Clinical Review

Maybe it’s nerves: Common pathway may explain pain

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New studies also shed light on transvaginal ultrasound, laparoscopic excision, adhesions, hysterectomy, drug therapy.


 

References

Many gynecologists now recognize that surgery is of little benefit in the initial diagnosis and treatment of the syndrome of chronic pelvic pain, but effective alternatives have not been well established either. Within the last year, however, new research has given us a better understanding of its causes, evaluation, and management. This Update discusses new findings on the following patient care issues:

  • How a common nerve pathway may affect chronic pelvic pain patterns
  • Transvaginal ultrasound in the evaluation of acute versus chronic pelvic pain
  • The placebo effect of surgery
  • What we can and cannot expect from endometriosis resection
  • The role of adhesions in pain
  • Limits of hysterectomy
  • Medical therapy

Any nerve plexus injury may lead to pain

Quinn M. Obstetric denervation–gynaecological reinnervation: disruption of the inferior hypogastric plexus in childbirth as a source of gynaecological symptoms. Med Hypoth. 2004;63:390–393.

When we fit together the pieces of the chronic pelvic pain puzzle, a picture emerges that suggests the pelvic organs are connected functionally, not just by anatomical proximity. Recent commercial promotion of drugs for diseases of the bladder and bowel has raised our awareness of interstitial cystitis and irritable bowel syndrome as factors in chronic pelvic pain, and we recognize that bowel and bladder symptoms often accompany gynecologic symptoms, such as dysmenorrhea and vulvodynia. Now, a hypothesis introduced by Martin Quinn suggests disruption of the inferior hypogastric nervous plexus during childbirth may result in reinnervation changes that cause visceral pain years later. He found collateral nervesprouting and a chaotic distribution of nerve fibers when special stains were used on surgical specimens.

According to this hypothesis:

  • Cesarean section is not the answer to this childbirth-related injury, because cesarean section injures the nerve plexus.
  • Hysterectomy would be effective for chronic pain only if abnormal nerve regeneration is restricted to the uterus.
Although Quinn focused on obstetric injury, it follows that other injury to the nerve plexus could have the same consequences; for example, gynecologic surgery (eg, laparoscopy), pelvic infection, or automobile trauma.

DIAGNOSISUltrasound is more useful for acute than chronic pain

Okaro E, Valentin L. The role of ultrasound in the management of women with acute and chronic pelvic pain. Best Pract Res Clin Obstet Gynaecol. 2004;18:105–123.

Clinicians are taught that a good history and physical examination are the most important diagnostic tools in evaluating symptoms, but we often use imaging studies as well, including routine transvaginal ultrasound in the evaluation of pelvic pain. This analysis of published studies identified transvaginal ultrasound as an extension of the bimanual exam, but observed its greatest utility for acute rather than chronic pelvic pain. In chronic pelvic pain, laparoscopic findings, if abnormal, commonly include endometriosis and adhesions—for which transvaginal ultrasound is not very useful unless there is fixation or enlargement of the ovary.

This review describes use of ultrasound for identification of heterogeneous myometrial echotexture, asymmetric uterine enlargement, and subendometrial cysts as features of adenomyosis, and reports a positive predictive value of 68% to 86% in published series.

SURGERYExcision can be effective—so can sham surgery

Abbott J, Hawe J, Hunter D, Holmes M, Finn P, Garry R. Laparoscopic excision of endometriosis: a randomized, placebo-controlled trial. Fertil Steril. 2004;82:878–884.

Some gynecologists still choose surgery as a first-line treatment, although a landmark randomized trial published 14 years ago proved that a nonsurgical approach more effectively resolves chronic pelvic pain symptoms.1 The enthusiasm for surgery is highest when endometriosis is suspected, and some gynecologists still believe that the only adequate treatment is physical removal or destruction of implants.

Pain relief has been attributed to laparoscopic treatment of endometriosis, but cause-and-effect is uncertain, in part because of confounding factors.

For example, in a report on outcomes after ablative therapy for stage 3 or 4 endometriosis with endometriotic cysts, Jones and Sutton2 considered surgery successful because 87.7% of subjects were satisfied 1 year later. This interpretation can be questioned, however, given that patients who did not want to conceive were treated with oral contraceptives or gonadotropin-releasing hormone analog after surgery. The extent to which symptoms responded to the medication rather than the surgery is not known.

Also unknown is the extent to which symptoms respond to the placebo effect of surgery. Sutton and colleagues had previously shown that pain relief 3 months after laser laparoscopy was no greater than after sham surgery,3 but by 6 months, pain relief in the sham surgery group was not sustained, and was lower than in the real surgery group.

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