Trigger Point Injections Followed by Immediate Myofascial Release in the Treatment of Myofascial Pelvic Pain

Abstract

Purpose

Pelvic floor physical therapy (PFPT) is first line therapy for treatment of myofascial pelvic pain (MFPP). Pelvic floor trigger point injections (PFTPI) are added if symptoms are refractive to conservative therapy or if patients experience a flare. The primary objective was to determine if a session of physical therapy with myofascial release immediately following PFTPI provides improved pain relief compared to trigger point injection alone.

Methods

This was a retrospective cohort analysis of 87 female patients with MFPP who underwent PFTPI alone or PFTPI immediately followed by PFPT. Visual analog scale (VAS) pain scores were recorded pre-treatment and 2 weeks post-treatment. The primary outcome was the change in VAS between patients who received PFTPI alone and those who received PFTPI followed by myofascial release.

Results

Of the 87 patients in this study, 22 received PFTPI alone and 65 patients received PFTPI followed by PFPT. The median pre-treatment VAS score was 8 for both groups. The median post-treatment score was 6 for the PFTPI only group and 4 for the PFTPI followed by PFPT group, showing a median change in VAS score of 2 and 4 respectively (p = 0.042). Seventy-seven percent of patients in the PFTPI followed by PFPT group had a VAS score improvement of 3 or more, while 45% of patients in the PFTPI only group had a VAS score improvement greater than 3 (p = 0.008).

Conclusions

PFTPI immediately followed by PFPT offered more improvement in pain for patients with MFPP. This may be due to greater tolerance of myofascial release immediately following injections.

Introduction

Myofascial pelvic pain is a subtype of chronic pelvic pain that is characterized by the presence of tender and distinct hyperirritable areas in taut muscle bands. These trigger points can be active or latent. Active trigger points occur spontaneously at rest and can be exacerbated by palpation, whereas latent trigger points do not cause pain spontaneously and only manifest after muscle compression or manipulation [1]. Pelvic floor myofascial pain and dysfunction affects approximately 13 to 22% of women and leads to chronic vaginal discomfort and dyspareunia [1], [2], [3]. Treatment modalities for myofascial pelvic pain aim to relax the pelvic floor and surrounding musculature. There are various conservative and invasive approaches in management of myofascial pelvic pain, including pelvic floor physical therapy, trigger point injections (with local anesthetics and steroids), and botulinum toxin injections [4], [5], [6].

Pelvic floor physical therapy with myofascial release is a first-line, low risk, minimally invasive therapy for treating pelvic floor dysfunction [7]. Internal therapy can strengthen weak muscles, stretch tight muscles, improve mobility, and decrease pain by manually releasing the painful trigger points and restrictions in connective tissue related to the pelvic floor [8]. A recent systematic review demonstrated that pelvic floor physical therapy significantly improved pelvic floor muscle resting tone, function, and pain [9]. Pharmacotherapy with muscle relaxants or neuromodulators can also be used, and behavioral therapy is important to address pain neuroscience re-education. In cases where conservative measures do not effectively treat MFPP symptoms, trigger point injections using various agents such as local anesthetics or steroids are indicated. [2]. Myofascial injections inactivate active trigger points resulting in the reduction of pain via mechanical disturbance of muscle fibers and associated nerves and disruption of the positive pain feedback loop. This causes decreased concentration of nociceptive substances. The injections provide immediate symptomatic relief which may last up to several weeks [2], [10].

The addition of corticosteroids to intramuscular injectates for synergistic efficacy in treating patients with trigger points is controversial due to the risk of muscle wasting and dimpling with repeated steroid use [8]. However, it is still thought to have benefit due to the effect of steroids on limiting expression of cytokines, inhibition of inflammatory mediator formation, and decrease in pain associated with muscular scarring [11], [12].

We propose that trigger point injections followed by immediate myofascial release therapy may offer improved synergistic pain control. The objective of this study is to evaluate treatment success by comparing VAS pain scores before and after the two interventions: trigger point injections alone, versus trigger point injections immediately followed by myofascial release.

