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BackgroundOne key contributor to lumbar stenosis is thickening of the ligamentum flavum (LF), a process still poorly understood. Wild-type transthyretin amyloid (ATTRwt) has been found in the LF of patients undergoing decompression surgery, suggesting that amyloid may play a role. However, it is unclear whether within patients harboring ATTRwt, the amount of amyloid is associated with LF thickness.MethodsFrom an initial cohort of 324 consecutive lumbar stenosis patients whose LF specimens from decompression surgery were sent for analysis (2018-2019), 33 patients met the following criteria: (1) Congo red-positive amyloid in the LF; (2) ATTRwt by mass spectrometry-based proteomics; and (3) an available preoperative MRI. Histological specimens were digitized, and amyloid load quantified through Trainable Weka Segmentation (TWS) machine learning. LF thicknesses were manually measured on axial T2-weighted preoperative MRI scans at each lumbar level, L1-S1. The sum of thicknesses at every lumbar LF level (L1-S1) equals “lumbar LF burden.”ResultsPatients had a mean age of 72.7 years (range 59-87), were mostly male (61%) and white (82%); and predominantly had surgery at L4-L5 levels (73%). Amyloid load was positively correlated with LF thickness (R=0.345, p=0.0492) at the levels of surgical decompression. Furthermore, amyloid load was positively correlated with lumbar LF burden (R=0.383, p=0.0279).ConclusionsAmyloid load is positively correlated with LF thickness and lumbar LF burden across all lumbar levels, in a dose-dependent manner. Further studies are needed to validate these findings, uncover the underlying pathophysiology, and pave the way towards using therapies that slow LF thickening.

Neuroimaging is a powerful tool to investigate potential associations between chronic pain and brain structure. However, the proliferation of studies across diverse chronic pain syndromes and heterogeneous results challenges data integration and interpretation. We conducted a preregistered anatomical likelihood estimate meta-analysis on structural magnetic imaging studies comparing patients with chronic pain and healthy controls. Specifically, we investigated a broad range of measures of brain structure as well as specific alterations in gray matter and cortical thickness. A total of 7849 abstracts of experiments published between January 1, 1990, and April 26, 2021, were identified from 8 databases and evaluated by 2 independent reviewers. Overall, 103 experiments with a total of 5075 participants met the preregistered inclusion criteria. After correction for multiple comparisons using the gold-standard family-wise error correction ( P < 0.05), no significant differences associated with chronic pain were found. However, exploratory analyses using threshold-free cluster enhancement revealed several spatially distributed clusters showing structural alterations in chronic pain. Most of the clusters coincided with regions implicated in nociceptive processing including the amygdala, thalamus, hippocampus, insula, anterior cingulate cortex, and inferior frontal gyrus. Taken together, these results suggest that chronic pain is associated with subtle, spatially distributed alterations of brain structure.

Background The global burden of neurosurgical disease is substantial, particularly in low- and middle-income countries (LMICs). Medical conferences are important in connecting those from LMICs to those from high-income countries for support and serve as an educational and networking tool. In this study, we sought to quantitatively assess the incorporation of global neurosurgery topics in international conferences related to the neurosurgical specialty. Methods A database of major international neurosurgical conferences, from the conference of a group of 9 major neurosurgical societies, that had global neurosurgery featured from 2015 to 2020 was created. We then did a retrospective analysis to study the characteristics of these conferences ranging from geographic location to number to different components of the conferences. Results There was an increase in the number of conferences with global neurosurgery since 2015. This, in addition to the occurrence of 3 wholly global neurosurgery-related conferences in recent years, is promising and suggests growth in the field. However, 52.6% of conferences took place in North American or European countries, the majority of which were high-income countries. Furthermore, a majority of the presence of global neurosurgery was in the form of individual talks (54.5%) as opposed to plenaries or sessions. Conclusions The preponderance of conferences in North America and Europe can pose barriers for those from LMICs including travel time, expenses, and visa problems. As global neurosurgery becomes an increasing part of the global health movement, we hope that these barriers are addressed. Conferences may become an even stronger tool to promote equity in neurosurgical education and practice.

