Endometriosis-associated Pain in Patients with and without Hormone Therapy

Mechanisms of peripheral sensitization in endometriosis patients with peritoneal lesions and acyclical pain

PURPOSE

Endometriosis (EM) is one of the most frequent differential diagnoses concerning chronic pelvic pain. Women under hormonal therapy (HT) often benefit from it but sometimes suffer a setback and develop acyclical pelvic pain. Due to the assumption that mechanisms of neurogenic inflammation are involved in the generation of chronic pelvic pain, we aimed to investigate the expression of sensory nerve markers in EM-associated nerve fibers of patients with/without HT.

METHODS

Laparoscopically excised peritoneal samples from 45 EM and 10 control women were immunohistochemically stained for: PGP9.5, Substance P (SP), NK1R, NGFp75, TRPV-1, and TrkA. Demographics and severity of pain were documented.

RESULTS

EM patients showed a higher nerve fiber density (PGP9.5 and SP) and increased expression of NGFp75, TRPV1, TrkA, and NK1R in blood vessels and immune cells compared with controls. Patients with HT have cycle-dependent pelvic pain but suffer from acyclical pelvic pain. Interestingly, reducing NK1R expression in blood vessels under HT was observed. A correlation between dyspareunia severity and nerve fibers density and between NGFRp75 expression in blood vessels and cycle-dependent pelvic pain severity was observed.

CONCLUSION

Patients under HT have no ovulation and no (menstrual) bleeding, which correlate with inflammation and cyclical pain. However, acyclical pain seems to be due to peripheral sensitization once it is present under treatment. Neurotransmitters, like SP and their receptors, are involved in mechanisms of neurogenic inflammation, which are relevant for pain initiation. These findings indicate that in both groups (EM with/without HT), neurogenic inflammation is present and responsible for acyclical pain.

Endometriosis, an Ongoing Pain—Step-by-Step Treatment

Endometriosis is a disease that is becoming more and more challenging for the medical community. The current therapeutic concepts (surgical therapy and/or hormonal therapies) often do not lead to sufficient pain control, and late diagnosis and high recurrence rates mean that women affected by the disease can suffer for decades before receiving proper treatment. Although the introduction of certified endometriosis centers has created contact points for surgical therapies performed by endometriosis experts, these centers are not sufficient to offer the affected patients the all-encompassing long-term support they need. In recent years, new findings regarding the pathogenesis and correlations of the pain phenomena caused by endometriosis have shown that conventional therapy strategies are not adequate and individual long-term concepts must be developed. Not only can endometriosis cause nociceptive pain, but it can also lead to a nociplastic reaction with central sensitization. Hence, aside from the classic cyclic complaints, patients increasingly suffer from atypical pain. Due to the high number of affected patients who are treated inadequately, it is necessary for gynecologists in private practices to become familiar with multimodal treatment concepts since they are the central point of contact of their patients. The following article will provide an overview of treatment strategies for chronic symptomatic endometriosis.

[Management of endometriosis pain : Stage-based treatment strategies and clinical experience]

BACKGROUND

Endometriosis is associated with various types of intense pain. In addition to nociceptive pain, there is also a nociplastic reaction with central sensitization. Atypical symptoms such as acyclic lower abdominal pain, radiating pain, non-specific bladder and intestinal complaints or even depression are frequent as are classic cyclical complaints such as severe dysmenorrhea, cyclical lower abdominal pain, dyspareunia, dysuria and dyschezia. In cases of a diverse range of symptoms, patients often consult not just gynecologists but specialists from other disciplines (e.g., internal medicine, gastroenterology, orthopedics, pain therapy, psychology).

AIMS

Overview about the pathophysiology and complexity of the disease and the resulting treatment options. A multimodal interdisciplinary concept might be able to take into consideration all aspects of the complex disease.

METHODS

Interdisciplinary concepts should be involved in the treatment of endometriosis patients along with hormonal and surgical therapy, which are generally under the supervision of a gynecologist. Pain management, dietary changes, psychological support, as well as physiotherapy should be included. The present article is intended to provide an overview of possible treatment strategies for chronic, symptomatic endometriosis.

CONCLUSION

The use of multimodal treatment strategies regarding the complex pathophysiological aspects of this disease might be helpful in significantly improving the quality of life of endometriosis patients.