Materials And Methods

This was a retrospective cohort study of gynecologic patients with myofascial pelvic pain who underwent trigger point injections alone or trigger point injections followed by pelvic floor physical therapy. The study period was October 1, 2018 to December 31, 2021. The study was deemed exempt by the Institutional Review Board at our institution. Patients were identified using a secure electronic medical record system. Eligibility criteria for the study included women with pelvic floor trigger points who failed initial physical therapy treatment and oral or transvaginal muscle relaxant medications. In our practice patients typically undergo 1 to 2 physical therapy sessions per week for 8 to 12 sessions by a trained pelvic floor physical therapist. A physical therapy session involves transvaginal manual release of painful trigger points, connective and scar tissue mobilization, and passive and active range of movement exercises. Medications include oral or transvaginal muscle relaxants. Patients with flares of their myofascial pelvic pain or who did not have significant improvements after maximum physical therapy treatment in combination with medication management, were recommended to try trigger point injections. Baseline clinical and demographic data were extracted from the electronic medical record. A self-reported VAS pain score was obtained by asking the patient to make a handwritten mark on a 10 cm horizontal line representing a continuum ranging from “no pain” (score of 0) to “worse pain ever experienced” (score of 10); VAS scores were obtained before treatment and 2 weeks after intervention, and adverse events during or after treatments were documented.

The 22 patients in the PFTPI only group had their procedure done during a one-year hiatus when no on-site pelvic floor physical therapist was present at our institution; hence they did not receive PFPT with myofascial release immediately following their PFTPI. The 65 patients who had procedures from October 1, 2019 to December 31, 2021 had PFPT immediately following PFTPI and were used as the comparison group.

All injections were performed in the outpatient gynecology clinic by one of two providers: a Female Pelvic Medicine and Reconstructive Surgeon or a Minimally Invasive Gynecologic Surgeon. Written informed consent was obtained from all patients prior to injection. With the patient in the lithotomy position, the provider performs single digit transvaginal palpation of the bilateral levator ani muscle complex (pubococcygeus, iliococcygeus, puborectalis) and obturator internus muscles (Fig. 1a and b). The presence of trigger points was defined as tight bands and pain with light but firm palpation. Verbal confirmation of the trigger point was verified by the patient. Each trigger point was injected with approximately 5 mL of 0.5% ropivacaine with or without 1 mL of 40 mg/mL of triamcinolone for a total of 20 mL. The steroid component was based on provider’s preference; but was not used in patients taking oral or other systemic steroids. For each injection, a 7 inch, 22-gauge spinal needle was passed transvaginally through an Iowa trumpet needle guide into the desired location. The depth of injection for each trigger point was approximately 2 cm. Negative aspiration was performed prior to injection to confirm no intravascular entry. All patients were observed post-procedure for adverse events such as dizziness, lightheadedness, peri-oral numbness, metallic taste, significant vaginal bleeding, or worsening pain. After trigger point injections were administered, patients in the PFTPI followed by PFPT group were seen by a licensed pelvic floor physical therapist for transvaginal myofascial release.

The sample size for the PFTPI only group was smaller, and it includes the patients who received the procedure during the one-year time frame when there was no available physical therapist to provide the immediate myofascial release. The PFTPI followed by PFPT group consisted of the patients receiving the procedure in the subsequent 26-month time period ending December 31, 2021. This time frame was chosen to yield a sample size in this group of approximately three times that of the PFTPI only group. The rationale for the differential comparative group size is that a fixed total sample size statistical power for comparisons between groups is typically optimized when group sizes are equal. However, when one group is fixed in size, power increases with increasing sample size of the other group, up to a ratio of group sizes of 3:1, beyond which gains are diminished.

Continuous variables were summarized as median (range) and mean (standard deviation), while categorical variables were reported as frequency (percentage). Unadjusted comparisons of patient characteristics and outcomes between the trigger point injection only and the trigger point injection followed by physical therapy (PT) groups were made using a Wilcoxon rank sum test (continuous variables) or Fisher’s exact test (categorical variables). All tests were two-sided with p value < 0.05 considered statistically significant. Statistical analyses were performed using R Statistical Software (version 4.0.3; R Foundation for Statistical Computing, Vienna, Austria).

