Association of chronic pelvic pain and endometriosis with signs of sensitization and myofascial pain

Abstract

Objective: To evaluate sensitization, myofascial trigger points, and quality of life in women with chronic pelvic pain with and without endometriosis.

Methods: A cross-sectional prospective study of women aged 18-50 years with pain suggestive of endometriosis and healthy, pain-free volunteers without a history of endometriosis. Patients underwent a physiatric neuromusculoskeletal assessment of clinical signs of sensitization and myofascial trigger points in the abdominopelvic region. Pain symptoms, psychosocial, and quality-of-life measures were also assessed. All participants with pain underwent laparoscopic excision of suspicious lesions to confirm endometriosis diagnosis by histologic evaluation.

Results: Patients included 18 with current, biopsy-proven endometriosis, 11 with pain only, and 20 healthy volunteers. The prevalence of sensitization as measured by regional allodynia and hyperalgesia was similar in both pain groups (83 and 82%) but much lower among healthy volunteers (15%, P<.001). Nearly all women with pain had myofascial trigger points (94 and 91%). Adjusting for study group, those with high anxiety (odds ratio [OR] 1.05, 95% confidence interval [CI] 1.004-1.099, P=.031) and depression (OR 1.06, 95% CI 1.005-1.113, P=.032) scores were more likely to have sensitization. Pain patients with any history of endometriosis had the highest proportion of sensitization compared with the others (87% compared with 67% compared with 15%; P<.001). Adjusting for any history of endometriosis, those with myofascial trigger points were most likely sensitized (OR 9.41, 95% CI 1.77-50.08, P=.009).

Conclusion: Sensitization and myofascial trigger points were common in women with pain regardless of whether they had endometriosis at surgery. Those with any history of endometriosis were most likely to have sensitization. Traditional methods of classifying endometriosis-associated pain based on disease, duration, and anatomy are inadequate and should be replaced by a mechanism-based evaluation, as our study illustrates.

Clinical trial registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00073801.

Level of evidence: II.

Figures

Figure 1

Study design. Those with chronic pelvic pain underwent laparoscopic surgery to assess for current diagnosis of endometriosis (n = 18) or no endometriosis (n = 11) confirmed on biopsy of all suspicious lesions. Of those without histology-confirmed endometriosis at study laparoscopy, six had a history of endometriosis (three had adhesions, one had fibroids, and two were without surgical findings). Those without prior history of endometriosis included: two women with adhesions, two without findings at surgery (one of these reported a history of abuse; the other had a vagal response to intraoperative bowel manipulation), and one had an urachal cyst and possible interstitial cystitis.

Figure 2

Duke Health Profile scores by study group. A. A trend of worse scores was observed in current biopsy-proven endometriosis followed by pain only, then healthy volunteers for depression and anxiety (P<.001 for both). B. General health scores were statistically significantly different among all three groups (P<.001); however, social health and self-esteem scores were not (P=1.0 and P=0.6, respectively). Women with pain only had worse general (P=.043) and social (P =.003) health with lower self-esteem (P=.009) than women with current biopsy-proven endometriosis. C. Current biopsy-proven endometriosis patients were most likely to indicate achiness (P <.001). D. Current biopsy-proven endometriosis were most likely to indicate tiring easily (P <.001) though both pain groups together indicated tiring easily more often than healthy volunteers (P <.001).