Markov models for clinical decision-making in radiation oncology: A systematic review

The intrinsic stochasticity of patients' response to treatment is a major consideration for clinical decision-making in radiation therapy. Markov models are powerful tools to capture this stochasticity and render effective treatment decisions. This paper provides an overview of the Markov models for clinical decision analysis in radiation oncology. A comprehensive literature search was conducted within MEDLINE using PubMed, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only studies published from 2000 to 2023 were considered. Selected publications were summarized in two categories: (i) studies that compare two (or more) fixed treatment policies using Monte Carlo simulation and (ii) studies that seek an optimal treatment policy through Markov Decision Processes (MDPs). Relevant to the scope of this study, 61 publications were selected for detailed review. The majority of these publications (n = 56) focused on comparative analysis of two or more fixed treatment policies using Monte Carlo simulation. Classifications based on cancer site, utility measures and the type of sensitivity analysis are presented. Five publications considered MDPs with the aim of computing an optimal treatment policy; a detailed statement of the analysis and results is provided for each work. As an extension of Markov model-based simulation analysis, MDP offers a flexible framework to identify an optimal treatment policy among a possibly large set of treatment policies. However, the applications of MDPs to oncological decision-making have been understudied, and the full capacity of this framework to render complex optimal treatment decisions warrants further consideration.

Burden of disease scenarios for 204 countries and territories, 2022-2050: a forecasting analysis for the Global Burden of Disease Study 2021

BACKGROUND

Future trends in disease burden and drivers of health are of great interest to policy makers and the public at large. This information can be used for policy and long-term health investment, planning, and prioritisation. We have expanded and improved upon previous forecasts produced as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) and provide a reference forecast (the most likely future), and alternative scenarios assessing disease burden trajectories if selected sets of risk factors were eliminated from current levels by 2050.

METHODS

Using forecasts of major drivers of health such as the Socio-demographic Index (SDI; a composite measure of lag-distributed income per capita, mean years of education, and total fertility under 25 years of age) and the full set of risk factor exposures captured by GBD, we provide cause-specific forecasts of mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) by age and sex from 2022 to 2050 for 204 countries and territories, 21 GBD regions, seven super-regions, and the world. All analyses were done at the cause-specific level so that only risk factors deemed causal by the GBD comparative risk assessment influenced future trajectories of mortality for each disease. Cause-specific mortality was modelled using mixed-effects models with SDI and time as the main covariates, and the combined impact of causal risk factors as an offset in the model. At the all-cause mortality level, we captured unexplained variation by modelling residuals with an autoregressive integrated moving average model with drift attenuation. These all-cause forecasts constrained the cause-specific forecasts at successively deeper levels of the GBD cause hierarchy using cascading mortality models, thus ensuring a robust estimate of cause-specific mortality. For non-fatal measures (eg, low back pain), incidence and prevalence were forecasted from mixed-effects models with SDI as the main covariate, and YLDs were computed from the resulting prevalence forecasts and average disability weights from GBD. Alternative future scenarios were constructed by replacing appropriate reference trajectories for risk factors with hypothetical trajectories of gradual elimination of risk factor exposure from current levels to 2050. The scenarios were constructed from various sets of risk factors: environmental risks (Safer Environment scenario), risks associated with communicable, maternal, neonatal, and nutritional diseases (CMNNs; Improved Childhood Nutrition and Vaccination scenario), risks associated with major non-communicable diseases (NCDs; Improved Behavioural and Metabolic Risks scenario), and the combined effects of these three scenarios. Using the Shared Socioeconomic Pathways climate scenarios SSP2-4.5 as reference and SSP1-1.9 as an optimistic alternative in the Safer Environment scenario, we accounted for climate change impact on health by using the most recent Intergovernmental Panel on Climate Change temperature forecasts and published trajectories of ambient air pollution for the same two scenarios. Life expectancy and healthy life expectancy were computed using standard methods. The forecasting framework includes computing the age-sex-specific future population for each location and separately for each scenario. 95% uncertainty intervals (UIs) for each individual future estimate were derived from the 2·5th and 97·5th percentiles of distributions generated from propagating 500 draws through the multistage computational pipeline.

FINDINGS

In the reference scenario forecast, global and super-regional life expectancy increased from 2022 to 2050, but improvement was at a slower pace than in the three decades preceding the COVID-19 pandemic (beginning in 2020). Gains in future life expectancy were forecasted to be greatest in super-regions with comparatively low life expectancies (such as sub-Saharan Africa) compared with super-regions with higher life expectancies (such as the high-income super-region), leading to a trend towards convergence in life expectancy across locations between now and 2050. At the super-region level, forecasted healthy life expectancy patterns were similar to those of life expectancies. Forecasts for the reference scenario found that health will improve in the coming decades, with all-cause age-standardised DALY rates decreasing in every GBD super-region. The total DALY burden measured in counts, however, will increase in every super-region, largely a function of population ageing and growth. We also forecasted that both DALY counts and age-standardised DALY rates will continue to shift from CMNNs to NCDs, with the most pronounced shifts occurring in sub-Saharan Africa (60·1% [95% UI 56·8-63·1] of DALYs were from CMNNs in 2022 compared with 35·8% [31·0-45·0] in 2050) and south Asia (31·7% [29·2-34·1] to 15·5% [13·7-17·5]). This shift is reflected in the leading global causes of DALYs, with the top four causes in 2050 being ischaemic heart disease, stroke, diabetes, and chronic obstructive pulmonary disease, compared with 2022, with ischaemic heart disease, neonatal disorders, stroke, and lower respiratory infections at the top. The global proportion of DALYs due to YLDs likewise increased from 33·8% (27·4-40·3) to 41·1% (33·9-48·1) from 2022 to 2050, demonstrating an important shift in overall disease burden towards morbidity and away from premature death. The largest shift of this kind was forecasted for sub-Saharan Africa, from 20·1% (15·6-25·3) of DALYs due to YLDs in 2022 to 35·6% (26·5-43·0) in 2050. In the assessment of alternative future scenarios, the combined effects of the scenarios (Safer Environment, Improved Childhood Nutrition and Vaccination, and Improved Behavioural and Metabolic Risks scenarios) demonstrated an important decrease in the global burden of DALYs in 2050 of 15·4% (13·5-17·5) compared with the reference scenario, with decreases across super-regions ranging from 10·4% (9·7-11·3) in the high-income super-region to 23·9% (20·7-27·3) in north Africa and the Middle East. The Safer Environment scenario had its largest decrease in sub-Saharan Africa (5·2% [3·5-6·8]), the Improved Behavioural and Metabolic Risks scenario in north Africa and the Middle East (23·2% [20·2-26·5]), and the Improved Nutrition and Vaccination scenario in sub-Saharan Africa (2·0% [-0·6 to 3·6]).

