Absence of the interthalamic adhesion (ITA) as a neuroanatomical association or risk factor for neuropsychiatric disorders: A systemic review and meta-analysis

Background

This study aimed to provide an up-to-date account of the frequency of "the absence of interthalamic adhesion (AITA) as a risk factor or association" in healthy subjects and neuropsychiatric patients. Owing to the increased interest in the contribution of ITA to neurological function in previous literature, a meta-analysis of its frequency and sex dependency is required.

Aim

This study aimed to study whether the AITA is associated with neuropsychiatric disorders.

Settings and Design

This study is a meta-analysis and systemic review.

Methods and Material

Literature searches were conducted in PubMed, Web of Science, and Google Scholar using the keywords "interthalamic adhesion," "massa intermedia," "adhesio interthalamica," and "adhesion" along with the Boolean operators (OR, AND, and NOT). Three reviewers independently assessed the abstracts and full texts for validation based on the inclusion criteria. The meta-analysis was performed using Microsoft Excel 2019 for descriptive studies and RevMan 5.2 for comparative studies.

Results

The incidence of absent ITA was 15.3% in healthy subjects and 28.76% in neuropsychiatric subjects. The relative probability of AITA was 2.30 [95% confidence interval (CI), 1.96-2.70] in neuropsychiatric illness. Healthy men were 1.91 times more likely, and men with neuropsychiatric disorders were 1.82 times more likely to have absent ITA than women.

Conclusions and Relevance

In this study, a consistent association of AITA with psychiatric disorders was observed, rendering the condition to be treated as an associated risk factor affecting the function of the habenula nuclear complex via the stria medullaris thalami. A cohort or longitudinal study is needed to compare the incidence of psychiatric disorders in individuals with or without ITA and to calculate the attributed risk.

Sharing of proximal fibers by the anterolateral and lateral collateral ligaments in the human knee: a cadaveric study

Literature is highly inconsistent in describing the proximal attachment of the anterolateral ligament (ALL) and its relationship with the lateral collateral ligament (LCL) in human knees. This observational study aims to investigate that lacuna. The gross dissection was performed in the lower limbs (n = 83) from the donated adult-age (> 18 years) embalmed cadavers from medical institutions in the north and east India. The dissected knee specimens were first examined macroscopically. Further routine and special staining and microscopic examinations were performed. The ALL was absent in approximately 20.4% of the studied knee specimens (17/83). In remaining, the sharing of ALL and LCL proximal fibers was observed as a consistent finding (~ 97%) with rare exceptions. The mean length of the tibial and meniscal limbs of ALL was 1.57 ± 0.8 cm [Range (R) 0.5-4 cm] and 0.73 ± 0.47 cm [Range (R) 0.1-1.6 cm], respectively. In addition, multiple variations in its presentation were observed. We propose that the proximal sharing of LCL-ALL fibers is a dominant feature in the studied population. The sharing of the fibers may impact the biomechanics and injury mechanisms for both ligaments. The possibility of ethnic variations in the ALL morphology should be a concern during reconstruction surgery.

SARS-CoV-2 Omicron Variant Genomic Sequences and Their Epidemiological Correlates Regarding the End of the Pandemic: In Silico Analysis

BACKGROUND

Emergence of the new SARS-CoV-2 variant B.1.1.529 worried health policy makers worldwide due to a large number of mutations in its genomic sequence, especially in the spike protein region. The World Health Organization (WHO) designated this variant as a global variant of concern (VOC), which was named "Omicron." Following Omicron's emergence, a surge of new COVID-19 cases was reported globally, primarily in South Africa.

OBJECTIVE

The aim of this study was to understand whether Omicron had an epidemiological advantage over existing variants.

METHODS

We performed an in silico analysis of the complete genomic sequences of Omicron available on the Global Initiative on Sharing Avian Influenza Data (GISAID) database to analyze the functional impact of the mutations present in this variant on virus-host interactions in terms of viral transmissibility, virulence/lethality, and immune escape. In addition, we performed a correlation analysis of the relative proportion of the genomic sequences of specific SARS-CoV-2 variants (in the period from October 1 to November 29, 2021) with matched epidemiological data (new COVID-19 cases and deaths) from South Africa.

RESULTS

Compared with the current list of global VOCs/variants of interest (VOIs), as per the WHO, Omicron bears more sequence variation, specifically in the spike protein and host receptor-binding motif (RBM). Omicron showed the closest nucleotide and protein sequence homology with the Alpha variant for the complete sequence and the RBM. The mutations were found to be primarily condensed in the spike region (n=28-48) of the virus. Further mutational analysis showed enrichment for the mutations decreasing binding affinity to angiotensin-converting enzyme 2 receptor and receptor-binding domain protein expression, and for increasing the propensity of immune escape. An inverse correlation of Omicron with the Delta variant was noted (r=-0.99, P<.001; 95% CI -0.99 to -0.97) in the sequences reported from South Africa postemergence of the new variant, subsequently showing a decrease. There was a steep rise in new COVID-19 cases in parallel with the increase in the proportion of Omicron isolates since the report of the first case (74%-100%). By contrast, the incidence of new deaths did not increase (r=-0.04, P>.05; 95% CI -0.52 to 0.58).

CONCLUSIONS

In silico analysis of viral genomic sequences suggests that the Omicron variant has more remarkable immune-escape ability than existing VOCs/VOIs, including Delta, but reduced virulence/lethality than other reported variants. The higher power for immune escape for Omicron was a likely reason for the resurgence in COVID-19 cases and its rapid rise as the globally dominant strain. Being more infectious but less lethal than the existing variants, Omicron could have plausibly led to widespread unnoticed new, repeated, and vaccine breakthrough infections, raising the population-level immunity barrier against the emergence of new lethal variants. The Omicron variant could have thus paved the way for the end of the pandemic.

Morpho-functional characterization of the submucosal glands at the nasopharyngeal end of the auditory tube in humans

BACKGROUND

The auditory tube (AT), an osteocartilaginous channel, connects the nasopharynx to the middle ear cavity. At the nasopharyngeal opening of the AT, there are dense collections of submucosal glands. In a recent article, Valstar et al. proposed these nasopharyngeal tubal glands conglomerate as salivary glands, which starkly contrasts with their previously known anatomy for being a component of the respiratory tract. This study examines the contesting views regarding the taxonomical categorization of the nasopharyngeal tubal glands.

MATERIALS AND METHODS

The AT glands in context were examined in human cadavers grossly, and microscopically using routine and special (Hematoxylin and Eosin [H&E] and Periodic acid-Schiff [PAS] respectively), as well as immunohistochemical (for alpha-SMA and salivary amylase) staining methods and compared with the major and minor salivary glands and the submucosal glands in the trachea. Further, a biochemical analysis was performed to detect the presence of salivary amylase in the oral and nasopharyngeal secretions of the four living human subjects, representing major salivary glands and tubal glands, respectively.

RESULTS

The submucosal seromucous glands with a surface lining of respiratory epithelium were observed at the nasopharyngeal end of AT. The cells in the tubal glands showed cytoplasmic positivity for alpha-SMA, which indicated the presence of the myoepithelial cells; however, this expression was significantly lower than in the seromucous submucosal glands within the trachea. Salivary alpha-amylase was undetectable in the cadaveric tissue samples. Moreover, the amylase level in the nasopharyngeal swabs was negligible compared to the oral swabs.

CONCLUSION

The anatomical location along the respiratory tract, the presence of respiratory epithelium in the overlying mucosa, their morpho-functional resemblance to the seromucous glands in the trachea, and the absence of salivary amylase strongly indicate that the tubal glands are taxonomically different from the salivary glands. Given the available evidence, their existing recognition as a part of the respiratory tract and an integral component of the AT seems more appropriate.

