Global Neurosurgery at the 76th World Health Assembly (2023): First Neurosurgery-Driven Resolution Calls for Micronutrient Fortification to Prevent Spina Bifida

Since 2018, a neurosurgery delegation has been actively engaged and consistently present at the World Health Assembly. Recognizing the growing impact of neurosurgical diseases, the neurosurgery delegation participated in the 76th World Health Assembly in May 2023, advocating for timely, safe, and affordable global neurosurgical care. The delegation focused on forging new collaborations, strengthening the World Health Organization-World Federation of Neurosurgical Societies official relations, and actively supporting resolutions that impact the neurosurgical patients. However, there is a long advocacy journey ahead to address unmet neurosurgical needs. Patient-centered advocacy is an inherent task of our profession and the essence of the Global Neurosurgery Bogota Declaration of 2016. The highlight of the 76th World Health Assembly was the adoption of the first neurosurgery-driven resolution calling for micronutrient fortification to prevent spina bifida and other micronutrient deficiencies. For the last 4 years, the Global Alliance for Prevention of Spina Bifida, a group spearheaded by neurosurgeons, advocated for spina bifida prevention. This Alliance collaborated with many stakeholders, notably, the Colombian government to promote the resolution: "Accelerating efforts for preventing micronutrient deficiencies and their consequences, including spina bifida and other neural tube defects, through safe and effective food fortification." This is a proud milestone for the neurosurgical profession. There are many strategies available for neurosurgeons, when working together with elected leaders, other stakeholders, and allied professionals, to implement initiatives that can prevent future cases of spina bifida and other neurological disorders and reduce the burden of neurosurgical disease.

Global, regional, and national burden of disorders affecting the nervous system, 1990-2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND

Disorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.

METHODS

We estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.

FINDINGS

Globally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378-521), affecting 3·40 billion (3·20-3·62) individuals (43·1%, 40·5-45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7-26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6-38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5-32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7-2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.

INTERPRETATION

As the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed.

FUNDING

Bill & Melinda Gates Foundation.

Correction: Academic global surgical competencies: A modified Delphi consensus study

[This corrects the article DOI: 10.1371/journal.pgph.0002102.].

Global Neurosurgery: Progress and Resolutions at the 75th World Health Assembly

Neurosurgical advocates for global surgery/neurosurgery at the 75th World Health Assembly gathered in person for the first time after the COVID-19 pandemic in Geneva, Switzerland, in May 2022. This article reviews the significant progress in the global health landscape targeting neglected neurosurgical patients, emphasizing high-level policy advocacy and international efforts to support a new World Health Assembly resolution in mandatory folic acid fortification to prevent neural tube defects. The process of developing global resolutions through the World Health Organization and its member states is summarized. Two new global initiatives focused on the surgical patients among the most vulnerable member states are discussed, the Global Surgery Foundation and the Global Action Plan on Epilepsy and other Neurological Disorders. Progress toward a neurosurgery-inspired resolution on mandatory folic acid fortification to prevent spina bifida-folate is described. In addition, priorities for moving the global health agenda forward for the neurosurgical patient as it relates to the global burden of neurological disease are reviewed after the COVID-19 pandemic.

Academic global surgical competencies: A modified Delphi consensus study

Academic global surgery is a rapidly growing field that aims to improve access to safe surgical care worldwide. However, no universally accepted competencies exist to inform this developing field. A consensus-based approach, with input from a diverse group of experts, is needed to identify essential competencies that will lead to standardization in this field. A task force was set up using snowball sampling to recruit a broad group of content and context experts in global surgical and perioperative care. A draft set of competencies was revised through the modified Delphi process with two rounds of anonymous input. A threshold of 80% consensus was used to determine whether a competency or sub-competency learning objective was relevant to the skillset needed within academic global surgery and perioperative care. A diverse task force recruited experts from 22 countries to participate in both rounds of the Delphi process. Of the n = 59 respondents completing both rounds of iterative polling, 63% were from low- or middle-income countries. After two rounds of anonymous feedback, participants reached consensus on nine core competencies and 31 sub-competency objectives. The greatest consensus pertained to competency in ethics and professionalism in global surgery (100%) with emphasis on justice, equity, and decolonization across multiple competencies. This Delphi process, with input from experts worldwide, identified nine competencies which can be used to develop standardized academic global surgery and perioperative care curricula worldwide. Further work needs to be done to validate these competencies and establish assessments to ensure that they are taught effectively.

An Umbrella Review With Meta-Analysis of Chest Computed Tomography for Diagnosis of COVID-19: Considerations for Trauma Patient Management

Background

RT-PCR testing is the standard for diagnosis of COVID-19, although it has its suboptimal sensitivity. Chest computed tomography (CT) has been proposed as an additional tool with diagnostic value, and several reports from primary and secondary studies that assessed its diagnostic accuracy are already available. To inform recommendations and practice regarding the use of chest CT in the in the trauma setting, we sought to identify, appraise, and summarize the available evidence on the diagnostic accuracy of chest CT for diagnosis of COVID-19, and its application in emergency trauma surgery patients; overcoming limitations of previous reports regarding chest CT accuracy and discussing important considerations regarding its role in this setting.

Methods

We conducted an umbrella review using Living Overview of Evidence platform for COVID-19, which performs regular automated searches in MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and more than 30 other sources. The review was conducted following the JBI methodology for systematic reviews. The Grading of Recommendations, Assessment, Development, and Evaluation approach for grading the certainty of the evidence is reported (registered in International Prospective Register of Systematic Reviews, CRD42020198267).

Results

Thirty studies that fulfilled selection criteria were included; 19 primary studies provided estimates of sensitivity (0.91, 95%CI = [0.88–0.93]) and specificity (0.73, 95%CI = [0.61; 0.82]) of chest CT for COVID-19. No correlation was found between sensitivities and specificities (ρ = 0.22, IC95% [–0.33; 0.66]). Diagnostic odds ratio was estimated at: DOR = 27.5, 95%CI (14.7; 48.5). Evidence for sensitivity estimates was graded as MODERATE, and for specificity estimates it was graded as LOW.