INTERPRETATION

Globally, life expectancy and age-standardised disease burden were forecasted to improve between 2022 and 2050, with the majority of the burden continuing to shift from CMNNs to NCDs. That said, continued progress on reducing the CMNN disease burden will be dependent on maintaining investment in and policy emphasis on CMNN disease prevention and treatment. Mostly due to growth and ageing of populations, the number of deaths and DALYs due to all causes combined will generally increase. By constructing alternative future scenarios wherein certain risk exposures are eliminated by 2050, we have shown that opportunities exist to substantially improve health outcomes in the future through concerted efforts to prevent exposure to well established risk factors and to expand access to key health interventions.

FUNDING

Bill & Melinda Gates Foundation.

Global fertility in 204 countries and territories, 1950-2021, with forecasts to 2100: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

BACKGROUND

Accurate assessments of current and future fertility-including overall trends and changing population age structures across countries and regions-are essential to help plan for the profound social, economic, environmental, and geopolitical challenges that these changes will bring. Estimates and projections of fertility are necessary to inform policies involving resource and health-care needs, labour supply, education, gender equality, and family planning and support. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 produced up-to-date and comprehensive demographic assessments of key fertility indicators at global, regional, and national levels from 1950 to 2021 and forecast fertility metrics to 2100 based on a reference scenario and key policy-dependent alternative scenarios.

METHODS

To estimate fertility indicators from 1950 to 2021, mixed-effects regression models and spatiotemporal Gaussian process regression were used to synthesise data from 8709 country-years of vital and sample registrations, 1455 surveys and censuses, and 150 other sources, and to generate age-specific fertility rates (ASFRs) for 5-year age groups from age 10 years to 54 years. ASFRs were summed across age groups to produce estimates of total fertility rate (TFR). Livebirths were calculated by multiplying ASFR and age-specific female population, then summing across ages 10-54 years. To forecast future fertility up to 2100, our Institute for Health Metrics and Evaluation (IHME) forecasting model was based on projections of completed cohort fertility at age 50 years (CCF50; the average number of children born over time to females from a specified birth cohort), which yields more stable and accurate measures of fertility than directly modelling TFR. CCF50 was modelled using an ensemble approach in which three sub-models (with two, three, and four covariates variously consisting of female educational attainment, contraceptive met need, population density in habitable areas, and under-5 mortality) were given equal weights, and analyses were conducted utilising the MR-BRT (meta-regression-Bayesian, regularised, trimmed) tool. To capture time-series trends in CCF50 not explained by these covariates, we used a first-order autoregressive model on the residual term. CCF50 as a proportion of each 5-year ASFR was predicted using a linear mixed-effects model with fixed-effects covariates (female educational attainment and contraceptive met need) and random intercepts for geographical regions. Projected TFRs were then computed for each calendar year as the sum of single-year ASFRs across age groups. The reference forecast is our estimate of the most likely fertility future given the model, past fertility, forecasts of covariates, and historical relationships between covariates and fertility. We additionally produced forecasts for multiple alternative scenarios in each location: the UN Sustainable Development Goal (SDG) for education is achieved by 2030; the contraceptive met need SDG is achieved by 2030; pro-natal policies are enacted to create supportive environments for those who give birth; and the previous three scenarios combined. Uncertainty from past data inputs and model estimation was propagated throughout analyses by taking 1000 draws for past and present fertility estimates and 500 draws for future forecasts from the estimated distribution for each metric, with 95% uncertainty intervals (UIs) given as the 2·5 and 97·5 percentiles of the draws. To evaluate the forecasting performance of our model and others, we computed skill values-a metric assessing gain in forecasting accuracy-by comparing predicted versus observed ASFRs from the past 15 years (2007-21). A positive skill metric indicates that the model being evaluated performs better than the baseline model (here, a simplified model holding 2007 values constant in the future), and a negative metric indicates that the evaluated model performs worse than baseline.

FINDINGS

During the period from 1950 to 2021, global TFR more than halved, from 4·84 (95% UI 4·63-5·06) to 2·23 (2·09-2·38). Global annual livebirths peaked in 2016 at 142 million (95% UI 137-147), declining to 129 million (121-138) in 2021. Fertility rates declined in all countries and territories since 1950, with TFR remaining above 2·1-canonically considered replacement-level fertility-in 94 (46·1%) countries and territories in 2021. This included 44 of 46 countries in sub-Saharan Africa, which was the super-region with the largest share of livebirths in 2021 (29·2% [28·7-29·6]). 47 countries and territories in which lowest estimated fertility between 1950 and 2021 was below replacement experienced one or more subsequent years with higher fertility; only three of these locations rebounded above replacement levels. Future fertility rates were projected to continue to decline worldwide, reaching a global TFR of 1·83 (1·59-2·08) in 2050 and 1·59 (1·25-1·96) in 2100 under the reference scenario. The number of countries and territories with fertility rates remaining above replacement was forecast to be 49 (24·0%) in 2050 and only six (2·9%) in 2100, with three of these six countries included in the 2021 World Bank-defined low-income group, all located in the GBD super-region of sub-Saharan Africa. The proportion of livebirths occurring in sub-Saharan Africa was forecast to increase to more than half of the world's livebirths in 2100, to 41·3% (39·6-43·1) in 2050 and 54·3% (47·1-59·5) in 2100. The share of livebirths was projected to decline between 2021 and 2100 in most of the six other super-regions-decreasing, for example, in south Asia from 24·8% (23·7-25·8) in 2021 to 16·7% (14·3-19·1) in 2050 and 7·1% (4·4-10·1) in 2100-but was forecast to increase modestly in the north Africa and Middle East and high-income super-regions. Forecast estimates for the alternative combined scenario suggest that meeting SDG targets for education and contraceptive met need, as well as implementing pro-natal policies, would result in global TFRs of 1·65 (1·40-1·92) in 2050 and 1·62 (1·35-1·95) in 2100. The forecasting skill metric values for the IHME model were positive across all age groups, indicating that the model is better than the constant prediction.

