Trigger Point Injections May Ease Pain of Endometriosis, Small Study Suggests

Trigger Point Injections May Ease Pain of Endometriosis, Small Study Suggests

Injections with anti-inflammatory and anesthetic agents to trigger points in the muscles of the pelvic floor may help to ease pain and improve pelvic function in people with endometriosis, a small study suggests.

But notable limitations to the work necessitates further research before firm conclusions can be drawn.

The study, “A Novel, Non‐Opioid Treatment for Chronic Pelvic Pain In Women with Previously Treated Endometriosis Utilizing Pelvic Floor Musculature Trigger Point Injections and Peripheral Nerve Hydrodissection,” was published in PM&R.

Pelvic pain is a common problem for people with endometriosis, and there remains a need for more effective treatments to manage this debilitating pain.

Researchers at the NYU Langone Health, in New York, tested a novel strategy that included injections of a numbing agent — lidocaine — to trigger points in pelvic floor muscles. Trigger points, the places where ‘knots’ form in muscles, have been previously identified as the source of pain in some patients with chronic pelvic pain and pelvic floor tenderness, which are associated with endometriosis.

In addition to lidocaine, some of the injections included dexamethasone or traumeel. Dexamethasone is a well-studied anti-inflammatory medication; traumeel is used as an anti-inflammatory agent in homeopathy, although  scientific evidence backing this use is scarce.

For the study, three pelvic muscles that are thought to be involved in chronic pelvic pain were targeted: the iliococcygeus, puborectalis, and pubococcygeus.

Sixteen people with biopsy-confirmed endometriosis participated in the study, ages 21 to 67.

Concurrently, these participants underwent nerve hydrodissection, which consists of the delivery of an anesthetic directly to a place in the body where pain is being generated. But, rather than targeting muscles, hydrodissection targets nerves. Here, the researchers targeted the pudendal nerve and the posterior femoral cutaneous nerve, both of which play integral roles in delivering pain signals from the pelvis to the brain.

Ultrasound was used to ensure that all of the injections went to the right place. In total, study participants received these treatments once a week over the course of six weeks. “Patients returned to work the same day of the procedure,” the researchers noted.

In addition to the above-described injections, participants received ongoing pelvic floor physical therapy, and were “advised to continue their current medication doses during the study.”

Both before and three months after the treatments, patients rated their pelvic pain using two scales: a visual analog scale (VAS) and the Functional Pelvic Pain Scale (FPPS). The first rates overall pain on a scale from 1-10, while the second rates pain as it relates to pelvic function in eight categories (bladder, bowel, intercourse, walking, sleeping, working, running, and lifting) from 0 to 4 (0 being normal function, and 4 being severe debilitation). Total scores ranged from 0 to 32.

Average pain scores assessed via both tests decreased significantly after the injections: from 6.00 to 2.94 for VAS, and from 14.44 to 9.13 for FPPS.

The researchers also looked at FPPS scores by category. There were statistically significant decreases, again meaning improvement, in three categories: intercourse, sleeping, and working, with average decreases of 1.28, 1.15, and 0.86, respectively.

These findings suggest that this strategy is effective at reducing pelvic pain for people with endometriosis.

“Our treatment protocol consisting of a combination of trigger point injections, peripheral nerve hydrodissection, and pelvic floor physical therapy was a multi-modal approach aimed at the multiple facets that contribute to pelvic pain. To our knowledge, this is the first study that examined the effectiveness of these three modalities in conjunction for chronic pelvic pain in women with a history of endometriosis,” the researchers wrote

However, a number of limitations in the study’s design are worth noting. This is quite a small study; as such, drawing broad conclusions is inadvisable. Additionally, the maximum follow-up time was three months, so the long-term efficacy of the treatment is unclear.

Furthermore, the study was not especially well-controlled: there was no placebo group, so the placebo effect cannot be ruled out. Participants also received physical therapy and continued to take whatever medications they were already on. This makes it impossible to say which part(s) of the treatment were actually responsible for the observed effect.

Still, the results suggest there is merit to the strategy as a whole, the researchers noted.

“This study opens the door to future studies investigating the long-term durability of this multi-faceted treatment and/or the effectiveness of each individual treatment modality,” they wrote.

More broadly, they added, their work “provides the foundation for future research with larger sample size and longer follow up.”