Chronic pelvic pain is a debilitating problem that afflicts 15% to 20% of women in the United States. Although more than 200,000 hysterectomies are performed annually for the treatment of chronic ...pelvic pain, previous studies indicate that 1 in 4 women undergo the discomfort and morbidity of hysterectomy without the relief of pain. The factors that predict treatment failure remain poorly characterized.
To describe the incidence of persistent pelvic pain 6 months following hysterectomy in women with chronic pelvic pain and determine whether a simple, self-reported measure of central sensitization is associated with a greater risk of persistent pelvic pain following hysterectomy.
We conducted a prospective, observational cohort study of women undergoing hysterectomy at an academic tertiary care center for a benign indication. Patients with preoperative chronic pelvic pain, defined as average pelvic pain ≥3 on a 0 to 10 numeric rating scale for >3 months before hysterectomy, were included in this analysis. The patients completed validated assessments of pain, anxiety, depression, and centralized pain (using the 2011 Fibromyalgia Survey Criteria, 0–31 points) preoperatively and 6 months after hysterectomy. The demographic information, surgical history, intraoperative findings, and surgical pathology were abstracted from the electronic medical records. Multivariate logistic regression was used to identify the independent predictors of persistent pelvic pain 6 months following hysterectomy, defined as <50% improvement in pelvic pain severity.
Among 176 participants with pelvic pain before hysterectomy, 126 (71.6%) were retained at 6 months, and 15 (11.9%) reported persistent pelvic pain. There was no difference in age (P=.46), race (P=.55), average pain severity during menses (P=.68), average overall pelvic pain (P=.10), or pain duration (P=.80) in those with and without persistent pelvic pain. Whereas intraoperative findings of endometriosis (P=.05) and uterine fibroids (P=.03) were associated with a higher incidence of persistent pain on univariate analysis, the surgical route (P=.46), pelvic adhesions (0.51), uterine weight (P=.66), and adenomyosis on histopathology (P=.27) were not related to the risk of persistent pain. Higher preoperative centralized pain scores (P=.01) but not depression (P=.64) or anxiety (P=.45) were more common in women with persistent pelvic pain. Multivariate logistic regression adjusting for age, preoperative pain severity, anxiety, depression, and operative findings of endometriosis and fibroids indicated that every 1-point increase in centralized pain before hysterectomy was associated with a 27% increase in the odds of persistent pelvic pain (odds ratio, 1.27; 95% confidence interval, 1.03–1.57) 6 months after surgery.
Although the majority of women with chronic pelvic pain report considerable improvement in pain following hysterectomy, higher degrees of centralized pain before hysterectomy is a robust predictor of persistent pelvic pain.
Endogenous opioid system dysfunction potentially contributes to chronic pain in fibromyalgia (FM), but it is unknown if this dysfunction is related to established neurobiological markers of ...hyperalgesia. We previously reported that µ-opioid receptor (MOR) availability was reduced in patients with FM as compared with healthy controls in several pain-processing brain regions. In the present study, we compared pain-evoked functional magnetic resonance imaging with endogenous MOR binding and clinical pain ratings in female opioid-naive patients with FM (n = 18) using whole-brain analyses and regions of interest from our previous research. Within antinociceptive brain regions, including the dorsolateral prefrontal cortex (r = 0.81, P < 0.001) and multiple regions of the anterior cingulate cortex (all r > 0.67; all P < 0.02), reduced MOR availability was associated with decreased pain-evoked neural activity. Additionally, reduced MOR availability was associated with lower brain activation in the nucleus accumbens (r = 0.47, P = 0.050). In many of these regions, pain-evoked activity and MOR binding potential were also associated with lower clinical affective pain ratings. These findings are the first to link endogenous opioid system tone to regional pain-evoked brain activity in a clinical pain population. Our data suggest that dysregulation of the endogenous opioid system in FM could lead to less excitation in antinociceptive brain regions by incoming noxious stimulation, resulting in the hyperalgesia and allodynia commonly observed in this population. We propose a conceptual model of affective pain dysregulation in FM.
