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Author Spotlight: A Unique Mouse Model of Asphyxia-Induced Cardiac Arrest
Published on: April 14, 2023
Exploratory Analyses of Cerebral Gray Matter Volumes After Out-of-Hospital Cardiac Arrest in Good Outcome Survivors
Aziza Byron-Alhassan1,2, Heather E Tulloch1,2,3, Barbara Collins1,2
1Department of Cardiac Prevention and Rehabilitation, University of Ottawa Heart Institute, Ottawa, ON, Canada.
Insights
Cardiac arrest survivors show brain gray matter volume (GMV) loss, similar to heart attack patients. Cognitive function in cardiac arrest survivors correlates with GMV, unlike in heart attack patients, suggesting hypoxia impacts brain reserve.
Area of Science:
- Neuroscience
- Cardiology
- Radiology
Background:
- Increased survival rates from cardiac arrest highlight the need to address associated neurological deficits.
- Prolonged hypoxia/ischemia following cardiac arrest poses a significant risk to brain health and function.
- Understanding the long-term neurological consequences in survivors is crucial for improving patient outcomes.
Purpose of the Study:
- To investigate the impact of out-of-hospital cardiac arrest (OHCA) on brain gray matter volume (GMV) in survivors.
- To correlate GMV with cognitive function and cardiac arrest-specific factors.
- To compare GMV in OHCA survivors with patients experiencing myocardial infarction (MI) and healthy controls.
Main Methods:
- Brain MRI (3T) was used to measure GMV via voxel-based morphometry in OHCA survivors (n=9), MI patients (n=19), and healthy controls (n=12).
- A comprehensive neuropsychological assessment was performed on all participants.
- Analyses of variance compared global GMV, while correlations examined relationships between GMV and cognition.
Main Results:
- Both OHCA and MI groups exhibited reduced GMV in specific brain regions (anterior cingulate cortex, hippocampus, prefrontal cortex, putamen, cerebellum) compared to controls.
- No significant differences in global or regional GMV were found between OHCA and MI groups.
- Cognitive function correlated with global GMV in OHCA survivors, but not in MI patients.
Conclusions:
- Regional brain atrophy is present in both OHCA and MI survivors, suggesting shared underlying mechanisms potentially related to cardiovascular disease.
- While regional GMV differences were similar between OHCA and MI groups, cognitive deficits were uniquely linked to GMV in OHCA survivors.
- Hypoxia/ischemia from cardiac arrest may exacerbate cognitive dysfunction by interacting with pre-existing reduced neural reserve.
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.
