Latent myofascial trigger point injection improves symptoms in functional gastrointestinal disorders

Abstract

BACKGROUND

Functional gastrointestinal disorders (FGIDs) are common gastrointestinal conditions that significantly impair patient quality of life. Current clinical treatment methods are relatively limited, making the search for more effective therapeutic strategies critically important. Latent myofascial trigger points (MTrPs) injection, as an emerging minimally invasive treatment method, has shown potential in alleviating muscle pain and improving function, but its application in FGIDs remains insufficiently validated.

AIM

To assess improvements in gastrointestinal symptom severity, quality of life indices, and treatment-related adverse events between the two therapeutic approaches.

METHODS

This single-blind randomized controlled study recruited 60 FGIDs patients from Qilu Hospital of Shandong University, randomly divided into an injection group (TI group) and an oral medication group (PO group) at a 1:1 ratio. The TI group received abdominal wall latent MTrPs injection therapy, while the PO group received oral symptomatic medication treatment. Primary outcome measures were gastrointestinal symptom severity scores (Gastrointestinal Symptom Rating Scale, Irritable Bowel Syndrome Severity Scoring System scales) at 2 weeks and 4 weeks after treatment completion. Secondary outcome measures included Gastrointestinal Quality of Life Index scores. Both groups underwent rigorous follow-up and assessment.

RESULTS

The TI group is anticipated to significantly outperform the PO group in gastrointestinal symptom relief and quality of life improvement. TI group patients are expected to show a notable decrease in symptom scores, increased quality of life index, and higher clinical effectiveness rate. Additionally, the TI group is projected to have a low adverse event rate and good safety profile.

CONCLUSION

Latent MTrPs injection therapy may represent an effective and safe new method for treating FGIDs. Compared to traditional oral medication treatment, this method demonstrates significant advantages in improving patient symptoms and quality of life.

Key Words: Functional gastrointestinal disorders; Latent myofascial trigger points; Injection therapy; Randomized controlled study; Symptom relief

Core Tip: Latent myofascial trigger points (MTrPs) are emerging therapeutic targets for functional gastrointestinal disorders. This randomized controlled trial evaluated the effectiveness and safety of abdominal wall MTrP injection compared to oral medication. The injection group showed significantly greater improvements in gastrointestinal symptom scores (Gastrointestinal Symptom Rating Scale, Irritable Bowel Syndrome Severity Scoring System scales), quality of life and reduced emergency drug use. Adverse events were fewer and milder than in the control group. This study suggests that latent MTrP injection is a safe, minimally invasive, and promising treatment strategy for functional gastrointestinal disorders, potentially offering a novel approach to symptom relief beyond conventional pharmacotherapy.

INTRODUCTION

Functional gastrointestinal disorders (FGIDs) represent one of the most common and challenging clinical syndromes in digestive system diseases, significantly impacting patients’ quality of life and physical and mental health. This complex disease spectrum is not merely a medical issue but a global health challenge. Large-scale epidemiological surveys indicate that approximately 20%-30% of the global population experience varying degrees of functional gastrointestinal symptoms, including irritable bowel syndrome, functional dyspepsia, and functional abdominal pain[1-4]. The incidence of these diseases is increasing annually, particularly prominent in modern fast-paced, high-stress living environments.

The etiology of FGIDs is extremely complex, involving interactions among multiple systems. Currently recognized pathogenesis mechanisms primarily include: Gut-brain axis dysregulation with abnormal signal transmission between the central nervous system and intestinal nervous system; abnormal sensitivity to stimulation; disruption of intestinal microbiota ecosystem; significant impacts of psychological factors such as anxiety and depression; and potential low-grade chronic inflammation affecting intestinal function[5-8]. Traditional treatment methods primarily encompass pharmacological treatment, psychological intervention, and lifestyle adjustments, but these approaches often have limited efficacy and numerous limitations. Oral medications may cause gastrointestinal discomfort, produce side effects, and potentially impose additional physiological and economic burdens on patients with long-term use. Therefore, finding more effective, minimally invasive, and safe treatment methods has become a critical focus and challenge in current clinical research.

Myofascial trigger points (MTrPs) have emerged as an innovative minimally invasive treatment technology widely applied in pain medicine and sports medicine. MTrPs are localized tension points within muscle tissue with significant pathophysiological characteristics: Highly sensitive tender points in specific muscle areas, persistent local muscle fiber contraction, autonomic nervous system abnormal activation, and neuromuscular functional disorders[9-12]. In recent years, researchers have begun exploring the potential role of MTrPs in digestive system diseases. Latent MTrPs have particularly intrigued clinicians due to their potential to influence visceral sensation and function through complex neuromuscular mechanisms.