A Bioinformatics Tool for Predicting Future COVID-19 Waves Based on a Retrospective Analysis of the Second Wave in India: Model Development Study

Background

Since the start of the COVID-19 pandemic, health policymakers globally have been attempting to predict an impending wave of COVID-19. India experienced a devastating second wave of COVID-19 in the late first week of May 2021. We retrospectively analyzed the viral genomic sequences and epidemiological data reflecting the emergence and spread of the second wave of COVID-19 in India to construct a prediction model.

Objective

We aimed to develop a bioinformatics tool that can predict an impending COVID-19 wave.

Methods

We analyzed the time series distribution of genomic sequence data for SARS-CoV-2 and correlated it with epidemiological data for new cases and deaths for the corresponding period of the second wave. In addition, we analyzed the phylodynamics of circulating SARS-CoV-2 variants in the Indian population during the study period.

Results

Our prediction analysis showed that the first signs of the arrival of the second wave could be seen by the end of January 2021, about 2 months before its peak in May 2021. By the end of March 2021, it was distinct. B.1.617 lineage variants powered the wave, most notably B.1.617.2 (Delta variant).

Conclusions

Based on the observations of this study, we propose that genomic surveillance of SARS-CoV-2 variants, complemented with epidemiological data, can be a promising tool to predict impending COVID-19 waves.

Morphometry and morphological analysis of carotico-clinoid foramen: an anatomical study with clinical implications

BACKGROUND

The dural fold between anterior and middle clinoid processes on mineralisation leads to the formation of caroticoclinoid foramen (CCF). Different morphology of this foramen presents with different clinical features. The present study reports the frequency of CCF in the population of Bihar, while providing an account of assimilated information from previous literature regarding the association of caroticoclinoid ligament ossification with age and human genetics.

MATERIALS AND METHODS

The study was conducted on 100 adult dry human skulls of unknown age and sex, and 50 lateral view radiographs of the head.

RESULTS

Of the 100 dry skull bones, 9 presented with different forms of CCF. Bilateral complete foramina were noticed in 2 (2%) skull bones, while the incomplete foramina were observed bilaterally in 3 (3%) and unilaterally in 4 (4%) skulls. The lateral view radiograph data (n = 50) presented with a bilateral foramen in one subject and unilateral complete CCF in two different subjects. On measurements of the diameters of the complete CCF the mean values observed were 4.06 mm and 4.51 mm on the right side, while that on the left side were 5.15 mm and 4.14 mm. For the incomplete foramina, the mean values for the vertical diameter were 4.48 mm on the right and 4.19 mm on the left side, respectively.

CONCLUSIONS

The frequency of CCF in the present study population of Bihar was much lesser than that of previously studied populations. However, the variation in frequency of different morphological types of CCF was observed to be the same across populations. The variations in CCF's metric data could help in predicting the morphological changes it causes to the clinoidal segment of the internal carotid artery, as well as in distinguishing its varieties.

Emerging SARS-CoV-2 variants can potentially break set epidemiological barriers in COVID-19

Young age, female sex, absence of comorbidities, and prior infection or vaccination are known epidemiological barriers for contracting the new infection and/or increased disease severity. Demographic trends from the recent coronavirus disease 2019 waves, which are believed to be driven by newer severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants, indicate that the aforementioned epidemiological barriers are being breached and a larger number of younger and healthy individuals are developing severe disease. The new SARS‐CoV‐2 variants have key mutations that can induce significant changes in the virus‐host interactions. Recent studies report that, some of these mutations, singly or in a group, enhance key mechanisms, such as binding of the receptor‐binding domain (RBD) of the viral spike protein with the angiotensin‐converting enzyme 2 (ACE2) receptor in the host‐cells, increase the glycosylation of spike protein at the antigenic sites, and enhance the proteolytic cleavage of the spike protein, thus leading to improved host‐cell entry and the replication of the virus. The putative changes in the virus–host interactions imparted by the mutations in the RBD sequence can potentially be the reason behind the breach of the observed epidemiological barriers. Susceptibility for contracting SARS‐CoV‐2 infection and the disease outcomes are known to be influenced by host‐cell expressions of ACE2 and other proteases. The new variants can act more efficiently, and even with the lesser availability of the viral entry‐receptor and the associated proteases, can have more efficient host‐cell entry and greater replication resulting in high viral loads and prolonged viral shedding, widespread tissue‐injury, and severe inflammation leading to increased transmissibility and lethality. Furthermore, the accumulating evidence shows that multiple new variants have reduced neutralization by both, natural and vaccine‐acquired antibodies, indicating that repeated and vaccine breakthrough infections may arise as serious health concerns in the ongoing pandemic.

Emerging SARS‐CoV‐2 variants:

Harbor key mutations altering the virus‐host interactions.

Show more efficient host‐cell entry and greater replication resulting in higher viral loads, prolonged viral shedding, and greater tissue injury.

Show reduced neutralization by natural and vaccine acquired antibodies.

Causing symptomatic illness in increasing number of young, women, and healthy individuals.

COVID-19 Mechanisms in the Human Body-What We Know So Far

More than one and a half years have elapsed since the commencement of the coronavirus disease 2019 (COVID-19) pandemic, and the world is struggling to contain it. Being caused by a previously unknown virus, in the initial period, there had been an extreme paucity of knowledge about the disease mechanisms, which hampered preventive and therapeutic measures against COVID-19. In an endeavor to understand the pathogenic mechanisms, extensive experimental studies have been conducted across the globe involving cell culture-based experiments, human tissue organoids, and animal models, targeted to various aspects of the disease, viz., viral properties, tissue tropism and organ-specific pathogenesis, involvement of physiological systems, and the human immune response against the infection. The vastly accumulated scientific knowledge on all aspects of COVID-19 has currently changed the scenario from great despair to hope. Even though spectacular progress has been made in all of these aspects, multiple knowledge gaps are remaining that need to be addressed in future studies. Moreover, multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have emerged across the globe since the onset of the first COVID-19 wave, with seemingly greater transmissibility/virulence and immune escape capabilities than the wild-type strain. In this review, we narrate the progress made since the commencement of the pandemic regarding the knowledge on COVID-19 mechanisms in the human body, including virus-host interactions, pulmonary and other systemic manifestations, immunological dysregulations, complications, host-specific vulnerability, and long-term health consequences in the survivors. Additionally, we provide a brief review of the current evidence explaining molecular mechanisms imparting greater transmissibility and virulence and immune escape capabilities to the emerging SARS-CoV-2 variants.

Adrenal Myelolipoma Mimics Ectopic Adrenal or Renal Tissue: An Incidental Finding During Cadaveric Dissection

Context

On naked eye examination adrenal myelolipoma (AML) tissue appears to be an ectopic adrenal or renal tissue, based on the similarity to their external texture. This necessitates a histo-pathological study for confirming the origin of the tissue.

Objective

To establish the origin and histological features of the incidental AML tissue found during cadaveric dissection and review the literature for similar findings with clinical picture and treatment description.

Subjects and Methods

Unilateral adrenal gland obtained from cadaveric dissection was subjected to histological study by H & E staining of the slides prepared. The literature review was done from articles published in PubMed indexed journals.

Case report

A case of an incidental finding of AML during cadaveric dissection is presented which on naked eye examination was appearing to be an ectopic adrenal or renal tissue, based on the similarity to their external texture. On histological examination, a thin rim of adrenocortical tissue, surrounding the mature adipose tissue, and attenuated by islets of myeloid, erythroid and megakaryocytic cell lines in varying proportions, resembling the mature bone marrow morphology, was observed. The literature review on PubMed explains similar incidental post-mortem autopsy findings due to the asymptomatic nature of the tumor. The incidence of AML varied between 0.08% and 0.2% in the last decade of the 20^th century, which increased up to 10 - 15% of incidental adrenal masses due to the widespread use of non-invasive imaging modalities leading to an increase in the diagnosis of the pathology.

