Traumatic Cervical Vertebral Artery Transection Associated with a Dural Tear Leading to Subarachnoid Extravasation

Abstract   Vertebral artery injuries can be seen following trauma. Most traumatic vertebral artery injuries are limited to an intimal dissection. Rarely, transection of the vertebral artery can be seen with extravasation of hemorrhage into the surrounding soft tissues of the neck. Dural tears are rare in the setting of trauma. They are usually the result of penetrating trauma or severe blunt trauma. We present a case with both a vertebral artery transection and a dural tear. The combination of these lethal injuries resulted in extravasation of hemorrhage into the soft tissues of the neck, through the dural tear, and into the subarachnoid space of the cervical spine. The subarachnoid hemorrhage extended superiorly into the brain. The diagnosis was made by computed tomography (CT) and computed tomography angiography (CTA). The treatment of traumatic vertebral artery transections and dural tears are discussed.     

Successful use of recombinant activated coagulation factor VII in a patient with massive hemoptysis from a penetrating thoracic injury

Acute massive hemoptysis is a rare complication of pulmonary injury and contusion, and it is particularly difficult to manage in the nontertiary care setting. Recombinant activated coagulation factor VII (rFVIIa) is a prothrombotic drug that is increasingly being used to treat coagulopathy in massively exsanguinating trauma patients. We report a case in which recombinant activated coagulation factor VII successfully controlled massive hemoptysis and improved ventilation from a severe pulmonary contusion in a noncoagulopathic patient who suffered a penetrating thoracic injury in a military setting in Afghanistan.     

Radiation exposure from diagnostic imaging in severely injured trauma patients

BACKGROUND: Trauma patients often require multiple imaging tests, including computed tomography (CT) scans. CT scanning, however, is associated with high-radiation doses. The purpose of this study was to measure the radiation doses trauma patients receive from diagnostic imaging. METHODS: A prospective cohort study was conducted from June 1, 2004 to March 31, 2005 at a Level I trauma center in Toronto, Canada. All trauma patients who arrived directly from the scene of injury and who survived to discharge were included. Three dosimeters were placed on each patient (neck, chest, and groin) before radiologic examination. Dosimeters were removed before discharge. Surface doses in millisieverts (mSv) at the neck, chest, and groin were measured. Total effective dose, thyroid, breast, and red bone marrow organ doses were then calculated. RESULTS: Trauma patients received a mean effective dose of 22.7 mSv. The standard "linear no threshold" (LNT) model used to extrapolate from effects observed at higher dose levels suggests that this would result in approximately 190 additional cancer deaths in a population of 100,000 individuals so exposed. In addition, the thyroid received a mean dose of 58.5 mSv. Therefore, 4.4 additional fatal thyroid cancers would be expected per 100,000 persons. In all, 22% of all patients had a thyroid dose of over 100 mSv (mean, 156.3 mSv), meaning 11.7 additional fatal thyroid cancers per 100,000 persons would result in this subgroup. CONCLUSION: Trauma patients are exposed to significant radiation doses from diagnostic imaging, resulting in a small but measurable excess cancer risk. This small individual risk may become a greater public health issue as more CT examinations are performed. Unnecessary CT scans should be avoided.     

Relation of a hypoxia metagene derived from head and neck cancer to prognosis of multiple cancers

Affymetrix U133plus2 GeneChips were used to profile 59 head and neck squamous cell cancers. A hypoxia metagene was obtained by analysis of genes whose in vivo expression clustered with the expression of 10 well-known hypoxia-regulated genes (e.g., CA9, GLUT1, and VEGF). To minimize random aggregation, strongly correlated up-regulated genes appearing in >50% of clusters defined a signature comprising 99 genes, of which 27% were previously known to be hypoxia associated. The median RNA expression of the 99 genes in the signature was an independent prognostic factor for recurrence-free survival in a publicly available head and neck cancer data set, outdoing the original intrinsic classifier. In a published breast cancer series, the hypoxia signature was a significant prognostic factor for overall survival independent of clinicopathologic risk factors and a trained profile. The work highlights the validity and potential of using data from analysis of in vitro stress pathways for deriving a biological metagene/gene signature in vivo.     

Major Incident Medical Management and Support (MIMMS): A practical,multiple casualty,disaster‐site training course for all Australian health care personnel

Major Incident Medical Management and Support is a 3‐day major incident training course designed specifically for doctors, nurses and ambulance personnel. It teaches a systematic, ‘all hazards’ approach to the principles of pre‐hospital, multiple‐casualty incident medical management. This article explores the origins and development of the course in Australia, it outlines the nature and content of the course, details the demographic profile of those who have successfully completed the course to date and, finally, looks at the future directions of the course in Australia. See Commentary, page 143.     

Microanatomy of facial vibrissae in the Florida manatee: the basis for specialized sensory function and oripulation.

