiac arrest (OHCA) patients managed by the EMS of the metropolitan city of Bologna, Italy.

Methods

We analyzed data from 2,310 OHCA events prospectively collected between January 2009 and June 2021. Discrimination was assessed with the area under the ROC curve (AUROC), while the calibration belts were used for the comparison of observed versus expected ROSC rates. The AUROCs from our cohort and other validation cohorts were compared using a studentized range test.

Results

The AUROC for the study population was 0.691, comparable to that described by previous validation studies. Despite an acceptable overall calibration, we found a poor calibration for asystole and low pROSC ranges in PEA and shockable rhythms. The model showed a good calibration for patients aged over 80, while no differences in performance were found when evaluating events before and after the implementation of 2015 ERC guidelines.

Conclusions

Despite AUROC values being similar in different validation studies for RACA score, we suggest separating the different rhythms when assessing ROSC probability with the RACA score, especially for asystole.

Long Term Cognitive Function After Cardiac Arrest: A Mini-Review

Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality worldwide. With better pre- and inhospital treatment, including cardiopulmonary resuscitation (CPR) as an integrated part of public education and more public-access defibrillators available, OHCA survival has increased over the last decade. There are concerns, after successful resuscitation, of cerebral hypoxia and degrees of potential acquired brain injury with resulting poor cognitive functioning. Cognitive function is not routinely assessed in OHCA survivors, and there is a lack of consensus on screening methods for cognitive changes. This narrative mini-review, explores available evidence on hypoxic brain injury and long-term cognitive function in cardiac arrest survivors and highlights remaining knowledge deficits.

Cognitive impairment caused by hypoxia: from clinical evidences to molecular mechanisms

Hypoxia is a state of reduced oxygen supply and excessive oxygen consumption. According to the duration of hypoxic period, it can be classified as acute and chronic hypoxia. Both acute and chronic hypoxia could induce abundant neurological deficits. Although there have been significant advances in the pathophysiological injuries, few studies have focused on the cognitive dysfunction. In this review, we focused on the clinical evidences and molecular mechanisms of cognitive impairment under acute and chronic hypoxia. Hypoxia can impair several cognitive domains such as attention, learning and memory, procession speed and executive function, which are similar in acute and chronic hypoxia. The severity of cognitive deficit correlates with the duration and degree of hypoxia. Recovery can be achieved after acute hypoxia, while sequelae or even dementia can be observed after chronic hypoxia, perhaps due to the different molecular mechanisms. Cardiopulmonary compensatory response, glycolysis, oxidative stress, calcium overload, adenosine, mitochondrial disruption, inflammation and excitotoxicity contribute to the molecular mechanisms of cognitive deficit after acute hypoxia. During the chronic stage of hypoxia, different adaptive responses, impaired neurovascular coupling, apoptosis, transcription factors-mediated inflammation, as well as Aβ accumulation and tau phosphorylation account for the neurocognitive deficit. Moreover, brain structural changes with hippocampus and cortex atrophy, ventricle enlargement, senile plaque and neurofibrillary tangle deposition can be observed under chronic hypoxia rather than acute hypoxia.

Neurocognitive function following out-of-hospital cardiac arrest: A systematic review

OBJECTIVES

The primary aim of this review was to investigate neurocognitive outcomes following out-of-hospital cardiac arrest (OHCA). Specifically, the focus was on identifying the different neurocognitive domains that are assessed, the measures used, and the level of, and criteria for, impairment.

DESIGN AND REVIEW METHODS

A systematic review of the literature from 2006 to 2021 was completed using Medline, Cinahl and Psychinfo. Criteria for inclusion were studies with participants over the age of 18, OHCA and at least one neurocognitive function measure. Qualitative and case studies were excluded. Reviewers assessed criteria and risk of bias using a modified version of Downs and Black.

RESULTS

Forty-three studies were identified. Most studies had a low risk of bias (n = 31) or moderate risk of bias (n = 11) and one had a high risk; however, only six reported effect sizes or power analyses. Multiple measures of neurocognitive outcomes were used (>50) and level of impairment criteria varied considerably. Memory impairments were frequently found and were also more likely to be impaired followed by executive function and processing speed.

DISCUSSION

This review highlights the heterogeneity of measures and approaches used to assess neurocognitive outcomes following OHCA as well as the need to improve risk of bias concerning generalizability. Improved understanding of the approaches used for assessment and the subsequent findings will facilitate a standardized evaluation of neurocognitive outcomes following OHCA.