Results

A total of 87 patients with pelvic floor tension myalgia refractive to conservative treatment (physical therapy and muscle relaxants) who underwent PFTPI alone or PFTPI immediately followed by PFPT were included in this retrospective study. Of the 87 patients, 22 (25.3%) received PFTPI alone and 65 (74.7%) patients received PFTPI followed by PFPT. There were no significant differences between the two treatment groups for any of the demographic characteristics (Table 1).

Pelvic pain was the most common presenting symptom among all patients (78%), but there was not a significant difference between the two groups (PFTPI + PFPT: 83% vs PFTPI only: 64%, p = 0.075). Compared to the PFTPI + PFPT group, the PFTPI only group had more instances of dyspareunia (50% vs 22%, p = 0.015) and prior trigger point injections (27% vs 5%, p = 0.007) (Table 2). However, adjustment analysis models for these 2 variables were performed and did not impact the overall study results.

Before treatment, there was no significant difference in the median pain score (VAS) between the 2 groups (Table 3). The median pre-treatment VAS score was 8 for both treatment groups (Fig. 2). However, the post-treatment pain score was significantly lower in the PFTPI + PFPT group compared to the PFTPI only group (Median: 4 vs 6, p = 0.042) (Fig. 3). The change in VAS score (post-treatment VAS minus pre-treatment VAS) was also calculated. Compared to the PFTPI only group, the PFTPI + PFPT group had a significantly greater change in VAS score (median: 4 vs 2, p = 0.030) (Figs. 4 and 5). A total of 77% patients in the PFTPI + PFPT group had a change in VAS score greater than 3, while 45% of patients in the PFTPI only group had a change in VAS score greater than 3 (p = 0.008), (Table 3).

Nine patients received triamcinolone as part of their injectate, and all nine patients were in the PFTPI followed by PT group. A subgroup analysis of these patients showed no statistically significant differences VAS score changes or improvement when compared with no steroid (Table 4).

Discussion

Pelvic floor tension myalgia is a common cause of chronic pelvic pain, with approximately 50–90% of chronic pelvic pain patients having an underlying musculoskeletal etiology [9]. Trigger point injections with local anesthetic medications are important components of therapy in women who have failed conservative measures. The primary finding of this study is that PFTPI injections immediately followed by PFPT had a statistically significant improvement in VAS pain scores compared to PFTPI alone. We performed a systematic search of the PubMed database from inception to April 2022 using the terms “trigger point injections,” “physical therapy,” “myofascial pelvic pain” and “pelvic floor tension myalgia.” According to this search, our study is the first to highlight patient response to trigger point injections followed by immediate myofascial release compared to trigger point injections alone.

Treatment with either pelvic floor physical therapy or trigger point injections have yielded impressive clinical results. Pelvic floor physical therapy has been reported to improve pelvic pain symptoms in 59–80% of patients with MFPP [3] [13]. Fouad et al [4] and Bartley et al [14] also demonstrated a 65% and 77% improvement in MFFP respectively for patients who received transvaginal trigger point injections. In another study that randomized 29 women to either transvaginal trigger point injections with steroid/bupivacaine or PFPT, both groups reported significant reduction in pain [12]. Despite the overall good success rate with each treatment modality, the response can be limited and transient [5]. By combining PFTPI with immediate PFPT, there is the potential for longer-lasting reduction in pelvic pain by allowing tolerance of deeper myofascial release during the effect of anesthesia. In our study, all patients had improvement in their VAS scores; with 77% of patients in the PFTPI followed by PFPT having a change in VAS score of 3 or more. It is imperative for patients to be relaxed during their physical therapy session, thus allowing for enough manual traction on the pelvic floor muscles that will lead to effective relief of the trigger points.