Conclusion

The value of chest CT appears to be that of an additional screening tool that can easily detect PCR false negatives, which are reportedly highly frequent. Upon the absence of PCR testing and impossibility to perform RT-PCR in trauma patients, chest CT can serve as a substitute with increased value and easy implementation.

Systematic Review Registration

[www.crd.york.ac.uk/prospero], identifier [CRD42020198267].

Primary stroke prevention worldwide: translating evidence into action

Stroke is the second leading cause of death and the third leading cause of disability worldwide and its burden is increasing rapidly in low-income and middle-income countries, many of which are unable to face the challenges it imposes. In this Health Policy paper on primary stroke prevention, we provide an overview of the current situation regarding primary prevention services, estimate the cost of stroke and stroke prevention, and identify deficiencies in existing guidelines and gaps in primary prevention. We also offer a set of pragmatic solutions for implementation of primary stroke prevention, with an emphasis on the role of governments and population-wide strategies, including task-shifting and sharing and health system re-engineering. Implementation of primary stroke prevention involves patients, health professionals, funders, policy makers, implementation partners, and the entire population along the life course.

Global, regional, and national burden of stroke and its risk factors, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019

BACKGROUND

Regularly updated data on stroke and its pathological types, including data on their incidence, prevalence, mortality, disability, risk factors, and epidemiological trends, are important for evidence-based stroke care planning and resource allocation. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) aims to provide a standardised and comprehensive measurement of these metrics at global, regional, and national levels.

METHODS

We applied GBD 2019 analytical tools to calculate stroke incidence, prevalence, mortality, disability-adjusted life-years (DALYs), and the population attributable fraction (PAF) of DALYs (with corresponding 95% uncertainty intervals [UIs]) associated with 19 risk factors, for 204 countries and territories from 1990 to 2019. These estimates were provided for ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage, and all strokes combined, and stratified by sex, age group, and World Bank country income level.

FINDINGS

In 2019, there were 12·2 million (95% UI 11·0-13·6) incident cases of stroke, 101 million (93·2-111) prevalent cases of stroke, 143 million (133-153) DALYs due to stroke, and 6·55 million (6·00-7·02) deaths from stroke. Globally, stroke remained the second-leading cause of death (11·6% [10·8-12·2] of total deaths) and the third-leading cause of death and disability combined (5·7% [5·1-6·2] of total DALYs) in 2019. From 1990 to 2019, the absolute number of incident strokes increased by 70·0% (67·0-73·0), prevalent strokes increased by 85·0% (83·0-88·0), deaths from stroke increased by 43·0% (31·0-55·0), and DALYs due to stroke increased by 32·0% (22·0-42·0). During the same period, age-standardised rates of stroke incidence decreased by 17·0% (15·0-18·0), mortality decreased by 36·0% (31·0-42·0), prevalence decreased by 6·0% (5·0-7·0), and DALYs decreased by 36·0% (31·0-42·0). However, among people younger than 70 years, prevalence rates increased by 22·0% (21·0-24·0) and incidence rates increased by 15·0% (12·0-18·0). In 2019, the age-standardised stroke-related mortality rate was 3·6 (3·5-3·8) times higher in the World Bank low-income group than in the World Bank high-income group, and the age-standardised stroke-related DALY rate was 3·7 (3·5-3·9) times higher in the low-income group than the high-income group. Ischaemic stroke constituted 62·4% of all incident strokes in 2019 (7·63 million [6·57-8·96]), while intracerebral haemorrhage constituted 27·9% (3·41 million [2·97-3·91]) and subarachnoid haemorrhage constituted 9·7% (1·18 million [1·01-1·39]). In 2019, the five leading risk factors for stroke were high systolic blood pressure (contributing to 79·6 million [67·7-90·8] DALYs or 55·5% [48·2-62·0] of total stroke DALYs), high body-mass index (34·9 million [22·3-48·6] DALYs or 24·3% [15·7-33·2]), high fasting plasma glucose (28·9 million [19·8-41·5] DALYs or 20·2% [13·8-29·1]), ambient particulate matter pollution (28·7 million [23·4-33·4] DALYs or 20·1% [16·6-23·0]), and smoking (25·3 million [22·6-28·2] DALYs or 17·6% [16·4-19·0]).

INTERPRETATION

The annual number of strokes and deaths due to stroke increased substantially from 1990 to 2019, despite substantial reductions in age-standardised rates, particularly among people older than 70 years. The highest age-standardised stroke-related mortality and DALY rates were in the World Bank low-income group. The fastest-growing risk factor for stroke between 1990 and 2019 was high body-mass index. Without urgent implementation of effective primary prevention strategies, the stroke burden will probably continue to grow across the world, particularly in low-income countries.

FUNDING

Bill & Melinda Gates Foundation.

Chest Computed Tomography for the Diagnosis of COVID-19 in Emergency Trauma Surgery Patients Who Require Urgent Care During the Pandemic: Protocol for an Umbrella Review

BACKGROUND

Many health care facilities in low- and middle-income countries are inadequately resourced. COVID-19 has the potential to decimate surgical health care services unless health systems take stringent measures to protect health care workers from viral exposure and ensure the continuity of specialized care for patients. Among these measures, the timely diagnosis of COVID-19 is paramount to ensure the use of protective measures and isolation of patients to prevent transmission to health care personnel caring for patients with an unknown COVID-19 status or contact during the pandemic. Besides molecular and antibody tests, chest computed tomography (CT) has been assessed as a potential tool to aid in the screening or diagnosis of COVID-19 and could be valuable in the emergency care setting.

OBJECTIVE

This paper presents the protocol for an umbrella review that aims to identify and summarize the available literature on the diagnostic accuracy of chest CT for COVID-19 in trauma surgery patients requiring urgent care. The objective is to inform future recommendations on emergency care for this category of patients.

