The glasgow lumbar spinal stenosis scale: an individualised measurement formula for the radiological assessment of lumbar spinal stenosis.

BACKGROUND: Lumbar spinal stenosis (LSS) is a common and important spinal surgical problem. Currently there is no universally accepted quantitative approach to the radiological measurement of LSS. LSS can be described qualitatively with reference to facet and ligamentous hypertrophy, lack of perineural or intraforaminal fat, and reduced CSF around the cauda equina. Quantitative descriptions do exist e.g., lumbar canal antero-posterior diameter, but these are unidimensional and do not consider normal variation in anatomy. We propose a universal and individualised measurement system for the quantitative radiological assessment of lumbar spinal stenosis. METHODS: A retrospective case series of patients who had undergone surgery for symptomatic lumbar spinal stenosis over a 3 year period. Pre-operative lumbar spine MRI were analysed. Each patient had the degree of lumbar canal stenosis quantified using our novel approach. RESULTS: Our novel formula for the quantitative radiological assessment of lumbar spinal stenosis is two dimensional, repeatable and presented as a percentage, to correct for the individual patient. The surface area of the lumbar spinal canal at the level of stenosis is measured in mm2 plus the adjacent 2 levels which are then averaged. The calculation then becomes (A-S/A) x 100 = R, where S is the canal surface area at the stenosed level in mm2, A is the average canal surface area of the two levels adjacent to the level of interest and R is the relative degree of lumbar spinal canal stenosis expressed as a percentage. Measurements are calculated using axial T2 weighted images. CONCLUSIONS: This novel quantitative measurement formula for the radiological assessment of lumbar canal spinal stenosis is quick and simple to calculate and most importantly adjusts for the individual patient's normal or degenerative anatomy. This new measurement tool will need validation against specific clinical and operative criteria in the future.

Emergency surgical decompression and long-term survival of glioblastoma presenting in coma in old age: case report and review of prognostic factors.

We present a case demonstrating that older age does not exclude long-term survival with glioblastoma. This is a malignant neoplasm with a median life expectancy of 14 months in patients treated with radical intent. Survival is dependent on several independent and interacting prognostic factors of which advancing age is a negative factor. We present a septuagenarian with a 3.5-year survival following aggressive management. The potential to improve glioblastoma survival in an elderly population by examination of additional prognostic factors and identifying biomarkers warrants further research.

Epidemiological and economic impact of COVID-19 in the US.

This research measures the epidemiological and economic impact of COVID-19 spread in the US under different mitigation scenarios, comprising of non-pharmaceutical interventions. A detailed disease model of COVID-19 is combined with a model of the US economy to estimate the direct impact of labor supply shock to each sector arising from morbidity, mortality, and lockdown, as well as the indirect impact caused by the interdependencies between sectors. During a lockdown, estimates of jobs that are workable from home in each sector are used to modify the shock to labor supply. Results show trade-offs between economic losses, and lives saved and infections averted are non-linear in compliance to social distancing and the duration of the lockdown. Sectors that are worst hit are not the labor-intensive sectors such as the Agriculture sector and the Construction sector, but the ones with high valued jobs such as the Professional Services, even after the teleworkability of jobs is accounted for. Additionally, the findings show that a low compliance to interventions can be overcome by a longer shutdown period and vice versa to arrive at similar epidemiological impact but their net effect on economic loss depends on the interplay between the marginal gains from averting infections and deaths, versus the marginal loss from having healthy workers stay at home during the shutdown.

Epidemiological and Economic Impact of COVID-19 in the US.