Cognitive dysfunction after out-of-hospital cardiac arrest: Rate of impairment and clinical predictors

BACKGROUND

The purpose of this study was to evaluate the rate and domains of cognitive impairment in out-of-hospital cardiac arrest (OHCA) survivors, as compared to patients who experienced a myocardial infarction (MI), and to explore mechanisms and predictors of this impairment.

METHODS AND RESULTS

OHCA survivors with "good" neurological recovery (i.e., Cerebral Performance Categories Scale ≤ 2) (n = 79), as well as a control group of MI patients (n = 69), underwent a comprehensive neuropsychological assessment. Forty-three percent of OHCA survivors were cognitively impaired (in the lowest decile on a global measure of cognitive functioning). Rates of impairment were approximately six times higher in the OHCA group than the MI group. Attention, memory, language and executive function were affected. Downtime was a significant predictor of cognitive impairment; the interaction between downtime and immediate intervention was significant such that, at short downtimes, receiving cardiopulmonary resuscitation (CPR) or defibrillation within 1 min of collapse predicted less cognitive impairment.

CONCLUSIONS

OHCA survivors - even those with seemingly good neurological recovery - are at risk for cognitive impairment. Cognitive rehabilitation may be an important consideration post-OHCA.

European Resuscitation Council Guidelines 2021: Epidemiology of cardiac arrest in Europe

In this section of the European Resuscitation Council Guidelines 2021, key information on the epidemiology and outcome of in and out of hospital cardiac arrest are presented. Key contributions from the European Registry of Cardiac Arrest (EuReCa) collaboration are highlighted. Recommendations are presented to enable health systems to develop registries as a platform for quality improvement and to inform health system planning and responses to cardiac arrest.

Motor and process skills in activities of daily living in survivors of out-of-hospital cardiac arrest: a cross-sectional study at hospital discharge

AIMS

An individuals' ability to perform basic activities of daily living (ADL) is said to be one of the strongest predictors of performance ability and independent living within the community. The Assessment of Motor and Process Skills (AMPS) tool was designed to assess global functional level during ADL by investigating motor and process skills. The purpose of this study was to assess ADL performance ability by investigating motor and process skills in a consecutive cohort of adult survivors of out-of-hospital cardiac arrest at the time of discharge from hospital.

METHODS AND RESULTS 

This cross-sectional study uses data from a prospective cohort of cardiac arrest survivors admitted to the Copenhagen University Hospital, Rigshospitalet. The specific data used in this study were obtained at the time of the days or the day before hospital discharge. Adult survivors of out-of-hospital cardiac arrest due to cardiac causes were eligible for inclusion. Assessment of Motor and Process Skills was used to assess ADL performance ability by investigating motor and process skills. The ADL ability of 61 individuals was assessed. The mean ADL ability measures recorded were AMPS process 1.40 logits (0.48) and AMPS motor 1.82 logits (0.40). Based on the dichotomized AMPS results, 23% were most likely to need assistance to live independently in the community.

CONCLUSION 

Performance ability during ADL revealed difficulty in the performance of process skill and an increased need for rehabilitation among survivors of out-of-hospital cardiac arrest at the time of hospital discharge.

Exploratory Analyses of Cerebral Gray Matter Volumes After Out-of-Hospital Cardiac Arrest in Good Outcome Survivors

Background

Survival rates of cardiac arrest have increased over recent years, however, survivors may still be left with significant morbidity and functional impairment. A primary concern in cardiac arrest survivors is the effect of prolonged hypoxia/ischemia on the brain. The objectives of the present study were threefold: (1) to explore the effect of cardiac arrest on brain gray matter volumes (GMV) in “good outcome” survivors of out-of-hospital cardiac arrest (OHCA), (2) to examine the relationship between GMV, cognitive functioning and arrest factors, and (3) to explore whether OHCA patients differ from a group of patients with myocardial infarction (MI) uncomplicated by cardiac arrest and a group of healthy controls in terms of GMV.

Methods

Medically stable OHCA survivors with preserved neurological function and who were eligible for magnetic resonance imaging scanning (MRI; n = 9), were compared to: (1) patients who had experienced a MI (n = 19) and (2) healthy controls (n = 12). Participants underwent brain MRI on a 3T Siemens Trio MRI scanner and GMV was measured by voxel-based morphometry. A comprehensive neuropsychological assessment was also conducted. Global GMV was compared in the three samples using analyses of variance. The relationships between cognition and GMV were examined within group using correlations.