METHODS

We will conduct several searches in the L·OVE (Living Overview of Evidence) platform for COVID-19, a system that performs automated regular searches in PubMed, Embase, Cochrane Central Register of Controlled Trials, and over 30 other sources. The search results will be presented according to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis). This review will preferentially consider systematic reviews of diagnostic test accuracy studies, as well as individual studies of such design, if not included in the systematic reviews, that assessed the sensitivity and specificity of chest CT in emergency trauma surgery patients. Critical appraisal of the included studies for risk of bias will be conducted. Data will be extracted using a standardized data extraction tool. Findings will be summarized narratively, and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach will be used to grade the certainty of evidence.

RESULTS

Ethics approval is not required for this systematic review, as there will be no patient involvement. The search for this systematic review commenced in October 2020, and we expect to publish the findings in early 2021. The plan for dissemination is to publish the findings in a peer-reviewed journal and present our results at conferences that engage the most pertinent stakeholders.

CONCLUSIONS

During the COVID-19 pandemic, protecting health care workers from infection is essential. Up-to-date information on the efficacy of diagnostic tests for detecting COVID-19 is essential. This review will serve an important role as a thorough summary to inform evidence-based recommendations on establishing effective policy and clinical guideline recommendations.

TRIAL REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews CRD42020198267; https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=198267.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/25207.

Neurosurgical Randomized Trials in Low- and Middle-Income Countries

BACKGROUND

The setting of a randomized trial can determine whether its findings are generalizable and can therefore apply to different settings. The contribution of low- and middle-income countries (LMICs) to neurosurgical randomized trials has not been systematically described before.

OBJECTIVE

To perform a systematic analysis of design characteristics and methodology, funding source, and interventions studied between trials led by and/or conducted in high-income countries (HICs) vs LMICs.

METHODS

From January 2003 to July 2016, English-language trials with >5 patients assessing any one neurosurgical procedure against another procedure, nonsurgical treatment, or no treatment were retrieved from MEDLINE, Scopus, and Cochrane Library. Income classification for each country was assessed using the World Bank Atlas method.

RESULTS

A total of 73.3% of the 397 studies that met inclusion criteria were led by HICs, whereas 26.7% were led by LMICs. Of the 106 LMIC-led studies, 71 were led by China. If China is excluded, only 8.8% were led by LMICs. HIC-led trials enrolled a median of 92 patients vs a median of 65 patients in LMIC-led trials. HIC-led trials enrolled from 7.6 sites vs 1.8 sites in LMIC-led studies. Over half of LMIC-led trials were institutionally funded (54.7%). The majority of both HIC- and LMIC-led trials evaluated spinal neurosurgery, 68% and 71.7%, respectively.

CONCLUSION

We have established that there is a substantial disparity between HICs and LMICs in the number of published neurosurgical trials. A concerted effort to invest in research capacity building in LMICs is an essential step towards ensuring context- and resource-specific high-quality evidence is generated.

Management of paediatric burns in low- and middle-income countries: assessing capacity using the World Health Organization Surgical Assessment Tool

BACKGROUND

Burns are a leading cause of global disease burden, with children in low- and middle-income countries (LMICs) disproportionately affected. Effective management improves outcomes; however, the availability of necessary resources in LMICs remains unclear. We evaluated surgical centres in LMICs using the WHO Surgical Assessment Tool (SAT) to identify opportunities to optimize paediatric burn care.

METHODS

We reviewed WHO SAT database entries for 2010-2015. A total of 1121 facilities from 57 countries met the inclusion criteria: facilities with surgical capacity in LMICs operating on children. Human resources, equipment and infrastructure relevant to paediatric burn care were analysed by WHO Regional and World Bank Income Classifications and facility type.

RESULTS

Facilities had an average of 147 beds and performed 485 paediatric operations annually. Discrepancies existed between procedures performed and resource availability; 86% of facilities performed acute burn care, but only 37% could consistently provide intravenous fluids. Many, particularly tertiary, centres performed contracture release and skin grafting (41%) and amputation (50%).

CONCLUSIONS

LMICs have limited resources to provide paediatric burn care but widely perform many interventions necessary to address the burden of burns. The SAT may not capture innovative and traditional approaches to burn care. There remains an opportunity to improve paediatric burn care globally.

Measuring the migration of surgical specialists

BACKGROUND

The lack of access to essential surgical care in low-income countries is aggravated by emigration of locally-trained surgical specialists to more affluent regions. Yet, the global diaspora of surgeons, obstetricians, and anesthesiologists from low-income and middle-income countries has never been fully described and compared with those who have remained in their country of origin. It is also unclear whether the surgical workforce is more affected by international migration than other medical specialists. In this study, we aimed to quantify the proportion of surgical specialists originating from low-income and middle-income countries that currently work in high-income countries.

METHODS

We retrieved surgical workforce data from 48 high-income countries and 102 low-income and middle-income countries using the database of the World Health Organization Global Surgical Workforce. We then compared this domestic workforce with more granular data on the country of initial medical qualification of all surgeons, anesthesiologists, and obstetricians made available for 14 selected high-income countries to calculate the proportion of surgical specialists working abroad.

RESULTS

We identified 1,118,804 specialist surgeons, anesthesiologists, or obstetricians from 102 low-income and middle-income countries, of whom 33,021 (3.0%) worked in the 14 included high-income countries. The proportion of surgical specialists abroad was greatest for the African and South East Asian regions (12.8% and 12.1%). The proportion of specialists abroad was not greater for surgeons, anesthesiologists, or obstetricians than for physicians and other medical specialists (P = .465). Overall, the countries with the lowest remaining density of surgical specialists were also the countries from which the largest proportion of graduates were now working in high-income countries (P = .011).

CONCLUSION

A substantial proportion of all surgeons, anesthesiologists, and obstetricians from low-income and middle-income countries currently work in high-income countries. In addition to decreasing migration from areas of surgical need, innovative strategies to retain and strengthen the surgical workforce could involve engaging this large international pool of surgical specialists and instructors.

