Thresholds for identifying pathological intracranial pressure in paediatric traumatic brain injury

Nucleic Acids-Based Biomarkers for Alzheimer's Disease Diagnosis and Novel Molecules to Treat the Disease

Alzheimer's disease (AD) represents the most common form of dementia and affects million people worldwide, with a high social burden and considerable economic costs. AD diagnosis benefits from a well-established panel of laboratory tests that allow ruling-in patients, along with FDG and amyloid PET imaging tools. The main laboratory tests used to identify AD patients are Aβ40, Aβ42, the Aβ42/Aβ40 ratio, phosphorylated Tau 181 (pTau181) and total Tau (tTau). Although they are measured preferentially in the cerebrospinal fluid (CSF), some evidence about the possibility for blood-based determination to enter clinical practice is growing up. Unfortunately, CSF biomarkers for AD and, even more, the blood-based ones, present a few flaws, and twenty years of research in this field did not overcome these pitfalls. The tale even worsens when the issue of treating AD is addressed due to the lack of effective strategies despite the many decades of attempts by pharmaceutic industries and scientists. Amyloid-based drugs failed to stop the disease, and no neuroinflammation-based drugs have been demonstrated to work so far. Hence, only symptomatic therapy is available, with no disease-modifying treatment on hand. Such a desolate situation fully justifies the active search for novel biomarkers to be used as reliable tests for AD diagnosis and molecular targets for treating patients. Recently, a novel group of molecules has been identified to be used for AD diagnosis and follow-up, the nuclei acid-based biomarkers. Nucleic acid-based biomarkers are a composite group of extracellular molecules consisting of DNA and RNA alone or in combination with other molecules, including proteins. This review article reports the main findings from the studies carried out on these biomarkers during AD, and highlights their advantages and limitations.

Degree of basal cisterns compression predicting mortality and functional outcome after craniotomy and primary decompressive craniectomy in acute subdural hematoma population

OBJECTIVES

The compression of basal cisterns on CT is one of the signs of intracranial hypertension in TBI population. This study evaluates the relationship between the degree of basal cisterns effacement and outcomes in aSDH population.

METHODS

The study includes prospectively collected data from 290 patients who underwent osteoplastic craniotomy (OC) or primary decompressive craniectomy (pDC) for aSDH from 2016 to 2021. Univariate and multivariate regression analyses were performed to evaluate the association of baseline characteristics and extent of basal cisterns compression on pre-operative and post-operative CT scans with the outcomes at the time of discharge. Outcomes were dichotomized into mortality (and unfavourable (GOS 1-3 vs GOS 4-5). The degree of cisternal compression was evaluated using the cisternal effacement score of perimesencephalic and quadrigeminal cisternal components. Critical thresholds associated with the outcomes were calculated.

RESULTS

Age and pre-/post-operative degree of cisternal compression were the strongest independent predictors of intrahospital mortality in a whole sample and separately in OC and pDC subgroups. The unfavourable outcome was independently predicted by age, pre-/post-operative status of cisternal compression and initial GCS. Critical thresholds associated with the mortality and poor functional outcome were, respectively, age ≥ 70 (OR 3.14 [CI 95% 1.82-5.46], p < 0.001) and ≥ 67 (OR 3.87 [CI 95% 2.33-6.54], p < 0.001), pre-operative cisternal effacement score ≥ 9 (OR 6.39 [CI 95% 3.62-11.53], p < 0.001) and ≥ 7 (OR 4.93 [CI 95% 2.96-8.38], p < 0.001), post-operative cisternal effacement score ≥ 6 (OR 20.6 [CI 95% 10.08-45.10], p < 0.001) and ≥ 3 (OR 7.47 [CI 95% 3.87-15.73], p < 0.001) and initial GCS ≤ 8 (OR 0.24 [CI 95% 0.13-0.43], p < 0.001 and OR 0.12 [CI 95% 0.07-0.21], p < 0.001).

CONCLUSIONS

After adjusting for baseline characteristics, age and degree of cisternal compression remained the independent predictors of mortality, whereas unfavourable outcomes were associated with age, cisternal obliteration and GCS on presentation.

An update on pediatric traumatic brain injury

INTRODUCTION

Traumatic brain injury (TBI) remains the commonest neurological and neurosurgical cause of death and survivor disability among children and young adults. This review summarizes some of the important recent publications that have added to our understanding of the condition and advanced clinical practice.

METHODS

Targeted review of the literature on various aspects of paediatric TBI over the last 5 years.