INTERPRETATION

Fertility is declining globally, with rates in more than half of all countries and territories in 2021 below replacement level. Trends since 2000 show considerable heterogeneity in the steepness of declines, and only a small number of countries experienced even a slight fertility rebound after their lowest observed rate, with none reaching replacement level. Additionally, the distribution of livebirths across the globe is shifting, with a greater proportion occurring in the lowest-income countries. Future fertility rates will continue to decline worldwide and will remain low even under successful implementation of pro-natal policies. These changes will have far-reaching economic and societal consequences due to ageing populations and declining workforces in higher-income countries, combined with an increasing share of livebirths among the already poorest regions of the world.

FUNDING

Bill & Melinda Gates Foundation.

Global incidence, prevalence, years lived with disability (YLDs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries in 204 countries and territories and 811 subnational locations, 1990-2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND

Detailed, comprehensive, and timely reporting on population health by underlying causes of disability and premature death is crucial to understanding and responding to complex patterns of disease and injury burden over time and across age groups, sexes, and locations. The availability of disease burden estimates can promote evidence-based interventions that enable public health researchers, policy makers, and other professionals to implement strategies that can mitigate diseases. It can also facilitate more rigorous monitoring of progress towards national and international health targets, such as the Sustainable Development Goals. For three decades, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) has filled that need. A global network of collaborators contributed to the production of GBD 2021 by providing, reviewing, and analysing all available data. GBD estimates are updated routinely with additional data and refined analytical methods. GBD 2021 presents, for the first time, estimates of health loss due to the COVID-19 pandemic.

METHODS

The GBD 2021 disease and injury burden analysis estimated years lived with disability (YLDs), years of life lost (YLLs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries using 100 983 data sources. Data were extracted from vital registration systems, verbal autopsies, censuses, household surveys, disease-specific registries, health service contact data, and other sources. YLDs were calculated by multiplying cause-age-sex-location-year-specific prevalence of sequelae by their respective disability weights, for each disease and injury. YLLs were calculated by multiplying cause-age-sex-location-year-specific deaths by the standard life expectancy at the age that death occurred. DALYs were calculated by summing YLDs and YLLs. HALE estimates were produced using YLDs per capita and age-specific mortality rates by location, age, sex, year, and cause. 95% uncertainty intervals (UIs) were generated for all final estimates as the 2·5th and 97·5th percentiles values of 500 draws. Uncertainty was propagated at each step of the estimation process. Counts and age-standardised rates were calculated globally, for seven super-regions, 21 regions, 204 countries and territories (including 21 countries with subnational locations), and 811 subnational locations, from 1990 to 2021. Here we report data for 2010 to 2021 to highlight trends in disease burden over the past decade and through the first 2 years of the COVID-19 pandemic.

FINDINGS

Global DALYs increased from 2·63 billion (95% UI 2·44-2·85) in 2010 to 2·88 billion (2·64-3·15) in 2021 for all causes combined. Much of this increase in the number of DALYs was due to population growth and ageing, as indicated by a decrease in global age-standardised all-cause DALY rates of 14·2% (95% UI 10·7-17·3) between 2010 and 2019. Notably, however, this decrease in rates reversed during the first 2 years of the COVID-19 pandemic, with increases in global age-standardised all-cause DALY rates since 2019 of 4·1% (1·8-6·3) in 2020 and 7·2% (4·7-10·0) in 2021. In 2021, COVID-19 was the leading cause of DALYs globally (212·0 million [198·0-234·5] DALYs), followed by ischaemic heart disease (188·3 million [176·7-198·3]), neonatal disorders (186·3 million [162·3-214·9]), and stroke (160·4 million [148·0-171·7]). However, notable health gains were seen among other leading communicable, maternal, neonatal, and nutritional (CMNN) diseases. Globally between 2010 and 2021, the age-standardised DALY rates for HIV/AIDS decreased by 47·8% (43·3-51·7) and for diarrhoeal diseases decreased by 47·0% (39·9-52·9). Non-communicable diseases contributed 1·73 billion (95% UI 1·54-1·94) DALYs in 2021, with a decrease in age-standardised DALY rates since 2010 of 6·4% (95% UI 3·5-9·5). Between 2010 and 2021, among the 25 leading Level 3 causes, age-standardised DALY rates increased most substantially for anxiety disorders (16·7% [14·0-19·8]), depressive disorders (16·4% [11·9-21·3]), and diabetes (14·0% [10·0-17·4]). Age-standardised DALY rates due to injuries decreased globally by 24·0% (20·7-27·2) between 2010 and 2021, although improvements were not uniform across locations, ages, and sexes. Globally, HALE at birth improved slightly, from 61·3 years (58·6-63·6) in 2010 to 62·2 years (59·4-64·7) in 2021. However, despite this overall increase, HALE decreased by 2·2% (1·6-2·9) between 2019 and 2021.

INTERPRETATION

Putting the COVID-19 pandemic in the context of a mutually exclusive and collectively exhaustive list of causes of health loss is crucial to understanding its impact and ensuring that health funding and policy address needs at both local and global levels through cost-effective and evidence-based interventions. A global epidemiological transition remains underway. Our findings suggest that prioritising non-communicable disease prevention and treatment policies, as well as strengthening health systems, continues to be crucially important. The progress on reducing the burden of CMNN diseases must not stall; although global trends are improving, the burden of CMNN diseases remains unacceptably high. Evidence-based interventions will help save the lives of young children and mothers and improve the overall health and economic conditions of societies across the world. Governments and multilateral organisations should prioritise pandemic preparedness planning alongside efforts to reduce the burden of diseases and injuries that will strain resources in the coming decades.

FUNDING

Bill & Melinda Gates Foundation.

Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990-2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND

Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021.

METHODS

The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk-outcome pairs. Pairs were included on the basis of data-driven determination of a risk-outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk-outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk-outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws.