Conclusions

Before considering the ectopic incidence of tissue during cadaveric dissection, a histo-pathological examination is mandatory for confirmation. Adreno-myelolipoma is an asymptomatic post-mortem finding in 10-15% of cases of adrenal tissue which mimics ectopic adrenal gland or renal tissue due to its external texture.

Evolution of the fabric of cardiovascular science: Saga of an enduring process of refinement

BACKGROUND

The core elements of cardiovascular science have been established by scholarly pursuits of numerous scientists across centuries. In this article, we have tried to trace the evolutionary journey of cardiovascular science from a rudimentary form in ancient period to a robust scientific discipline in modern times.

METHODS

A literature search of relevant, peer-reviewed, published articles was undertaken from indexed databases (Medline & Pubmed, Scopus, Embase, CINAHL Plus, Web of Science and Google Scholar).

RESULTS

Cardiovascular science has its roots in antiquity, when Greek scholars mostly relied on philosophical thoughts and ancient texts. This was followed by addition of few structural details to the theory of circulation by Galen based on animal dissection. Arab scholar Ibn al-Nafis provided new insights regarding circulation pathway in humans. Nevertheless, an erroneous concept prevailed into the onset of European Renaissance. Even with legalization of human dissection, little headway could be made till sixteenth century due to persistent reliance of anatomists on ancient Galenic principles. During seventeenth century, the circulatory pathway (as we know it today) was established due to significant contributions from scholars like Harvey and Malpighi. Their efforts were based on findings from experiments and logical conclusions. Eighteenth century witnessed the emergence of autopsy based methods which led to valuable contributions from Vieussens, Thebesius, Morgagni and Hunter regarding normal and pathologic anatomy of cardiovascular system. With structural details mostly established, researchers during nineteenth century focussed on innovations in diagnostic methods based on human experiments. Further development of advanced human experiment models during twentieth century led to emergence of contemporary treatment methods for various cardiac conditions. In the twenty-first century, cardiovascular science is undergoing comprehensive progress at an exponential rate due to technological advances.

CONCLUSION

The evolutionary journey of cardiovascular science as a discipline across centuries has been intriguing and eventful.

SARS-CoV-2-specific virulence factors in COVID-19

The paucity of knowledge about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific virulence factors has greatly hampered the therapeutic management of patients with coronavirus disease 2019 (COVID-19). Recently, a cluster of studies appeared, which presented empirical evidence for SARS-CoV-2-specific virulence factors that can explain key elements of COVID-19 pathology. These studies unravel multiple structural and nonstructural specifics of SARS-CoV-2, such as a unique FURIN cleavage site, papain-like protease (SCoV2-PLpro), ORF3b and nonstructural proteins, and dynamic conformational changes in the structure of spike protein during host cell fusion, which give it an edge in infectivity and virulence over previous coronaviruses causing pandemics. Investigators provided robust evidence that SARS-CoV-2-specific virulence factors may have an impact on viral infectivity and transmissibility and disease severity as well as the development of immunity against the infection, including response to the vaccines. In this article, we are presenting a summarized account of the newly reported studies.

Expression of SARS-CoV-2 Host Cell Entry Factors in Immune System Components of Healthy Individuals and Its Relevance for COVID-19 Immunopathology

Intense immunological dysregulation including immune cell lesions has been characteristically observed in severe cases of coronavirus disease-2019 (COVID-19), for which molecular mechanisms are not properly understood. A study of physiological expressions of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) host cell entry-related factors in immune system components may help explain molecular mechanisms involved in COVID-19 immunopathology. We analyzed transcriptomic and proteomic expression metadata for SARS-CoV-2 host cell entry receptor ACE2 and entry associated proteases (TMPRSS2, CTSL, and FURIN) in silico across immune system components including the blood lineage cells. ACE2 was not detected in any of the studied immune cell components; however, varying transcriptomic and proteomic expressions were observed for TMPRSS2, CTSL, and FURIN. Nondetectable expressions of SARS-CoV-2 host cell entry receptor ACE2 in immune system components or blood lineage cells indicate it does not mediate immune cell lesions in COVID-19. Alternative mechanisms need to be explored for COVID-19 immunopathogenesis.

Does the Prevalence of Ossified Fabella Vary in Knee Osteoarthritis and Age-Related Degeneration? A Meta-Analysis of About 11,000 Knees

OBJECTIVE

Osteoarthritis (OA) and age-related degeneration (ARD) are stimulants for the development of the fabella in the knee joint. This meta-analysis updates previous studies and reviews on the prevalence of the fabella in OA or ARD knee joints. In addition, it provides a quantitative estimation of the fabellar prevalence in knees having OA and ARD.

METHODOLOGY

Twenty studies containing data from 11,056 knee joints were utilized in the investigation, consisting of 6,819 knees of individuals with OA (including those with age greater than 40 years) and 4,237 knees of individuals without OA (including less than 40 years of age), respectively. Totally, 2,434 knees of the OA subjects had fabellae (including more than 40 years), while in the non-OA subjects, 844 had fabellae (including less than 40years). The odds ratio (OR) and relative risk (RR) were calculated.

RESULTS

The fabellar prevalence was observed to be higher in OA knees, where the risk ratio of developing fabella was 2.55 (2.15-3.02). Compared with this, the risk ratio for the incidence of fabella in ARD knee was 1.71 (1.59-1.85). The bilateral occurrence of fabella was more common than unilateral. The risk of developing fabella in individuals aged less than 40-year was 0.59 which was 41% less than individuals aged more than 40 years. The risk ratio of developing fabella in co-exposure of ARD and OA was 1.84 [1.66, 2.04, 95% CI].

CONCLUSION

OA and ARD would increase the prevalence of ossified fabella by 84%, thus acting as stimulants or associations and risk factors for ossified fabella.

SARS-CoV-2 cell entry receptor ACE2 mediated endothelial dysfunction leads to vascular thrombosis in COVID-19 patients

Several studies have described unusually high incidence of vascular thrombosis in coronavirus disease-2019 (COVID-19) patients. Pathogenesis of the vascular thrombosis in COVID-19 is least understood for now and presents a challenge to the treating physicians. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative pathogen for COVID-19, has been shown to bind to angiotensin converting enzyme 2 (ACE2) protein in human epithelial cells which facilitates its entry in the organ and mediate tissue specific pathogenesis. For ACE2 mediated cell entry of the SARS-CoV-2, co-expression of one more protein-Transmembrane protease serine 2 (TMPRSS2) is essential. Existing studies suggested significant expression of ACE2 and TMPRSS2 in human vascular endothelium. Vascular endothelial dysfunction can potentially activate coagulation cascade eventually resulting in thrombosis. ACE2 has proven role in the maintenance of endothelial integrity inside the vessels. Existing in situ evidence for SARS-CoV-1 (the causative agent for SARS pandemic of 2002, which shared ACE2 as cell entry receptor) suggested that virus binding can downregulate ACE2, thus can induce endothelial dysfunction. Recently, in situ evidence has been presented that SARS-CoV-2 can infect cells in engineered human vascular endothelium, which can be effectively blocked by using clinical-grade recombinant human ACE2. Based on the circumstantial evidence present in the literature, we propose a SARS-CoV-2 cell entry receptor ACE2 based mechanism for vascular thrombosis in COVID-19 patients.