Towards high-quality peri-operative care: a global perspective

Article 25 of the United Nations' Universal Declaration of Human Rights enshrines the right to health and well-being for every individual. However, universal access to high-quality healthcare remains the purview of a handful of wealthy nations. This is no more apparent than in peri-operative care, where an estimated five billion individuals lack access to safe, affordable and timely surgical care. Delivery of surgery and anaesthesia in low-resource environments presents unique challenges that, when unaddressed, result in limited access to low-quality care. Current peri-operative research and clinical guidance often fail to acknowledge these system-level deficits and therefore have limited applicability in low-resource settings. In this manuscript, the authors priority-set the need for equitable access to high-quality peri-operative care and analyse the system-level contributors to excess peri-operative mortality rates, a key marker of quality of care. To provide examples of how research and investment may close the equity gap, a modified Delphi method was adopted to curate and appraise interventions which may, with subsequent research and evaluation, begin to address the barriers to high-quality peri-operative care in low- and middle-income countries.

Global neurosurgery: continued momentum at the 72nd World Health Assembly

Global neurosurgery is the practice of neurosurgery with the primary purpose of delivering timely, safe, and affordable neurosurgical care to all who need it. This field is led by neurosurgeons, and global neurosurgery sessions are now part of every major international neurosurgical meeting. The World Federation of Neurosurgical Societies (WFNS) is working to coordinate activities and align all related activities for greater impact. This report updates the contributions made by the WFNS-WHO Liaison Committee at the most recent World Health Assembly (WHA) in 2019. The WHA is a decision-making body of the World Health Organization (WHO), attended by its 194 Member States. The WFNS has maintained official relations as a nongovernmental organization with the WHO for over 30 years, and this year 15 neurosurgical delegates attended events during the WHA. Participation by neurosurgeons continues to grow as many WHA events focused on global surgery have intrinsically involved neurosurgical leadership and participation. This year, resolution WHA72.31, entitled "Emergency and trauma care, Emergency care systems for universal health coverage: ensuring timely care for the acutely ill and injured," was passed. This resolution provides further opportunities for neurosurgical advocacy as the landscape of global surgery gains recognition and momentum.

Global neurosurgery: current and potential impact of neurosurgeons at the World Health Organization and the World Health Assembly. Executive summary of the World Federation of Neurosurgical Societies-World Health Organization Liaison Committee at the 71st World Health Assembly

Since the creation of the World Health Organization (WHO) in 1948, the annual World Health Assembly (WHA) has been the major forum for discussion, debate, and approval of the global health agenda. As such, it informs the framework for the policies and budgets of many of its Member States. For most of its history, a significant portion of the attention of health ministers and Member States has been given to issues of clean water, vaccination, and communicable diseases. For neurosurgeons, the adoption of WHA Resolution 68.15 changed the global health landscape because the importance of surgical care for universal health coverage was highlighted in the document. This resolution was adopted in 2015, shortly after the publication of The Lancet Commission on Global Surgery Report titled "Global Surgery 2030: evidence and solutions for achieving health, welfare and economic development." Mandating global strengthening of emergency and essential surgical care and anesthesia, this resolution has led to the formation of surgical and anesthesia collaborations that center on WHO and can be facilitated via the WHA. Participation by neurosurgeons has grown dramatically, in part due to the official relations between WHO and the World Federation of Neurosurgical Societies, with the result that global neurosurgery is gaining momentum.

Operative and consultative proportions of neurosurgical disease worldwide: estimation from the surgeon perspective

OBJECTIVEThe global magnitude of neurosurgical disease is unknown. The authors sought to estimate the surgical and consultative proportion of diseases commonly encountered by neurosurgeons, as well as surgeon case volume and perceived workload.METHODSAn electronic survey was sent to 193 neurosurgeons previously identified via a global surgeon mapping initiative. The survey consisted of three sections aimed at quantifying surgical incidence of neurological disease, consultation incidence, and surgeon demographic data. Surgeons were asked to estimate the proportion of 11 neurological disorders that, in an ideal world, would indicate either neurosurgical operation or neurosurgical consultation. Respondent surgeons indicated their confidence level in each estimate. Demographic and surgical practice characteristics-including case volume and perceived workload-were also captured.RESULTSEighty-five neurosurgeons from 57 countries, representing all WHO regions and World Bank income levels, completed the survey. Neurological conditions estimated to warrant neurosurgical consultation with the highest frequency were brain tumors (96%), spinal tumors (95%), hydrocephalus (94%), and neural tube defects (92%), whereas stroke (54%), central nervous system infection (58%), and epilepsy (40%) carried the lowest frequency. Similarly, surgery was deemed necessary for an average of 88% cases of hydrocephalus, 82% of spinal tumors and neural tube defects, and 78% of brain tumors. Degenerative spine disease (42%), stroke (31%), and epilepsy (24%) were found to warrant surgical intervention less frequently. Confidence levels were consistently high among respondents (lower quartile > 70/100 for 90% of questions), and estimates did not vary significantly across WHO regions or among income levels. Surgeons reported performing a mean of 245 cases annually (median 190). On a 100-point scale indicating a surgeon's perceived workload (0-not busy, 100-overworked), respondents selected a mean workload of 75 (median 79).CONCLUSIONSWith a high level of confidence and strong concordance, neurosurgeons estimated that the vast majority of patients with central nervous system tumors, hydrocephalus, or neural tube defects mandate neurosurgical involvement. A significant proportion of other common neurological diseases, such as traumatic brain and spinal injury, vascular anomalies, and degenerative spine disease, demand the attention of a neurosurgeon-whether via operative intervention or expert counsel. These estimates facilitate measurement of the expected annual volume of neurosurgical disease globally.

Global neurosurgery: the current capacity and deficit in the provision of essential neurosurgical care. Executive Summary of the Global Neurosurgery Initiative at the Program in Global Surgery and Social Change

OBJECTIVE

Worldwide disparities in the provision of surgical care result in otherwise preventable disability and death. There is a growing need to quantify the global burden of neurosurgical disease specifically, and the workforce necessary to meet this demand.

