A comprehensive analysis of the triad of frailty, aging, and obesity in spine surgery: the risk analysis index predicted 30-day mortality with superior discrimination.

BACKGROUND CONTEXT: The United States has experienced substantial shifts in its population dynamics due to an aging population and increasing obesity rates. Nonetheless, there is limited data about the interplay between the triad of frailty, aging, and obesity. PURPOSE: To investigate discriminative thresholds and independent associations of the Risk Analysis Index (RAI), Modified Frailty Index-5 (mFI-5), and greater patient age. STUDY DESIGN: An observational retrospective cohort study. PATIENT SAMPLE: We analyzed 49,754 spine surgery patients from the American College of Surgeons National Surgical Quality Improvement Program database from 2012 to 2020. OUTCOME MEASURE: A total of 30-day postoperative mortality. METHODS: Using receiver operating characteristic (ROC) and multivariable (odds ratios [OR] and 95% confidence intervals [CI]) analyses, we compared the discriminative thresholds and independent associations of RAI, mFI-5, and greater patient age in elderly obese patients who underwent spine surgery. RESULTS: There were 49,754 spine surgery patients, with a median age of 71 years (IQR: 68-75), largely white (82.6%) and male (51.9%). The ROC analysis for 30-day postoperative mortality demonstrated superior discrimination for RAI (C-statistic 0.779, 95%CI 0.54-0.805) compared to mFI-5 (C-statistic 0.623, 95% CI 0.594-0.651) and greater patient age (C-statistic 0.627, 95% CI 0.598-0.656). Multivariable analyses revealed a dose-dependent association and a larger effect magnitude for RAI: frail patients OR: 19.52 (95% CI 18.29-20.82) and very frail patients OR: 65.81 (95% CI 62.32-69.50). A similar trend was observed in the interaction evaluating RAI-age-obesity (p<.001). CONCLUSION: Our study highlights a strong association between frailty and 30-day postoperative mortality in elderly obese spine patients, revealing a dose-dependent relationship. The RAI has superior discrimination than the mFI-5 and greater patient age in predicting 30-day postoperative mortality after spine surgery. Using the RAI in preoperative assessments may improve outcomes and help healthcare providers effectively communicate accurate surgical risks and potential benefits, set realistic recovery expectations, and enhances patient satisfaction.

Endocannabinoid Modulation of Nucleus Accumbens Microcircuitry and Terminal Dopamine Release.

The nucleus accumbens (NAc) is located in the ventromedial portion of the striatum and is vital to valence-based predictions and motivated action. The neural architecture of the NAc allows for complex interactions between various cell types that filter incoming and outgoing information. Dopamine (DA) input serves a crucial role in modulating NAc function, but the mechanisms that control terminal DA release and its effect on NAc neurons continues to be elucidated. The endocannabinoid (eCB) system has emerged as an important filter of neural circuitry within the NAc that locally shapes terminal DA release through various cell type- and site-specific actions. Here, we will discuss how eCB signaling modulates terminal DA release by shaping the activity patterns of NAc neurons and their afferent inputs. We then discuss recent technological advancements that are capable of dissecting how distinct cell types, their afferent projections, and local neuromodulators influence valence-based actions.

Evolution of in vivo dopamine monitoring techniques.

The brain dopamine system is central to numerous behavioral processes, including movement, learning, and motivation. Accordingly, disruptions of this neural system underlie numerous neurological and psychiatric disorders. Current understanding of how dopamine neurotransmission contributes to behavior and its dysfunction has been driven by technological advancements that permit spatiotemporally-defined measurements of dopaminergic signaling in behaving animals. In this review, we will discuss the evolution of in vivo neural monitoring technologies for measuring dopamine neuron function. We focus on the dopamine system for two reasons: (1) the central role of dopamine neurotransmission in normal behavior and disease, and (2) dopamine neuron measurements have long been at the forefront of in vivo neural monitoring technologies. We will provide a brief overview of standard techniques for monitoring dopamine function, including electrophysiology, microdialysis, and voltammetry. Then, we will discuss recent advancements in optical technologies using genetically-encoded fluorescent proteins (GEFPs), including a critical evaluation of their advantages and limitations.