Obesity and Postoperative Cognitive Dysfunction: A Curious Association.

Postoperative cognitive dysfunction (POCD) is a medical condition that impacts cognitive function after surgery, particularly major procedures. Patients with POCD may experience physical symptoms, such as depression, anxiety, and fatigue, severely undermining their quality of life. Research establishes the connection between obesity and cognitive dysfunction since patients diagnosed with obesity are more susceptible to cognitive decline. Although obesity poses a significant risk factor for cognitive impairment, the link between obesity and POCD is still inadequately understood. Therefore, this systematic review explores the correlation between obesity and POCD by detailing potential mechanisms underlying this relationship and identifying areas for further research. Following the guidelines for systematic reviews, we conducted a literature search between August 2022 and April 2023, which identified studies with a substantial number of patients with POCD after major surgeries, including coronary artery bypass grafting, gastrointestinal procedures, cholecystectomy, and carotid endarterectomy. Our findings also demonstrated that a significant percentage of these had obesity, which was statistically significant as a risk factor for cognitive decline. Pathological processes, such as changes in vascular endothelium integrity, systemic inflammation induced by obesity, and apolipoprotein E-epsilon-4 expression, have been identified to contribute to POCD after surgery. Despite the promising results, there remains a gap in the literature. Thus, it is crucial to investigate the relationship between obesity and POCD further, uncover more potential underlying pathophysiological processes, and identify therapeutic targets. These measures would enable healthcare practitioners to prevent or reduce cognitive dysfunction associated with obesity in surgical patients.

Inhibition of casein kinase 1 δ/ε improves cognitive performance in adult C57BL/6J mice.

Time-of-day effects have been noted in a wide variety of cognitive behavioral tests, and perturbation of the circadian system, either at the level of the master clock in the SCN or downstream, impairs hippocampus-dependent learning and memory. A number of kinases, including the serine-threonine casein kinase 1 (CK1) isoforms CK1δ/ε, regulate the timing of the circadian period through post-translational modification of clock proteins. Modulation of these circadian kinases presents a novel treatment direction for cognitive deficits through circadian modulation. Here, we tested the potential for PF-670462, a small molecule inhibitor of CK1δ/ε, to improve cognitive performance in C57BL/6J mice in an array of behavioral tests. Compared to vehicle-treated mice tested at the same time of the circadian day, mice treated with PF-670462 displayed better recall of contextual fear conditioning, made fewer working memory errors in the radial arm water maze, and trained more efficiently in the Morris Water Maze. These benefits were accompanied by increased expression of activity-regulated cytoskeleton-associated protein (Arc) in the amygdala in response to an acute learning paradigm. Our results suggest the potential utility of CK1δ/ε inhibition in improving time-of-day cognitive performance.

Establishing benchmarks for the volume-outcome relationship for common lumbar spine surgical procedures.

BACKGROUND CONTEXT: The importance of surgeon volume as a quality measure has been defined for a number of surgical specialties. Meaningful procedural volume benchmarks have not been established, however, particularly with respect to lumbar spine surgery. PURPOSE: We aimed to establish surgeon volume benchmarks for the performance of four common lumbar spine surgical procedures (discectomy, decompression, lumbar interbody fusion, and lumbar posterolateral fusion). STUDY DESIGN: A retrospective review of data in the Florida Statewide Inpatient Dataset (2011-2014) was carried out. PATIENT SAMPLE: Patients who underwent one of the four lumbar spine surgical procedures under study comprised the study sample. OUTCOME MEASURE: The development of a complication or hospital readmission within 90 days of the surgical procedure was the surgical outcome. METHODS: For each specific procedure, individual surgeon volume was separately plotted against the number of complications and readmissions in a spline analysis that adjusted for co-variates. Spline cut-points were used to create a categorical variable of procedure volume for each individual procedure. Log-binomial regression analysis was then separately performed using the categorical volume-outcome metric for each individual procedure and for the outcomes of 90-day complications and 90-day readmissions. RESULTS: In all, 187,185 spine surgical procedures met inclusion criteria, performed by 5,514 different surgeons at 178 hospitals. Spline analysis determined that the procedure volume cut-point was 25 for decompressions, 40 for discectomy, 43 for interbody fusion, and 35 for posterolateral fusions. For surgeons who failed to meet the volume metric, there was a 63% increase in the risk of complications following decompressions, a 56% increase in the risk of complications following discectomy, a 15% increase in the risk of complications following lumbar interbody fusions, and a 47% increase in the risk of complications following posterolateral fusions. Findings were similar for readmission measures. CONCLUSIONS: The results of this work allow us to identify meaningful volume-based benchmarks for the performance of common lumbar spine surgical procedures including decompression, discectomy, and fusion-based procedures. Based on our determinations, readily achievable goals for individual surgeons would approximate an average of four discectomy and lumbar interbody fusion procedures per month, three posterolateral lumbar fusions per month, and at least one decompression surgery every other week.

Biomechanical Comparison of Spinopelvic Fixation Constructs: Iliac Screw Versus S2-Alar-Iliac Screw.

STUDY DESIGN: Biomechanical cadaveric study. OBJECTIVE: To compare the biomechanical properties of the iliac and S2-Alar-Iliac (S2AI) screw in a similar spinopelvic fixation construct. SUMMARY OF BACKGROUND DATA: Spinopelvic fixation is used in the correction of pelvic obliquity, high-grade spondylolisthesis, and long spinal fusions. With the development of pedicle screw fixation, the iliac screw has been used as an anchor point to the pelvis. The associated morbidity with this fixation has led to the development of the S2AI screw. Many studies have examined the biomechanical properties of iliac and S2AI screws; however, a direct comparison has not been performed. METHODS: Eight cadaveric spines were instrumented with pedicle screws bilaterally at L5 and S1. Four specimens were further instrumented with iliac screws placed with a starting point at the posterior superior iliac spine, and four specimens were instrumented with S2AI screws placed with a starting point 1 mm inferolateral to the S1 foramen. Screws were connected with 6.35 mm rods. Subfailure testing was performed by loading at 1°/second to a torque of 10 Nm in four directions: left bending, right bending, extension, and flexion. Specimens then underwent a monotonic load to failure under flexion at a rate of 1°/second. RESULTS: There were no significant differences for torsional stiffness in extension, flexion, left bending, or right bending between S2AI and iliac screw constructs. There were no significant differences in S2AI versus iliac screws for failure torque (30.9 ± 12.00 Nm vs. 22.61 ± 6.25 Nm) and yield torque (11.86 ± 0.41 Nm vs. 12.01 ± 1.70 Nm). CONCLUSION: Iliac screws have been associated with increased dissection, wound complications, an additional construct failure point, and hardware prominence. The S2AI screw was developed as an alternative and has been associated with less morbidity. The iliac and S2AI screw demonstrate no statistical difference in stiffness and load-to-failure in a spinopelvic fixation model. LEVEL OF EVIDENCE: Level V.