METHODS

Results from a multinational collaborative effort to describe the global neurosurgical burden were aggregated and summarized. First, country registries, third-party modeled data, and meta-analyzed published data were combined to generate incidence and volume figures for 10 common neurosurgical conditions. Next, a global mapping survey was performed to identify the number and location of neurosurgeons in each country. Finally, a practitioner survey was conducted to quantify the proportion of disease requiring surgery, as well as the median number of neurosurgical cases per annum. The neurosurgical case deficit was calculated as the difference between the volume of essential neurosurgical cases and the existing neurosurgical workforce capacity.

RESULTS

Every year, an estimated 22.6 million patients suffer from neurological disorders or injuries that warrant the expertise of a neurosurgeon, of whom 13.8 million require surgery. Traumatic brain injury, stroke-related conditions, tumors, hydrocephalus, and epilepsy constitute the majority of essential neurosurgical care worldwide. Approximately 23,300 additional neurosurgeons are needed to address more than 5 million essential neurosurgical cases-all in low- and middle-income countries-that go unmet each year. There exists a gross disparity in the allocation of the surgical workforce, leaving large geographic treatment gaps, particularly in Africa and Southeast Asia.

CONCLUSIONS

Each year, more than 5 million individuals suffering from treatable neurosurgical conditions will never undergo therapeutic surgical intervention. Populations in Africa and Southeast Asia, where the proportion of neurosurgeons to neurosurgical disease is critically low, are especially at risk. Increasing access to essential neurosurgical care in low- and middle-income countries via neurosurgical workforce expansion as part of surgical system strengthening is necessary to prevent severe disability and death for millions with neurological disease.

Birth weight and childhood obesity: a 12-country study

OBJECTIVES

Few studies have investigated the association between the full range of birth weight and the risk of childhood obesity in high-, middle- and low-income countries. The aim of the present study is to assess the association between different levels of birth weight and the risk of obesity among children aged 9-11 years in 12 countries.

METHODS

A multinational, cross-sectional study of 5141 children aged 9-11 years was conducted in 12 countries. Height and weight were obtained using standardized methods. Time spent in moderate-to-vigorous physical activity (MVPA), sedentary and sleeping were objectively measured using 24-h, waist-worn accelerometer (Actigraph GT3X+) monitored for 7 days. Birth weight and other factors (regions, parental education, maternal history of gestational diabetes, children age, gender, breast feeding, gestational age, unhealthy diet scores and healthy diet scores) were collected by parental and children's questionnaires. Multilevel modeling was used to account for the nested nature of the data.

RESULTS

The overall prevalence of obesity (BMI z-score>+2 s.d.) was 15.4% for boys and 10.0% for girls. There was a positive association between birth weight and BMI z-scores. The multivariable-adjusted odds ratios (ORs) of childhood obesity were significantly higher among children whose birth weights were 3500-3999 g (OR 1.45; 95% confidence interval (CI): 1.10-1.92), and >4000 g (OR 2.08; 95% CI: 1.47-2.93), compared with the reference group (2500-2999 g). The positive association between birth weight and the odds of childhood obesity was seen in girls, whereas a U-shaped association appeared in boys.

CONCLUSIONS

High levels of birth weight, defined as birth weight ⩾3500 g, were associated with increased odds of obesity among 9-11-year-old children in 12 countries. However, sex differences in the association between birth weight and the risk of obesity need to be considered when planning interventions to reduce childhood obesity.

CD4 deficit and tuberculosis risk persist with delayed antiretroviral therapy: 5-year data from CIPRA HT-001

SETTING

Port-au-Prince, Haiti.

OBJECTIVE

To determine long-term effects of early vs. delayed initiation of antiretroviral therapy (ART) on immune recovery and tuberculosis (TB) risk in human immunodeficiency virus (HIV) infected individuals.

DESIGN

Open-label randomized controlled trial of immediate ART in HIV-infected adults with CD4 counts between 200 and 350 cells/mm(3) vs. deferring ART until the CD4 count was <200 cells/mm(3). The primary comparisons were CD4 counts over time and risk for incident TB, with 5 years of follow-up.

RESULTS

A total of 816 participants were enrolled, with 408 in each treatment arm. The early treatment group started ART within 2 weeks, while the deferred treatment group started ART a median of 1.3 years after enrollment. After 5 years, the mean CD4 count in the early treatment group was significantly higher than in the deferred treatment group (496 cells/mm(3), 95% confidence interval [CI] 477-515 vs. 373 cells/mm(3), 95%CI 357-389; P < 0.0001). TB risk was higher in the deferred treatment group (unadjusted HR 2.41, 95%CI 1.56-3.74; P < 0.0001) and strongly correlated with lower CD4 counts in time-dependent multivariate analysis.

CONCLUSION

Delays in ART initiation for HIV-infected adults with CD4 counts of 200-350 cells/mm(3) can result in long-term immune dysfunction and persistent increased risk for TB.

Oxytocin increases the influence of public service advertisements

This paper presents a neurophysiologic model of effective public service advertisements (PSAs) and reports two experiments that test the model. In Experiment 1, we show that after watching 16 PSAs participants who received oxytocin, compared to those given a placebo, donated to 57% more causes, donated 56% more money, and reported 17% greater concern for those in the ads. In Experiment 2, we measured adrenocorticotropin hormone (ACTH) and oxytocin levels in blood before and after participants watched a PSA. As predicted by the model, donations occurred when participants had increases in both ACTH and oxytocin. Our results indicate that PSAs with social content that cause OT release will be more effective than those that do not. Our results also explain why some individuals do not respond to PSAs.