This research measures the epidemiological and economic impact of COVID-19 spread in the US under different mitigation scenarios, comprising of non-pharmaceutical interventions. A detailed disease model of COVID-19 is combined with a model of the US economy to estimate the direct impact of labor supply shock to each sector arising from morbidity, mortality, and lock down, as well as the indirect impact caused by the interdependencies between sectors. During a lockdown, estimates of jobs that are workable from home in each sector are used to modify the shock to labor supply. Results show trade-offs between economic losses, and lives saved and infections averted are non-linear in compliance to social distancing and the duration of lockdown. Sectors that are worst hit are not the labor-intensive sectors such as Agriculture and Construction, but the ones with high valued jobs such as Professional Services, even after the teleworkability of jobs is accounted for. Additionally, the findings show that a low compliance to interventions can be overcome by a longer shutdown period and vice versa to arrive at similar epidemiological impact but their net effect on economic loss depends on the interplay between the marginal gains from averting infections and deaths, versus the marginal loss from having healthy workers stay at home during the shutdown.

Medical costs of keeping the US economy open during COVID-19.

We use an individual based model and national level epidemic simulations to estimate the medical costs of keeping the US economy open during COVID-19 pandemic under different counterfactual scenarios. We model an unmitigated scenario and 12 mitigation scenarios which differ in compliance behavior to social distancing strategies and in the duration of the stay-home order. Under each scenario we estimate the number of people who are likely to get infected and require medical attention, hospitalization, and ventilators. Given the per capita medical cost for each of these health states, we compute the total medical costs for each scenario and show the tradeoffs between deaths, costs, infections, compliance and the duration of stay-home order. We also consider the hospital bed capacity of each Hospital Referral Region (HRR) in the US to estimate the deficit in beds each HRR will likely encounter given the demand for hospital beds. We consider a case where HRRs share hospital beds among the neighboring HRRs during a surge in demand beyond the available beds and the impact it has in controlling additional deaths.

Medical Costs of Keeping the US Economy Open During COVID-19.

We use an individual based model and national level epidemic simulations to estimate the medical costs of keeping the US economy open during COVID-19 pandemic under different counterfactual scenarios. We model an unmitigated scenario and 12 mitigation scenarios which differ in compliance behavior to social distancing strategies and to the duration of the stay-home order. Under each scenario we estimate the number of people who are likely to get infected and require medical attention, hospitalization, and ventilators. Given the per capita medical cost for each of these health states, we compute the total medical costs for each scenario and show the tradeoffs between deaths, costs, infections, compliance and the duration of stay-home order. We also consider the hospital bed capacity of each Hospital Referral Region (HRR) in the US to estimate the deficit in beds each HRR will likely encounter given the demand for hospital beds. We consider a case where HRRs share hospital beds among the neighboring HRRs during a surge in demand beyond the available beds and the impact it has in controlling additional deaths.

Evaluating the impact of international airline suspensions on the early global spread of COVID-19.

Global airline networks play a key role in the global importation of emerging infectious diseases. Detailed information on air traffic between international airports has been demonstrated to be useful in retrospectively validating and prospectively predicting case emergence in other countries. In this paper, we use a well-established metric known as effective distance on the global air traffic data from IATA to quantify risk of emergence for different countries as a consequence of direct importation from China, and compare it against arrival times for the first 24 countries. Using this model trained on official first reports from WHO, we estimate time of arrival (ToA) for all other countries. We then incorporate data on airline suspensions to recompute the effective distance and assess the effect of such cancellations in delaying the estimated arrival time for all other countries. Finally we use the infectious disease vulnerability indices to explain some of the estimated reporting delays.

Multiplicity of phenotypes and RNA evolution.

Motivation Motoo Kimura's neutral theory stipulates that evolution is predominantly driven by neutral mutations. RNA, realizing both genotype (its linear sequence of nucleotides) as well as phenotype (its folded secondary structure) represents a particularly well suited test bed for studying neutrality. This leads to neutral networks of RNA secondary structures, i.e. sets of sequences all of which folding into a fixed phenotype and whose organization plays a crucial role for neutral evolution. In this paper we bring a new perspective to the neutral theory by studying the consequences of the mostly ignored fact that the genotype-to-phenotype map for RNA is often one-to-many. In fact 29.5% of random RNA sequences realize more than one phenotype (minimum free energy structure). We call two genotypes to be quasineutral if their sets of associated phenotypes have non-empty intersection. Results We show that even though the energy profile of quasineutral mutations is almost identical to the neutral ones, a walk in the genotype space whose consecutive steps are quasineutral, can percolate phenotype space and so such walks bridge between neutral and random walks. This provides further evidence that evolution is continuous. We also study how these drift walks transition between neutral networks.