FINDINGS

Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7-9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4-9·2]), smoking (5·7% [4·7-6·8]), low birthweight and short gestation (5·6% [4·8-6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8-6·0]). For younger demographics (ie, those aged 0-4 years and 5-14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9-27·7]) and environmental and occupational risks (decrease of 22·0% [15·5-28·8]), coupled with a 49·4% (42·3-56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9-21·7] for high BMI and 7·9% [3·3-12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6-1·9) for high BMI and 1·3% (1·1-1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4-78·8) for child growth failure and 66·3% (60·2-72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP).

INTERPRETATION

Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions.

FUNDING

Bill & Melinda Gates Foundation.

Cluster-Based Toxicity Estimation of Osteoradionecrosis Via Unsupervised Machine Learning: Moving Beyond Single Dose-Parameter Normal Tissue Complication Probability by Using Whole Dose-Volume Histograms for Cohort Risk Stratification

PURPOSE

Given the limitations of extant models for normal tissue complication probability estimation for osteoradionecrosis (ORN) of the mandible, the purpose of this study was to enrich statistical inference by exploiting structural properties of data and provide a clinically reliable model for ORN risk evaluation through an unsupervised-learning analysis that incorporates the whole radiation dose distribution on the mandible.

METHODS AND MATERIALS

The analysis was conducted on retrospective data of 1259 patients with head and neck cancer treated at The University of Texas MD Anderson Cancer Center between 2005 and 2015. During a minimum 12-month posttherapy follow-up period, 173 patients in this cohort (13.7%) developed ORN (grades I to IV). The (structural) clusters of mandibular dose-volume histograms (DVHs) for these patients were identified using the K-means clustering method. A soft-margin support vector machine was used to determine the cluster borders and partition the dose-volume space. The risk of ORN for each dose-volume region was calculated based on incidence rates and other clinical risk factors.

RESULTS

The K-means clustering method identified 6 clusters among the DVHs. Based on the first 5 clusters, the dose-volume space was partitioned by the soft-margin support vector machine into distinct regions with different risk indices. The sixth cluster entirely overlapped with the others; the region of this cluster was determined by its envelopes. For each region, the ORN incidence rate per preradiation dental extraction status (a statistically significant, nondose related risk factor for ORN) was reported as the corresponding risk index.

CONCLUSIONS

This study presents an unsupervised-learning analysis of a large-scale data set to evaluate the risk of mandibular ORN among patients with head and neck cancer. The results provide a visual risk-assessment tool for ORN (based on the whole DVH and preradiation dental extraction status) as well as a range of constraints for dose optimization under different risk levels.

Global prevalence of urinary tract infection in pregnant mothers: a systematic review and meta-analysis

OBJECTIVE

Urinary tract infection (UTI) is a prevalent infection during pregnancy that can lead to complications for both the mother and the foetus. The objective of this systematic review and meta-analysis is to determine the global prevalence of UTIs (both symptomatic and asymptomatic) during pregnancy, based on previous studies in this area. Furthermore, this study aims to identify any factors that contribute to heterogeneity in the prevalence of UTIs during pregnancy.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines on August 8, 2022. To conduct the systematic review and meta-analysis, a search was performed using the keywords "urinary tract system", "UTI", "pregnancy", and "gestation" was performed in several databases, including Web of Science (WoS), PubMed, Scopus, ScienceDirect, Embase, and Google Scholar, without a time limit until September 18, 2022. The analysis was performed using a random-effects model, and the heterogeneity of the studies was assessed using the I2 index. The Comprehensive Meta-Analysis software (Version 2) was used for data analysis.

RESULTS

The systematic review and meta-analysis of 27 studies, which included a total of 30,641 pregnant women, showed an overall prevalence of UTI (both symptomatic and asymptomatic) to be 23.9% (95% confidence interval: 16.2-33.8). Meta-regression analysis was conducted to examine the impact of two factors, namely study sample size and study year, on the heterogeneity of the meta-analysis. The results revealed that an increase in sample size, and the study year was associated with a decrease in the prevalence of UTI in pregnant women (P < 0.05).

CONCLUSION

The results of our study indicate a global prevalence of UTI in pregnant women to be 23.9%. Therefore, it is recommended that all pregnant women undergo regular UTI screening tests and receive prompt treatment if diagnosed with UTI. Early detection and treatment of UTI during pregnancy are crucial to prevent complications that may affect the health of both the mother and the foetus.

Cluster-Based Toxicity Estimation of Osteoradionecrosis via Unsupervised Machine Learning: Moving Beyond Single Dose-Parameter Normal Tissue Complication Probability by Using Whole Dose-Volume Histograms for Cohort Risk Stratification

Purpose

Given the limitations of extant models for normal tissue complication probability estimation for osteoradionecrosis (ORN) of the mandible, the purpose of this study was to enrich statistical inference by exploiting structural properties of data and provide a clinically reliable model for ORN risk evaluation through an unsupervised-learning analysis.

Materials and Methods

The analysis was conducted on retrospective data of 1,259 head and neck cancer (HNC) patients treated at the University of Texas MD Anderson Cancer Center between 2005 and 2015. The (structural) clusters of mandibular dose-volume histograms (DVHs) were identified through the K-means clustering method. A soft-margin support vector machine (SVM) was used to determine the cluster borders and partition the dose-volume space. The risk of ORN for each dose-volume region was calculated based on the clinical risk factors and incidence rates.

Results

The K-means clustering method identified six clusters among the DVHs. Based on the first five clusters, the dose-volume space was partitioned almost perfectly by the soft-margin SVM into distinct regions with different risk indices. The sixth cluster overlapped the others entirely; the region of this cluster was determined by its envelops. These regions and the associated risk indices provide a range of constraints for dose optimization under different risk levels.

Conclusion

This study presents an unsupervised-learning analysis of a large-scale data set to evaluate the risk of mandibular ORN among HNC patients. The results provide a visual risk-assessment tool (based on the whole DVH) and a spectrum of dose constraints for radiation planning.