Results

The OHCA and MI groups showed a similar pattern of differences compared to the healthy control group. Both groups had decreased GMV in the anterior cingulate cortex, bilateral hippocampus, right dorsolateral prefrontal cortex, right putamen, and bilateral cerebellum. There were no significant differences in global or regional GMV between the OHCA and MI groups. Cognitive functioning was correlated with global GMV in the OHCA group; no such correlation was observed in the MI group.

Conclusion

Regional atrophy was observed in OHCA and MI survivors, compared to a healthy control group, suggesting a common mechanism, presumably preexisting cardiovascular disease. Although similar regional volume differences were observed between the MI and OHCA groups, the relationship between GMV and cognition was only observed in OHCA survivors. We suggest the acute hypoxia/ischemia ensuing from the arrest may interact with diminished neural reserve in select brain areas to expose occult cognitive dysfunction.

Sudden Cardiac Arrest Survivorship: A Scientific Statement From the American Heart Association

Cardiac arrest systems of care are successfully coordinating community, emergency medical services, and hospital efforts to improve the process of care for patients who have had a cardiac arrest. As a result, the number of people surviving sudden cardiac arrest is increasing. However, physical, cognitive, and emotional effects of surviving cardiac arrest may linger for months or years. Systematic recommendations stop short of addressing partnerships needed to care for patients and caregivers after medical stabilization. This document expands the cardiac arrest resuscitation system of care to include patients, caregivers, and rehabilitative healthcare partnerships, which are central to cardiac arrest survivorship.

Communicative and swallowing disorders in anoxic patients: A retrospective study on clinical outcomes and performance measures

BACKGROUND

Anoxic brain injury (ABI) is a neurological condition associated to a severe deterioration of brain functioning, whose symptomatology and clinical outcomes may be heterogeneous: cognitive deficits, language disorders like dysarthria and swallowing impairments. Nevertheless, there is still a lack of information on the rehabilitation outcomes.

OBJECTIVE

To confirm the occurrence of communication and swallowing deficits in 37 ABI patients and to examine whether intensive rehabilitation may contribute to any improvements and its relation to ABI severity and functional autonomy.

METHODS

37 patients, hospitalized at IRCCS San Camillo Hospital from 2011 to 2018 were analyzed retrospectively. All patients completed a functional evaluation and a language and swallowing assessment, within one week from hospital admission (T0). The assessment was repeated after an intensive rehabilitation treatment (T1).

RESULTS

Results show that dysphagia is a frequent and severe outcome in anoxic patients, whereas communication disorders (aphasia and dysarthria) are less severe. Moreover, ABI patients seem to be positively sensitive to an intensive rehabilitation program.

CONCLUSIONS

An early multidisciplinary management of communicative-linguistic and swallowing functions is crucial in order to prevent adverse events and to plan a tailored rehabilitation pathway.

Gender differences in cognitive outcome after cardiac arrest: A retrospective cohort study

Introduction: Recent studies have suggested gender disparities in neurologic outcome after cardiac arrest (CA). However, the relation between gender and cognitive outcome has been rarely examined. Here we investigated whether sex is associated with cognitive outcome after CA events.Methods: A retrospective analysis was conducted using data collected at our institution from January 2006 to May 2017. Patients were included if they had a documented CA and were able to participate in structured neuropsychological testing. Cognitive status was assessed at about 2.1 month after CA and included tests of attention as well as short and long-term memory. Gender was used as the main predictor of outcome and was studied in relation to age, depressive mood, therapeutic hypothermia (TH), and other potential confounders.Results: Males were more likely to show favorable cognitive outcome in both univariate and multivariate analyses. Women were more likely to exhibit depressive mood. Patients who underwent TH (31% of the patients) did not show any gender differences in benefits from the treatment. Among males and females, no significant differences between age groups could be observed.Conclusions: Male sex was associated with favorable cognitive outcome after CA which could not be attributed to baseline characteristics.

Neuropsychological Outcomes of Children 1 Year After Pediatric Cardiac Arrest: Secondary Analysis of 2 Randomized Clinical Trials

Importance

Little is known about neuropsychological outcomes of children who survived pediatric cardiac arrest (CA).

Objective

To describe the neuropsychological outcomes of CA survivors enrolled in the Therapeutic Hypothermia After Pediatric Cardiac Arrest In-Hospital (THAPCA-IH) and Out-of-Hospital (THAPCA-OH) trials and compare the results with the primary outcome measure for these trials.