Low vitamin D levels, prediabetes and prehypertension in healthy African American adults

AIMS

To determine if customary lower serum vitamin D concentrations in healthy African American (AA) adults are associated with modest elevations in fasting plasma glucose (FPG) and/or resting blood pressure (BP). Numerous health disparities between African American (AA) and Caucasian American (CA) adults, especially those which increase cardiovascular morbidity and mortality, have been attributed to lower serum vitamin D concentrations in the AA. Prediabetes (PreDM) and prehypertension (PreHTN) are significantly more prevalent in healthy disease free CA adults with serum vitamin D concentrations below the 75th percentile for the Caucasian cohort. We hypothesized that despite overall lower serum vitamin D concentrations in AA, an increase in the prevalence for PreDM and PreHTN would be seen in those with low vitamin D levels.

METHODS AND RESULTS

Disease free AA adults in the National Health and Nutrition Examination Survey 2001-2006 were assessed. PreDM and PreHTN were diagnosed using the ADA and JNC 7 criteria: (FPG) 100-125 mg/dL and resting systolic (SBP) 120-139 and/or diastolic (DBP) 80-89 mm Hg, respectively. Logistic regression was employed to assess effects of low vitamin D concentrations on the odds for PreDM and PreHTN (n = 621). Age, gender and BMI adjusted odds ratio for co-morbid PreDM and PreHTN in AA men (n = 343) and women (n = 278) with vitamin D levels ≤45.4 versus >45.4 nmol/L was 2.02 (1.11, 3.68), (p < 0.021).

CONCLUSIONS

Evaluating serum vitamin D levels, with consideration for supplementation in seemingly healthy AA adults with prediabetes, prehypertension, or co-existing prediabetes and prehypertension, has merit.

Fractionated proton radiotherapy for benign cavernous sinus meningiomas

PURPOSE

To evaluate the efficacy of fractionated proton radiotherapy for a population of patients with benign cavernous sinus meningiomas.

METHODS AND MATERIALS

Between 1991 and 2002, 72 patients were treated at Loma Linda University Medical Center with proton therapy for cavernous sinus meningiomas. Fifty-one patients had biopsy or subtotal resection; 47 had World Health Organization grade 1 pathology. Twenty-one patients had no histologic verification. Twenty-two patients received primary proton therapy; 30 had 1 previous surgery; 20 had more than 1 surgery. The mean gross tumor volume was 27.6 cm(3); mean clinical target volume was 52.9 cm(3). Median total doses for patients with and without histologic verification were 59 and 57 Gy, respectively. Mean and median follow-up periods were 74 months.

RESULTS

The overall 5-year actuarial control rate was 96%; the control rate was 99% in patients with grade 1 or absent histologic findings and 50% for those with atypical histology. All 21 patients who did not have histologic verification and 46 of 47 patients with histologic confirmation of grade 1 tumor demonstrated disease control at 5 years. Control rates for patients without previous surgery, 1 surgery, and 2 or more surgeries were 95%, 96%, and 95%, respectively.

CONCLUSIONS

Fractionated proton radiotherapy for grade 1 cavernous sinus meningiomas achieves excellent control rates with minimal toxicities, regardless of surgical intervention or use of histologic diagnosis. Disease control for large lesions can be achieved by primary fractionated proton therapy.

Subchronic oral toxicity and cardiovascular safety pharmacology studies of resveratrol, a naturally occurring polyphenol with cancer preventive activity

To characterize the subchronic oral toxicity of resveratrol, CD rats received daily gavage doses of 0, 200, 400, or 1000 mg resveratrol/kg/day, and beagle dogs received daily capsule doses of 0, 200, 600, or 1200 mg resveratrol/kg/day for 90 days. Resveratrol induced only minimal toxicity, consisting of dose-related reductions in body weight gain in female rats and both sexes of dogs, and a statistically significant increase in bilirubin levels in rats at the 1000 mg/kg/day dose. Clinical observations, hematology, ophthalmology, neurotoxicity evaluations (functional observational batteries), organ weights, and gross pathology provided no biologically significant evidence of resveratrol toxicity in either species. In rats, the high dose of resveratrol reduced the incidence of cardiomyopathy; no other microscopic changes were seen. Histopathologic changes in dogs were limited to minimal inflammatory infiltrates in the kidney and urinary bladder, which were not considered toxicologically significant. A cardiovascular safety pharmacology (telemetry) study in dogs revealed no evidence of resveratrol toxicity. Based on body weight effects, the No Observed Adverse Effect Level (NOAEL) for resveratrol was 200mg/kg/day in rats and 600 mg/kg/day in dogs. The apparent cardioprotective activity of resveratrol in rats demonstrates that its potentially beneficial activities may extend beyond efficacy in cancer prevention.

Use of intralesional tPA in spontaneous intracerebral hemorrhage: retrospective analysis

INTRODUCTION

Neurosurgical treatment of spontaneous intracerebral hemorrhage (ICH) is controversial, with a lack of evidence-based guidelines contributing to the high variety of treatments. In our study we examine the outcome and complication from use of intralesional tissue plasminogen activator (IL tPA).

METHOD

Patients who have been treated with IL tPA for spontaneous ICH were reviewed retrospectively. We compared clot sizes before and after tPA infusion, and outcome based on the modified Rankin score.

RESULTS

Nine patients received IL tPA during the period 1999-2009. No immediate complications with use of IL tPA were found. There was a statistically significant volume reduction in clot sizes on computed tomography. Four patients recovered to independent functional status. Three patients were discharged to SNF, and two patients died as a result of ICH. Our results appear to demonstrate superior outcome to supportive management and no worse result than surgical management.

CONCLUSION

It appears a subset of ICH patients benefits from use of IL tPA. This study demonstrates that IL tPA use is safe and has the potential to improve outcome compared to conservative management without the risk of surgical complications. Our patient size is small, and larger prospective studies are needed to provide solid guidelines for management of ICH.

Variety of spinal vascular pathology seen in adult Cobb syndrome

Cobb syndrome is a rare clinical entity that includes the combination of a vascular skin nevus and an angioma in the spinal canal present at identical dermatomal level(s) (cutaneomeningospinal angiomatosis). To date, 38 cases have been reported, only 18 of which are in adults (> 18 years of age). The majority of these cases have been described in the era predating current neuroimaging techniques, and most authors have assumed that each case involves similar vascular pathology. This report highlights 2 patients presenting with similar thoracic cutaneous vascular nevi yet with markedly differing spinal vascular pathology.

