Citations

BACKGROUND AND OBJECTIVES: Stereotactic procedures are used to manage a diverse set of patients across a variety of clinical contexts. The stereotactic devices and software used in these procedures vary between surgeons, but the fundamental principles that constitute safe and accurate execution do not. The aim of this work is to describe these principles to equip readers with a generalizable knowledge base to execute and understand stereotactic procedures. METHODS: A combination of a review of the literature and empirical experience from several experienced surgeons led to the creation of this work. Thus, this work is descriptive and qualitative by nature, and the literature is used to support instead of generate the ideas of this framework. RESULTS: The principles detailed in this work are categorized based on 5 clinical domains: imaging, registration, mechanical accuracy, target planning and adjustment, and trajectory planning and adjustment. Illustrations and tables are used throughout to convey the concepts in an efficient manner. CONCLUSION: Stereotactic procedures are complex, requiring a thorough understanding of each step of the workflow. The concepts described in this work enable functional neurosurgeons with the fundamental knowledge necessary to provide optimal patient care.

BACKGROUND AND OBJECTIVES: Identifying and characterizing sources of targeting error in stereotactic procedures is essential to maximizing accuracy, potentially improving surgical outcomes. We aim to describe a generic framework which characterizes sources of stereotactic inaccuracy. METHODS: We assembled a list of stereotactic systems: ROSA, Neuromate, Mazor Renaissance, ExcelsiusGPS, Cirq, STarFix (FHC), Nexframe, ClearPoint, CRW, and Leksell. We searched the literature for qualitative and quantitative work identifying and quantifying potential sources of inaccuracy and describing each system's implementation using Standards for Reporting Qualitative Research guidelines. Our literature search spanned 1969 to 2024, and various studies were included, with formats ranging from phantom studies to systematic reviews. Keyword searches were conducted, and the details about each system were used to create a framework for identifying and describing the unique targeting error profile of each system. RESULTS: We describe and illustrate the details of various sources of stereotactic inaccuracies and generate a framework to unify these sources into a single framework. This framework entails 5 domains: imaging, registration, mechanical accuracy, target planning and adjustment, and trajectory planning and adjustment. This framework was applied to 10 stereotactic systems. CONCLUSION: This framework provides a rubric to analyze the sources of error for any stereotactic system. Illustrations allow the reader to understand sources of error conceptually so that they may apply them to their practice.

We studied movement-associated spectral changes in human motor thalamus and observed focal increases in broadband power with movement. This biomarker may be used as a tool for intraoperative functional mapping, DBS targeting, and closed-loop device control.

Abstract Background Systemic arterial compliance and venous capacitance are typically impaired in patients with heart failure with preserved ejection fraction (HFpEF), contributing to hemodynamic congestion with stress. Sodium-glucose cotransporter-2 inhibitors (SGLT2i) reduce hemodynamic congestion and improve clinical outcomes in patients with HFpEF, but the mechanisms remain unclear. Purpose This study tested the hypothesis that SGLT2i dapagliflozin would improve systemic arterial compliance and venous capacitance during exercise in patients with HFpEF. Methods In this secondary analysis from the RCT trial, patients with HFpEF underwent invasive hemodynamic exercise testing at baseline and following treatment for 24 weeks with dapagliflozin or placebo. Patients were required to display pulmonary capillary wedge pressure (PCWP) ≥25 mmHg during exercise at the time of baseline evaluation. Radial artery pressure (BP) was measured continuously using a fluid-filled catheter with transformation to aortic pressure, central hemodynamics were measured using high-fidelity micromanometers, and stressed blood volume was estimated (eSBV) from hemodynamic indices fit to a comprehensive cardiovascular model. Results A total of 37 patients completed the study and were included in this analysis (21 dapagliflozin and 16 placebo). Patients were predominantly women (24/37, 65%) and older (mean age 67 years). There was no statistically significant effect of dapagliflozin on resting BP, but dapagliflozin reduced systolic BP during peak exercise (estimated treatment difference [ETD], -18.8 mmHg, 95% CI: -33.9 to -3.7, P=0.016) (Figure 1A). Dapagliflozin improved exertional total arterial compliance (TAC) index (ETD, 0.06 mL/mmHg/m2, 95% CI: 0.003 to 0.11, P=0.039) (Figure 1B) and aortic root characteristic impedance (ETD, -2.6 mmHg/ml*sec, 95% CI: -5.1 to -0.03, P=0.048) during peak exercise, with no significant effect on systemic vascular resistance. Dapagliflozin reduced eSBV at rest and during peak exercise (ETD, -292 mmHg, 95% CI: -530 to -53, P=0.018) (Figure 1C), and improved venous capacitance evidenced by a decline in ratio of eSBV to total blood volume (ETD, -7.3%, 95% CI -13.3 to -1.3, P=0.020). Each of these effects of dapagliflozin during peak exercise were also observed during matched 20W exercise intensity. Improvements in TAC index and eSBV were correlated with decreases in body weight, and reduction in systolic BP with treatment was correlated with the change in eSBV during exercise (r=0.40, P=0.019) (Figure 2A). Decreases in BP were correlated with reduction in PCWP during exercise (r=0.56, P<0.001) (Figure 2B). Conclusion In patients with HFpEF, treatment with dapagliflozin improved systemic arterial compliance and venous capacitance during exercise, while reducing aortic characteristic impedance, suggesting a reduction in arterial wall stiffness. These vascular effects may partially explain the clinical benefits with SGLT2i in HFpEF.