Design, Setting, and Participants

Secondary analysis of 222 CA survivors aged 1 to 18 years who received chest compressions for 2 minutes or more, remained comatose and required mechanical ventilation after return of circulation, and were enrolled in targeted temperature-management trials from 41 pediatric intensive care units. Data were collected from September 3, 2009, to February 3, 2016, and analyzed from March 10, 2017, to April 20, 2018.

Main Outcomes and Measures

The Vineland Adaptive Behavior Scales, Second Edition (VABS-II), a standardized measure of neurobehavioral functioning based on caregiver report (age-corrected mean [SD] scores = 100 [15]), was used to evaluate pre-CA functioning within 24 hours after enrollment; VABS-II<70 indicated significant developmental delays; VABS-II and neuropsychological testing were completed 1 year after CA. Neuropsychological testing included the Mullen Scales of Early Learning (Mullen) for children younger than 6 years and the Wechsler Abbreviated Scale of Intelligence (WASI) and neuropsychological measures of attention, memory, processing speed, and executive functioning for older children.

Results

Of 160 participants who completed neuropsychological testing, 96 (60.0%) were male; the median (interquartile range [IQR]) age was 2.5 years (1.3-6.1 years). Ninety-six (60.0%) were white, 41 (25.6%) were black, and 23 (14.4%) were of other/unknown race; 343 (21.2%) were Hispanic or Latino; 119 (74.4%) were non-Hispanic or Latino; and 7 (4.4%) were of unknown ethnicity. One hundred fourteen participants (71.2%) were classified as having favorable outcomes (VABS-II ≥70). Impairments (>2 SD below the mean for age) across neuropsychological measures ranged from 7% to 61%. Correlations between global cognitive and VABS-II scores were strong for younger children (Mullen, r = 0.69-0.87) but moderate for older children (r = 0.21-0.54 for the WASI). Of 111 children with favorable outcomes on VABS-II, 25.2% had global cognitive impairment and 30 of 35 older children (85.7%) had selective neuropsychological deficits.

Conclusions and Relevance

In this prospectively evaluated cohort of pediatric CA survivors who were initially comatose, although 71.2% were classified as having favorable outcomes, significant neuropsychological deficits were identified in pediatric CA survivors who were classified as having favorable outcomes. The findings provide clinicians with a greater understanding of the spectrum of neuropsychological outcomes of pediatric CA survivors and the complex relationship between standardized caregiver-reported functional outcome measures incorporated in clinical trials and performance-based neuropsychological assessments.

Cortical Thickness and Cognitive Performance After Out-of-Hospital Cardiac Arrest

BACKGROUND

Cognitive impairment is common in long-term survivors of out-of-hospital cardiac arrest (OHCA) but corresponding neuroimaging data are lacking.

OBJECTIVES

This study explored the relationship among the cortical brain structure, cognitive performance, and clinical variables after OHCA.

METHODS

Three months after resuscitation, 13 OHCA survivors who had recovered from a coma to living independently and 19 healthy controls were assessed by cerebral magnetic resonance imaging and neuropsychological tests quantifying memory, fine-motor coordination, and attention/executive functions. Cortical thickness (Cth) and surface area (SA) were compared between groups and analyzed for relationships with cognitive performance as well as the clinical variables of coma duration and the time to return of spontaneous circulation (ROSC). All analyses were controlled for age and sex.

RESULTS

Analyses of SA revealed no significant differences. Compared with controls, survivors had significantly reduced memory and fine-motor coordination and significantly thinner cortex in large clusters in the frontal, parietal, and inferior temporal cortices, with additional regions in the left occipital lobe and the left temporal lobe. Widespread thinner cortical regions were significantly associated with decreased memory performance in survivors when compared with those in controls and were significantly associated with an increased time to ROSC and increased coma duration in the OHCA group. Increased coma duration, but not increased time to ROSC, was significantly correlated with cognitive test performance.

CONCLUSIONS

The results suggest that widespread Cth reductions correspond to the cognitive impairments observed after OHCA. Neuroimaging studies of long-term OHCA survivors are warranted to guide the development of diagnostics and treatment options.

Long-term neurological outcomes in out-of-hospital cardiac arrest patients treated with targeted-temperature management

BACKGROUND

This study aimed to assess long-term cognitive and functional outcomes in out-of-hospital cardiac arrest (OHCA) patients treated with targeted-temperature management, investigate the existence of prognostic factors that could be assessed during initial admission and evaluate the usefulness of classic neurological scales in this clinical scenario.

METHODS

Patients admitted due to OHCA from August 2007 to November 2015 and surviving at least one year were included. Each patient completed a structured interview focused on the collection of clinical, social and demographic data. All available information in clinical records was reviewed and a battery of neurocognitive and psychometric tests was performed.