Relevance of SARS-CoV-2 related factors ACE2 and TMPRSS2 expressions in gastrointestinal tissue with pathogenesis of digestive symptoms, diabetes-associated mortality, and disease recurrence in COVID-19 patients

COVID-19 is caused by a new strain of coronavirus called SARS-coronavirus-2 (SARS-CoV-2), which is a positive sense single strand RNA virus. In humans, it binds to angiotensin converting enzyme 2 (ACE2) with the help a structural protein on its surface called the S-spike. Further, cleavage of the viral spike protein (S) by the proteases like transmembrane serine protease 2 (TMPRSS2) or Cathepsin L (CTSL) is essential to effectuate host cell membrane fusion and virus infectivity. COVID-19 poses intriguing issues with imperative relevance to clinicians. The pathogenesis of GI symptoms, diabetes-associated mortality, and disease recurrence in COVID-19 are of particular relevance because they cannot be sufficiently explained from the existing knowledge of the viral diseases. Tissue specific variations of SARS-CoV-2 cell entry related receptors expression in healthy individuals can help in understanding the pathophysiological basis the aforementioned collection of symptoms. ACE2 mediated dysregulation of sodium dependent glucose transporter (SGLT1 or SLC5A1) in the intestinal epithelium also links it to the pathogenesis of diabetes mellitus which can be a possible reason for the associated mortality in COVID-19 patients with diabetes. High expression of ACE2 in mucosal cells of the intestine and GB make these organs potential sites for the virus entry and replication. Continued replication of the virus at these ACE2 enriched sites may be a basis for the disease recurrence reported in some, thought to be cured, patients. Based on the human tissue specific distribution of SARS-CoV-2 cell entry factors ACE2 and TMPRSS2 and other supportive evidence from the literature, we hypothesize that SARS-CoV-2 host cell entry receptor-ACE2 based mechanism in GI tissue may be involved in COVID-19 (i) in the pathogenesis of digestive symptoms, (ii) in increased diabetic complications, (iii) in disease recurrence.

Pathogenesis guided therapeutic management of COVID-19: an immunological perspective

Lack of standardized therapeutic approaches is arguably the significant contributor to the high burden of mortality observed in the ongoing pandemic of the Coronavirus disease, 2019 (COVID-19). Evidence is accumulating on SARS-CoV-2 specific immune cell dysregulation and consequent tissue injury in COVID-19. Currently, no definite drugs or vaccines are available against the disease; however initial results of the ongoing clinical trials have raised some hope. In this article, taking insights from the emerging empirical evidence about host-virus interactions, we deliberate upon plausible pathogenic mechanisms and suitable therapeutic approaches for COVID-19.

Predicting susceptibility for SARS-CoV-2 infection in domestic and wildlife animals using ACE2 protein sequence homology

The article is presenting a bioinformatics based method predicting susceptibility for SARS‐CoV‐2 infection in domestic and wildlife animals. Recently, there were reports of cats and ferrets, dogs, minks, golden hamster, rhesus monkeys, tigers, and lions testing for SARS‐CoV‐2 RNA which indicated for the possible interspecies viral transmission. Our method successfully predicted the susceptibility of these animals for contracting SARS‐CoV‐2 infection. This method can be used as a screening tool for guiding viral RNA testing for domestic and wildlife animals at risk of getting COVID‐19. We provide a list of the animals at risk of developing COVID‐19 based on the susceptibility score.

Zoonotic spillover of SARS‐CoV‐2 from humans have been reported recently

Homology to viral cell entry receptor ACE2 can predict susceptibility for contracting SARS‐CoV‐2

On the basis of a paired homology to complete protein sequence and viral binding hotspots on ACE2, we provide a list of susceptible animals

Possible routes of SARS-CoV-2 invasion in brain: In context of neurological symptoms in COVID-19 patients

Manifestation of neurological symptoms in certain patients of coronavirus disease-2019 (COVID-19) has warranted for their virus-induced etiogenesis. SARS-CoV-2, the causative agent of COVID-19, belongs to the genus of betacoronaviruses which also includes SARS-CoV-1 and MERS-CoV; causative agents for severe acute respiratory syndrome (SARS) in 2002 and Middle East respiratory syndrome (MERS) in 2012, respectively. Studies demonstrating the neural invasion of SARS-CoV-2 in vivo are still scarce, although such characteristics of certain other betacoronaviruses are well demonstrated in the literature. Based on the recent evidence for the presence of SARS-CoV-2 host cell entry receptors in specific components of the human nervous and vascular tissue, a neural (olfactory and/or vagal), and a hematogenous-crossing the blood-brain barrier, routes have been proposed. The neurological symptoms in COVID-19 may also arise as a consequence of the "cytokine storm" (characteristically present in severe disease) induced neuroinflammation, or co-morbidities. There is also a possibility that, there may be multiple routes of SARS-CoV-2 entry into the brain, or multiple mechanisms can be involved in the pathogenesis of the neurological symptoms. In this review article, we have discussed the possible routes of SARS-CoV-2 brain entry based on the emerging evidence for this virus, and that available for other betacoronaviruses in literature.

Ossification around intercavernous sinus: An osteological finding that can complicate trans - sphenoidal surgery

The aim of the study was to document an anatomical variation around the sella turcica which was unique and lacked any reference in the literature. A low lying osseous bar connecting the right middle clinoid process to the midpoint of the right lateral border of the dorsum sella was observed in a human skull specimen. The osseous bar was forming a foramen close to the floor of the sella, and the structure in association with this part of sella is the inferior intercavernous sinus. Measurements of the sella turcica bridge (STB), carotico-clinoid foramen (CCF), interclinoid foramen (ICF) on both sides and that of the ossified bar and foramen formed by itself were taken with the help of ImageJ software. The values observed for the measurements of different parameters of STB and its components, for CCF and ICF were bilaterally different. While the values for the osseous bar and foramen formed by it cannot be compared because of its unilateral occurrence. The presence of foramen around the inferior intercavernous sinus may lead to difficulty in performing procedures like transsphenoidal surgery (TSS) or extended TSS (eTSS) while extracting intradural lesions, thus increasing the chances of haemorrhage.

Anatomy of nervous system and emergence of neuroscience: A chronological journey across centuries

Scholars began exploring anatomy of nervous system from ancient times; however, considerable progress could only be made during the European Renaissance from the 14^th century onwards. The present study aimed to document significant discoveries in this context in chronological order to establish the cascading pattern of advancement in knowledge. The findings of Leonardo da Vinci (15^th century), Vesalius (16^th century) and their contemporaries, which were based on macroscopic dissection, helped to break the shackles of misconceptions in hypotheses prevalent from the time of Galen. However, very little headway could be achieved beyond superficial descriptions. Willis (17^th century), through his experimental studies, provided the much-needed impetus and his discoveries put the study of brain and nervous system on their modern footing. In the following years, prominent researchers through their observations based on the use of microscopy and advanced histological techniques (prevalent after invention of microtome) contributed towards significant discoveries related to the morphological details of different components of nervous system. Such scientific activities culminated in remarkable advancements by the middle of 19^th century. The advent of Golgi's staining technique and subsequent histological exploits of Cajal (late 19^th century) established the neuron theory, which is central to comprehending the functioning of nervous system. Availability of Golgi's staining technique remarkably contributed in detailing the anatomical structure of nervous system at microscopic level. Access to structural details pertaining to living anatomy (late 20^th century) and focus on findings at the molecular level by turn of 21^st century have firmly established neuroscience as a sovereign academic discipline.

