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Dive into the research topics where Dan Neal is active.

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Featured researches published by Dan Neal.


Neurosurgery | 2013

A Multicenter Study of Stent-Assisted Coiling of Cerebral Aneurysms With a Y Configuration

Kyle M. Fargen; J Mocco; Dan Neal; Michael C. Dewan; John F. Reavey-Cantwell; Henry H. Woo; David Fiorella; Maxim Mokin; Adnan H. Siddiqui; Aquilla S Turk; Raymond D Turner; Imran Chaudry; Kalani My; Felipe C. Albuquerque; Brian L. Hoh

BACKGROUND Stent-assisted coiling with 2 stents in a Y configuration is a technique for coiling complex wide-neck bifurcation aneurysms. OBJECTIVE We sought to provide long-term clinical and angiographic outcomes with Y-stent coiling, which are not currently established. METHODS Seven centers provided deidentified, retrospective data on all consecutive patients who underwent stent-assisted coiling for an intracranial aneurysm with a Y-stent configuration. RESULTS Forty-five patients underwent treatment by Y-stent coiling. Their mean age was 57.9 years. Most aneurysms were basilar apex (87%), and 89% of aneurysms were unruptured. Mean size was 9.9 mm. Most aneurysms were treated with 1 open-cell and 1 closed-cell stent (51%), with 29% treated with open-open stents and 16% treated with 2 closed-cell stents. Initial aneurysm occlusion was excellent (84% in Raymond grade I or II). Procedural complications occurred in 11% of patients. Mean clinical follow-up was 7.8 months, and 93% of patients had a modified Rankin Scale score of 0 to 2 at last follow-up. Mean angiographic follow-up was 9.8 months, and 92% of patients had Raymond grade I or II occlusion on follow-up imaging. Of those patients with initial Raymond grade III occlusion and follow-up imaging, all but 1 patient progressed to a better occlusion grade (83%; P < .05). Three aneurysms required retreatment because of recanalization (10%). There was no difference in initial or follow-up angiographic occlusion, clinical outcomes, incidence of aneurysm retreatment, or in-stent stenosis among open-open, open-closed, or closed-closed stent groups. CONCLUSION In a large multicenter series of Y-stent coiling for bifurcation aneurysms, there were low complication rates and excellent clinical and angiographic outcomes.


Journal of NeuroInterventional Surgery | 2015

A meta-analysis of prospective randomized controlled trials evaluating endovascular therapies for acute ischemic stroke

Kyle M. Fargen; Dan Neal; David Fiorella; Aquilla S Turk; Michael T. Froehler; J Mocco

Introduction A recent randomized controlled trial (RCT), the Multicenter Randomized CLinical trial of Endovascular treatment for Acute ischemic stroke in the Netherlands (MR CLEAN), demonstrated better outcomes with endovascular treatment compared with medical therapy for acute ischemic stroke (AIS). However, previous trials have provided mixed results regarding the efficacy of endovascular treatment for AIS. A meta-analysis of all available trial data was performed to summarize the available evidence. Methods A literature search was performed to identify all prospective RCTs comparing endovascular therapies with medical management for AIS. Two datasets were created: (1) all patients randomized after confirmation of large vessel occlusion (LVO) (consistent with the contemporary standard of practice at the majority of centers); and (2) all patients with outcome data who underwent randomization regardless of qualifying vascular imaging. The pre-specified primary outcome measure was modified Rankin Scale score of 0–2 at 90 days. A fixed-effect model was used to determine significance. Results Five prospective RCTs comparing endovascular therapies with medical management were included in dataset 1 (1183 patients) and six were included in dataset 2 (1903 total patients). Endovascular therapies were associated with significantly improved outcomes compared with medical management (OR 1.67, 95% CI 1.29 to 1.16, p=0.0001) for patients with LVO (dataset 1). This benefit persisted when patients from all six RCTs were included, even in the absence of confirmation of LVO (OR 1.27, 95% CI 1.05 to 1.54, p=0.019; dataset 2). Conclusions A meta-analysis of prospective RCTs comparing endovascular therapies with medical management demonstrates superior outcomes in patients randomized to endovascular therapy.


