BACKGROUND: Although magnetic resonance imaging, particularly diffusion-weighted imaging, has increasingly been used as part of a multimodal approach to prognostication in patients who are comatose after cardiac arrest, the performance of quantitative analysis of apparent diffusion coefficient (ADC) maps, as compared to standard radiologist impression, has not been well characterized. This retrospective study evaluated quantitative ADC analysis to the identification of anoxic brain injury by diffusion abnormalities on standard clinical magnetic resonance imaging reports.
METHODS: The cohort included 204 previously described comatose patients after cardiac arrest. Clinical outcome was assessed by (1) 3-6 month post-cardiac-arrest cerebral performance category and (2) coma recovery to following commands. Radiological evaluation was obtained from clinical reports and characterized as diffuse, cortex only, deep gray matter structures only, or no anoxic injury. Quantitative analyses of ADC maps were obtained in specific regions of interest (ROIs), whole cortex, and whole brain. A subgroup analysis of 172 was performed after eliminating images with artifacts and preexisting lesions.
RESULTS: Radiological assessment outperformed quantitative assessment over all evaluated regions (area under the curve [AUC] 0.80 for radiological interpretation and 0.70 for the occipital region, the best performing ROI, p = 0.011); agreement was substantial for all regions. Radiological assessment still outperformed quantitative analysis in the subgroup analysis, though by smaller margins and with substantial to near-perfect agreement. When assessing for coma recovery only, the difference was no longer significant (AUC 0.83 vs. 0.81 for the occipital region, p = 0.70).
CONCLUSIONS: Although quantitative analysis eliminates interrater differences in the interpretation of abnormal diffusion imaging and avoids bias from other prediction modalities, clinical radiologist interpretation has a higher predictive value for outcome. Agreement between radiological and quantitative analysis improved when using high-quality scans and when assessing for coma recovery using following commands. Quantitative assessment may thus be more subject to variability in both clinical management and scan quality than radiological assessment.

Cardiac arrest survivors suffer the repercussions of anoxic brain injury, a critical factor influencing long-term prognosis. This injury is characterised by profound and enduring metabolic impairment. Ketone bodies, an alternative energetic resource in physiological states such as exercise, fasting, and extended starvation, are avidly taken up and used by the brain. Both the ketogenic diet and exogenous ketone supplementation have been associated with neuroprotective effects across a spectrum of conditions. These include refractory epilepsy, neurodegenerative disorders, cognitive impairment, focal cerebral ischemia, and traumatic brain injuries. Beyond this, ketone bodies possess a plethora of attributes that appear to be particularly favourable after cardiac arrest. These encompass anti-inflammatory effects, the attenuation of oxidative stress, the improvement of mitochondrial function, a glucose-sparing effect, and the enhancement of cardiac function. The aim of this manuscript is to appraise pertinent scientific literature on the topic through a narrative review. We aim to encapsulate the existing evidence and underscore the potential therapeutic value of ketone bodies in the context of cardiac arrest to provide a rationale for their use in forthcoming translational research efforts.

BACKGROUND: Few data characterize the role of brain computed tomography (CT) after resuscitation from in-hospital cardiac arrest (IHCA). We hypothesized that identifying a neurological etiology of arrest or cerebral edema on brain CT are less common after IHCA than after resuscitation from out-of-hospital cardiac arrest (OHCA).
METHODS: We included all patients comatose after resuscitation from IHCA or OHCA in this retrospective cohort analysis. We abstracted patient and arrest clinical characteristics, as well as pH and lactate, to estimate systemic illness severity. Brain CT characteristics included quantitative measurement of the grey-to-white ratio (GWR) at the level of the basal ganglia and qualitative assessment of sulcal and cisternal effacement. We compared GWR distribution by stratum (no edema ≥1.30, mild-to-moderate <1.30 and >1.20, severe ≤1.20) and newly identified neurological arrest etiology between IHCA and OHCA groups.
RESULTS: We included 2,306 subjects, of whom 420 (18.2%) suffered IHCA. Fewer IHCA subjects underwent post-arrest brain CT versus OHCA subjects (149 (35.5%) vs 1,555 (82.4%), p < 0.001). Cerebral edema for IHCA versus OHCA was more often absent (60.1% vs. 47.5%) or mild-to-moderate (34.3% vs. 27.9%) and less often severe (5.6% vs. 24.6%). A neurological etiology of arrest was identified on brain CT in 0.5% of IHCA versus 3.2% of OHCA.
CONCLUSIONS: Although severe edema was less frequent in IHCA relative to OHCA, mild-to-moderate or severe edema occurred in one in three patients after IHCA. Unsuspected neurological etiologies of arrest were rarely discovered by CT scan in IHCA patients.