Variations in the morphology of stylomastoid foramen: a possible solution to the conundrum of unexplained cases of Bell's palsy

BACKGROUND

Stylomastoid foramen is the terminal part of facial canal and is the exit gateway for facial nerve from skull base. We hypothesized that anatomical variations of this foramen could be a risk factor for the injury of facial nerve resulting in unilateral facial nerve paralysis or Bell's palsy. Hence the present study was conducted to study the variations in size and shape of stylomastoid foramen in dry adult human skulls.

MATERIALS AND METHODS

The study was conducted on 37 dry adult human skulls of unknown age and sex. High resolution images of the skulls under study were processed by ImageJ software and observations were undertaken.

RESULTS

Total eight variations of stylomastoid foramen were observed in terms of shape. The common variants were round, oval and square (present in 83.79% skulls on right side and 81.07% skulls on left side), whereas the rare variants were triangular, rectangular, serrated, bean-shaped and irregular. It was noted that stylomastoid foramen were associated with extensions (45.95% skulls) and also adjacent foramen (18.92% skulls). Exclusively unilateral observations included bifurcation of foramen (16.22% skulls), foramen situated deep inside skull groove (5.41% skulls) and foramen interrupted by bony spur (2.7% skulls). No significant differences were observed between the mean diameters (antero-posterior and transverse) of the stylomastoid foramen.

CONCLUSIONS

The unilateral variations along with rare variations in terms of shape such as serrated, bean-shaped and irregular foramen (which were also unilateral findings) could be potential risk factors towards injury of facial nerve at the point of exit from skull base leading to Bell's palsy.

Altered Expression of a Unique Set of Genes Reveals Complex Etiology of Schizophrenia

Background: The etiology of schizophrenia is extensively debated, and multiple factors have been contended to be involved. A panoramic view of the contributing factors in a genome-wide study can be an effective strategy to provide a comprehensive understanding of its causality. Materials and Methods: GSE53987 dataset downloaded from GEO-database, which comprised mRNA expression data of post-mortem brain tissue across three regions from control (C) and age-matched subjects (T) of schizophrenia (N = Hippocampus [HIP]: C-15, T-18, Prefrontal cortex [PFC]: C-15, T-19, Associative striatum [STR]: C-18, T-18). Bio-conductor-affy-package used to compute mRNA expression, and further t-test applied to investigate differential gene expression. The analysis of the derived genes performed using the PANTHER Classification System and NCBI database. Further, a protein interactome analysis of the derived gene set was performed using STRING v10 database (https://string-db.org/) Results: A set of 40 genes showed significantly altered (p < 0.01) expression across all three brain regions. The analyses unraveled genes implicated in biological processes and events, and molecular pathways relating basic neuronal functions. Conclusions: The aberrant expression of genes maintaining basic cell machinery explains compromised neuronal processing in SCZ.

Osteomyelitis of the skull in early-acquired syphilis: evaluation by MR imaging and CT

We present an unusual case of acquired secondary syphilis manifesting as osteomyelitis of the skull in a patient with a history of human immunodeficiency virus infection, evaluated by CT, volumetric CT reconstructions, and MR imaging.

The relationship of psychopathology and hyperhidrosis

BACKGROUND

Hyperhidrosis is a common yet poorly understood disease that is often exacerbated by emotional stress. While a psychiatric explanation of causality is frequently offered, there is little evidence to support or reject the view that the condition is primarily an anxiety-based disorder.

OBJECTIVES

To quantify objectively the degree of psychopathology in patients with hyperhidrosis.

METHODS

Forty-two patients diagnosed as having hyperhidrosis were examined prior to endoscopic sympathectomies. All patients took the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) and State-Trait Anxiety Inventory (STAI) before surgery. Results were compared with established norms.

RESULTS

The group scored well within established norms on both psychometric measures. On scales measuring anxiety, depression and conversion phenomena, 88% of the MMPI-2 profiles lacked elevations, and 86% of the patients lacked elevations on the STAI State and Trait Anxiety scales. Personality variables were not associated with postsurgical outcome.

CONCLUSIONS

Most individuals suffering from essential hyperhidrosis lack overt psychopathology. While some patients subjectively describe symptoms of anxiety, mild depression and social isolation, these complaints appear often to be in reaction to or superimposed upon an organic disease process and not the primary cause of their condition.

Anti-urokinase-type plasminogen activator monoclonal antibodies inhibit the proliferation of human breast cancer cell lines in vitro

The levels of several tumor-associated proteases, including plasminogen activators (PA), are elevated in many malignant tumors compared to their benign tumor counterparts. Extracellular matrix degradation mediated by PA may facilitate tumor cell invasion and metastasis. In this study, the anti-proliferative activities of anti-urokinase-type plasminogen activator monoclonal antibodies (anti-UK MAbs) against human breast cancer cell lines were tested. Immunofluorescence studies localized urokinase (UK) on the surfaces of breast cancer cells. Inhibition studies showed that anti-UK MAb concentrations exerted 50% inhibition of 3H-thymidine uptake by human breast cancer cell lines; CRL-1500 and CRL-1504 were 5.6 x 10(-9)-1.82 x 10(-13) and 3.16 x 10(-10)-3.54 x 10(-12) M, respectively. Anti-UK MAbs exhibited little effect (10-20%) on normal human lymphocyte and liver cell lines. Dye exclusion indicated that anti-UK MAbs had a potent cytolytic effect on human breast cancer cells. Taken together, these results demonstrated the potential of anti-UK MAbs to be a valuable reagent for cancer immunotherapy and anti-metastatic therapy.

Prolonged cyclooxygenase-2 induction in neurons and glia following traumatic brain injury in the rat

Cyclooxygenase-2 (COX2) is a primary inflammatory mediator that converts arachidonic acid into precursors of vasoactive prostaglandins, producing reactive oxygen species in the process. Under normal conditions COX2 is not detectable, except at low abundance in the brain. This study demonstrates a distinctive pattern of COX2 increases in the brain over time following traumatic brain injury (TBI). Quantitative lysate ribonuclease protection assays indicate acute and sustained increases in COX2 mRNA in two rat models of TBI. In the lateral fluid percussion model, COX2 mRNA is significantly elevated (>twofold, p < 0.05, Dunnett) at 1 day postinjury in the injured cortex and bilaterally in the hippocampus, compared to sham-injured controls. In the lateral cortical impact model (LCI), COX2 mRNA peaks around 6 h postinjury in the ipsilateral cerebral cortex (fivefold induction, p < 0.05, Dunnett) and in the ipsilateral and contralateral hippocampus (two- and six-fold induction, respectively, p < 0.05, Dunnett). Increases are sustained out to 3 days postinjury in the injured cortex in both models. Further analyses use the LCI model to evaluate COX2 induction. Immunoblot analyses confirm increased levels of COX2 protein in the cortex and hippocampus. Profound increases in COX2 protein are observed in the cortex at 1-3 days, that return to sham levels by 7 days postinjury (p < 0.05, Dunnett). The cellular pattern of COX2 induction following TBI has been characterized using immunohistochemistry. COX2-immunoreactivity (-ir) rises acutely (cell numbers and intensity) and remains elevated for several days following TBI. Increases in COX2-ir colocalize with neurons (MAP2-ir) and glia (GFAP-ir). Increases in COX2-ir are observed in cerebral cortex and hippocampus, ipsilateral and contralateral to injury as early as 2 h postinjury. Neurons in the ipsilateral parietal, perirhinal and piriform cortex become intensely COX2-ir from 2 h to at least 3 days postinjury. In agreement with the mRNA and immunoblot results, COX2-ir appears greatest in the contralateral hippocampus. Hippocampal COX2-ir progresses from the pyramidal cell layer of the CA1 and CA2 region at 2 h, to the CA3 pyramidal cells and dentate polymorphic and granule cell layers by 24 h postinjury. These increases are distinct from those observed following inflammatory challenge, and correspond to brain areas previously identified with the neurological and cognitive deficits associated with TBI. While COX2 induction following TBI may result in selective beneficial responses, chronic COX2 production may contribute to free radical mediated cellular damage, vascular dysfunction, and alterations in cellular metabolism. These may cause secondary injuries to the brain that promote neuropathology and worsen behavioral outcome.