RESULTS

Recent literature has provided new insights into the burden of paediatric TBI and patient outcome across geographical divides and the severity spectrum. Although CT scans remain a standard, rapid sequence MRI without sedation has been increasingly used in the frontline. Advanced MRI sequences are also being used to better understand pathology and to improve prognostication. Various initiatives in paediatric and adult TBI have contributed regionally and internationally to harmonising research efforts in mild and severe TBI. Emerging data on advanced brain monitoring from paediatric studies and extrapolated from adult studies continues to slowly advance our understanding of its role. There has been growing interest in non-invasive monitoring, although the clinical applications remain somewhat unclear. Contributions of the first large scale comparative effectiveness trial have advanced knowledge, especially for the use of hyperosmolar therapies and cerebrospinal fluid drainage in severe paediatric TBI. Finally, the growth of large and even global networks is a welcome development that addresses the limitations of small sample size and generalizability typical of single-centre studies.

CONCLUSION

Publications in recent years have contributed iteratively to progress in understanding paediatric TBI and how best to manage patients.

Liquid Biopsy in Neurological Diseases

The most recent and non-invasive approach for studying early-stage biomarkers is liquid biopsy. This implies the extraction and analysis of non-solid biological tissues (serum, plasma, saliva, urine, and cerebrospinal fluid) without undergoing invasive procedures to determine disease prognosis. Liquid biopsy can be used for the screening of several components, such as extracellular vesicles, microRNAs, cell-free DNA, cell-free mitochondrial and nuclear DNA, circulating tumour cells, circulating tumour DNA, transfer RNA, and circular DNA or RNA derived from body fluids. Its application includes early disease diagnosis, the surveillance of disease activity, and treatment response monitoring, with growing evidence for validating this methodology in cancer, liver disease, and central nervous system (CNS) disorders. This review will provide an overview of mentioned liquid biopsy components, which could serve as valuable biomarkers for the evaluation of complex neurological conditions, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, stroke, traumatic brain injury, CNS tumours, and neuroinfectious diseases. Furthermore, this review highlights the future directions and potential limitations associated with liquid biopsy.

Impact of Chronological Age and Biological Sex on Cerebrovascular Reactivity in Moderate/Severe Traumatic Brain Injury: A CAnadian High-Resolution TBI (CAHR-TBI) Study

Impaired cerebrovascular reactivity has emerged as an important associate with poor long-term outcome after moderate/severe traumatic brain injury (TBI). However, our understanding of what drives or modulates the degree of impaired cerebrovascular function remains poor. Age and biological sex remain important modifiers of cerebrovascular function in health and disease, yet their impact on cerebrovascular reactivity after TBI remains unclear. The aim of this study was to explore subgroup responses based on age and biological sex on cerebral physiology. Data from 283 TBI patients from the CAnadian High Resolution TBI (CAHR-TBI) Research Collaborative were evaluated. Cerebrovascular reactivity was determined using high-frequency cerebral physiology for the derivation of three intracranial pressure (ICP) based indices: (1). PRx - correlation between ICP and mean arterial pressure (MAP), (2). PAx - correlation between pulse amplitude of ICP (AMP) and MAP and (3). RAC - correlation between AMP and cerebral perfusion pressure (CPP). Insult burden (% time above clinically defined thresholds) were calculated for these indices. These cerebral physiology indices were studied for their relationship with age via linear regression, age trichotomization (< 40, 40 - 60, > 60) and decades of age (< 30, 30 - 39, 40 - 49, 50 - 59, 60 - 69, > 69) schemes. Similarly, differences based on biological sex were assessed. A statistically significant positive linear correlation was found between PAx, RAC and age. In corollary, a statistically significant relationship was found between increasing age on trichotomized and decades of age analysis with PAx and RAC measures. PRx failed to demonstrate such relationships to advancing age. There was no clear difference in cerebrovascular reactivity profiles between biological sex categories. These findings suggest that AMP-based cerebrovascular reactivity indices may be better positioned to detect impairment in TBI patients with advancing age. Further investigation into the utility of PAx and RAC is required, as they may prove useful for certain subgroups of patients.