Management of Giant Calcified Thoracic Disks and Description of the Trench Vertebrectomy Technique.

STUDY DESIGN: Case series and review of the literature. OBJECTIVE: To review the management of giant calcified disks in our large cohort and compare with the existing literature. We discuss our surgical technique. METHODS: Twenty-nine cases of herniated thoracic disk between 2000 and 2013 were reviewed. Eighteen patients were identified as having giant calcified thoracic disks, defined as diffusely calcified disks occupying at least 40% of the spinal canal. Demographic data was collected in addition to presentation, imaging findings, operative details, and outcomes using the modified Japanese Orthopaedic Association (mJOA) scale. RESULTS: Giant calcified thoracic disks (GCTDs) are unique clinical entities that require special neurosurgical consideration owing to significant (≥40%) involvement of the spinal canal and compression of the spinal cord, often leading to myelopathy. The median age at diagnosis was 51.2 years (range 37 to 70) with the mean duration of presenting symptoms being 9.9 months (range 2 weeks to 3 years). Seventeen (94.4%) patients presented with at least one sign of myelopathy (hyperreflexia, hypertonia, bladder or bowel dysfunction) with the remaining 1 (5.6%) patient presenting with symptoms in keeping with radiculopathy. Thoracotomy was performed on 17 (94.4%) patients, and 1 (5.6%) patient had a costotransverse approach. Mean follow-up was 19.8 months (range 7 months to 2 years). mJOA score improved in 15 (83.3%) patients. mJOA scores in the other patients remained stable. CONCLUSIONS: GCTDs are difficult neurosurgical challenges owing to their size, degree of spinal cord compression, and consistency. We recommend a trench vertebrectomy via a thoracotomy in their surgical management. This procedure safely allows the identification of normal dura on either side of the compressed segment prior to performing a diskectomy. Excellent fusion rates were achieved with insertion of rib head autograft in the trench.

EpiCaster: An Integrated Web Application For Situation Assessment and Forecasting of Global Epidemics.

Public health decision makers need access to high resolution situation assessment tools for understanding the extent of various epidemics in different regions of the world. In addition, they need insights into the future course of epidemics by way of forecasts. Such forecasts are essential for planning the allocation of limited resources and for implementing several policy-level and behavioral intervention strategies. The need for such forecasting systems became evident in the wake of the recent Ebola outbreak in West Africa. We have developed EpiCaster, an integrated Web application for situation assessment and forecasting of various epidemics, such as Flu and Ebola, that are prevalent in different regions of the world. Using EpiCaster, users can assess the magnitude and severity of different epidemics at highly resolved spatio-temporal levels. EpiCaster provides time-varying heat maps and graphical plots to view trends in the disease dynamics. EpiCaster also allows users to visualize data gathered through surveillance mechanisms, such as Google Flu Trends (GFT) and the World Health Organization (WHO). The forecasts provided by EpiCaster are generated using different epidemiological models, and the users can select the models through the interface to filter the corresponding forecasts. EpiCaster also allows the users to study epidemic propagation in the presence of a number of intervention strategies specific to certain diseases. Here we describe the modeling techniques, methodologies and computational infrastructure that EpiCaster relies on to support large-scale predictive analytics for situation assessment and forecasting of global epidemics.

Conservative management of type II and III odontoid fractures in the elderly at a regional spine centre: A prospective and retrospective cohort study.