The early assessment and intensive care unit management of patients with severe traumatic brain and spinal cord injuries

The assessment and management of neurotrauma have progressed significantly over the past several years. Improved understanding of the physiology of injured neural tissue and advances in technology have refined the approach to the care of patients suffering neurologic injury. Evidence-based clinical management guidelines, such as those developed by the Brain Trauma Foundation and the American Association of Neurological Surgeons, for the management of traumatic brain injury have been introduced to standardize certain aspects of care. The ongoing evolution of critical care also has had a significant impact on the care of patients suffering from neurotrauma. This article reviews some current issues related to the diagnosis and management of traumatic brain injury and spinal cord injury as we head into the next millennium.

Propofol in the treatment of moderate and severe head injury: a randomized, prospective double-blinded pilot trial

OBJECT

Sedation regimens for head-injured patients are quite variable. The short-acting sedative-anesthetic agent propofol is being increasingly used in such patients, yet little is known regarding its safety and efficacy. In this multicenter double-blind trial, a titratable infusion of 2% propofol accompanied by low-dose morphine for analgesia was compared with a regimen of morphine sulfate in intubated head-injured patients. In both groups, other standard measures of controlling intracranial pressure (ICP) were also used.

METHODS

Forty-two patients from 11 centers were evaluated to assess both the safety and efficacy of propofol: 23 patients in the propofol group (mean time of propofol usage 95+/-87 hours) and 19 patients in the morphine group (mean time of morphine usage 70+/-54 hours). There was a higher incidence of poor prognostic indicators in the propofol group than in the morphine group: patient age older than 55 years (30.4% compared with 10.5%, p < 0.05), initial Glasgow Coma Scale scores of 3 to 5 (39.1% compared with 15.8%, p < 0.05), compressed or absent cisterns on initial computerized tomography scanning (78.3% compared with 57.9%, p < 0.05), early hypotension and/or hypoxia (26.1% compared with 10.5%, p = 0.07). During treatment there was a trend toward greater use of vasopressors in the propofol group. However, the mean daily ICP and cerebral perfusion pressure were generally similar between groups and, on therapy Day 3, ICP was lower in the propofol group compared with the morphine group (p < 0.05). Additionally, there was less use of neuromuscular blocking agents, benzodiazepines, pentobarbital, and cerebrospinal fluid drainage in the propofol group (p < 0.05). At 6 months postinjury, a favorable outcome (good recovery or moderate disability) was observed in 52.1% of patients receiving propofol and in 47.4% receiving morphine; the mortality rates were 17.4% and 21.1%, respectively. Patients who received the highest doses of propofol for the longest duration tended to have the best outcomes. There were no significant differences between groups in terms of adverse events.

CONCLUSIONS

Despite a higher incidence of poor prognostic indicators in the propofol group, ICP therapy was less intensive, ICP was lower on therapy Day 3, and long-term outcome was similar to that of the morphine group. These results suggest that a propofol-based sedation and an ICP control regimen is a safe, acceptable, and, possibly, desirable alternative to an opiate-based sedation regimen in intubated head-injured patients.

In vitro inhibition of human malignant brain tumour cell line proliferation by anti-urokinase-type plasminogen activator monoclonal antibodies

A brain tumour-associated marker, urokinase (UK), was investigated using rabbit anti-UK polyclonal and murine anti-UK monoclonal antibodies, which were prepared by immunization with low molecular weight UK (LMW-UK) and high molecular weight urokinase (HMW-UK) synthetic peptide respectively. The polyclonal antibody cross-reacted with both LMW-UK and HMW-UK, whereas the murine MAbs were specific for HMW-UK. These immunological probes were used to study urokinase in glioma extracts, tissues, sera and cell lines that had been prepared from primary cultures of freshly dissected gliomas. Radioimmunoassays showed that glioma extracts had much higher level (5- to 44-fold) of UK than normal human brain extracts. This result was confirmed by immunoblotting of electrophoresis gels of glioma and human brain extracts. Immunohistochemical study using anti-UK MAb demonstrated much higher levels of UK in glioma tissue than normal brain tissue. Immunohistochemical study using anti-UK MAbs localized UK on the cell surface of glioma cells. Anti-UK MAbs inhibited the proliferation of AA cell lines and GB cell lines (50% to > 90%) and exerted minor effects (< or = 20%) on normal human liver, intestine and lymphocyte cell lines. Taken together, these results suggest that anti-UK MAbs may have therapeutic potential for human gliomas and cancer metastasis.

Human glioma associated intermediate filament proteins: over-expression, co-localization and cross-reactivity

The identification of human brain tumor-associated markers could facilitate the development of new diagnostic and therapeutic strategies for these malignancies. The type III intermediate filament proteins (IFPs): vimentin, desmin and glial fibrillary acidic protein (GFAP) were studied in human glioma tissue extracts, in sera from glioma patients and in low passage glioma cell lines prepared from primary cultures of freshly dissected tumors. Radioimmunoassay (RIA) studies, using anti-GFAP, anti-desmin and anti-vimentin mAbs, showed high levels of these proteins in glioma extracts. Binding studies with authentic IFPs indicated the absence of circulating antibodies against these proteins in the sera of glioma patients. On the other hand, these sera showed high levels of vimentin. Binding studies with these antibodies using RIAs and western immunoblotting, showed that while anti-GFAF mAbs were specific to GFAP, anti-desmin mAb cross-reacted completely with GFAP, anti-vimentin mAb cross-reacted substantially with desmin and GFAP. Immunofluorescence staining of frozen sections revealed high levels of neurofilaments in gliomas and strikingly low levels in normal brain tissue. Double immunofluorescence staining showed co-occurrence of all three IFPs in the same filaments. This suggests either co-expression or cross-reactivity of these proteins due to their high degree of homology. Thus, caution should be exercised in the use and interpretation of immunohistochemical data using antibodies to IFs.

In vitro efficacy of anti-glial fibrillary acidic protein monoclonal antibodies against human malignant glioma cell lines

Our studies have confirmed the presence of large concentrations of various intermediate filament proteins (IFPs) in glioma tissue compared to normal brain. This avenue of research was extended to assess the anti-proliferative activity of anti-intermediate filament protein monoclonal antibodies (anti-IFP mAbs) against human glioma cells. In this study, anti-proliferative activity of glial fibrillary acidic protein monoclonal antibodies (anti-GFAP mAbs) has been tested in vitro, using glioma cell lines prepared and established from freshly resected brain tumors. One anaplastic astrocytoma (AA), two glioblastoma multiforme (GB1 and GB2) cell lines and three anti-GFAP mAbs (B12C4, B12B4 and B6C6, all IgG1, kappa) were used. Immunofluorescence study indicated the ability of anti-GFAP mAbs to recognize the cell surface of glioma cells and the inhibition study showed that mAb B12B4 inhibited the proliferation of GB1 (96%), GB2 (85%) and AA (93%) at a concentration of 3.2 x 10(-10) M. mAb B12C4 inhibited the proliferation of GB1 (95%), GB2 (86%) and AA (94%) at a concentration of 3.26 x 10(-10) M and mAb B6C6 inhibited the proliferation of GB1 (75%), GB2 (75%) and AA (91%) at a concentration of 2.074 x 10(-10) M. Thymidine release assay demonstrated the cytolytic activities of anti-GFAP mAbs towards these glioma cell lines, and this observation was confirmed by dye exclusion, which indicated the lysis of glioma cells after anti-GFAP mAbs treatment. Anti-GFAP mAbs had little effect (< or = 20%) on normal human lymphocyte, liver and intestine cell lines. These results look promising for radioimaging and immunotherapy of human gliomas.