Journal of Stroke & Cerebrovascular Diseases | 2014

Race and Income Disparity in Ischemic Stroke Care: Nationwide Inpatient Sample Database, 2002 to 2008

Matthew M. Kimball; Dan Neal; Michael F. Waters; Brian L. Hoh

BACKGROUND Health care disparities exist between demographic groups with stroke. We examined whether patients of particular ethnicity or income levels experienced reduced access to or delays in receiving stroke care. METHODS We studied all admissions for ischemic stroke in the Nationwide Inpatient Sample (NIS) database between 2002 and 2008. We used statistical models to determine whether median income or race were associated with intravenous (i.v.) thrombolysis treatment, in-hospital mortality, discharge disposition, hospital charges, and LOS in high- or low-volume hospitals. RESULTS There were a total of 477,474 patients with ischemic stroke: 10,781 (2.3%) received i.v. thrombolysis, and 380,400 (79.7%) were treated in high-volume hospitals. Race (P < .0001) and median income (P < .001) were significant predictors of receiving i.v. thrombolysis, and minorities and low-income patients were less likely to receive i.v. thrombolysis. Median income was a predictor of access to high-volume hospitals (P < .0001), with wealthier patients more likely to be treated in high-volume hospitals, which had lower mortality rates (P = .0002). Patients in high-volume hospitals were 1.84 times more likely to receive i.v. thrombolysis (P < .0001). CONCLUSIONS African Americans, Hispanics, and low median income patients are less likely to receive i.v. thrombolysis for ischemic stroke. Low median income patients are less likely to be treated at high-volume hospitals. High-volume hospitals have lower mortality rates and a higher likelihood of treating patients with i.v. thrombolysis. There is evidence for an influence of socioeconomic status and racial disparity in the treatment of ischemic stroke.


Journal of Neurosurgery | 2013

The prevalence of patient safety indicators and hospital-acquired conditions in patients with ruptured cerebral aneurysms: establishing standard performance measures using the Nationwide Inpatient Sample database

Kyle M. Fargen; Dan Neal; Maryam Rahman; Brian L. Hoh

OBJECT The Agency for Healthcare Research and Quality (AHRQ) patient safety indicators (PSIs) and the Centers for Medicare and Medicaid Services hospital-acquired conditions (HACs) are publicly reported metrics used to gauge the quality of health care provided by health care institutions. To better understand the prevalence of these events in hospitalized patients treated for ruptured cerebral aneurysms, the authors determined the incidence rates of PSIs and HACs among patients with a diagnosis of subarachnoid hemorrhage and procedure codes for either coiling or clipping in the Nationwide Inpatient Sample database. METHODS The authors queried the Nationwide Inpatient Sample database, part of the AHRQs Healthcare Cost and Utilization Project, for all hospitalizations between 2002 and 2010 involving coiling or clipping of ruptured cerebral aneurysms. The incidence rate of each PSI and HAC was determined by searching the hospital records for ICD-9 codes. The authors used the SAS statistical software package to calculate incidence rates and perform multivariate analyses to determine the effects of patient variables on the probability of developing each indicator. RESULTS There were 62,972 patient admissions with a diagnosis code of subarachnoid hemorrhage between the years 2002 and 2010; 10,274 (16.3%) underwent clipping and 8248 (13.1%) underwent endovascular coiling. A total of 6547 PSI and HAC events occurred within the 10,274 patients treated with clipping; at least 1 PSI or HAC occurred in 47.9% of these patients. There were 5623 total PSI and HAC events among the 8248 patients treated with coils; at least 1 PSI or HAC occurred in 51.0% of coil-treated patients. Age, sex, comorbidities, hospital size, and hospital type had statistically significant associations with indicator occurrence. Compared with patients without events, those treated by either clipping or coiling and had at least 1 PSI during their hospitalization had significantly longer lengths of stay (p < 0.001), higher hospital costs (p < 0.001), and higher in-hospital mortality rates (p < 0.001). CONCLUSIONS These results estimate baseline national rates of PSIs and HACs in patients treated for ruptured cerebral aneurysms. These data may be used to gauge individual institutional quality of care and patient safety metrics in comparison with national data.