BACKGROUND: The optimal management of odontoid fractures in the elderly population is unclear and management of this group of patients is complicated by multiple co-morbidities. This study aimed to determine the outcomes after conservative management strategies were applied in this patient group. METHODS: We carried out retrospective and prospective analyses of all patients with axial cervical spine injuries, at a single centre. We included patients aged over 60 years with type II and III odontoid fractures. Information was gathered on demographics, ASA grading-associated injuries and complications. The outcome measures were rates and type of union, pain and neurological functions, specifically ambulation. RESULTS: Fifty-seven adult patients with a median age of 78 years (range 60-92 years) were included. There were 42 type II and 15 type III odontoid fractures. Three patients required surgical fixation due to displaced fractures, which could not be reduced with manual traction. Twenty-four (41%) patients were managed with a rigid pinned halo orthosis to obtain adequate reduction and immobilisation. The remaining 30 (53%) were managed in a hard cervical collar. Patients managed with a halo were significantly younger and had more associated injuries than patients managed in a collar (age: t-test=4.05, p<0.01, associated injuries: Chi-square=4.38, p<0.05). At a mean follow-up of 25 weeks, 87% of type II and 100% of type III fractures had achieved bony union or stable, fibrous non-union. There were no statistical differences in fracture type, follow-up or neurological outcomes between the halo and collar groups. However, overall more patients managed in a collar developed stable fibrous non-union than bony fusion (Fisher's exact test, p<0.05), although this was not significant when analysed by each fracture type individually. A regression model was constructed and identified fracture type as the only independent predictor of time to union, with type III fractures healing faster than type II. CONCLUSIONS: High rates of bony union and stable fibrous non-union with a good functional outcome can be achieved in the elderly population sustaining type II or III odontoid fractures, when managed non-surgically. Halo orthosis may not offer any clear advantage over hard collar in this group. Close follow-up is needed for late complications and there must be a willingness to perform surgery if conservative measures fail.

Applications of the ultrasonic bone cutter in spinal surgery--our preliminary experience.

OBJECTIVE: To present our experience with the Misonix Ultrasonic Bone scalpel in spinal surgery, highlighting its potential applications and advantages. METHODS: Between March and December 2011, a total of 937 spinal cases were performed at a single centre. The Misonix Bone Scalpel (MBS) was used in 62 of these cases. Data were collected prospectively using the Spine Tango registry. Patient demographics, disease type, surgery performed and complications were all recorded along with pre- and post-operative core measures outcome index (COMI). RESULTS: The majority of cases were for spinal degenerative disorders, in particular, revision cases. The bone cutter was also used to achieve laminotomies for access to intradural tumours, corpectomies and a mixture of other pathologies. Of the 62 patients only 1 (1.6%) experienced a blood loss greater than 500 ml, and there was only 1 dural tear (1.6%) as a direct result of the MBS. Four illustrative cases are discussed. CONCLUSIONS: The MBS is a useful adjunct in spinal surgery with particular value in revision cases where scar tissue distorts the normal anatomy. There was a low complication rate with a trend to reduced blood loss. This was most apparent to the senior authors during cervical and thoracic corpectomies.

A simulation environment for the dynamic evaluation of disaster preparedness policies and interventions.

Disasters affect a society at many levels. Simulation-based studies often evaluate the effectiveness of 1 or 2 response policies in isolation and are unable to represent impact of the policies to coevolve with others. Similarly, most in-depth analyses are based on a static assessment of the "aftermath" rather than capturing dynamics. We have developed a data-centric simulation environment for applying a systems approach to a dynamic analysis of complex combinations of disaster responses. We analyze an improvised nuclear detonation in Washington, District of Columbia, with this environment. The simulated blast affects the transportation system, communications infrastructure, electrical power system, behaviors and motivations of population, and health status of survivors. The effectiveness of partially restoring wireless communications capacity is analyzed in concert with a range of other disaster response policies. Despite providing a limited increase in cell phone communication, overall health was improved.