Evaluation of a regional oxygen saturation catheter for monitoring SjvO2 in head injured patients

OBJECTIVES

Monitoring jugular venous oxygen saturation (SjvO2) has been useful for the early identification and treatment of cerebral ischemia in patients with severe head injury. However, the catheters that have been used for this purpose have not performed optimally. The purpose of this study was to evaluate the performance of a new regional oxygen saturation catheter for monitoring SjvO2.

METHODS

Eighteen regional oxygen saturation catheters, 4-Fr in diameter (Baxter Healthcare Corporation, Edward Critical Care), were used in this study. Each catheter was inserted percutaneously into the dominant jugular vein and the catheter's tip position in the jugular bulb was verified by radiograph. The catheter was calibrated in vitro prior to insertion using the optic calibrator provided by the manufacturer. The catheter was recalibrated every 8 to 12 hours by comparing the oxygen saturation value from the catheter with that measured by a co-oximeter in a blood sample drawn through the catheter.

RESULTS

In vitro calibration using the optic calibrator was not always successful. Five catheters could not be calibrated. The remaining 13 catheters could all be calibrated, but only 9 provided a value that was within 4% of the oxygen saturation derived from the blood sample. After the first in vivo calibration, the correlation between the catheter and the blood sample values was improved. A total of 196 comparisons were made. The median, 25th, and 75th quartile differences between the catheter and the blood sample measurement of SjvO2 were 0.00, -1.15, and 1.25%, respectively. Using longitudinal data regression, the overall slope of the regression between the catheter and blood values was 0.997 (p = 0.001).

CONCLUSIONS

The new regional oxygen saturation catheter provided reliable measurement of SjvO2 83% of the time when the signal quality index was < or = 3, and may be useful for continuous monitoring of SjvO2.

Lactic acid and amino acid fluctuations measured using microdialysis reflect physiological derangements in head injury

We examined the extracellular neurochemical milieu in 34 head injured patients using microdialysis while simultaneously monitoring intracranial pressure, cerebral perfusion pressure, and jugular venous oxygen saturation. Derangements of anaerobic metabolism reflected by increased lactate and lactate/pyruvate ratios, and release of amino acids were seen at the same time as physiological deterioration in the majority of instances. Clinical microdialysis may provide insights into the neurochemistry of head injury, and such information may lead to new methods of monitoring and treating head injured patients.

SjvO2 monitoring in head-injured patients

Jugular venous oxygen saturation (SjvO2) measures the balance between cerebral oxygen delivery and cerebral oxygen consumption. Abnormalities that increase oxygen consumption (e.g., fever or seizures) or that decrease oxygen delivery (e.g., increased ICP, hypotension, hypoxia, hypocapnia, or anemia) can decrease SjvO2. Measuring SjvO2 continuously in the ICU in 177 patients with severe head injury, jugular venous desaturation (SjvO2 < 50%) was identified at least once in 39% of the patients. Approximately half of the episodes of desaturation were due to intracranial hypertension and half were due to systemic causes. The occurrence of one or more episodes of desaturation was strongly associated with a poor outcome, suggesting that the reduction in oxygen delivery identified with the SjvO2 monitoring contributed to the neurological injury. In the operating room, jugular venous desaturation was identified in 6 of 8 patients who were monitored during emergency evacuation of a traumatic intracranial hematoma. The lowest SjvO2 observed was 28%. In all 8 cases, the SjvO2 increased, from 47 +/- 10% to 63 +/- 5% after evacuation of the hematoma. Additional data supporting the hypothesis that these secondary insults identified with the SjvO2 monitoring contribute to the patient's neurological injury come from measurement of the extracellular concentrations of lactate and excitatory amino acids in the brain using microdialysis. Lactate concentration increased from 0.9 +/- 0.3 to 2.4 +/- 0.5 mumol/L and glutamate increased from 11.5 +/- 8.5 to 55.0 +/- 10.4 mumol/L during 8 episodes of jugular venous desaturation in 7 of 22 patients monitored with microdialysis. SjvO2 identifies global reductions in cerebral oxygenation due to a variety of causes, and is useful as a monitor for secondary insults in patients with severe head injury.

Development of guidelines for the management of severe head injury

Organized neurosurgery has taken a major step forward in developing guidelines for the management of severe head injury. This represents the first area in which neurosurgeons have tackled this difficult but important undertaking. The head injury guidelines, which are to be published soon, are evidenced-based, i.e., they are based upon published data rather than on expert opinion. The quality of data has been carefully analyzed and graded. The level of the recommendations, i.e., standard, guideline, or option, is based upon the strength of the data available. An attempt is made to provide a summary of the terminology and methodology used to develop guidelines. Arguments for and against practice guidelines are also summarized.

Early detection of delayed traumatic intracranial hematomas using near-infrared spectroscopy

Delayed intracranial hematomas are an important treatable cause of secondary brain injury in patients with head trauma. Early identification and treatment of these lesions, which appear or enlarge after the initial computerized tomography (CT) scan, may improve neurological outcome. Serial examinations using near-infrared spectroscopy (NIRS) to detect the development of delayed hematomas were performed in 167 patients. The difference in absorbance of light (delta OD) at 760 nm between the normal and the hematoma side was measured serially during the first 3 days after injury. Twenty-seven (16%) of the patients developed a type of late hematoma: intracerebral hematoma in eight, extracerebral hematoma in six, and postoperative hematoma in 13 patients. Eighteen of the delayed hematomas caused significant mass effect and required surgical evacuation. The hematomas appeared between 2 and 72 hours after admission. In 24 of the 27 patients, a significant increase (> 0.3) in the delta OD occurred prior to an increase in intracranial pressure, a change in the neurological examination, or a change on CT scan. A favorable outcome occurred in 67% of the patients with delayed hematomas, which suggests that early diagnosis using NIRS may allow early treatment and reduce secondary injury caused by delayed hematomas.

Clinical evaluation of a miniature strain-gauge transducer for monitoring intracranial pressure

In 25 patients, we evaluated the accuracy of a new miniature strain-gauge transducer developed for the measurement of intracranial pressure (ICP). The ICP in each patient was measured with the intraventricular, miniature strain-gauge transducer, and that value was compared with the ICP measured with a ventriculostomy catheter coupled to an external strain-gauge transducer. From the two monitors, 2218 simultaneous measurements of ICP were obtained. The average ICP measured with the miniature strain-gauge transducer was 15.9 +/- 10.0 mm Hg (range, -3 to 104 mm Hg). The ICP measured with the ventriculostomy-catheter transducer averaged 15.4 +/- 10.1 mm Hg (range, -9 to 104 mm Hg). A highly significant correlation was found over the wide range of pressures observed (n = 2218, r = 0.97, P < 0.001). The average difference between the two measurements of the ICP was 0.5 +/- 2.6 mm Hg, and the differences were equally positive and negative, demonstrating no consistent bias. The two values for the ICP were within 2 mm Hg of each other on 63% of the measurements and within 4 mm Hg of each other on 89% of the measurements. The average zero drift of the miniature strain-gauge transducer, measured at ambient pressure after removal of the catheter, was 0.2 +/- 0.5 mm Hg. The results indicate that this miniature strain-gauge transducer is highly accurate and stable and that it is a reliable alternative to a ventriculostomy for monitoring the ICP.

