The Association between Meteorological Parameters and Aneurysmal Subarachnoid Hemorrhage: A Nationwide Analysis

Prior research has suggested that regional weather patterns impact the risk of rupture of cerebral aneurysms, but the findings in the literature have been inconsistent. Furthermore, no nationwide analysis to date has examined the association between meteorological factors and the post-procedural outcomes of patients after the treatment for ruptured cerebral aneurysms. The purpose of this study was to use a nationwide sample to analyze the association between specific meteorological parameters—temperature, precipitation, sunlight, and humidity—and hospital admission rate for and outcome after aneurysmal subarachnoid hemorrhage. Patients were identified using the Nationwide Inpatient Sample (2001–2010): Those with an ICD-9 diagnosis code for subarachnoid hemorrhage and a procedural code for aneurysm repair were included. Climate data were obtained from the State of the Climate Report 2010 released by the National Climatic Data Center. Multivariate regression models were constructed to analyze the association between average state monthly temperature, precipitation, and percent possible sunlight, as well as relative morning humidity and both monthly hospital admission rate, adjusted for annual state population in millions, and in-hospital mortality. 16,970 admissions were included from 723 hospitals across 41 states. Decreased daily sunlight and lower relative humidity were associated with an increased rate of admission for ruptured cerebral aneurysms (p<0.001), but had no association with differential inpatient mortality. No significant changes in these observed associations were seen when multivariate analyses were constructed. This is the first nationwide study to suggest that decreased sunlight and lower relative humidity are associated with admission for ruptured cerebral aneurysms. While it has been postulated that external atmospheric factors may cause hormonal and homeostatic changes that impact the risk of rupture of cerebral aneurysms, additional research is needed to confirm and further understand these relationships

Posterior Cerebral Artery Angle and the Rupture of Basilar Tip Aneurysms

Since the initial publication of the International Study of Unruptured Intracranial Aneurysms (ISUIA), management of unruptured intracranial aneurysms has been mainly based on the size of the aneurysm. The contribution of morphological characteristics to treatment decisions of unruptured aneurysms has not been well studied in a systematic and location specific manner. We present a large sample of basilar artery tip aneurysms (BTA) that were assessed using a diverse array of morphological variables to determine the parameters associated with ruptured aneurysms. Demographic and clinical risk factors of aneurysm rupture were obtained from chart review. CT angiograms (CTA) were evaluated with Slicer, an open source visualization and image analysis software, to generate 3-D models of the aneurysms and surrounding vascular architecture. Morphological parameters examined in each model included aneurysm volume, aspect ratio, size ratio, aneurysm angle, basilar vessel angle, basilar flow angle, and vessel to vessel angles. Univariate and multivariate analyses were performed to determine statistical significance. From 2008–2013, 54 patients with BTA aneurysms were evaluated in a single institution, and CTAs from 33 patients (15 ruptured, 18 unruptured) were available and analyzed. Aneurysms that underwent reoperation, that were associated with arteriovenous malformations, or that lacked preoperative CTA were excluded. Multivariate logistic regression revealed that a larger angle between the posterior cerebral arteries (P1-P1 angle, p = 0.037) was most strongly associated with aneurysm rupture after adjusting for other morphological variables. In this location specific study of BTA aneurysms, the larger the angle formed between posterior cerebral arteries was found to be a new morphological parameter significantly associated with ruptured BTA aneurysms. This is a physically intuitive parameter that can be measured easily and readily applied in the clinical setting

The Impact of Insurance Status on the Outcomes after Aneurysmal Subarachnoid Hemorrhage