Overtightening of halo pins resulting in intracranial penetration, pneumocephalus, and epileptic seizure.

A 60-year-old man sustained an undisplaced type III odontoid fracture following a fall down a full flight of stairs. His medical history was remarkable for a partial pancreatectomy and splenectomy in 2006 for chronic pancreatitis. This had rendered him diabetic, on insulin, and he required long-term administration of penicillin V. The fracture was treated with a halo vest, and, unknowing of its potentially serious consequences, the patient continued to tighten the halo pins himself. He presented 1 month later following a witnessed seizure. A computed tomography scan was performed, which demonstrated 2 cranial perforations, with the halo pins penetrating the cranium and resultant pneumocephalus. He was started on antiepileptic medication and was placed in a pinless halo system. He had no further seizures and has made an uneventful neurological recovery. This paper serves to highlight the potential complications which may arise from the use of a halo vest. Proper patient education is essential to avoid these serious yet avoidable events, and patients with low bone density and the immunosuppressed should be monitored closely.

Human initiated cascading failures in societal infrastructures.

In this paper, we conduct a systematic study of human-initiated cascading failures in three critical inter-dependent societal infrastructures due to behavioral adaptations in response to a crisis. We focus on three closely coupled socio-technical networks here: (i) cellular and mesh networks, (ii) transportation networks and (iii) mobile call networks. In crises, changes in individual behaviors lead to altered travel, activity and calling patterns, which influence the transport network and the loads on wireless networks. The interaction between these systems and their co-evolution poses significant technical challenges for representing and reasoning about these systems. In contrast to system dynamics models for studying these interacting infrastructures, we develop interaction-based models in which individuals and infrastructure elements are represented in detail and are placed in a common geographic coordinate system. Using the detailed representation, we study the impact of a chemical plume that has been released in a densely populated urban region. Authorities order evacuation of the affected area, and this leads to individual behavioral adaptation wherein individuals drop their scheduled activities and drive to home or pre-specified evacuation shelters as appropriate. They also revise their calling behavior to communicate and coordinate among family members. These two behavioral adaptations cause flash-congestion in the urban transport network and the wireless network. The problem is exacerbated with a few, already occurring, road closures. We analyze how extended periods of unanticipated road congestion can result in failure of infrastructures, starting with the servicing base stations in the congested area. A sensitivity analysis on the compliance rate of evacuees shows non-intuitive effect on the spatial distribution of people and on the loading of the base stations. For example, an evacuation compliance rate of 70% results in higher number of overloaded base stations than the evacuation compliance rate of 90%.

Unusual presentation of tuberculosis with multiple spinal deposits.

We discuss the relevant imaging of an unusual case of disseminated tuberculosis presenting with multifocal spinal deposits.

Pin site allergic contact dermatitis: an unusual complication of halo fixation.

We report a case of halo pin site allergic contact dermatitis, a rare complication of halo vest immobilisation (HVI), necessitating device removal. Although uncommon, pin site allergic contact dermatitis should be considered in patients who develop an acute dermatitis within hours to days of HVI application.

Economic and social impact of influenza mitigation strategies by demographic class.

BACKGROUND: We aim to determine the economic and social impact of typical interventions proposed by the public health officials and preventive behavioral changes adopted by the private citizens in the event of a "flu-like" epidemic. METHOD: We apply an individual-based simulation model to the New River Valley area of Virginia for addressing this critical problem. The economic costs include not only the loss in productivity due to sickness but also the indirect cost incurred through disease avoidance and caring for dependents. RESULTS: The results show that the most important factor responsible for preventing income loss is the modification of individual behavior; it drops the total income loss by 62% compared to the base case. The next most important factor is the closure of schools which reduces the total income loss by another 40%. CONCLUSIONS: The preventive behavior of the private citizens is the most important factor in controlling the epidemic.