Intracranial pressure waveform indices in transient and refractory intracranial hypertension

Analysis of data obtained by continuous computerized monitoring of intracranial pressure (ICP) in 109 adult patients with severe head trauma was performed to examine the pattern of change in indices of the ICP waveform. Indices derived from direct measurement of the ICP wave and obtained from a Fast Fourier Transform (FFT) were examined. Concurrent physiologic measurements were made. Two types of intracranial hypertension (ICH) were defined for comparison. 'Transient intracranial hypertension' occurred when an abrupt rise in ICP was followed by a return to below 25 mm Hg (n = 63). Increases in ICP that were progressive and led to neurologic deterioration and death were termed 'refractory intracranial hypertension' (n = 18). During transient ICH heart rate, arterial pressure, end-tidal carbon dioxide and jugular venous oxygen saturation all increased, while these measures either were unchanged or decreased during refractory ICH. The pulse amplitude of the ICP wave increased in both types of ICHtn. Other changes in the waveform indices were consistent with this change in pulse amplitude. HFC responded differently to the two types of changes, with an increase during the transient changes and a decrease during the refractory changes. The differences in changes in physiologic measurements as ICH occurred in the 2 groups suggest that in refractory ICH cerebral blood flow is maintained against the mounting ICP, while in transient ICH the hypertension is caused by an increase in cerebral blood flow. The waveform indices do not discriminate between the two types of changes.

Survey of critical care management of comatose, head-injured patients in the United States

OBJECTIVE

This survey was designed to study current practices in the monitoring and treatment of patients with severe head injury in the United States.

DATA SOURCES

The collected data represent answers to telephone interviews of nurse managers, clinical specialists, and staff nurses specializing in neurotrauma care at 277 randomly selected hospitals from a total pool of 624 trauma centers. Overall, 261 (94%) centers participated in the survey. Of the participating centers, 219 (84%) were providers of care for severely head-injured patients. In order to assess reliability and account for differences among respondents, personnel from 40 (15%) centers were resurveyed 6 months later and a different nursing professional was interviewed, although the questions remained the same.

DATA EXTRACTION

The largest group of respondents came from level I centers (49%), followed by level II (32%) and level III (2%). Thirty-four percent of the surveyed hospitals had a designated neurologic/neurosurgical intensive care unit, and 24% of all units surveyed were under the direction of either a neurosurgeon or a neurologist. Twenty-eight percent of the centers routinely performed intracranial pressure monitoring, while 7% of the centers reported never using this technique. The use of ventriculostomy catheters for intracranial pressure monitoring was employed in 72% of the centers, but cerebrospinal fluid drainage was utilized by only 44% of the hospitals. The percentage of patients who had their intracranial pressure monitored was significantly higher in level I trauma centers and at hospitals that treated larger numbers of severely head-injured patients (15 to 30 patients per month, which represented 15% of the hospitals surveyed). Hyperventilation and osmotic diuretics were used in 83% of centers to reduce intracranial hypertension. The administration of barbiturates was reported in 33% of the units as a treatment for intracranial hypertension. Corticosteroids were used more than half of the time in 64% of trauma centers. Twenty-nine percent of the centers reported aiming for PaCO2 values of < 25 torr (< 3.3 kPa).

CONCLUSIONS

The survey data indicate that there is a considerable variation in the management of patients with severe head injury in the United States. The establishment of guidelines for the management of head injury based on available scientific data and moderated by practical and financial considerations may lead to improvement in the standard of care.

Jugular venous desaturation and outcome after head injury

Early experience with continuous monitoring of jugular venous oxygen saturation (SjvO2) suggested that this technology might allow early identification of global cerebral ischaemia in patients with severe head injury. The purpose of the present study was to examine the relationship between episodes of jugular venous desaturation and neurological outcome. One hundred and sixteen severely head-injured patients had continuous monitoring of SjvO2 during days 1-5 after injury. Episodes of jugular venous desaturation (SjvO2 < 50% for more than 10 minutes) were prospectively identified, and the incidence of desaturation was correlated with neurological outcome: 77 episodes of desaturation occurred in 46 of the 116 patients; 27 had one episode and 19 had multiple episodes of desaturation. The causes of these episodes were systemic (n = 36), cerebral (n = 35), or both (n = 6). Most of the episodes were less than 1 hour in duration, and it is probable that many of them would not have been detected without continuous measurement of SjvO2. Episodes of desaturation were most common on day 1 after injury, and were twice as common in patients with a reduced cerebral blood flow as in patients with a normal or elevated cerebral blood flow. The occurrence of jugular venous desaturation was strongly associated with a poor neurological outcome. The percentage of patients with a poor neurological outcome was 90% with multiple episodes of desaturation and 74% in patients with one desaturation, compared to 55% in patients with no episodes of desaturation. When adjusted for all co-variates that were found to be significant, including age, Glasgow coma score, papillary reactivity, type of injury, lowest recorded cerebral perfusion pressure, and highest recorded temperature, the incidence of desaturation remained significantly associated with a poor outcome. Although a cause and effect relationship with outcome cannot be established in this study, the data suggest that monitoring SvO2 might allow early identification and therefore treatment of many types of secondary injury to the brain.

Evaluation of a microsensor intracranial pressure transducer

This report describes the results of a laboratory evaluation of a new device for monitoring intracranial pressure (ICP), consisting of a miniature pressure transducer mounted on a pressure sensing diaphragm. In in vitro tests, 6 microsensor transducers were monitored for drift at pressures of 10 mmHg and 20 mmHg. The maximal drift of any of the transducers was 1 mmHg over 9 days. In in vivo tests, the ICP measurement obtained with the microsensor transducer correlated well with pressures recorded from a catheter in the cisternal magna with a Statham transducer over a wide range of ICP values (n = 511, r = 0.998, P < 0.001). If these laboratory findings can be duplicated in clinical studies, this microsensor transducer may be a useful alternative to the ventriculostomy catheter and other currently used devices for monitoring ICP.

The relationship between hormonal mediators and systemic hypermetabolism after severe head injury

The relationships of hormonal mediators to the systemic hypermetabolism and catabolism of head injury were studied in 15 patients with severe head injuries. Resting energy expenditure (REE), urinary nitrogen balance, and plasma glucose concentration were measured daily for the first 2 weeks after injury as the major indicators of hypermetabolism. These dependent variables were correlated with daily measurements of urinary epinephrine, norepinephrine, metanephrine, normetanephrine, dopamine, and cortisol, and with plasma levels of insulin, glucagon, and C-reactive protein. Urinary catecholamine and cortisol excretion were markedly elevated in these patients throughout the 2 weeks of study. Catecholamine excretion peaked between days 7 and 10, whereas cortisol excretion tended to be highest on day 5 after injury. Urinary levels of norepinephrine, normetanephrine, and cortisol were highest in the two patients with Glasgow Coma Scale scores of 4. Plasma insulin and glucagon concentrations were elevated on day 1 after injury and tended to increase throughout the 2-week period of study. The variables significantly associated with REE were the severity of injury, reflected by the GCS score, the urinary excretion of norepinephrine during the first 2 days after injury, and the urinary excretion of epinephrine and norepinephrine during days 3 to 7 after injury. A negative nitrogen balance was associated with the urinary excretion of epinephrine and norepinephrine, with caloric balance, and with plasma C-reactive protein during days 1 and 2 after injury. During days 3 to 7, a negative nitrogen balance was associated with the urinary excretion of epinephrine and norepinephrine and with caloric balance, and during days 8 to 14, a negative nitrogen balance was associated primarily with urinary cortisol excretion.