Investigation into the association of insurance status with the outcomes of patients undergoing neurosurgical intervention has been limited: this is the first nationwide study to analyze the impact of primary payer on the outcomes of patients with aneurysmal subarachnoid hemorrhage who underwent endovascular coiling or microsurgical clipping. The Nationwide Inpatient Sample (2001–2010) was utilized to identify patients; those with both an ICD-9 diagnosis codes for subarachnoid hemorrhage and a procedure code for aneurysm repair (either via an endovascular or surgical approach) were included. Hierarchical multivariate regression analyses were utilized to evaluate the impact of primary payer on in-hospital mortality, hospital discharge disposition, and length of hospital stay with hospital as the random effects variable. Models were adjusted for patient age, sex, race, comorbidities, socioeconomic status, hospital region, location (urban versus rural), and teaching status, procedural volume, year of admission, and the proportion of patients who underwent ventriculostomy. Subsequent models were also adjusted for time to aneurysm repair and time to ventriculostomy; subgroup analyses evaluated for those who underwent endovascular and surgical procedures separately. 15,557 hospitalizations were included. In the initial model, the adjusted odds of in-hospital mortality were higher for Medicare (OR 1.23, p<0.001), Medicaid (OR 1.23, p<0.001), and uninsured patients (OR 1.49, p<0.001) compared to those with private insurance. After also adjusting for timing of intervention, Medicaid and uninsured patients had a reduced odds of non-routine discharge (OR 0.75, p<0.001 and OR 0.42, p<0.001) despite longer hospital stays (by 8.35 days, p<0.001 and 2.45 days, p = 0.005). Variations in outcomes by primary payer–including in-hospital post-procedural mortality–were more pronounced for patients of all insurance types who underwent microsurgical clipping. The observed differences by primary payer are likely multifactorial, attributable to varied socioeconomic factors and the complexities of the American healthcare delivery system

Spatially-distributed coverage optimization and control with limited-range interactions

This paper presents coordination algorithms for groups of mobile agents performing deployment and coverage tasks. As an important modeling constraint, we assume that each mobile agent has a limited sensing/communication radius. Based on the geometry of Voronoi partitions and proximity graphs, we analyze a class of aggregate objective functions and propose coverage algorithms in continuous and discrete time. These algorithms have convergence guarantees and are spatially distributed with respect to appropriate proximity graphs. Numerical simulations illustrate the results.Comment: 31 pages, some figures left out because of size limits. Complete preprint version available at http://motion.csl.uiuc.ed

Relationships between lumbar inter-vertebral kinematics and paraspinal myoelectric activity during sagittal flexion: a quantitative fluoroscopy and surface electromyography study

Introduction. Previous investigations that have attempted to relate mechanical parameters to NSLBP groups are often contradictory of each other, and currently clear mechanical markers for LBP remain elusive. In order to move forward in this area, it may be necessary to take a step back, and improve understanding of ‘normal’ spinal biomechanics (i.e. in low back pain free populations). Indeed, Peach et al. (1998) stated “By knowing what is “normal” and what is “abnormal” it may be possible to provide objective evaluation of rehabilitation protocols, and possibly classify different low back pathologies” (Peach et al. 1998). Therefore, an improved understanding of biomechanical behaviours in groups of back pain free people is desirable, particularly at an inter-vertebral level, an area where clear knowledge gaps still exist. Control of the spine during voluntary movement requires finely-tuned coordination of numerous trunk muscles. This dynamic control is believed to be achieved via communication between three sub-systems, the passive (vertebrae, discs and ligaments), the active (muscles and tendons) and the control (central and peripheral nervous system) systems. Investigating the interplay between these sub-systems however is difficult, as the spine is a complex structure with a hidden kinematic chain. Quantitative fluoroscopy (QF) is an imaging technology capable of measuring continuous spinal kinematics at the inter-vertebral level, and surface electromyography (sEMG) provides a non-invasive means of objectively quantifying muscle activity. This study used QF and sEMG technologies concurrently to investigate relationships between and amongst lumbar kinematic (QF determined) and muscle activity (sEMG determined) variables, during weight-bearing active forward flexion. This was the first time such technologies have been combined to investigate the biomechanics of the lumbar spine in vivo. An improved understanding of normal lumbar kinematic and myoelectric behaviour, will assist in the interpretation of what is abnormal in terms of inter-vertebral spinal mechanics. Methods. Contemporaneous lumbar sEMG and QF motion sequences were recorded during controlled active flexion of 60° in 20 males with no history of low back pain in the previous year. Electrodes were placed adjacent to the spinous processes of T9, L2 and L5 bilaterally, to record the myoelectric activity of the thoracic and lumbar erector spinae (TES and LES) and lumbar multifidus (LMU) respectively. QF was used concurrently to measure the maximum inter-vertebral rotation during flexion (IV-RoMmax) and initial attainment rate for the inter-vertebral levels between L2 and S1, as well as each participant’s lordotic angle. The sEMG amplitude data were expressed as a percentage of a sub-maximal voluntary contraction (sMVC). Ratios were calculated between the mean sEMG amplitudes of all three muscles examined. Each flexion cycle was also divided into five epochs, and the changes in mean sEMG amplitude between epochs were calculated. This was repeated to determine changes between all epochs for each muscle group. Relationships between IV-RoMmax and all other kinematic, morphological (i.e. lordosis) and muscle activity variables were determined using correlation coefficients, and simple linear regression was used to determine the effects of any significant relationships. The reliability and agreement of the IV-RoMmax, initial attainment rate, and normalised RMS sEMG measurements were also assessed. Results. The reliability and agreement of IV-RoMmax, initial attainment rate and sEMG amplitude measurements were high. There were significant correlations between the IV-RoMmax at specific levels and the IV-RoMmax at other lumbar motion segments (r = -0.64 to 0.65), lordosis (r = -0.52 to 0.54), initial attainment rate (-0.64 to 0.73), sEMG amplitude ratios (r = -0.53) and sEMG amplitude changes (r = -0.48 to 0.59). Simple linear regression analysis of all significant relationships showed that these variables predict between 18% and 42% of the variance in IV-RoMmax. Conclusion. The study found moderately strong relationships between kinematic, morphological and muscle activity amplitude variables and the IV-RoMmax of lumbar motion segments. The effects of individual parameters, when combined, may be important when such inter-vertebral levels are considered to be sources of pain generation or targets for therapy. This is an important consideration for future non-specific low back pain (NSLBP) research, as any attempts to associate these parameters with low back pain (LBP), should also now take in to account the normal biomechanical behaviour of an individual’s lumbar spine. Indeed, consideration should be given to the interactions that exists between such parameters, and they should not be considered in isolation. Multivariate investigations in larger samples are warranted to determine the relative independent contribution of these variables to the IV-RoMmax