OBJECTIVE: To determine the association between spontaneous hypothermia (SH), defined as initial post-resuscitation core body temperature less than 34°C, and diffuse anoxic brain injury (DABI) on initial CT scan of the head (CTH) in post-cardiac arrest patients.
METHODS: This was a retrospective, observational cohort study. This study was performed at the University of Rochester Medical Center Strong Memorial Hospital. All in-hospital and out-of-hospital cardiac arrest patients with return of spontaneous circulation admitted between January 1, 2022, and October 31, 2022, were included.
METHODS: The primary outcomes were the odds of DABI on initial CTH for patients with SH compared with patients without SH post-cardiac arrest using a multivariable logistic regression controlling for patient covariates including basic demographics and arrest features. DABI on initial CTH was measured qualitatively and quantitatively using neuroradiologist interpretation and calculated gray-white matter ratio of the basal ganglia, respectively. Secondary outcome measures included length of stay (LOS), inpatient mortality, and those who underwent withdrawal of life-sustaining therapy (WOLST) or progression to brain death.
RESULTS: Out of the observed 150 cases of cardiac arrest, 31 patients (21%) had SH. Of the 128 patients who had an initial CTH performed, 27 (21%) had DABI. The adjusted odds ratio of DABI on initial CTH associated with SH was 3.55 (95% CI, 1.08-11.64; p = 0.036) and 2.18 (95% CI, 0.69-6.91; p = 0.182) when DABI was measured qualitatively and quantitatively, respectively, after controlling for multiple covariates. There was a difference observed in LOS between the groups (3 vs. 10 d; p = 0.0005) and this was driven by early WOLST.
CONCLUSIONS: Patients presenting with SH after cardiac arrest may be at greater risk of early DABI on initial CTH compared with those with higher body temperatures in the post-arrest period. Recognition of early SH may help to risk stratify post-cardiac arrest patients at highest risk of DABI.

BACKGROUND: Drowning is a leading cause of brain injury in children. Long-term outcome data for drowning survivors are sparse. This study reports neurocognitive outcomes for 154 children hospitalized following drowning.
METHODS: A survey for parent caregivers was distributed online. Likert scale items assessed 10 outcome variables in four domains: motor (three), perception (three), language (three), and social/emotional (one). Cluster analysis, outcome relative risk, and descriptive statistics were applied.
RESULTS: Of 208 surveys received, 154 met inclusion criteria. Coma was the most common admission status (n = 137). Cluster analysis identified three outcome groups: Mild (n = 39), Moderate (n = 75), and Severe (n = 40). Motor impairment with cognitive and perceptual sparing (deefferentation) was present in Moderate (P < 1 × 10-26) and Severe (P < 1 × 10-12) but absent in Mild. Locked-in state was endorsed in both Moderate (83%) and Severe (70%). The strongest predictor of good outcome (Mild) was hospitalization with no medical intervention (relative risk [RR] = 6.7). Responsivity on admission (RR = 4.2) or discharge (RR = 12.22) also predicted good outcome. In-hospital prognostication and counseling predicted outcome weakly (RR = 1.3) or not at all.
CONCLUSIONS: Long-term outcomes in pediatric drowning ranged widely. Overall, motor impairments exceeded perceptual or cognitive (P < 1 × 10-18), with \"locked-in state\" endorsed in most (93 of 154). The strongest predictors of good outcome were the lack of necessity for interventions and responsivity on admission or discharge. The eponym \"Conrad syndrome\" is proposed for locked-in state following nonfatal drowning in children.