Risk Model-Based Lung Cancer Screening : A Cost-Effectiveness Analysis

BACKGROUND

In their 2021 lung cancer screening recommendation update, the U.S. Preventive Services Task Force (USPSTF) evaluated strategies that select people based on their personal lung cancer risk (risk model-based strategies), highlighting the need for further research on the benefits and harms of risk model-based screening.

OBJECTIVE

To evaluate and compare the cost-effectiveness of risk model-based lung cancer screening strategies versus the USPSTF recommendation and to explore optimal risk thresholds.

DESIGN

Comparative modeling analysis.

DATA SOURCES

National Lung Screening Trial; Surveillance, Epidemiology, and End Results program; U.S. Smoking History Generator.

TARGET POPULATION

1960 U.S. birth cohort.

TIME HORIZON

45 years.

PERSPECTIVE

U.S. health care sector.

INTERVENTION

Annual low-dose computed tomography in risk model-based strategies that start screening at age 50 or 55 years, stop screening at age 80 years, with 6-year risk thresholds between 0.5% and 2.2% using the PLCOm2012 model.

OUTCOME MEASURES

Incremental cost-effectiveness ratio (ICER) and cost-effectiveness efficiency frontier connecting strategies with the highest health benefit at a given cost.

RESULTS OF BASE-CASE ANALYSIS

Risk model-based screening strategies were more cost-effective than the USPSTF recommendation and exclusively comprised the cost-effectiveness efficiency frontier. Among the strategies on the efficiency frontier, those with a 6-year risk threshold of 1.2% or greater were cost-effective with an ICER less than $100 000 per quality-adjusted life-year (QALY). Specifically, the strategy with a 1.2% risk threshold had an ICER of $94 659 (model range, $72 639 to $156 774), yielding more QALYs for less cost than the USPSTF recommendation, while having a similar level of screening coverage (person ever-screened 21.7% vs. USPSTF's 22.6%).

RESULTS OF SENSITIVITY ANALYSES

Risk model-based strategies were robustly more cost-effective than the 2021 USPSTF recommendation under varying modeling assumptions.

LIMITATION

Risk models were restricted to age, sex, and smoking-related risk predictors.

CONCLUSION

Risk model-based screening is more cost-effective than the USPSTF recommendation, thus warranting further consideration.

PRIMARY FUNDING SOURCE

National Cancer Institute (NCI).

Optimized decision support for selection of transoral robotic surgery or (chemo)radiation therapy based on posttreatment swallowing toxicity

BACKGROUND

A primary goal in transoral robotic surgery (TORS) for oropharyngeal squamous cell cancer (OPSCC) survivors is to optimize swallowing function. However, the uncertainty in the outcomes of TORS including postoperative residual positive margin (PM) and extranodal extension (ENE), may necessitate adjuvant therapy, which may cause significant swallowing toxicity to survivors.

METHODS

A secondary analysis was performed on a prospective registry data with low- to intermediate-risk human papillomavirus-related OPSCC possibly resectable by TORS. Decision trees were developed to model the uncertainties in TORS compared with definitive radiation therapy (RT) and chemoradiation therapy (CRT). Swallowing toxicities were measured by Dynamic Imaging Grade of Swallowing Toxicity (DIGEST), MD Anderson Dysphagia Inventory (MDADI), and the MD Anderson Symptom Inventory-Head and Neck (MDASI-HN) instruments. The likelihoods of PM/ENE were varied to determine the thresholds within which each therapy remains optimal.

RESULTS

Compared with RT, TORS resulted in inferior swallowing function for moderate likelihoods of PM/ENE (>60% in short term for all instruments, >75% in long term for DIGEST and MDASI) leaving RT as the optimal treatment. Compared with CRT, TORS remained the optimal therapy based on MDADI and MDASI but showed inferior swallowing outcomes based on DIGEST for moderate-to-high likelihoods of PM/ENE (>75% for short-term and >40% for long-term outcomes).

CONCLUSION

In the absence of reliable estimation of postoperative PM/ENE concurrent with significant postoperative PM, the overall toxicity level in OPSCC patients undergoing TORS with adjuvant therapy may become more severe compared with patients receiving nonsurgical treatments thus advocating definitive (C)RT protocols.

Physiological role of adiponectin in different tissues: a review

Adiponectin is the most important adipokine secreted by the adipose tissue. It carries out an important role in setting up the metabolism and improving the function of various organs. Adiponectin in the kidneys prevents degradation of the renal arteries, reduces protein excretion, and improves filtration. This role is accomplished by regulating anabolic pathways and reducing oxidative stress in the renal tissue. This hormone in the liver prevents the accumulation of fat and free radicals that cause damage to liver cells and tissue. This adipokine, by preventing inflammatory processes, oxidative stress, obesity and insulin resistance, improves vascular function and prevents the development of atherosclerosis. It seems that adiponectin can also be a therapeutic target for many metabolic diseases. This study aims to clarify the adipose tissue discharge. Here, the diverse physiological actions of adiponectin were reviewed to provide an overview of its therapeutic potential in different metabolic disorders.

Libman-Sacks endocarditis in patients with systemic lupus erythematosus with secondary antiphospholipid syndrome

Background:

Libman-Sacks endocarditis (LSE) is characterized by sterile lesions that commonly affect the aortic and mitral heart valves. Antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) have been associated with LSE. Cardiac manifestations including LSE could be interrelated with other manifestations and early diagnosis could help in preventing further complications.

Case presentation:

Here, we report three cases of LSE in SLE patients with secondary APS. All patients presented with neurological manifestations and LSE was diagnosed by Transesophageal echocardiography (TEE). All three patients were treated for the underlying disease and also received anticoagulant therapy.

Conclusion:

In all patients with SLE and secondary APS, LSE should be considered if a patient manifests any evidence of neurologic involvement.

Efficacy of Methotrexate on Pain Severity Reduction and Improvement of Quality of Life in Patients with Moderate to Severe Knee Osteoarthritis

Background

Knee osteoarthritis (OA) leads to low quality of life due to pain and limitation in daily activities. Recent studies indicated that Methotrexate (MTX) could reduce pain due to its anti-inflammatory effects.

Objectives

In this study, the researchers aimed at evaluating the efficacy of MTX in pain control and improvement of quality of life in patients with moderate to severe knee OA.

