Peripheral changes in endometriosis-associated pain.
Level 5 - mechanism / opinion, no new human data
Systematic review focusing on mechanism-based biological and histological pathology rather than clinical trials.
PubMed 24859987 · doi:10.1093/humupd/dmu021
What was done
The authors conducted a systematic review searching PubMed, MEDLINE, EMBASE, and CINAHL for studies published between January 1977 and October 2013. The review evaluated the role of the peripheral nervous system, including nerve fiber density, neurotrophins, angiogenic factors, and peritoneal interactions, in the generation and modulation of endometriosis-associated pain.
What was found
The abstract reports no numerical metrics or statistical effect sizes. Qualitatively, endometriotic lesions and peritoneal fluid demonstrated neuroangiogenic properties, including increased nerve fiber expression, altered sensory/autonomic fiber distribution, and upregulation of neurotrophins. Deep infiltrating and bowel endometriosis lesions exhibited higher nerve fiber density than peritoneal lesions and endometriomas. Nerve fiber presence in eutopic endometrium showed a better correlation with pain symptoms, but this finding was not exclusive to endometriosis. Elevated neurotrophin levels did not correlate with pain severity.
Why it matters
This review synthesizes the biological mechanisms of peripheral neuroangiogenesis in endometriosis, highlighting that while localized nerve proliferation occurs, structural nerve presence alone does not straightforwardly explain clinical pain severity.
Limits
The abstract provides no sample sizes, number of included studies, or quantitative estimates. The findings rely on mechanistic and observational tissue analyses that show associations rather than direct causation, and eutopic endometrial nerve changes lack specificity for endometriosis.
Cited by
- supports Endometriotic lesions develop increased vascularity and grow nerve fibers around each lesion.