Neurosurgery | 2013

Cerebral aneurysms in pregnancy and delivery: pregnancy and delivery do not increase the risk of aneurysm rupture.

Young Woo Kim; Dan Neal; Brian L. Hoh

BACKGROUND It is not known what effect pregnancy or delivery has on the risk of rupture of an intracranial aneurysm, and, consequently, the optimal management of unruptured aneurysms in pregnancy is unclear. OBJECTIVE To study the effect of pregnancy and delivery on the risk of rupture of intracranial aneurysms and to delineate trends in neurosurgical and obstetric management of pregnant women with intracranial aneurysms. METHODS The Nationwide Inpatient Sample data were analyzed for years 1988 to 2009 to estimate the risk of aneurysm rupture during pregnancies and deliveries. We calculated the risk by dividing the observed number of patients with ruptured aneurysm during pregnancy and delivery by the expected number based on the incidence among women of pregnancy age. RESULTS There were 714 and 172 hospitalizations involving ruptured aneurysms with pregnancy and delivery, respectively. Assuming 1.8% prevalence of unruptured aneurysms among all women of pregnancy age, we estimated that 48,873 women hospitalized for pregnancy and 312,128 women hospitalized for delivery had unruptured aneurysms. The risks of rupture during pregnancy and deliveries were 1.4% (95% confidence interval [CI] = [1.35, 1.57]) and 0.05% (95% CI = [0.0468, 0.0634]), respectively. Of 218 deliveries performed with unruptured aneurysm, 153 were cesarean deliveries (70.18%, 95% CI = [64.06, 76.30%]), suggesting that the rate of cesarean deliveries in patients with unruptured aneurysms is significantly higher than in the general population (P < .001). CONCLUSION We were not able to find an increased association between pregnancy or delivery and the risk of rupture of cerebral aneurysms. The significantly higher rate of cesarean deliveries performed in patients with unruptured aneurysms may not be necessary.


Parkinsonism & Related Disorders | 2012

GPi and STN deep brain stimulation can suppress dyskinesia in Parkinson's disease

Genko Oyama; Kelly D. Foote; Charles E. Jacobson; Frances Velez-Lago; Criscely L. Go; Natlada Limotai; Pamela Zeilman; Janet Romrell; Samuel S. Wu; Dan Neal; Michael S. Okun

OBJECTIVES To compare subthalamic nucleus (STN) to globus pallidus internus (GPi) deep brain stimulation (DBS) for control of motor fluctuations and for potential dyskinesia-suppressing qualities. METHODS We conducted a retrospective database review of all patients who underwent GPi or STN DBS for idiopathic Parkinsons disease. Direct dyskinesia suppression (dDS) was defined as improvement in dyskinesia subscore of the unified Parkinsons disease rating scale (UPDRS) part IV (items 32-34), despite lack of reduction in dopaminergic medication dosage. We analyzed the data using methods appropriate for a case-control study. RESULTS A total of 133 patients were evaluated. At the last evaluation Dyskinesia scores and motor fluctuations significantly improved in both the GPi (p < 0.0001) and STN groups (p < 0.0001). The GPi group was more likely than the STN group to experience dDS (odds ratio = 1.95, 95% CI = 0.556, 3.21). However, the association between DBS target and dDS was not statistically significant (Pearson chi-square = 2.286, p = 0.131). CONCLUSIONS The overall clinical outcome of STN and GPi DBS for control of dyskinesia and motor fluctuations was similar. STN and GPi DBS both had some direct dyskinesia suppression effects.