Impact of Age and Biological Sex on Cerebrovascular Reactivity in Adult Moderate/Severe Traumatic Brain Injury: An Exploratory Analysis

Age and biological sex are two potential important modifiers of cerebrovascular reactivity post-traumatic brain injury (TBI) requiring close evaluation for potential subgroup responses. The goal of this study was to provide a preliminary exploratory analysis of the impact of age and biological sex on measures of cerebrovascular function in moderate/severe TBI. Forty-nine patients from the prospectively maintained TBI database at the University of Manitoba with archived high-frequency digital cerebral physiology were evaluated. Cerebrovascular reactivity indices were derived as follows: PRx (correlation between intracranial pressure [ICP] and mean arterial pressure [MAP]), PAx (correlation between pulse amplitude of ICP [AMP] and MAP), and RAC (correlation between AMP and cerebral perfusion pressure [CPP]). Time above clinically significant thresholds for each index was calculated over different periods of the acute intensive care unit stay. The association between PRx, PAx, and RAC measures with age was assessed using linear regression, and an age trichotomization scheme (<40, 40-60, >60) using Kruskal-Wallis testing. Similarly, association with biological sex was tested using Mann-Whitney U testing. Biological sex did not demonstrate an impact on any measures of cerebrovascular reactivity. Linear regression between age and PAx and RAC demonstrated a statistically significant positive linear relationship. Median PAx and RAC measures between trichotomized age categories demonstrated statistically significant increases with advancing age. The PRx failed to demonstrate any statistically significant relationship with age in this cohort, suggesting that in elderly patients with controlled ICP, PAx and RAC may be better metrics for detecting impaired cerebrovascular reactivity. Biological sex appears to not be associated with differences in cerebrovascular reactivity in this cohort. The PRx performed the worst in detecting impaired cerebrovascular reactivity in those with advanced age, where PAx and RAC appear to have excelled. Future work is required to validate these findings and explore the utility of different cerebrovascular reactivity indices.

Acute Imaging Findings Predict Recovery of Cognitive and Motor Function after Inpatient Rehabilitation for Pediatric Traumatic Brain Injury: A Pediatric Brain Injury Consortium Study

Traumatic brain injury (TBI) is a major cause of morbidity and mortality in children; survivors experience long-term cognitive and motor deficits. To date, studies predicting outcome following pediatric TBI have primarily focused on acute behavioral responses and proxy measures of injury severity; unsurprisingly, these measures explain very little of the variance following heterogenous injury. In adults, certain acute imaging biomarkers help predict cognitive and motor recovery following moderate to severe TBI. This multi-center, retrospective study, characterizes the day-of-injury computed tomographic (CT) reports of pediatric, adolescent, and young adult patients (2 months to 21 years old) who received inpatient rehabilitation services for TBI (n = 247). The study also determines the prognostic utility of CT findings for cognitive and motor outcomes assessed by the Pediatric Functional Independence Measure, converted to age-appropriate developmental functional quotient (DFQ), at discharge from rehabilitation. Subdural hematomas (66%), contusions (63%), and subarachnoid hemorrhages (59%) were the most common lesions; the majority of subjects had less severe Rotterdam CT scores (88%, ≤ 3). After controlling for age, gender, mechanism of injury, length of acute hospital stay, and admission DFQ in multivariate regression analyses, the highest Rotterdam score (β = -25.2, p < 0.01) and complete cisternal effacement (β = -19.4, p < 0.05) were associated with lower motor DFQ, and intraventricular hemorrhage was associated with lower motor (β = -3.7, p < 0.05) and cognitive DFQ (β = -4.9, p < 0.05). These results suggest that direct detection of intracranial injury provides valuable information to aid in prediction of recovery after pediatric TBI, and needs to be accounted for in future studies of prognosis and intervention.

Traumatic brain injury biomarkers in pediatric patients: a systematic review

Traumatic brain injury (TBI) is the main cause of pediatric trauma death and disability worldwide. Recent studies have sought to identify biomarkers of TBI for the purpose of assessing functional outcomes. The aim of this systematic review was to evaluate the utility of TBI biomarkers in the pediatric population by summarizing recent findings in the medical literature. A total of 303 articles were retrieved from our search. An initial screening to remove duplicate studies yielded 162 articles. After excluding all articles that did not meet the inclusion criteria, 56 studies were gathered. Among the 56 studies, 36 analyzed serum biomarkers; 11, neuroimaging biomarkers; and 9, cerebrospinal fluid (CSF) biomarkers. Most studies assessed biomarkers in the serum, reflecting the feasibility of obtaining blood samples compared to obtaining CSF or performing neuroimaging. S100B was the most studied serum biomarker in TBI, followed by SNE and UCH-L1, whereas in CSF analysis, there was no unanimity. Among the different neuroimaging techniques employed, diffusion tensor imaging (DTI) was the most common, seemingly holding diagnostic power in the pediatric TBI clinical setting. The number of cross-sectional studies was similar to the number of longitudinal studies. Our data suggest that S100B measurement has high sensitivity and great promise in diagnosing pediatric TBI, ideally when associated with head CT examination and clinical decision protocols. Further large-scale longitudinal studies addressing TBI biomarkers in children are required to establish more accurate diagnostic protocols and prognostic tools.