2019 News from the Research Team Articles

May 2019

Article Summary by IPPS Research Committee Members Dr. Laura Payne

Pathophysiology of Endometriosis-Associated Pain: A Review of Pelvic and Central Nervous System Mechanisms

Lydia Coxon, Andrew W. Horne, and Katy Vincent
Epub 2018 Feb 15

Summary: Pain associated with endometriosis may arise from a number of potential mechanisms. Peripheral pain mechanisms, such as nerve fibers and inflammatory markers, are very likely involved in generating pain in endometriosis. However, results have been mixed with some studies finding more nerve fibers in peritoneal endometriotic lesions in women with endometriosis compared to controls, and other studies showing no differences. Few studies have examined the relationship of nerve fibers to self-reported pain, but existing research suggests a positive correlation between nerve growth/nerve fiber density and pain symptoms. Inflammatory markers may also be elevated in the peritoneal fluid of women with endometriosis. Central changes in structure and functional connectivity of brain regions may also be evident in women with endometriosis; however, these alterations appear to be related to reported pain experience more than endometriosis itself. The relationship between HPA axis functioning and endometriosis is more complex, but limited existing data suggests self-reported pain may be the biggest predictor of salivary cortisol levels. Depression, anxiety, and pain catastrophizing is also elevated in women with endometriosis, which likely contributes to ongoing pain and disability, while more research on autonomic nervous system functioning is needed in this population to be able to generate conclusions about sympathetic and parasympathetic functioning. Given the multiple potential causes and factors contributing to pain in this population, stratifying patients with endometriosis based on pain characteristics may help inform both research and treatment approaches.

Conclusion: Endometriosis-associated pain likely stems from a variety of factors, including peripheral and central mechanisms, and shares many similarities with chronic pain conditions.

April 2019

Article Summary by IPPS Research Committee Members Dr. Georgine Lamvu and Dr. Sawsan As-Sanie

Association of Early Physical Therapy with Long-Term Opioid Use Among Opioid-Naïve Patients with Musculoskeletal Pain

Sun E, Moshfegh J, Rishel C, Cook CE, Goode A, George S
JAMA Network Open. 2018; 1(8):e185909

Summary: This study was conducted to determine if early physical therapy(PT) is associated with reduced opioid use in patients with musculoskeletal diagnoses of shoulder, neck, knee or low back pain. The study was a cross-sectional analysis of health care insurance claims data between 2007 and 2015. The study sample was composed of 88,985 patients aged 18-64, who were newly diagnosed with these disorders and were opioid-naïve. Researchers then evaluated claims data to determine whether patients who received early PT (within 90 days of diagnosis) were more, or less likely to use opioids. Patients who received early PT, compared with those who did not, were10% less likely to use long term opioids if they had shoulder, neck, knee and low back pain. Of those who received PT and started opioids, patients tended to use 5-10% less opioids, when compared with patients who used opioids without PT. These results are largely in line with other research confirming similar findings in patients with low back pain and neck pain. The study was limited by its observational, retrospective nature and the inability to specify what type of PT patients received.

Conclusion: Early PT could play a role in reducing the risk of transitioning to chronic long-term opioid use for patients with shoulder, neck, knee and low back pain. Indices of pain processing do not differ in women with PDM compared to healthy women, but other psychosocial factors, such as depression and anxiety, may play an important role in central sensitization in PDM.

March 2019

Article Summary by IPPS Research Committee Member Dr. Laura Payne

Behavioral and Neural Responses to Aversive Visceral Stimuli in Women with Primary Dysmenorrhea

Bettina Böttcher, Elke R. Gizewski, Christian Siedentopf, Ruth Steiger, Michael Verius, David Riedl, Anja Ischebeck, Julia Schmid, Ludwig Wildt, and Sigrid Elsenbruch
European Journal of Pain, 2019

Summary: Women with primary dysmenorrhea (PDM) often show enhanced pain sensitivity to painful stimuli both on and outside areas of referred pain, suggesting the role of central sensitization in the pathophysiology of PDM. However, much less is known about the relationship of PDM and visceral pain stimuli, and how pain responses interact with endocrine and neural functioning. The current study compared 23 women with PDM and 23 healthy women. PDM was defined as self-reported menstrual pain of 54mm or higher on a 0 – 100mm visual analog scale of pain intensity. All participants completed the study at some point within days 1 – 5 of the menstrual cycle. Blood and urine samples were collected for analysis of luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone. Participants underwent a series of painful rectal distensions before and during a structural MRI and fMRI. Results indicated no group differences in pain threshold during rectal distension, as well as no group differences in neural activation in response to painful stimuli. These results contradict previous findings that have shown group differences in visceral pain thresholds and activation/deactivation of brain regions involved in pain processing. However, the authors acknowledge that their sample may have not had sufficient statistical power to test results. They conclude that PDM may not show a generalized interoceptive sensitization, particularly if there are no other psychological comorbidities present.

Conclusion: Indices of pain processing do not differ in women with PDM compared to healthy women, but other psychosocial factors, such as depression and anxiety, may play an important role in central sensitization in PDM.

February 2019

Article Summary by IPPS Research Committee Member Dr. Laura Payne

What Women Say About Their Dysmenorrhea: A Qualitative Thematic Analysis

Chen X. Chen, Claire B. Draucker, and Janet S. Carpenter
BMC Women’s Health, 2018

Summary: Dysmenorrhea (menstrual pain) is very common among reproductive-age women, and although many studies have focused on dysmenorrhea, very little is known about women’s individual experiences. This study aimed to better understand women’s thoughts and experiences related to dysmenorrhea through qualitative analysis in order to provide more personalized treatment approaches. Participants for the study were 762 women at least 18 years old who were living in the United States and reported having menstrual pain the last 6 months. An open-ended question was used for analysis: “Please write anything else you’d like to share with us about your dysmenorrhea experience.” Data were analyzed using a process to identify specific themes and patterns. Results indicated that 6 themes emerged, “(1) The dysmenorrhea symptom experience varied among women; (2) The dysmenorrhea symptom experience varied across time, (3) A variety of factors influenced the dysmenorrhea symptom experience, (4) Dysmenorrhea symptoms could have a negative impact on the women’s daily lives, (5) Dysmenorrhea was not seen as a legitimate health issue by the women, health care providers, or society, and (6) Treatment for women with dysmenorrhea varied in acceptability and effectiveness.” The authors suggest that these results indicate the need for improved assessment of dysmenorrhea symptoms, tracking of dysmenorrhea symptoms over time, and personalized approaches to interventions. Study findings may be limited by a recall bias in participants reporting past experiences of menstrual pain, as well as a sample selection bias by using the Internet for the survey.

Conclusion: Women have varied experiences with dysmenorrhea and personalized approaches are needed to address this significant problem.