Methods

In this randomized clinical trial, 100 patients with moderate to severe knee OA were allocated to receive MTX (n = 50) 7.5 mg weekly to be increased to 15 mg weekly after first months or placebo (n = 50) for six months. Pain severity was measured using the numerical rating scale (NRS), so was functional status by Western Ontario and McMaster Universities Arthritis Index (WOMAC) and quality of life by SF-12 questionnaire before the treatment, and three months and six months after the intervention. The results were compared between the groups subsequently. Nine patients from the MTX group were excluded due to the use of corticosteroids during the treatment period.

Results

The MTX group compared to the placebo group had significant improvement in pain severity and quality of life during six months and WOMAC parameters at three and six months after the intervention. The need for NSAIDS was slightly higher in the placebo group with no significant difference (22% versus 36%, P = 0.14). The MTX adverse effects were not observed.

Conclusions

Treatment of moderate to severe knee OA with MTX could reduce pain severity and improve functional status and quality of life in OA patients.

Development of Hepatic Steatosis After Chemotherapy for Non-Hodgkin Lymphoma

Nonalcoholic fatty liver disease is the most common liver disorder in the developed world. Although typically reflecting caloric overload, it can also be secondary to drug toxicity. We aimed to describe the incidence and risk factors for de novo steatosis during chemotherapy for non‐Hodgkin lymphoma (NHL). In this retrospective case‐control study, adult patients with NHL were treated with rituximab, cyclophosphamide, doxorubicin, prednisone, and vincristine (R‐CHOP) or R‐CHOP + etoposide (EPOCH‐R). Patients with liver disease or steatosis were excluded. Abdominal computed tomography was performed pretreatment and at 3‐ to 6‐month intervals and reviewed for steatosis. Patients with de novo steatosis were matched 1:1 to controls by age, sex, and ethnicity. Of 251 treated patients (median follow‐up 53 months), 25 (10%) developed de novo steatosis, with the vast majority (23 of 25; 92%) developing it after chemotherapy. Of those, 14 (61%) developed steatosis within the first 18 months posttreatment and 20 (87%) within 36 months. Cases had higher baseline body mass index (BMI; mean ± SD, 29.0 ± 6.5 versus 26.0 ± 5.2 kg/m²; P = 0.014) and hyperlipidemia (12% versus 2%; P = 0.035). Although their weights did not change during chemotherapy, BMI in cases increased by 2.4 ± 2 kg/m² (mean ± SD) from end of treatment to steatosis compared to 0.68 ± 1.4 in controls (P = 0.003). Etoposide‐containing regimens were associated with a shorter time to steatosis (median 34 weeks versus 154 weeks; P < 0.001) despite similar baseline risk factors. Conclusion: The recovery period from NHL chemotherapy appears to be a “hot spot” for development of fatty liver, driven by early posttreatment weight gain, especially in subjects with baseline risk factors.

The effect of Cardiac Arrhythmias Simulation Software on the nurses' learning and professional development

INTRODUCTION

One of the important tasks of nurses in intensive care unit is interpretation of ECG. The use of training simulator is a new paradigm in the age of computers. This study was performed to evaluate the impact of cardiac arrhythmias simulator software on nurses' learning in the subspecialty Vali-Asr Hospital in 2016.

METHODS

This study was conducted by quasi-experimental randomized Salomon four group design with the participation of 120 nurses in subspecialty Vali-Asr Hospital in Tehran, Iran in 2016 that were selected purposefully and allocated in 4 groups. By this design other confounding factors such as the prior information, maturation and the role of sex and age were controlled by Solomon 4 design. The valid and reliable multiple choice test tools were used to gather information; the validity of the test was approved by experts and its reliability was obtained by Cronbach's alpha coefficient 0.89. At first, the knowledge and skills of the participants were assessed by a pre-test; following the educational intervention with cardiac arrhythmias simulator software during 14 days in ICUs, the mentioned factors were measured for the two groups again by a post-test in the four groups. Data were analyzed using the two way ANOVA. The significance level was considered as p<0.05.

RESULTS

Based on randomized four-group Solomon designs and our test results, using cardiac arrhythmias simulator software as an intervention was effective in the nurses' learning since a significant difference was found between pre-test and post-test in the first group (p<0.05). Also, other comparisons by ANOVA test showed that there was no interaction between pre-test and intervention in all of the three knowledge areas of cardiac arrhythmias, their treatments and their diagnosis (P>0.05).

CONCLUSION

The use of software-based simulator for cardiac arrhythmias was effective in nurses' learning in light of its attractive components and interactive method. This intervention increased the knowledge of the nurses in cognitive domain of cardiac arrhythmias in addition to their diagnosis and treatment. Also, the package can be used for training in other areas such as continuing medical education.

Effectiveness of meglumine antimoniate against L. tropica in a recently emerged focus of cutaneous leishmaniasis in Birjand, eastern Islamic Republic of Iran

With limited options to treat cutaneous leishmaniasis, constant monitoring of the rate of resistance to pentavalent antimony-based drugs is needed. This study identified the infecting Leishmania species and evaluated the results of meglumine antimoniate (Glucantime®) therapy in a new focus of cutaneous leishmaniasis in Birjand, eastern Islamic Republic of Iran. Smears from 150 patients showed that 141 patients were infected by L. tropica and 9 by L. major. In total, 141 patients with L. tropica infection completed Glucantime® treatment and follow-up; 63.8% were treated intralesionally and 36.2% by intramuscular administration. The overall success rate after one course of therapy with Glucantime® was 96.5% (136/141), and all the failures (5/141) occurred with intramuscular injections. Statistical analysis showed a significant difference between the failure rates of intramuscular and intralesional injections. Children < 10 years old had a significantly higher failure rate than adults.

The Efficacy of Hydration with Normal Saline Versus Hydration with Sodium Bicarbonate in the Prevention of Contrast-induced Nephropathy

BACKGROUND

Contrast-induced acute kidney injury [contrast-induced nephropathy (CIN)] is one of the major causes of hospital-acquired acute renal failure. Volume supplementation is the most effective strategy to prevent acute renal failure caused by contrast; but the effects of sodium bicarbonate regimens are unknown in CIN prevention. The aim of this survey is to compare the efficacy of hydration with normal saline versus hydration with sodium bicarbonate in the prevention of the CIN in patients undergoing coronary angiography.