It is unknown how chronic inflammation impacts the brain. Here, we examined whether higher levels of peripheral inflammation were associated with brain connectivity and structure in 54 rheumatoid ...arthritis patients using functional and structural MRI. We show that higher levels of inflammation are associated with more positive connections between the inferior parietal lobule (IPL), medial prefrontal cortex, and multiple brain networks, as well as reduced IPL grey matter, and that these patterns of connectivity predicted fatigue, pain and cognitive dysfunction. At a second scan 6 months later, some of the same patterns of connectivity were again associated with higher peripheral inflammation. A graph theoretical analysis of whole-brain functional connectivity revealed a pattern of connections spanning 49 regions, including the IPL and medial frontal cortex, that are associated with peripheral inflammation. These regions may play a critical role in transducing peripheral inflammatory signals to the central changes seen in rheumatoid arthritis.
Pelvic pain in women with endometriosis is attributed to neuroinflammation and afferent nociceptor nerves in ectopic and eutopic endometrium. The hypothesis that uterine nociception is activated by ...IL-1β, a prominent cytokine in endometriosis, was tested herein. Immunofluorescence histochemistry confirmed the presence of neurons in human endometrial tissue. Expression of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and their receptors in endometrial tissue and cells was validated by immunohistochemistry and Western blotting. Isolated endometrial stromal cells (ESCs) were subjected to dose-response and time-course experiments with IL-1β and kinase inhibitors to characterize in vitro biomarkers. Neural biomarkers were co-localized in endometrial nerve fibers. NGF, BDNF, and their receptors tropomyosin receptor kinase (Trk) A, TrkB, and p75 neurotrophin receptor were all expressed in primary ESCs. IL-1β stimulated higher TrkA/B expression in ESCs derived from endometriosis cases (2.8- ± 0.2-fold) than cells from controls (1.5- ± 0.3-fold, t-test, P < 0.01), effects that were mediated via the c-Jun N-terminal kinase (JNK) pathway. BDNF concentrations trended higher in peritoneal fluid of endometriosis cases but were not statistically different from controls (P = 0.16). The results support the hypothesis that NGF and BDNF and their corresponding receptors orchestrate innervation of the endometrium, which is augmented by IL-1β. We postulate that JNK inhibitors, such as SP600125, have the potential to reduce neuroinflammation in women with endometriosis.
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Neuroimaging has enhanced our understanding of the neural correlates of pain. Yet, how neural circuits interact and contribute to persistent pain remain largely unknown. Here, we investigate the ...mesoscale organization of the brain through intrinsic functional communities generated from resting state functional MRI data from two independent datasets, a discovery cohort of 43 Fibromyalgia (FM) patients and 20 healthy controls (HC) as well as a replication sample of 34 FM patients and 21 HC. Using normalized mutual information, we found that the global network architecture in chronic pain patients is less stable (more variable). Subsequent analyses of node community assignment revealed the composition of the communities differed between FM and HC. Furthermore, differences in network organization were associated with the changes in the composition of communities between patients with varying levels of clinical pain. Together, this work demonstrates that intrinsic network communities differ substantially between patients with FM and controls. These differences may represent a novel aspect of the pathophysiology of chronic nociplastic pain.
Stimulation of zona incerta in rodent models has been shown to modulate behavioral reactions to noxious stimuli. Sensory changes observed in Parkinsonian patients with subthalamic deep brain ...stimulation suggest that this effect is translatable to humans. Here, we utilized the serendipitous placement of subthalamic deep brain stimulation leads in 6 + 5 Parkinsonian patients to directly investigate the effects of zona incerta stimulation on human pain perception. We found that stimulation at 20 Hz, the physiological firing frequency of zona incerta, reduces experimental heat pain by a modest but significant amount, achieving a 30% reduction in one fifth of implants. Stimulation at higher frequencies did not modulate heat pain. Modulation was selective for heat pain and was not observed for warmth perception or pressure pain. These findings provide a mechanistic explanation of sensory changes seen in subthalamic deep brain stimulation patients and identify zona incerta as a potential target for neuromodulation of pain.