The VAS score as used in this study is an effective pain assessment tool as it standardizes patient’s pain perceptions. The VAS remains one of the most widely used quantification tools for pain in published studies and is an acceptable measure of subjective pain evolution [15]. However, the minimum clinically important difference (MCID) in VAS has not been defined for pelvic pain. A clinically significant change in VAS score has been adopted from studies on chronic lower back pain where the suggested that the MCID is a VAS of at least 2 [16]. This lowest cut off value discriminates best between patients who had improvement in their pain and those whose pain intensity remains unchanged [17].

Pelvic floor dysfunction is multifactorial in etiology and affects up to 70% of women with gastrointestinal, genitourinary, and sexual disorders [18]. Women with non-relaxing pelvic floor muscle dysfunction tend to present with a recognizable pattern of symptoms including irritative voiding, chronic constipation with difficulty evacuating stool, dyspareunia, chronic pelvic pain, and low back pain [8]. In our study, the most common presenting symptoms were pelvic pain, dyspareunia, urinary, or bowel symptoms. Thirty-one percent of patients presented with urinary symptoms and 10.32% presented with bowel-related symptoms. This highlights the fact that myofascial pelvic pain rarely exists in isolation and patients should be evaluated for other treatable medical pathologies. A multidisciplinary approach with referral to specialists in gastroenterology, physical medicine and rehabilitation, sexual medicine, or urology is appropriate in some cases.

Our providers preferentially use ropivacaine due to its longer duration of clinical effect (2–6 hours) [2]. Ropivacaine is less cardiotoxic with fewer central nervous system side effects than bupivacaine [19]. Systemic toxicity risk is minimized by using a negative aspiration technique and limiting injection dose to 20 mL. In our study, 14% of patients in the PFTPI followed by PFPT received triamcinolone as part of their injected medications. A subgroup analysis showed no statistical benefit from the addition of steroid. A study by Bartley et al used steroids in 90.2% of patients but were unable to determine overall significant clinical benefit [14]. This is an area for further study, since triamcinolone has been shown to be potent in myalgia relief in non-gynecologic conditions[12]. Adverse effects of trigger point injections include inadvertent intravascular injection, syncope, localized infection, and hematomas. None of these side effects were observed in our patients during the study period.

Strengths of this study includes the fact that we were able to follow up all patients in each group and document improvement in pain after each procedure. Limitations of the study include the retrospective design and small sample size, making it vulnerable to a type II error. Additionally, follow up beyond 2 weeks would have given more information regarding the sustained improvement in pain symptoms after injections and physical therapy. We are also aware that not all centers have a pelvic floor physical therapist or clinical personnel trained in myofascial release which can limit generalizability. There is room for further research with large prospective randomized trials to determine treatment outcomes for MFFP with trigger point injections and PFPT incorporating sexual health and quality of life improvement measures.

Conclusions

PFTPI followed by immediate myofascial release is a safe and effective treatment option for patients with myofascial pelvic pain, offering better improvement in pain than PFTPI alone. The pain-relieving effect provided by the PFTPI may allow for tolerance of deeper physical therapy and internal manual release. Multidisciplinary and multimodal treatment is a crucial part of management of patients with pelvic floor myofascial pain. Standardization of examination, diagnosis, and treatment algorithms will allow for improved clinical outcomes.

Declarations

Author Contributions

GK Lewis: Project development, Data Collection, Manuscript writing/editing

AH Chen: Project development, Data Collection, Manuscript writing/editing

EC Craver: Data management, Data analysis 

JE Crook: Data management, Data analysis  

AR Carrubba: Project development, Data Collection, Manuscript writing/editing 

Compliance with Ethical Standards

Conflicts of Interest: All authors involved in this study declare that they have no conflicts of interest. 

Ethical approval: This article does not contain any studies with animals performed by any of the authors.

Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

The Mayo Clinic  Institutional Review Board approved this study (IRB: 4/16/2021; study #: 21-003737).

Statements and Declarations

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

The authors have no relevant financial or non-financial interests to disclose.

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