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

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.