A 29-year-old man presented with cutaneous hemangioma and a progressive paraparesis and paresthesia of the lower extremities. A 20 × 20–cm port-wine stain over his right upper midback (T6–10) correlated precisely with MR imaging that demonstrated an enhancing epidural mass between T-6 and T-10 causing compression of the cord and cord edema. A 34-year-old man also presented with progressive myelopathy and a 15 × 20–cm port-wine stain within the same dermatomal region as a Type III spinal arteriovenous malformation.

Workup for each patient included pre- and postoperative contrast-enhanced MR imaging with vascular sequencing and spinal angiography. The first patient was treated with bilateral laminectomy at the T6–10 levels, with significant postoperative improvement in motor strength. The second patient underwent coil embolization of an intranidal aneurysm, with follow-up embolization 8 years later.

Cobb syndrome is an unusual entity in the adult population and should be considered when there is a constellation of cutaneous manifestation and underlying neurological deficit. The vascular skin nevus associated with Cobb syndrome is accompanied by a wide variety of vascular pathologies.

Surgery and radiotherapy: complementary tools in the management of benign intracranial tumors

Historically, radiation therapy has been used extensively in the treatment of malignant and aggressive intracranial tumors, and the importance of its role has been repeatedly verified by prolonged patient survival rates and increased tumor control. As more modern capabilities are employed in surgery and radiotherapy, attention is being directed to the utility of radiation as either primary or secondary treatment of benign tumors. Specifically, primary treatment encompasses irradiation of small benign tumors without biopsy confirmation of tumor type; secondary treatment involves postoperative radiation therapy, with the possibility that less-aggressive tumor resection may be performed in areas that have a higher probability of resultant neurological deficit. Current literature suggests that this is not only a possible treatment strategy, but that it may be superior to more radical resection in some cases, for example, in vestibular schwannomas and meningiomas. This article provides an overview of factors to consider in the use of radiation therapy and reviews the relationships between radiation and surgery, notably the unique complementary role each plays in the treatment of benign intracranial tumors.

Radiation therapy in the treatment of pituitary tumors

✓ The treatment of pituitary tumors has progressed into a multidisciplinary approach that involves neurosurgeons, radiation oncologists, and endocrinologists. This has allowed improved outcomes in treatment of pituitary tumors due to a combination of surgical, medical, and radiation therapies. In this study, the authors review the role of radiation therapy in the treatment of pituitary adenomas.

A SAS program for calculating cumulative incidence of events (with confidence limits) and number at risk at specified time intervals with partially censored data

Correct analysis and interpretation of longitudinal (cohort) studies with partially censored time-to-event data requires that the cumulative count of events and censored observations as well as the number at risk be calculated at appropriate time points (for example, every year), by baseline group or stratum. We present here a simple SAS program, for use in situations in which competing risks do not need to be accounted for, that calculates, by baseline group or stratum, the cumulative event count, cumulative event probability (with upper and lower 95% confidence limits), and number at risk at selected time points that can be chosen by the user. We demonstrate the use of the program in the analysis of longitudinal time-to-event data from a prospective study, the Atherosclerosis Risk In Communities (ARIC) Study, for four groups and a 10-year follow-up. The SAS code presented here is easy to follow and modify and can be incorporated quickly by the user for immediate use. It provides an especially valuable tool for less experienced SAS users.

Subchronic oral toxicity studies of Se-methylselenocysteine, an organoselenium compound for breast cancer prevention

Se-methylselenocysteine (MSC) is an organoselenium compound being developed for breast cancer chemoprevention. To characterize MSC toxicity, CD rats received daily gavage doses of 0, 0.5, 1.0, or 2.0 mg/kg/day (0, 3, 6, or 12 mg/m(2)/day), and beagle dogs received daily gavage doses of 0, 0.15, 0.3, or 0.6 mg/kg/day (0, 3, 6, or 12 mg/m(2)/day) for 28 days. In rats, MSC induced dose-related hepatomegaly in both sexes; mild anemia, thrombocytopenia, and elevated liver enzymes were observed in high dose females only. Microscopic pathology included hepatocellular degeneration (high dose males, all doses in females); arrested spermatogenesis (high dose males); and atrophy of corpora lutea (middle and high dose females). In dogs, MSC induced mild anemia in middle and high dose males, and in high dose females. Toxicologically significant microscopic lesions in dogs were seen only in the liver (peliosis and vacuolar degeneration in high dose males, midzonal necrosis in males in all dose groups). Based on liver pathology seen in female rats in all dose groups, the no observed adverse effect level (NOAEL) for MSC in rats is <0.5mg/kg/day. Based on alterations in hematology parameters and liver morphology in male dogs in all dose groups, the NOAEL for MSC in dogs is <0.15 mg/kg/day.

Recurrent spinal hydatidosis in North America

Spinal hydatidosis is an uncommon manifestation of the parasite Echinococcus, affecting fewer than 1% of patients with hydatid disease. The authors report on a 34-year-old Turkish woman who presented with recurrent primary spinal hydatid disease. The patient originally presented with progressive numbness and paraparesis that was reversed after T5–6 laminectomy and cyst removal. Pathological findings indicated parasitic infection and she underwent treatment for cysticercosis. Nevertheless, she returned 4 years later with back pain, numbness, and monoparesis. Neuroimaging studies revealed spinal cord compression with multiple cysts that were again resected. Pathological findings were consistent with Echinococcus.

Although this disease is uncommon, particularly in North America, the authors conclude that spinal hydatidosis should be considered in the differential diagnosis of any patient who has lived or traveled within endemic areas and who presents with spine lesions and cord compression. The authors review the literature pertaining to the epidemiological features, presentation, diagnosis, neuroimaging characteristics, recommended treatments, and overall prognosis of spinal hydatidosis.