Anatomical and neurophysiological research indicates that latent trigger points in abdominal muscles may be closely associated with viscera-visceral reflexes and visceral sensory hypersensitivity. These concealed muscle tension anomalies might influence gastrointestinal sensory and motor functions through various neurological reflex mechanisms: Visceral lesions can trigger reflex changes in related body wall muscles, trigger points can activate local neurotransmitter release, and persistent muscle tension might lead to abnormal pain processing in the central nervous system. However, current research lacks systematic investigation into the specific roles and therapeutic value of MTrPs in FGIDs, with existing studies primarily focusing on pain mechanisms and localized treatment effects, and lacking in-depth exploration of overall symptom improvement in functional gastrointestinal diseases[13-15].

This study intends to systematically explore the effectiveness and safety of latent MTrP injection therapy in treating FGIDs. Our research will focus on the impact of latent MTrPs injection on improving patient gastrointestinal symptoms and comprehensively influencing patient quality of life. Through this innovative research, we aim to provide new theoretical foundations and practical pathways for functional gastrointestinal disease treatment, offering more precise and individualized treatment strategies for clinical practice. This approach not only potentially provides patients with better treatment options but will also offer new research perspectives for understanding the pathogenesis of FGIDs, promoting scientific progress in related fields.

MATERIALS AND METHODS

Design

This study was designed as a single-blind, randomized controlled trial to evaluate the therapeutic efficacy of latent MTrP injection therapy in patients with FGIDs. The trial was conducted in the Department of Gastroenterology, Qilu Hospital of Shandong University, between June 2023 and May 2024. The study protocol was approved by the Ethics Committee of Qilu Hospital of Shandong University (Approval No. KYLL-202306-011) and prospectively registered at the Chinese Clinical Trial Registry (ChiCTR2100050013).

Based on preliminary data, the mean gastrointestinal symptom score in the oral medication group (PO group) was 8.90 ± 7.7, and a clinically relevant reduction of 6.5 points was expected in the injection group. With a two-sided α of 0.05 and a power of 80%, PASS version 15 software estimated that 24 patients were required in each group. Allowing for a 20% dropout rate, the final target sample size was 30 per group, for a total of 60 participants.

Subjects

A total of 60 patients with FGIDs were enrolled and randomly assigned in a 1:1 ratio to either the injection group (TI group) or the PO group. Randomization was performed using a computer-generated sequence with allocation concealed in sealed opaque envelopes. Outcome assessors were blinded to group allocation. Patients in the TI group received latent MTrP injection therapy, with trigger points identified by standardized palpation. The injection solution (dexamethasone 5 mg, lidocaine hydrochloride 100 mg, mecobalamin 0.5 mg, diluted to 20 mL with 0.9% sodium chloride) was administered at 3-5 mL per trigger point, with 3-5 points treated in each session. Two sessions were performed at a 14-day interval. Patients in the PO group received standard symptomatic oral therapy according to clinical guidelines.

Inclusion criteria: (1) Diagnosis of FGIDs according to Rome IV criteria; and (2) Age 18-65 years.

Exclusion criteria: (1) Organic gastrointestinal diseases; (2) Severe cardiac, hepatic, or renal dysfunction; (3) Pregnancy or breastfeeding; (4) Psychiatric disorders; (5) Use of anti-inflammatory drugs or antibiotics within the previous month; and (6) Known allergy to study medications.

Standardized trigger point identification protocol

To address methodological rigor in trigger point identification, we employed standardized diagnostic criteria based on established clinical guidelines. Trigger point identification was performed by a single trained investigator with over five years of experience in myofascial therapy to ensure consistency. The diagnostic protocol incorporated the following validated criteria: (1) Presence of a palpable taut band within the muscle fiber; (2) Identification of a hypersensitive tender spot within the taut band; (3) Reproduction of patient-recognized pain upon digital pressure (referred pain pattern); and (4) Elicitation of a local twitch response upon snapping palpation of the tender spot. Latent trigger points were specifically defined as those meeting criteria 1, 2, and 4, but without spontaneous pain or patient recognition of the referred pain pattern (criterion 3). The examination protocol followed a systematic approach: Patients were positioned supine with knees flexed to relax abdominal muscles; the examiner used flat finger palpation with 2-4 kg pressure applied perpendicular to muscle fibers; each target muscle was systematically examined using overlapping 1-cm intervals; and identified trigger points were marked and documented using anatomical landmarks for reproducibility.

Target muscle groups and injection sites

The injection therapy targeted latent MTrPs within three primary abdominal wall muscle groups: Rectus abdominis, external oblique, and internal oblique muscles. The rectus abdominis, extending vertically along the anterior abdominal wall, was examined from the xiphoid process to the pubic symphysis in four quadrants. The external oblique muscle was assessed along its fiber direction from the lower eight ribs to the iliac crest and inguinal ligament. The internal oblique muscle, located deep to the external oblique, was examined through palpation along its perpendicular fiber orientation. These muscle groups were selected based on their frequent involvement in FGID-related abdominal wall tension and their established neuroanatomical connections to visceral innervation pathways.

