Does the Association Between Psychosocial Factors and Opioid Use After Elective Spine Surgery Differ by Sex in Older Adults?

Purpose: Psychosocial disorders have been linked to chronic postoperative opioid use and the development of postoperative pain. The potential interaction between sex and psychosocial factors with respect to opioid use after elective spine surgery in the elderly has not yet been evaluated. Our aim was to assess whether any observed association of anxiety or depression indicators with opioid consumption in the first 72 hours after elective spine surgery varies by sex in adults ≥65 years. Patients and Methods: Secondary analysis of a retrospective cohort of 647 elective spine surgeries performed at Brigham and Women's Hospital, July 1, 2015-March 15, 2017, in patients ≥65. Linear mixed-effects models were used to test whether history of anxiety, anxiolytic use, history of depression, and antidepressant use were associated with opioid consumption 0-24, 24-48, and 48-72 post surgery, and whether these potential associations differed by sex. Results: History of anxiety, anxiolytic use, history of depression, and antidepressant use were more common among women (51.3% of the sample). During the first 24 hours after surgery, men with a preoperative history of anxiety consumed an adjusted mean of 19.5 morphine milligram equivalents (MME) (99.6% CI: 8.1, 31.0) more than men without a history of anxiety; women with a history of anxiety only consumed an adjusted mean 2.9 MME (99.6% CI: -3.1, 8.9) more than women without a history of anxiety (P value for interaction between sex and history of anxiety <0.001). No other interactions were detected between sex and psychosocial factors with respect to opioid use after surgery. Conclusion: Secondary analysis of this retrospective cohort study found minimal evidence that the association between psychosocial factors and opioid consumption after elective spine surgery differs by sex in adults ≥65.

Sensory innervation of the nonspecialized connective tissues in the low back of the rat.

Chronic musculoskeletal pain, including low back pain, is a worldwide debilitating condition; however, the mechanisms that underlie its development remain poorly understood. Pathological neuroplastic changes in the sensory innervation of connective tissue may contribute to the development of nonspecific chronic low back pain. Progress in understanding such potentially important abnormalities is hampered by limited knowledge of connective tissue's normal sensory innervation. The goal of this study was to evaluate and quantify the sensory nerve fibers terminating within the nonspecialized connective tissues in the low back of the rat. With 3-dimensional reconstructions of thick (30-80 µm) tissue sections we have for the first time conclusively identified sensory nerve fiber terminations within the collagen matrix of connective tissue in the low back. Using dye labeling techniques with Fast Blue, presumptive dorsal root ganglia cells that innervate the low back were identified. Of the Fast Blue-labeled cells, 60-88% also expressed calcitonin gene-related peptide (CGRP) immunoreactivity. Based on the immunolabeling with CGRP and the approximate size of these nerve fibers (≤2 µm) we hypothesize that they are Aδ or C fibers and thus may play a role in the development of chronic pain.

Effect of restorative yoga vs. stretching on diurnal cortisol dynamics and psychosocial outcomes in individuals with the metabolic syndrome: the PRYSMS randomized controlled trial.

PURPOSE: Chronic stimulation and dysregulation of the neuroendocrine system by stress may cause metabolic abnormalities. We estimated how much cortisol and psychosocial outcomes improved with a restorative yoga (relaxation) versus a low impact stretching intervention for individuals with the metabolic syndrome. METHODS: We conducted a 1-year multi-center randomized controlled trial (6-month intervention and 6-month maintenance phase) of restorative yoga vs. stretching. Participants completed surveys to assess depression, social support, positive affect, and stress at baseline, 6 months and 12 months. For each assessment, we collected saliva at four points daily for three days and collected response to dexamethasone on the fourth day for analysis of diurnal cortisol dynamics. We analyzed our data using multivariate regression models, controlling for study site, medications (antidepressants, hormone therapy), body mass index, and baseline cortisol values. RESULTS: Psychosocial outcome measures were available for 171 study participants at baseline, 140 at 6 months, and 132 at 1 year. Complete cortisol data were available for 136 of 171 study participants (72 in restorative yoga and 64 in stretching) and were only available at baseline and 6 months. At 6 months, the stretching group had decreased cortisol at waking and bedtime compared to the restorative yoga group. The pattern of changes in stress mirrored this improvement, with the stretching group showing reductions in chronic stress severity and perseverative thoughts about their stress. Perceived stress decreased by 1.5 points (-0.4; 3.3, p=0.11) at 6 months, and by 2.0 points (0.1; 3.9, p=0.04) at 1 year in the stretching compared to restorative yoga groups. Post hoc analyses suggest that in the stretching group only, perceived increases in social support (particularly feelings of belonging), but not changes in stress were related to improved cortisol dynamics. CONCLUSIONS: We found significant decreases in salivary cortisol, chronic stress severity, and stress perception in the stretching group compared to the restorative yoga group. Group support during the interactive stretch classes may have contributed to these changes.

Stretching of the back improves gait, mechanical sensitivity and connective tissue inflammation in a rodent model.

The role played by nonspecialized connective tissues in chronic non-specific low back pain is not well understood. In a recent ultrasound study, human subjects with chronic low back pain had altered connective tissue structure compared to human subjects without low back pain, suggesting the presence of inflammation and/or fibrosis in the low back pain subjects. Mechanical input in the form of static tissue stretch has been shown in vitro and in vivo to have anti-inflammatory and anti-fibrotic effects. To better understand the pathophysiology of lumbar nonspecialized connective tissue as well as potential mechanisms underlying therapeutic effects of tissue stretch, we developed a carrageenan-induced inflammation model in the low back of a rodent. Induction of inflammation in the lumbar connective tissues resulted in altered gait, increased mechanical sensitivity of the tissues of the low back, and local macrophage infiltration. Mechanical input was then applied to this model as in vivo tissue stretch for 10 minutes twice a day for 12 days. In vivo tissue stretch mitigated the inflammation-induced changes leading to restored stride length and intrastep distance, decreased mechanical sensitivity of the back and reduced macrophage expression in the nonspecialized connective tissues of the low back. This study highlights the need for further investigation into the contribution of connective tissue to low back pain and the need for a better understanding of how interventions involving mechanical stretch could provide maximal therapeutic benefit. This tissue stretch research is relevant to body-based treatments such as yoga or massage, and to some stretch techniques used with physical therapy.