Heterogeneity in physician practice within nursing homes (NHs) may explain variations in quality. However, data on physician practice organization in NHs are hard to obtain. We characterized NH physician practice using two claims-based measures: (a) concentration of NH care among physicians (measured by Herfindahl–Hirschman index of visits); and (b) physician NH practice specialization (measured by the proportion of a physician’s visits to NHs). We examined the relationship between the measures and NH administrator perceptions of physician practice reported in the Shaping Long-Term Care in America (SLTCA) Survey. All 2011 Part B claims from 13,718 physicians who treated Medicare fee-for-service patients in 2,095 NHs in the SLTCA survey were analyzed. The median Herfindahl–Hirschman index was 0.44 (interquartile range [IQR] 0.28-0.70), and the median specialization was 38.1% (IQR 19.9% to 60.9%). NHs with higher physician specialization reported more frequent physician participation in care coordination activities. Claims-based measures could inform the study of NH physician practice.

Intracranial hemorrhage (ICH) in patients with left ventricular assist devices (LVAD) is a devastating complication. Demographic risk factors for ICH in LVAD patients are defined, however anatomic predispositions to ICH are unknown. We sought to interrogate intracranial radiographic risk factors for ICH in LVAD patients.We reviewed 440 patients who received an LVAD from 2008-2021. We selected patients with CT scans of the head either before or after LVAD placement, but typically within 5 years. 288 patients (21 ICH, 267 Control) with imaging were included. A detailed chart review was performed on demographics, radiographic features, and management.The incidence of ICH in our total cohort was 8.6% (38/440). The presence of pump thrombosis (p=0.001), driveline infection (p=0.034), other hemorrhage (p=0.001), or previous placement of a cardio-defibrillator (p=.003) was associated with increased risk for ICH. An analysis of imaging revealed that the presence of a mass (p=0.006), vascular pathology (p=0.001), and microangiopathy (p=0.04) was significantly associated with ICH in LVAD patients. These radiographic features were validated with a multivariate logistic regression which confirmed presence of a mass (aOR 332.1, 95% CI: 14.7-7485.1, p0.001), vascular pathology (aOR 69.7, 95% CI: 1.8-2658.8, p=0.022), and microangiopathy (aOR 6.5, 95% CI: 1.1-37.6, p=0.035) were independently associated with ICH.Radiographic evidence of microangiopathy, intracranial mass, and vascular pathology are independent risk factors for ICH which are readily identified by imaging. We advocate that CT imaging be used to further stratify patients at highest risk of ICH during treatment with an LVAD.

Characterizing a reliable, pain-related neural signature is critical for translational applications. Many prior fMRI studies have examined acute nociceptive pain-related brain activation in healthy participants. However, synthesizing these data to identify convergent patterns of activation can be challenging due to the heterogeneity of experimental designs and samples. To address this challenge, we conducted a comprehensive meta-analysis of fMRI studies of stimulus-induced pain in healthy participants. Following pre-registration, two independent reviewers evaluated 4,927 abstracts returned from a search of 8 databases, with 222 fMRI experiments meeting inclusion criteria. We analyzed these experiments using Activation Likelihood Estimation with rigorous type I error control (voxel height p < 0.001, cluster p < 0.05 FWE-corrected) and found a convergent, largely bilateral pattern of pain-related activation in the secondary somatosensory cortex, insula, midcingulate cortex, and thalamus. Notably, these regions were consistently recruited regardless of stimulation technique, location of induction, and participant sex. These findings suggest a highly-conserved core set of pain-related brain areas, encouraging applications as a biomarker for novel therapeutics targeting acute nociceptive pain.

This meta-analysis assesses differential brain responses to noxious stimuli in patients with chronic pain using functional magnetic resonance imaging while adhering to current best practices for neuroimaging meta-analyses., Key Points Question Do the brains of patients with chronic pain respond differently to noxious stimuli? Findings This systematic review and meta-analysis of 37 experiments from 29 unique articles including 944 participants found that patients with chronic pain were not associated with significant differential responses to noxious stimuli that induce pain compared with healthy controls. Meaning Chronic pain does not appear to be associated with consistent marked alterations in the brain’s response to noxious stimuli., Importance Functional neuroimaging is a valuable tool for understanding how patients with chronic pain respond to painful stimuli. However, past studies have reported heterogenous results, highlighting opportunities for a quantitative meta-analysis to integrate existing data and delineate consistent associations across studies. Objective To identify differential brain responses to noxious stimuli in patients with chronic pain using functional magnetic resonance imaging (fMRI) while adhering to current best practices for neuroimaging meta-analyses. Data Sources All fMRI experiments published from January 1, 1990, to May 28, 2019, were identified in a literature search of PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, PsycINFO, and SCOPUS. Study Selection Experiments comparing brain responses to noxious stimuli in fMRI between patients and controls were selected if they reported whole-brain results, included at least 10 patients and 10 healthy control participants, and used adequate statistical thresholding (voxel-height P