Concept of arteriovenous malformation compartments and surgical management

Cerebral AVMs are known to be a source of intracranial hemorrhages and epileptic seizures. Their natural history indicates approximately 15% mortality and 35% morbidity over a 15-year period. This significant mortality and morbidity mandates a need for satisfactory treatment of this entity, ideally by elimination of AVMs. Microsurgical resection, endovascular embolization and radiosurgery (irradiation) are the three effective modes of treatment currently available. However, no objective criteria have been established for which mode(s) of treatment should be selected for individual patients with AVMs. Considering the complexity of AVMs and variable conditions of individual patients, neurosurgeons, intravascular interventionalists and radiosurgeons must make their own decisions on how to treat each patient based on their experience. In practice, treatment of small AVMs in non-functional areas is favored equally by each of these specialists, while they tend to avoid treatment of large AVMs, particularly those in functional areas of the brain. The authors report the surgical intervention of large AVMs, including those located in functional areas of the hemisphere by special techniques. One can demonstrate AVM compartments by using angiography and with the aid of color Doppler ultrasonography, each compartment can be outlined and dissected individually until all the compartments are isolated without causing any damage to the surrounding brain and the entire AVM is rendered shrunken and then removed. The concept of compartmental treatment of AVMs may be applied in the future to radiosurgery and intravascular embolization of large AVMs.

Interventions to modify sexual risk behaviors for preventing HIV infection in men who have sex with men

BACKGROUND

MSM remain at great risk for HIV infection. Program planners and policy makers need descriptions of interventions and quantitative estimates of intervention effects to make informed decisions concerning prevention efforts.

OBJECTIVES

1. To locate and describe outcome studies evaluating the effects of behavioral and social interventions targeting MSM. 2. To summarize the effectiveness of these interventions among MSM. 3. To stratify results by characteristics of interventions and participants. 4. To identify gaps and indicate future research, policy, and practice needs.

SEARCH STRATEGY

We searched electronic databases (MedLine, PsycInfo, etc.); several current journals (e.g., AIDS, AIDS and Behavior, AIDS Education and Prevention, American Journal of Public Health, Journal of Acquired Immune Deficiency Syndromes, etc.); manuscripts submitted by researchers; bibliographies of relevant articles; and other published reviews, for published and unpublished reports from 1988 through 1997.

SELECTION CRITERIA

Studies were considered in scope if they examined the effects of behavioral interventions to reduce risk for HIV or STD transmission. We reviewed studies in scope for criteria of outcome relevance (measurement of at least one of a list of behavioral or biologic outcomes, e.g., unprotected sex or incidence of HIV infections) and methodologic rigor (randomized controlled trials or certain strong quasi-experimental designs with comparison groups).

DATA COLLECTION AND ANALYSIS

As of June 1998 we had identified 13 eligible studies. Twelve studies (7 trials of small group interventions, 3 community-level interventions, and 2 individual level interventions) reported intervention effects on unprotected sex. Because few studies reported effects on condom use (3 studies), number of sex partners without regard to condom use (4 studies), or HIV or STD incidence (1 study in which no infections occurred) we do not address these outcomes at this time. We present those analyses which can be performed in the current Cochrane RevMan software, followed by more complete analyses that permit inclusion of community-level studies, adjustment for baseline conditions, calculation of effect sizes from a wider variety of statistics (e.g., an F-statistic from a one-way ANOVA), and simultaneous meta-analysis of continuous and dichotomous outcomes (Johnson 2002b). We translate the summary effect to reduction in risk behavior based on the background prevalence of unprotected sex. Finally we provide analyses stratified by intervention content (interpersonal skills addressed or not), intervention format (community vs small group or individual) and mean age of participants (23 to 31 vs. 32 to 36).

MAIN RESULTS

A summary measure of intervention effects on reducing unprotected sex was favorable (odds ratio = 0.73) and statistically significant (CI, 0.60 to 0.88), corresponding to a 23% reduction in the proportion of men engaging in unprotected sex. Effects were homogeneous among studies, but were slightly more favorable among community-level interventions, those that served populations in their 20s rather than their 30s, and those that promoted interpersonal skills.

REVIEWER'S CONCLUSIONS

These studies demonstrate that interventions can promote risk reduction among MSM. Yet given the epidemiology of HIV in Pattern I countries, the small number of rigorous controlled intervention trials for this population is striking. Many more rigorous evaluations of HIV prevention efforts with MSM are needed to ascertain with confidence the effects of specific intervention components, population characteristics, and methodologic features.

Fractionated proton beam radiotherapy for acoustic neuroma

OBJECTIVE

This study evaluated proton beam irradiation in patients with acoustic neuroma. The aim was to provide maximal local tumor control while minimizing complications such as cranial nerve injuries.

METHODS

Thirty-one acoustic neuromas in 30 patients were treated with proton beam therapy from March 1991 to June 1999. The mean tumor volume was 4.3 cm(3). All patients underwent pretreatment neurological evaluation, contrast enhanced magnetic resonance imaging, and audiometric evaluation. Standard fractionated proton radiotherapy was used at daily doses of 1.8 to 2.0 cobalt Gray equivalent: patients with useful hearing before treatment (Gardner-Robertson Grade I or II) received 54.0 cobalt Gray equivalent in 30 fractions; patients without useful hearing received 60.0 cobalt Gray equivalent in 30 to 33 fractions.

RESULTS

Twenty-nine of 30 patients were assessable for tumor control and cranial nerve injury. Follow-up ranged from 7 to 98 months (mean, 34 mo), during which no patients demonstrated disease progression on magnetic resonance imaging scans. Eleven patients demonstrated radiographic regression. Of the 13 patients with pretreatment Gardner-Robertson Grade I or II hearing, 4 (31%) maintained useful hearing. No transient or permanent treatment-related trigeminal or facial nerve dysfunction was observed.

CONCLUSION

Fractionated proton beam therapy provided excellent local control of acoustic neuromas when treatment was administered in moderate doses. No injuries to the Vth or VIIth cranial nerves were observed. A reduction in the tumor dose is being evaluated to increase the hearing preservation rate.