PLOS ONE | 2014

Increased precursor cell proliferation after deep brain stimulation for Parkinson's disease: a human study.

Vinata Vedam-Mai; Bronwen Gardner; Michael S. Okun; Florian A. Siebzehnrubl; Monica Kam; Palingu Aponso; Dennis A. Steindler; Anthony T. Yachnis; Dan Neal; Brittany U. Oliver; Sean J. Rath; Richard L.M. Faull; Brent A. Reynolds; Maurice A. Curtis

Objective Deep brain stimulation (DBS) has been used for more than a decade to treat Parkinsons disease (PD); however, its mechanism of action remains unknown. Given the close proximity of the electrode trajectory to areas of the brain known as the “germinal niches,” we sought to explore the possibility that DBS influences neural stem cell proliferation locally, as well as more distantly. Methods We studied the brains of a total of 12 idiopathic Parkinsons disease patients that were treated with DBS (the electrode placement occurred 0.5–6 years before death), and who subsequently died of unrelated illnesses. These were compared to the brains of 10 control individuals without CNS disease, and those of 5 PD patients with no DBS. Results Immunohistochemical analyses of the subventricular zone (SVZ) of the lateral ventricles, the third ventricle lining, and the tissue surrounding the DBS lead revealed significantly greater numbers of proliferating cells expressing markers of the cell cycle, plasticity, and neural precursor cells in PD-DBS tissue compared with both normal brain tissue and tissue from PD patients not treated with DBS. The level of cell proliferation in the SVZ in PD-DBS brains was 2–6 fold greater than that in normal and untreated PD brains. Conclusions Our data suggest that DBS is capable of increasing cellular plasticity in the brain, and we hypothesize that it may have more widespread effects beyond the electrode location. It is unclear whether these effects of DBS have any symptomatic or other beneficial influences on PD.


World Neurosurgery | 2013

Establishing Standard Performance Measures for Adult Stroke Patients: A Nationwide Inpatient Sample Database Study

Maryam Rahman; Dan Neal; Kyle M. Fargen; Brian L. Hoh

BACKGROUND The Agency for Healthcare Research and Quality patient safety indicators (PSIs) and the Centers for Medicare and Medicaid Services hospital-acquired conditions (HACs) are used to evaluate the safety and quality of health care provided by health care systems and individual facilities. To understand better the incidence of PSIs and HACs in hospitalized patients with stroke, we determined the rates of these events among patients with a diagnosis of stroke in the Nationwide Inpatient Sample (NIS) database. METHODS We queried the NIS for all hospitalizations involving ischemic stroke. We determined the incidence of various PSIs and HACs by searching the hospital records for International Classification of Diseases, 9th edition, codes indicating each PSI or HAC. Statistical analysis was performed with SAS statistical software package. RESULTS There were 903,647 hospitalizations involving stroke in the NIS database for years 2002-2010. Among these hospitalizations, 137,161 (15.2%) patients experienced ≥1 Agency for Healthcare Research and Quality PSIs. The most common PSIs included postoperative respiratory failure (9.44%), sepsis (4.43%), and pressure ulcer (2.19%). Of stroke patients, 28,323 (3.13%) experienced ≥1 HACs. The most common HACs included falls and trauma (2.51%) and stage III and IV pressure ulcers (0.43%). Increasing comorbidity score (P ≤ 0.001) was associated with increased likelihood of all PSIs and HACs. The presence of PSIs or HACs resulted in increased length of stay, increased hospital charges, and an increase in mortality rates (P < 0.0001). CONCLUSIONS Our results estimate baseline national incidence rates of PSIs and HACs in patients with stroke. These data may be used to determine individual institutional improvements or success by comparison.