Sirenians, including Florida manatees, possess an array of hairs and bristles on the face. These are distributed in a pattern involving nine distinct regions of the face, unlike that of any other mammalian order. Some of these bristles and hairs are known to be used in tactile exploration and in grasping behaviors. In the present study we characterized the microanatomical structure of the hair and bristle follicles from the nine regions of the face. All follicles had the attributes of vibrissae, including a dense connective tissue capsule, prominent blood sinus complex, and substantial innervation. Each of the nine regions of the face exhibited a distinct combination of these morphological attributes, congruent with the previous designation of these regions based on location and external morphological criteria. The present data suggest that perioral bristles in manatees might have a tactile sensory role much like that of vibrissae in other mammals, in addition to their documented role in grasping of plants during feeding. Such a combination of motor and sensory usages would be unique to sirenians. Finally, we speculate that the facial hairs and bristles may play a role in hydrodynamic reception.     

Sharp thresholds limit the benefit of defector avoidance in cooperation on networks

Consider a cooperation game on a spatial network of habitat patches, where players can relocate between patches if they judge the local conditions to be unfavorable. In time, the relocation events may lead to a homogeneous state where all patches harbor the same relative densities of cooperators and defectors, or they may lead to self-organized patterns, where some patches become safe havens that maintain an elevated cooperator density. Here we analyze the transition between these states mathematically. We show that safe havens form once a certain threshold in connectivity is crossed. This threshold can be analytically linked to the structure of the patch network and specifically to certain network motifs. Surprisingly, a forgiving defector avoidance strategy may be most favorable for cooperators. Our results demonstrate that the analysis of cooperation games in ecological metacommunity models is mathematically tractable and has the potential to link topics such as macroecological patterns, behavioral evolution, and network topology.

Cooperation, behavior that leads to benefits for others at a cost to oneself, is widespread across biological systems, ranging from cells cooperating to form organisms, to cooperation among individuals in populations and among microbiotic and macrobiotic taxa in ecosystems. In many cases the costs of cooperation are high. Hence, how cooperative behavior persists in a population represents a fundamental question in biology (1–8). In general, cooperation is most likely to evolve and persist if there are mechanisms that directly or indirectly benefit cooperators’ reproductive success. Examples include kin selection, punishment of defectors who forgo the cooperative investment, or a direct self-benefit such as in cases of investment into a common good (4).Among the most general mechanisms that can favor cooperation is the notion of network or spatial reciprocity (1, 9–11). In classical examples of reciprocity, cooperation creates favorable conditions for other proximal cooperators (4). A result is the emergence of cooperative havens, where the rewards generated by mutual cooperation have enriched some physical or topological neighborhoods. The formation of cooperative neighborhoods in structured populations, where individuals interact with only a limited subset of the population, has traditionally been studied on networks, where each node represents an individual agent and an edge means that the two connected individuals play against each other (1, 10, 12–19). By assuming weak selection and treating space implicitly, the resulting systems can often be analyzed mathematically. Although this framework has become a powerful tool for conceptual understanding, it represents a strong abstraction from real-world ecology where interactions, and hence cooperative behaviors, occur often randomly within a location that is itself embedded in a larger spatial context (20–23). By focusing on spatially explicit models of cooperation, we gain the opportunity to understand feedbacks between the rules of the game, movement strategies, and long-term persistence of cooperation at larger scales (10, 20, 23–27).Here we study a model of cooperation in spatially structured populations inspired by ecological metacommunities (21–23, 28), where network nodes—instead of individuals—represent habitat patches containing many interacting individuals, and edges mean that two patches are connected by dispersal of those individuals (Fig. 1A). Each patch is a location where games are played, harboring cooperator and defector subpopulations which grow and shrink in time due to internal interactions and movement among locations. Metacommunity models allow one to represent the effects of physical spatial structure directly and explicitly. Moreover, they can be analyzed using master stability functions, which can be used to untangle the impacts of local dynamics and network structure (28–30). We use this ability to explore how different movement strategies impact the outcomes of a cooperation game as a function of network structure.Open in a separate windowFig. 1.Emergence of a heterogeneous stationary state on a two-patch network. (A) Schematic of the spatial game, showing local payoff (Π) relationships among cooperators and defectors occupying the same patch (gray circles) and the dispersal route between them. (B) Difference in equilibrium densities of both types in patches 1 and 2 as link strength is varied. Arrows refer to the example time series shown in C and D. Initial conditions were uniformly drawn from [10−4,10−3], and the patch with the largest initial cooperator density is patch 1. (C) The homogeneous steady state, with the same equilibrium densities of C and D across locations. (Inset) Network showing the proportions of each type in each patch. (D) The same game but with faster diffusion (larger δ), showing emergence of a heterogeneous steady state with higher cooperator densities in patch 1. Parameters are R = 3, S=2, T = 5, P=0.2, μ = 1, and α=3.