Abstract Background Excess fat, particularly visceral fat, plays an important role in the development of heart failure with preserved ejection fraction (HFpEF). Sodium glucose cotransporter-2 inhibitors improve hemodynamics, reduce symptom severity, and decrease risk of hospitalization, but their impact on body composition, as well as potential relationships between changes in body composition and hemodynamic effects, are unknown in HFpEF. Purpose Evaluate the effect of dapagliflozin on body and blood composition and examined the potential correlation of such changes on cardiac hemodynamics. Methods The CAMEO-DAPA trial, a single-center, double-blind, randomized, placebo-controlled study, showed that 24 weeks of dapagliflozin reduced resting and exercise pulmonary capillary wedge pressures (PCWP) in patients with HFpEF. This prespecified secondary analysis reports the effects of dapagliflozin on body composition using dual energy x-ray absorptiometry (DEXA), blood composition (radiolabeled iodinated albumin), and cardiac hemodynamics using high-fidelity micromanometers. Analysis was performed based on the intention-to-treat. Relative change was calculated by dividing the absolute change on the baseline value. Results Overall, 37 patients (67 years, 65% women, 70% with obesity, 27% overweight) completed the trial. As compared with baseline, dapagliflozin decreased total body fat compared with placebo [mean (SD) absolute change: -2.29 (2.94) kg vs -0.32 (1.84) in placebo, p=0.03; relative change: -4.6% (5.4) vs -0.8% (4.3), p=0.02], Figure 1. This was primarily due to greater loss of upper body trunk fat [absolute change: -1.53 (1.70) kg vs +0.31 (0.99) in placebo, p<.001; relative change: -5.2% (5.6) vs +1.1% (4.1), p<.001], Figure 1. Reductions in trunk fat were correlated with decreases in PCWP (r=0.41, p=0.03), Figure 2. Total body fat-free mass (FFM) tended to decrease in the dapagliflozin group [absolute change: -0.63 (1.85) kg vs +0.34 (1.76), p=0.12]; reductions in leg, android, and gynoid FFM were all greater than placebo (p<0.05). Dapagliflozin reduced plasma volume [absolute change: -170 (343) ml vs +112 (346), p=0.02] compared with placebo, and the decrease in plasma volume was correlated with the reduction in FFM (r=0.47, p=0.006), Figure 2. Treatment with dapagliflozin had no effect on resting metabolic rate but was associated with modest reduction in bone mineral content [-16 (47) g vs +26 (61), p=0.03]. Conclusions In patients with HFpEF, dapagliflozin decreases body fat, particularly trunk fat, suggesting greater effect on visceral adipose, which is correlated with favorable hemodynamic effects. Dapagliflozin also tends to reduce FFM, which may relate to reduction in total body water with or without reduction is muscle mass, in tandem with modest decreases in bone mineral content.Figure 1:Relative change in fat massFigure 2

Background: Serum C-peptide concentration is often utilized for diagnostic, prognostic, or therapeutic assessment in diabetes mellitus. However, there are limited clinical data regarding diagnostic and predictive value of C-peptide measured during hospitalizations for hyperglycemia. Materials and Methods: Adults admitted to Mayo Clinic inpatient facilities due to an acute hyperglycemic emergency between January 2017 and November 2022 were included in our study. Predictive capacity of C-peptide for discontinuation of therapeutic insulin was examined in the entire cohort and the subgroup of non-autoimmune non-pancreatitis diabetes (NANP-DM). Results: We included 187 patients (63 women) in our study. During hospitalization, patients with type 1 diabetes antibodies displayed diminished serum C-peptide concentration ( P = 0.014), correlating inversely with subsequent hemoglobin A1c% [ r = (−0.22), P = 0.005]. Initial C-peptide concentrations did not differ between patients requiring insulin therapy during follow-up and those who did not ( P = 0.16). C-peptide concentrations showed limited predictive capacity for achieving glycemic control. Subgroup analyses in NANP-DM exhibited similar limited capacity for anticipating therapeutic insulin needs and achieving glycemic controls. Discussion: C-peptide concentration did not exhibit a robust predictive capability for future need of insulin therapy and achieving glycemic control, limiting its utility in clinical practice within inpatient settings.

OBJECTIVE Stereoelectroencephalography (SEEG) has become the predominant method for intracranial seizure localization. When imaging, semiology, and scalp EEG findings are not in full agreement or definitively localizing, implanted SEEG recordings are used to test candidate seizure onset zones (SOZs). Discovered SOZs may then be targeted for resection, laser ablation, or neurostimulation. If an SOZ is eloquent, resection and ablation are both contraindicated, so identifying functional representation is crucial for therapeutic decision-making. The authors present a novel functional brain mapping technique that utilizes task-based electrophysiological changes in SEEG during behavioral tasks and test this in pediatric and adult patients. METHODS SEEG was recorded in 20 patients with epilepsy who ranged in age from 6 to 39 years (12 female, 18 of 20 patients < 21 years of age) and underwent implanted monitoring to identify seizure onset. Each performed 1) visually cued simple repetitive movements of the hand, foot, or tongue while electromyography was recorded; and 2) simple picture-naming or verb-generation speech tasks while audio was recorded. Broadband changes in the power spectrum of the SEEG recording were compared between behavior and rest. RESULTS Electrophysiological functional mapping of movement and/or speech areas was completed in all 20 patients. Eloquent representation was identified in both cortex and white matter and generally corresponded to classically described functional anatomical organization as well as other clinical mapping results. Robust maps of brain activity were identified in healthy brain, regions of developmental or acquired structural abnormality, and SOZs. CONCLUSIONS Task-based electrophysiological mapping using broadband changes in the SEEG signal reliably identifies movement and speech representation in pediatric and adult epilepsy patients.