BACKGROUND: Grey-white ratio (GWR) can estimate severity of cytotoxic cerebral edema secondary to hypoxic-ischemic brain injury after cardiac arrest and predict progression to death by neurologic criteria (DNC). Current approaches to calculating GWR are not standardized and have variable interrater reliability. We tested if measures of variance of brain density on early computed tomographic (CT) imaging after cardiac arrest could predict DNC.
METHODS: We performed a retrospective cohort study, identifying post-arrest patients treated between 2011 and 2020 at our single center. We extracted demographic data from our registry and Digital Imaging and Communication in Medicine (DICOM) files for each patient\'s first brain CT. We analyzed slices 15-20 of each DICOM, corresponding to the level of the basal ganglia while accommodating differences in patient anatomy. We extracted pixel arrays and converted the radiodensities to Hounsfield units (HU). To focus on brain tissue densities, we excluded HU > 60 and < 10. We calculated the variance of each patient\'s HU distribution and the difference between the means of a two-group Gaussian finite mixture model. We compared these novel metrics to existing measures of cerebral edema, then randomly divided our data into 80% training and 20% test sets and used logistic regression to predict DNC.
RESULTS: Of 1,133 included subjects, 457 (40%) were female, mean (standard deviation) age was 58 (16) years, and 115 (10%) progressed to DNC. CTs were obtained a median [interquartile range] of 4.2 [2.8-5.7] hours post-arrest. Our novel measures correlated weakly with GWR. HU variance, but not difference between mixture model means, differed significantly between subjects with and without sulcal or cistern effacement. GWR outperformed our novel measures in predicting progression to DNC with an area under the receiver operating characteristic curve (AUC) of 0.82, compared to HU variance (AUC = 0.73) and the difference between mixture model means (AUC = 0.56).
CONCLUSIONS: There are differences in the distribution of HU on post-arrest CT in patients with qualitative measures of cerebral edema. Current methods to quantify cerebral edema outperform simple measures of attenuation variance on early brain CT. Further analyses could investigate if these measures of variance, or other distributional characteristics of brain density, have improved predictive performance on brain CTs obtained later in the clinical course or derived from discrete regions of anatomical interest.

Emerging science continues to establish the detrimental effects of malnutrition in acute neurological diseases such as traumatic brain injury, stroke, status epilepticus and anoxic brain injury. The primary pathological pathways responsible for secondary brain injury include neuroinflammation, catabolism, immune suppression and metabolic failure, and these are exacerbated by malnutrition. Given this, there is growing interest in novel nutritional interventions to promote neurological recovery after acute brain injury. In this review, we will describe how malnutrition impacts the biomolecular mechanisms of secondary brain injury in acute neurological disorders, and how nutritional status can be optimized in both pediatric and adult populations. We will further highlight emerging therapeutic approaches, including specialized diets that aim to resolve neuroinflammation, immunodeficiency and metabolic crisis, by providing pre-clinical and clinical evidence that their use promotes neurologic recovery. Using nutrition as a targeted treatment is appealing for several reasons that will be discussed. Given the high mortality and both short- and long-term morbidity associated with acute brain injuries, novel translational and clinical approaches are needed.

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Diffuse cortical diffusion changes on magnetic resonance imaging (MRI) are characteristically ascribed to global cerebral anoxia, typically after cardiac arrest. Far from being pathognomonic, however, this neuroimaging finding is relatively nonspecific, and can manifest in a myriad of disease states including hypoxia, metabolic derangements, infections, seizure, toxic exposures, and neuroinflammation. While these various conditions can all produce a neuroimaging pattern of widespread cortical diffusion restriction, many of these underlying causes do have subtly unique imaging features that are appreciable on MRI and can be of clinical and diagnostic utility. Specific populations of neurons are variably sensitive to certain types of injury, whether due to differences in perfusion, receptor type density, or the unique tropisms of infectious organisms. In this narrative review, we discuss a number of distinct etiologies of diffuse cortical diffusion restriction on MRI, the unique pathophysiologies responsible for tissue injury, and the resulting neuroimaging characteristics that can be of assistance in differentiating them. As widespread cortical injury from any cause often presents with altered mental status or coma, the differential diagnosis can be enhanced with rapid acquisition of MRI when clinical history or detailed physical examination is limited. In such settings, the distinct imaging features discussed in this article are of interest to both the clinician and the radiologist.