RESULTS

Seventy-nine patients were finally included in the analysis. Forty-three patients (54.4%) scored below the usual cut-off points for the diagnosis of mild cognitive impairment, even though most of these deficits went unnoticed when patients were assessed using CPC and modified Rankin scale. Nineteen (24%) developed certain degree of impairment in their attention capacity and executive functions. A significant proportion developed new memory-related disorders (43%), depressive symptoms (17.7%), aggressive/uninhibited behavior (12.7%) and emotional lability (8.9%). A greater number of weekly hours of intellectual activity and a qualified job were independent protective factors for the development of cognitive impairment. However, being older at the time of the cardiac arrest was identified as a poor prognostic factor.

CONCLUSIONS

There is a high prevalence of long-term cognitive deficits and functional limitations in OHCA survivors. Most commonly used clinical scales in clinical practice are crude and lack sensitivity to detect most of these deficits.

Prediction of cognitive dysfunction after resuscitation - a systematic review

Cardiac arrest (CA) due to cardiovascular disease is the leading cause of death in developed countries. It is estimated that over 350,000 people in Europe suffer from out-of-hospital cardiac arrest. According to the literature, the longer the episode of cardiac arrest, the greater the risk of cognitive impairment, especially short-term memory, as well as immediate and delayed recall. Other common dysfunctions include attention deficits and executive function disorders. The aim of this systematic review was to summarize current research on cognitive impairment in patients after sudden cardiac arrest. The electronic databases PubMed/MEDLINE, OVID, Web of Science, and EBSCO were searched using the following key words: 'sudden cardiac arrest', 'out-of-hospital cardiac arrest', 'cognitive function', 'cognitive impairment', 'functional outcome', 'cardiopulmonary resuscitation'. The most recent studies from the last 7 years (2011-2018) were included. Cognitive disorders occurred in a broad range of cases: from 13% to even 100%. In one study, cognitive deficits did not occur at all. Amongst the reviewed articles only two studies were carried out on a large group of patients. The remaining studies were conducted on a small group of respondents; therefore there was no possibility to generalize the results to the entire population. The areas in which the most cognitive impairment occurred were memory, executive functions and visual-motor skills. One of the conclusions derived from the reviewed literature is the importance of continuous training of cognitive functions, especially for people with cardiovascular risk.

Long-term effects of brief hypoxia due to cardiac arrest: Hippocampal reductions and memory deficits

OBJECTIVE

To examine the effects of brief hypoxia (<7 min) due to cardiac arrest on the integrity of the brain and performance on memory and executive functions tasks.

METHODS

Patients after out-of-hospital cardiac arrest (CA) (n = 9), who were deemed neurologically intact on discharge, were compared to matched patients with myocardial infarction (MI) (n = 9). A battery of clinical and experimental memory and executive functions neuropsychological tests were administered and MRI scans for all patients were collected. Measures of subcortical and cortical volumes and cortical thickness were obtained using FreeSurfer. Manual segmentations of the hippocampus were also performed. APACHE-II scores were calculated based on metrics collected at admission to ICCU for all patients.

RESULTS

Significant differences between the two groups were observed on several verbal memory tests. Both hippocampi were significantly reduced (p < 0.05) in the CA patients, relative to MI patients. Hippocampal subfields segmentation showed significantly reduced presubiculum volumes bilaterally. CA patients had on average 10% reduction in volumes bilaterally across hippocampal subfields. No cortical thickness differences survived correction. Significant correlations were observed in the CA group only between the hippocampal volumes and performance on verbal memory tasks, including recollection. Hippocampal volumes and several memory measures (but not other cognitive domains) were strongly correlated with APACHE-II scores on admission in the CA group, but not in the MI group CONCLUSIONS: Chronic patients with cardiac arrest who were discharged from hospital in "good neurological condition" showed an average of 10% reduction in hippocampal volume bilaterally and significant verbal memory deficits relative to matched controls with myocardial infarction, suggesting even brief hypoxic periods suffice to lead to specific hippocampal damage.

Neuropsychological Outcome following Resuscitation after Out-of-Hospital Cardiac Arrest: A One-Year Follow-Up

A 61-year-old woman survived resuscitation after out-of-hospital cardiac arrest. The heterogeneity of the resulting cognitive impairments and the recovery over a one-year period are presented, highlighting the need for standardized neuropsychological testing even after short cardiac arrests and for effective treatment both out of hospital and in hospital.