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Traumatic brain injury (TBI) is associated with the development of a range of neurodegenerative pathologies, including chronic traumatic encephalopathy (CTE). Current consensus diagnostic criteria define the pathognomonic cortical lesion of CTE neuropathologic change (CTE-NC) as a patchy deposition of hyperphosphorylated tau in neurons, with or without glial tau in thorn-shaped astrocytes, typically towards the depths of sulci and clustered around small blood vessels. Nevertheless, although incorporated into consensus diagnostic criteria, the contribution of the individual cellular components to identification of CTE-NC has not been formally evaluated. To address this, from the Glasgow TBI Archive, cortical tissue blocks were selected from consecutive brain donations from contact sports athletes in which there was known to be either CTE-NC (n = 12) or Alzheimer's disease neuropathologic change  (n = 4). From these tissue blocks, adjacent tissue sections were stained for tau antibodies selected to reveal either solely neuronal pathology (3R tau; GT-38) or mixed neuronal and astroglial pathologies (4R tau; PHF-1). These stained sections were then randomised and independently assessed by a panel of expert neuropathologists, blind to patient clinical history and primary antibody applied to each section, who were asked to record whether CTE-NC was present. Results demonstrate that, in sections stained for either 4R tau or PHF-1, consensus recognition of CTE-NC was high. In contrast, recognition of CTE-NC in sections stained for 3R tau or GT-38 was poor; in the former no better than chance. Our observations demonstrate that the presence of both neuronal and astroglial tau pathologies facilitates detection of CTE-NC, with its detection less consistent when neuronal tau pathology alone is visible. The combination of both glial and neuronal pathologies, therefore, may be required for detection of CTE-NC.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged from Wuhan, China, in 2019 and has since created a global pandemic. (1,2) The spectrum of disease caused by SARS-CoV-2 infection in [...], * Context.--This study represents the largest compilation to date of clinical and postmortem data from decedents with coronavirus disease 2019 (COVID-19). It will augment previously published small series of autopsy case reports, refine clinicopathologic considerations, and improve the accuracy of future vital statistical reporting. Objective.--To accurately reflect the preexisting diseases and pathologic conditions of decedents with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection through autopsy. Design.--Comprehensive data from 135 autopsy evaluations of COVID-19-positive decedents is presented, including histologic assessment. Postmortem examinations were performed by 36 pathologists at 19 medical centers or forensic institutions in the United States and Brazil. Data from each autopsy were collected through the online submission of multiple-choice and open-ended survey responses. Results.--Patients dying of or with COVID-19 had an average of 8.89 pathologic conditions documented at autopsy, spanning a combination of prior chronic disease and acute conditions acquired during hospitalization. Virtually all decedents were cited as having more than 1 preexisting condition, encompassing an average of 2.88 such diseases each. Clinical conditions during terminal hospitalization were cited 395 times for the 135 autopsied decedents and predominantly encompassed acute failure of multiple organ systems and/or impaired coagulation. Myocarditis was rarely cited. Conclusions.--Cause-of-death statements in both autopsy reports and death certificates may not encompass the severity or spectrum of comorbid conditions in those dying of or with COVID-19. If supported by additional research, this finding may have implications for public health decisions and reporting moving forward through the pandemic. doi: 10.5858/arpa.2020-0786-SA

Electronic cigarettes, or e-cigarettes, are handheld, battery-powered devices that heat an inner liquid containing a number of chemical ingredients to be aerosolized and inhaled. The chemical ingredients principally include nicotine [...], * Context.--Electronic cigarettes are handheld devices that heat an inner liquid containing chemicals to be aerosolized and inhaled, and have become a popular alternative to conventional cigarettes. Their use, termed vaping, has been linked to severe injury, with 2711 cases of associated lung injury and 60 deaths reported to the Centers for Disease Control and Prevention at the time of writing. Published case reports and series have emerged detailing clinical and imaging characteristics of vaping-induced lung injury. However, the pathologic characteristics of these induced injuries are still being established, particularly findings occurring over time. Objective.--To illustrate the autopsy findings of an older patient who died of vaping-induced injury after prolonged symptomology and to provide a review of the most recent literature regarding the basic science, epidemiology, clinical presentation, imaging characteristics, and pathology of vaping-induced lung injury. Data Sources.--Autopsy case and peer-reviewed literature. Conclusions.--Vaping-induced lung injury has emerged as a public health issue, and this case represents a rare opportunity to evaluate this issue at autopsy. Most commonly, the injury has been attributed to tetrahydro-cannabinol product use as opposed to nicotine. This case demonstrates that as today's young and relatively healthy "vapers" grow older and develop the comorbidities that come with advanced age, there is serious risk of chronic lung damage from vaping that could result in death. Further observations and studies, particularly autopsy evidence, are clearly important to understand the possible outcomes. doi: 10.5858/arpa.2019-0637-RA