Journal of Dental Research | 2013

Surface Degradation of Dental Ceramics as a Function of Environmental pH

Josephine F. Esquivel-Upshaw; F.Y. Dieng; Arthur E. Clark; Dan Neal; Kenneth J. Anusavice

We tested the hypotheses that glass-ceramic veneers and overglazes degrade by ion exchange in an acidic environment, and that they degrade by breakdown of the silica network in a basic environment. Disk specimens of glass-ceramic veneer and glaze were fabricated and immersed in pH 2, 7, or 10 buffer solutions, for 1, 3, 5, 10, 15, and 30 days. Each specimen was placed in a shaker bath containing de-ionized distilled water at 80°C. Concentrations of Al3+, Ca2+, Zn2+, Li2+, and Si4+ were analyzed by means of inductively coupled plasma atomic emission spectrometry (ICP/AES). Statistical analyses were performed by factorial ANOVA. Significant differences occurred among leached ion concentrations as a function of material type, solution pH, and exposure time. A substantial release of Si occurred at pH 10 over time, leading to a breakdown of the glass phase. At pH 2, dissolution was controlled by an ionic exchange mechanism. We conclude that ceramic veneers and glazes may be susceptible to considerable degradation in low- and high-pH buffer solutions.


Proceedings of the National Academy of Sciences of the United States of America | 2015

Haptoglobin phenotype predicts the development of focal and global cerebral vasospasm and may influence outcomes after aneurysmal subarachnoid hemorrhage

Jenna L Leclerc; Spiros Blackburn; Dan Neal; Nicholas V. Mendez; Jeffrey A. Wharton; Michael F. Waters; Sylvain Doré

Significance Subarachnoid hemorrhage (SAH) is a devastating stroke subtype associated with an early age at onset and significant morbidity and mortality. Cerebral vasospasm (CV) is a common complication of SAH and a key contributor to poor outcomes due to the resulting brain ischemia and/or infarction. Blood bioproducts have been implicated in the development of CV, and haptoglobin (Hp), the hemoglobin-binding protein, may aid in attenuating this cascade of toxic effects. Here, we demonstrate that Hp phenotype is an independent risk factor for focal CV, and importantly, for global CV. We also show that Hp phenotype predicts mortality and poor outcomes. Although this work focuses on SAH, we expect that these findings will also apply to other acute neurological conditions. Cerebral vasospasm (CV) and the resulting delayed cerebral ischemia (DCI) significantly contribute to poor outcomes following aneurysmal subarachnoid hemorrhage (aSAH). Free hemoglobin (Hb) within the subarachnoid space has been implicated in the pathogenesis of CV. Haptoglobin (Hp) binds free pro-oxidant Hb, thereby modulating its harmful effects. Humans can be of three Hp phenotypes: Hp1-1, Hp2-1, or Hp2-2. In several disease states, the Hp2-2 protein has been associated with reduced ability to protect against toxic free Hb. We hypothesized that individuals with the Hp2-2 phenotype would have more CV, DCI, mortality, and worse functional outcomes after aSAH. In a sample of 74 aSAH patients, Hp2-2 phenotype was significantly associated with increased focal moderate (P = 0.014) and severe (P = 0.008) CV and more global CV (P = 0.014) after controlling for covariates. Strong trends toward increased mortality (P = 0.079) and worse functional outcomes were seen for the Hp2-2 patients with modified Rankin scale at 6 wk (P = 0.076) and at 1 y (P = 0.051) and with Glasgow Outcome Scale Extended at discharge (P = 0.091) and at 1 y (P = 0.055). In conclusion, Hp2-2 phenotype is an independent risk factor for the development of both focal and global CV and also predicts poor functional outcomes and mortality after aSAH. Hp phenotyping may serve as a clinically useful tool in the critical care management of aSAH patients by allowing for early prediction of those patients who require increased vigilance due to their inherent genetic risk for the development of CV and resulting DCI and poor outcomes.

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Adam W. Beck

University of Alabama at Birmingham

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