MATERIALS AND METHODS

In a clinical trial, 350 patients undergoing coronary interventions were randomized into two groups: One group received normal saline and another group received sodium bicarbonate before and after infusion of the contrast. Patients in both the groups had received N-acetylcysteine. CIN was defined as relative increase in serum creatinine equal to or more than 25% of baseline or increase to 0.5 mg/dl in 48 h after the injection of the contrast.

RESULTS

CIN was seen in 46 patients (13.1%) after coronary interventions. Incidence of CIN in patients receiving normal saline (19.4%) was more than in patients receiving sodium bicarbonate (6.9%) (P = 0.001). Hemodialysis was needed only in one patient who received saline normal. Relative risk to induce CIN in both groups was as 2.8 and was in the range of 1.50-5.25 with confidence interval of 95% and P = 0.001. Thus, the probability of CIN was significantly more in the usage of normal saline.

CONCLUSION

This survey showed that hydration with sodium bicarbonate is superior to hydration with normal saline and has better protection effects.

The effects of farming system and season on the prevalence of lameness in sheep in northwest Iran

AIMS

To determine the prevalence of lameness in sheep in Urmia, northwest Iran, and compare the effects of production system and season on prevalence.

METHODS

A cross-sectional study, using cluster sampling, was conducted. The selected flocks included 18 with 2,315 sheep from farmed production and 28 with 7,619 sheep from semi-migratory systems, and were visited once in summer (grazing season) and once in winter (housing season). Sheep showing signs of lameness were examined to detect the causes of lameness. Bacteriology and histopathology were also performed if required.

RESULTS

The probability of overall lameness was not affected by farming system (p = 0.40), but in the grazing season was less (OR = 0.62; 95% CI = 0.56-0.69) than in the housing season. Footrot was most the common cause of lameness, occurring in 1,047/1,880 (56%) cases. Among flocks, 40/46 (87%) had ≥ 1 case of footrot. Farming system had no effect on occurrence of footrot (p = 0.85), but the probability of footrot in the grazing season was less (OR = 0.21; 95% CI = 0.18-0.25) than in the housing season. Semi-migratory flocks had less hoof overgrowth (OR = 0.30; 95% CI = 0.16-0.56) than farmed flocks, and the probability of hoof overgrowth in the grazing season was less (OR = 0.19; 95% CI = 0.12-0.29) than in the housing season. The probability of digital abscess was less in semi-migratory flocks (OR = 0.64; 95% CI = 0.46-0.88) than farmed flocks, and in the grazing season was more (OR = 2.14; 95 CI = 1.61-2.85) than in the housing season. The probability of interdigital gland infection was higher (OR = 7.15; 95% CI = 5.36-9.55) in the grazing season than in the housing season. Staphylococcus aureus was isolated from 9/11 (82%) sheep affected with interdigital gland infection.

CONCLUSIONS

Footrot was the main cause of lameness in sheep in both farmed and semi-migratory farming systems in this study, especially in the housing season. In the grazing season, digital abscess and interdigital gland infection should be considered as common causes of sporadic lameness in sheep.

CLINICAL RELEVANCE

In practice, lameness in sheep can be a major concern both in farmed and semi-migratory farming systems, with a high occurrence in the housing season. Footrot was a main cause of lameness in sheep in northwest Iran.

Expression and Purification of Recombinant Mycobacterium Tuberculosis (TB) Antigens, ESAT-6, CFP-10 and ESAT- 6/CFP-10 and Their Diagnosis Potential for Detection of TB Patients

BACKGROUND

One of the most widely used methods to detect tuberculosis (TB) infection is the tuberculin skin test (TST). The completion of Mycobacterium tuberculosis (M. tuberculosis) genome sequence has led to identification of several antigens that can be utilized for accurate diagnosis and control of TB. The aim of this study was to purify the recombinant M. tuberculosis antigens for the evaluation of their potential in TB diagnosis.

METHODS

The recombinant secretory antigens, ESAT-6, CFP-10 and ESAT-6/CFP-10 were produced by PCR and cloning methods. To investigate antigen specific responses of these recombinant antigens in detection of TB, ex vivo enzyme linked immunospot (ELISPOT) test in 30 clinically diagnosed TB patients was evaluated.

RESULTS

The selected M. tuberculosis antigens were cloned, expressed and purified in Escherichia coli (BL21). ELISPOT assay for detection of TB showed the sensitivity of 93, 90 and 100% for recombinant ESAT-6, CFP-10 and ESAT-6/CFP-10 proteins respectively, which is significantly higher than conventional TST.

CONCLUSION

The recombinant antigens of ESAT-6, CFP-10 and ESAT-6/CFP-10 can be used as an accurate means of detecting TB in Iran.

Rat xenograft chondrosarcoma development by human tissue fragment

Chondrosarcoma is one of the most difficult types of cancers to diagnose and treatment. Therefore, the development of a reliable animal model for chondrosarcoma would be a helpful tool to study of the tumor's growth and progression.

AIM

We conducted this study to develop a chondrosarcoma on rat by graft of human chondrosarcoma tumor tissue.

METHODS

Fourteen male Sprague-Dawley rats equally divided in xenograft-implanted and control groups. On the lateral side of the right femur distal 1/3, 5 mm incision was done on the skin after animal anesthesia. Then, was drilled 3 mm on the bone and implanted the xenograft in the bone. Radiography was taken from the operated femur weekly until the fourth week and monthly for 3 months. Four animals of each group were sacrificed after 4 weeks of operation; femur was harvested for histopathological study.

RESULTS

Radiological images showed sclerotic area on the implanted bone after 4 weeks of operation. Sections from tumoral areas reveal cartilage forming hypercellular neoplastic tissue with lobular pattern of growth and foci of adjacent tissue invasion such as bone trabeculas and bone marrow.

CONCLUSION

the present study showed that rat xenograft chondrosarcoma can develop by human chondrosarcoma fresh tissue fragments.