Chlamydia pneumoniae Infection of the Central Nervous System Worsens Experimental Allergic Encephalitis

Experimental allergic encephalitis (EAE) is considered by many to be a model for human multiple sclerosis. Intraperitoneal inoculation of mice with Chlamydia pneumoniae, after immunization with neural antigens, increased the severity of EAE. Accentuation of EAE required live infectious C. pneumoniae, and the severity of the disease was attenuated with antiinfective therapy. After immunization with neural antigens, systemic infection with C. pneumoniae led to the dissemination of the organism into the central nervous system (CNS) in mice with accentuated EAE. Inoculation with Chlamydia trachomatis did not worsen EAE and infectious organisms were not seen in the CNS. These observations suggest that dissemination of C. pneumoniae results in localized infection in CNS tissues in animals with EAE. We propose that infection of the CNS by C. pneumoniae can amplify the autoreactive pool of lymphocytes and regulate the expression of an autoimmune disease

Asymmetric Cyclopropanation of Styrene Catalyzed by Chiral Macrocyclic Iron(II) Complexes

Three chiral tetraaza macrocyclic ligands (4a−c) were synthesized by the cyclization reaction of diamines with dithioaldehydes. The iron(II) complexes of ligands 4a and 4c, as well as two chiral iron(II) porphyrin complexes, FeII(D4-TpAP) and Fe(α2β2-BNP), are efficient catalysts for the cyclopropanation of styrene with diazoacetate reagents. The cyclopropyl esters were produced with high diastereoselectivities and good yields. However, the enantioselectivities were modest at best. The rationalization of the stereoselectivity in these cyclopropanation reactions is presented. The results of a single-crystal X-ray analysis of the ligand 4a are also reported

What Sequences on High-Field MR Best Depict Temporal Resolution of Experimental ICH and Edema Formation in Mice?

Background and Purpose. Pilot study to examine the use of T1-, T2-, and T2*-weighted images for evaluating hematoma size and extent of edema in mouse brain at high field. Methods. Following collagenase-induced intracerebral hemorrhage, nine mice were imaged at 4.7 T using T1-, T2-, and T2*-weighted images for hematoma and edema quantitation on days 1, 3, 10, and 21 after surgery. Values were compared with morphometric analysis of cryosections at the time of final MR imaging. Results. For hematoma quantitation, the Spearman correlation coefficient (r) between T1 signal change and histology was 0.70 (P < 0.04) compared with r = 0.61 (P < 0.09) for T2*. The extent of perihematomal edema formation on cryosections was well reflected on T2 with r = 0.73 (P < 0.03). Conclusions. Within the limits of our pilot study, MR imaging on 4.7 T appears to approximate the temporal changes in hematoma and edema sizes in murine ICH well, thus laying the groundwork for longitudinal studies on hematoma resorption and edema formation