There are currently no non-invasive imaging methods available for astrogliosis assessment or mapping in the central nervous system despite its essential role in the response to many disease states, such as infarcts, neurodegenerative conditions, traumatic brain injury and infection. Multidimensional MRI is an increasingly employed imaging modality that maximizes the amount of encoded chemical and microstructural information by probing relaxation (T1 and T2) and diffusion mechanisms simultaneously. Here, we harness the exquisite sensitivity of this imagining modality to derive a signature of astrogliosis and disentangle it from normative brain at the individual level using machine learning. We investigated ex vivo cerebral cortical tissue specimens derived from seven subjects who sustained blast-induced injuries, which resulted in scar-border forming astrogliosis without being accompanied by other types of neuropathological abnormality, and from seven control brain donors. By performing a combined post-mortem radiology and histopathology correlation study we found that astrogliosis induces microstructural and chemical changes that are robustly detected with multidimensional MRI, and which can be attributed to astrogliosis because no axonal damage, demyelination or tauopathy were histologically observed in any of the cases in the study. Importantly, we showed that no one-dimensional T1, T2 or diffusion MRI measurement can disentangle the microscopic alterations caused by this neuropathology. Based on these findings, we developed a within-subject anomaly detection procedure that generates MRI-based astrogliosis biomarker maps ex vivo , which were significantly and strongly correlated with co-registered histological images of increased glial fibrillary acidic protein deposition (r = 0.856, P < 0.0001; r = 0.789, P < 0.0001; r = 0.793, P < 0.0001, for diffusion-T2, diffusion-T1 and T1–T2 multidimensional data sets, respectively). Our findings elucidate the underpinning of MRI signal response from astrogliosis, and the demonstrated high spatial sensitivity and specificity in detecting reactive astrocytes at the individual level, and if reproduced in vivo , will significantly impact neuroimaging studies of injury, disease, repair and aging, in which astrogliosis has so far been an invisible process radiologically. [ABSTRACT FROM AUTHOR]

Emerging evidence from autopsy studies indicates that interface astroglial scarring (IAS) at the gray-white matter junction is a pathological signature of repeated blast brain injury in military personnel. However, there is currently no in vivo neuroimaging test that detects IAS, which is a major barrier to diagnosis, prevention, and treatment. In 27 active-duty U.S. Special Operations Forces personnel with high levels of cumulative blast exposure, we performed translocator protein (TSPO) positron emission tomography (PET) using [ 11 C]PBR28 to detect neuroinflammation at the cortical gray-white matter interface, a neuroanatomic location where IAS has been reported in autopsy studies. TSPO signal in individual Operators was compared with the mean TSPO signal in a control group of nine healthy civilian volunteers. We identified five Operators (18.5%) with TSPO signal at the cortical gray-white matter interface that was more than 2 standard deviations above the control mean. Cumulative blast exposure, as measured by the generalized blast exposure value, did not differ between the five Operators with elevated TSPO signal and the 22 Operators without elevated TSPO signal. While the pathophysiologic link between neuroinflammation and IAS remains uncertain, these preliminary observations provide the basis for further investigation into TSPO PET as a potential biomarker of repeated blast brain injury., (© The Author(s) 2024. Published by Mary Ann Liebert, Inc.)

2023 was an important year for research in traumatic brain injury (TBI), particularly as it concerned interests in neuropathology. After reviewing the literature, we present the advancements that we felt were of particular importance to the neuropathology community. Highlighted are articles that report upon: (1) the first large-cohort assessment for the neuropathology of intimate partner violence, (2) the assessment of chronic traumatic encephalopathy (CTE) in young athletes, (3) the observation of cortical sulcal depth vascular changes in CTE, (4) a proposal for a tau immunohistochemical panel to evaluate complex cases of CTE in the context of multiple tauopathies, (5) the relationship of TBI and/or CTE with TDP-43 pathology, (6) repetitive TBI inducing pathology in C9orf72 -transgenic mice, (7) radiologic patterns of head and neck injury following vehicular underbody blast exposure, (8) chronic alterations in brain metal content following repetitive impact TBI, (9) neurovascular unit injury following low-level blast exposure, and finally (10) an assessment of Muhammad Ali's clinical history leading to the conclusion that he suffered from young-onset, idiopathic Parkinson Disease. We close our writing with in memoriam to Dr. Byron A. Kakulas, a renowned figure in the neuropathology of spinal cord injury who we lost in 2023., Competing Interests: The authors do not have any conflict of interest to declare.

2022 was a productive year for research in traumatic brain injury (TBI) and resultant neuropathology. After an extensive review, we present related studies and publications which we felt were of particular importance to the neuropathology community. First, 2022 was highlighted by important advancements in the diagnosis and, moreover, our understanding of chronic traumatic encephalopathy (CTE). Important publications include a pair concluding that CTE primarily concerns neuronal accumulation of phosphorylated tau ( ptau ), but that glial ptau accumulation often helps to facilitate diagnosis. In addition, a new large community study from Australia continues the indication that CTE is relatively uncommon in the community, and the first large-cohort study on brains of military personnel similarly demonstrates that CTE appears to be uncommon among service members and does not appear to explain high rates of neuropsychiatric sequelae suffered by the warfighter. The causation of CTE by impact-type TBI was supported by the application of the Bradford Hill criteria, within the brains of headbutting bovids, and interestingly within an artificial head model exposed to linear impact. Finally, a large-scale analysis of APOE genotypes contends that gene status may influence CTE pathology and outcomes. In experimental animal work, a study using mouse models provided important evidence that TDP-43 facilitates neurodegenerative pathology and is implicated in cognitive dysfunction following TBI, and another study using a swine model for concussion demonstrated that evidence that axonal sodium channel disruption may be a driver of neurologic dysfunction after concussion. Finally, we end with memoriam to Dr. John Q. Trojanowski, a giant of neurodegenerative research and an important contributor to the neurotrauma literature, who we lost in 2022., Competing Interests: The authors do not have any conflict of interest to declare.