Investigation of fine nanoparticles syngas catalyst (POM) considering their various morphology

Ni/SiO2 fine nanoparticles were prepared by coprecipitation method using various nonionic surfactants as templates with Tylose as a binder dispersant. Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) have been used to study the templates influence on the morphology of the produced samples. Although the phase structure remained as a tetrahedron amorphous cristobalite-sin-SiO2 (101,100), rhombohedron and cubic NiO, but samples with different morphology (homogeneous nano spherical, nano rose flower and nano cubic shapes) have been achieved. These fine nanoparticles as syngas catalysts in Partial Oxidation of Methane to Hydrogen and Carbon Monoxide (POM) have been studied. Because of high Hydrogen production, it is a candidate to be a green fuel. A fixed-bed reactor at P = 1 atm, T = 800 degrees C, H2/CO = 1.8, GHSV (CH4) = 6000/hr and BET = 25, 63.5 and 87.1 m2/gr have been used as POM catalyst. From other hand these fine compounds could be converted to metallic nanotube (nanofiber) at above 850 degrees C and also bamboo shape tip mode carbon nanotube by thermal chemical vapor deposition at 800 degrees C. Transmission Electron Microscopy confirmed the metallic nanotube or single nano crystal growth. The Raman spectroscopy of all samples has been studied to confirm the different formation of Ni-Si. Choosing different templates for production of these nanoparticles could create width range of medical and industrial applications.

Temporal meningiomas presenting as chronic otitis media

Two cases of temporal bone meningiomas presenting as chronic drainage ears are presented. One case was indicated by computer tomographic scan at the time of initial surgery to be limited to the middle ear, but recurred 9 months later with extensive cerebellopontine angle extension and cranial nerve palsies. The tumor in the second case extended from the middle ear to the cavernous sinus, with extensive intradural involvement. Meningiomas involving the middle ear must be considered to have intracranial extension, and magnetic resonance is the imaging study of choice.

Somatosensory evoked potentials in the evaluation of lumbosacral radiculopathy

We performed lower extremity somatosensory evoked potential (SEP) studies in 59 patients with signs or symptoms suggestive of lumbosacral radiculopathy and compared them with results of myelography with post-myelogram CT (myelogram/CT), MRI, and other electrodiagnostic studies. Of 38 patients with abnormal myelogram/CTs, 32 had abnormal SEPs, while 11 demonstrated EMG abnormalities. All 21 patients with normal myelogram/CTs had normal SEPs. SEP improved electrodiagnostic sensitivity in patients with weakness or reflex changes as well as in those with sensory deficits only. SEP was less sensitive in patients in whom spinal stenosis was the only radiographic finding. MRI generally corresponded well with the results of myelogram/CT and SEP but overestimated the significance of disk bulges in some patients. SEP is useful in the electrodiagnostic evaluation of lumbosacral radiculopathy, particularly when EMG is nondiagnostic.

Synchronous occurrence of parathyroid carcinoma and adenoma in an elderly woman

The simultaneous occurrence of parathyroid carcinoma and other pathologic conditions of the parathyroid on a sporadic basis is extremely rare. Parathyroid exploration in an otherwise healthy 78-year-old woman with no underlying risk factors revealed synchronous right upper parathyroid adenoma and left upper parathyroid carcinoma. The patient's modest hypercalcemia (11.5 to 12.3 mg/dl) was seemingly at variance with remarkable parathormone elevations of 30 to 70 times normal.

Spontaneous dissection of the extracranial vertebral arteries

Though the syndrome of carotid artery dissection is well known, "spontaneous" vertebral artery dissection is rarely recognized. We now report clinical and radiologic findings in five patients with presumed vertebral dissection, one pathologically confirmed. Mean age was 35.2 years (range 27-41). Two were men; three women. None had hypertension, vascular disease, or trauma. Headache and neck or occipital pain was prominent in all, often preceding other symptoms. Four of five patients had unilateral partial alteral medullary syndromes, in one accompanied by medial medullary signs. One patient had a cerebellar infarct. Angiography in four patients showed severe irregular stenosis of the distal extracranial vertebral artery (three bilaterally). A fifth patient with irregular stenosis above the vertebral origin had verified extensive dissection in the resected segment. No patient developed late ischemia. Repeat angiography in three showed healing. We conclude that spontaneous vertebral artery dissection, though rare, has recognizable clinical and radiologic features.

Caudate hemorrhage

We studied 12 patients with intracerebral hemorrhage in the head of the caudate nucleus. These cases accounted for 7% of a consecutive series of intracerebral hemorrhage. The clinical findings differed from more common varieties of supratentorial hemorrhage. All patients had acute onset of vomiting, headache, stiff neck, decreased level of consciousness, and behavioral changes in a pattern that simulated subarachnoid hemorrhage. Seven patients had gaze paresis and hemiparesis, with or without sensory loss. Two of these seven patients had, in addition, elements of Horner's syndrome. The prognosis for recovery was good. No patient had recurrent hemorrhage or persistent hydrocephalus.

Intracerebral hemorrhage secondary to cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a cause of intracerebral hemorrhage in a significant proportion of normotensive patients. Two cases of pathologically proved multiple intracerebral hemorrhages due to CAA are reported. These hemorrhages are accurately demonstrated on computed tomography and are typically superficial in location. CAA should be considered as a cause of such hemorrhages in elderly patients who are often normotensive and demented.

Calcified pseudocyst of the pancreas

Pancreatic pseudocysts are encapsulated collections of fluid which may complicate trauma or inflammation of the pancreas. The correct preoperative diagnosis of the pseudocyst can be established easily by the modern techniques of ultrasonography or computed tomography (1-3). However, recognition of the lesion on plain radiographs of the abdomen is rarely possible because the wall and content of pancreatic pseudocysts do not show a visually perceptible difference in density from the adjacent soft tissues (4). This report concerns an exceptional instance whereby a pancreatic pseudocyst was clearly demarcated by virtue of radiographically detectable calcium deposits in its wall.

Giant serpentine intracranial aneurysm

Giant serpentine aneurysms are considered a distinct subgroup of giant aneurysms because of their characteristic angiographic appearance and clinical behavior. A case of this unusual vascular abnormality showing progressive enlargement documented by computed tomography and cerebral angiography is presented, along with a review of the literature. Etiology, pertinent radiological findings, and a probable mechanism of serpentine channel formation are discussed.