Pain with bladder filling remains an unexplained clinical presentation with limited treatment options. Here, we aim to establish the clinical significance of bladder filling pain using a standardized ...test and the associated neural signature. We studied individuals diagnosed with urologic chronic pelvic pain syndrome (UCPPS) recruited as part of the multidisciplinary approach to the study of chronic pelvic pain (MAPP) study. Patients with urologic chronic pelvic pain syndrome (N = 429) and pain-free controls (N = 72) underwent a test in which they consumed 350 mL of water and then reported pain across an hour-long period at baseline and 6 months. We used latent class trajectory models of these pain ratings to define UCPPS subtypes at both baseline and 6 months. Magnetic resonance imaging of the brain postconsumption was used to examine neurobiologic differences between the subtypes. Healthcare utilization and symptom flare-ups were assessed over the following 18 months. Two distinct UCPPS subtypes were identified, one showing substantial pain related to bladder filling and another with little to no pain throughout the test. These distinct subtypes were seen at both baseline and 6 month timepoints. The UCPPS subtype with bladder-filling pain (BFP+) had altered morphology and increased functional activity in brain areas involved in sensory and pain processing. Bladder-filling pain positive status predicted increased symptom flare-ups and healthcare utilization over the subsequent 18 months when controlling for symptom severity and a self-reported history of bladder-filling pain. These results both highlight the importance of assessing bladder filling pain in heterogeneous populations and demonstrate that persistent bladder-filling pain profoundly affects the brain.
Bladder inflammation frequently causes cystitis pain and lower urinary tract dysfunction (LUTD) such as urinary frequency and urgency. Although mast cells have been identified to play a critical role ...in bladder inflammation and pain, the role of mast cells in cystitis-associated LUTD has not been demonstrated. Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic and debilitating inflammatory condition of the urinary bladder characterized by the hallmark symptoms of pelvic pain and LUTD. In this study we investigated the role of mast cells in LUTD using a transgenic autoimmune cystitis model (URO-OVA) that reproduces many clinical correlates of IC/BPS. URO-OVA mice express the membrane form of the model antigen ovalbumin (OVA) as a self-antigen on the urothelium and develop bladder inflammation upon introduction of OVA-specific T cells. To investigate the role of mast cells, we crossed URO-OVA mice with mast cell-deficient KitW-sh mice to generate URO-OVA/KitW-sh mice that retained urothelial OVA expression but lacked endogenous mast cells. We compared URO-OVA mice with URO-OVA/KitW-sh mice with and without mast cell reconstitution in response to cystitis induction. URO-OVA mice developed profound bladder inflammation with increased mast cell counts and LUTD, including increased total number of voids, decreased mean volume voided per micturition, and decreased maximum volume voided per micturition, after cystitis induction. In contrast, similarly cystitis-induced URO-OVA/KitW-sh mice developed reduced bladder inflammation with no mast cells and LUTD detected. However, after mast cell reconstitution URO-OVA/KitW-sh mice restored the ability to develop bladder inflammation and LUTD following cystitis induction. We further treated URO-OVA mice with cromolyn, a mast cell membrane stabilizer, and found that cromolyn treatment reversed bladder inflammation and LUTD in the animal model. Our results provide direct evidence for the role of mast cells in cystitis-associated LUTD, supporting the use of mast cell inhibitors for treatment of certain forms of IC/BPS.
Highlights • We measured inflammatory responses in PBMCs to TLR stimulation in IC/BPS patients. • Greater responses to TLR-4 stimulation were associated with widespread pain. • Greater responses to ...TLR-4 stimulation were associated with comorbid conditions. • TLR-4 mediated inflammation may be a therapeutic target in unexplained chronic pain.
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