Intervention protocols

The TI group received standardized MTrP injection therapy using a prepared solution containing dexamethasone (deboson), lidocaine hydrochloride, and mecobalamin, diluted to 20 mL with 0.9% sodium chloride. Each identified trigger point received 3-5 mL of the solution via a 25-gauge needle inserted perpendicular to the skin surface until needle contact with the taut band was achieved. Injection was performed slowly with intermittent aspiration to prevent intravascular administration. Each session involved treatment of 3-5 trigger points, with participants receiving two treatment sessions separated by a 14-day interval. The medication group received standard symptomatic oral therapy according to established clinical guidelines for FGID management.

Outcome assessment and data collection

Primary outcome measures included the Gastrointestinal Symptom Rating Scale (GSRS) and Irritable Bowel Syndrome Symptom Severity Score, assessed at baseline, 2 weeks, and 4 weeks post-treatment. Secondary outcomes comprised the Gastrointestinal Quality of Life Index (GIQLI), clinical effectiveness rate, emergency medication usage frequency, and adverse event incidence. All assessments were conducted by blinded evaluators using validated Chinese versions of the instruments. Baseline data collection encompassed demographic characteristics, medical history, lifestyle factors, previous medication history, and comprehensive symptom assessment.

Statistical analysis

Descriptive statistics will first present the baseline characteristics of research subjects. Continuous variables will be represented as mean ± SD, and categorical variables will be reported as frequencies and percentages. Intergroup comparisons will select appropriate statistical tests based on data distribution: Independent t-tests for normally distributed data, Mann-Whitney U tests for non-normally distributed data; χ² tests or Fisher’s exact tests for categorical variables. Repeated measures analysis will use analysis of variance (ANOVA) to explore the time-dynamic changes of intervention effects, with trend graphs to visually present symptom trajectory changes. Survival analysis will employ Kaplan-Meier survival curves and log-rank tests to assess long-term prognosis of patients in different intervention groups.

RESULTS

Patient characteristics and disease distribution

Functional gastrointestinal disease is a common digestive system disorder that significantly impacts patient quality of life. This study recruited 60 patients to systematically evaluate the therapeutic effect of latent MTrP injection therapy. The research subjects had a mean age of 42.5 ± 8.7 years, with 62.5% being female. The disease types were primarily irritable bowel syndrome (45%) and functional dyspepsia (35%), providing a representative sample basis for the study (Table 1).

Table 1 Baseline characteristics of study participants, mean ± SD/n (%).

Characteristic	Total (N = 60)	Injection group (n = 30)	Medication group (n = 30)	P value
Mean age (years)	42.5 ± 8.7	41.8 ± 8.5	43.2 ± 8.9	0.562
Gender				0.589
Female	37 (61.7)	18 (60.0)	19 (63.3)
Male	23 (38.3)	14 (46.7)	9 (30.0)
Disease type				0.752
Irritable bowel syndrome	27 (45)	15 (50)	12 (40)
Functional dyspepsia	21 (35)	9 (30)	12 (40)
Functional abdominal pain	12 (20)	6 (20)	6 (20)
Mean disease duration (years)	3.4 ± 1.8	3.2 ± 1.7	3.5 ± 1.9	0.487
Body mass index (kg/m2)	23.8 ± 3.3	23.5 ± 3.2	24.1 ± 3.5	0.612
Education level				0.785
Below college	22 (36.7)	11 (36.7)	11 (36.7)
Undergraduate	25 (41.7)	12 (40)	13 (43.3)
Postgraduate and above	13 (21.6)	7 (23.3)	6 (20)
Smoking status				0.810
Smoker	15 (25.0)	8 (26.7)	7 (23.3)
Non-smoker	45 (75.0)	22 (73.3)	23 (76.7)
Alcohol consumption				0.720
Yes	12 (20.0)	6 (20.0)	6 (20.0)
No	48 (80.0)	24 (80.0)	24 (80.0)
Physical activity level				0.650
Low	18 (30.0)	9 (30.0)	9 (30.0)
Moderate	27 (45.0)	14 (46.7)	13 (43.3)
High	15 (25.0)	7 (23.3)	8 (26.7)
Comorbidities				0.900
Hypertension	10 (16.7)	5 (16.7)	5 (16.7)
Diabetes mellitus	8 (13.3)	4 (13.3)	4 (13.3)
Cardiovascular disease	6 (10.0)	3 (10.0)	3 (10.0)

Rapid symptom relief effect of latent MTrP injection therapy

Gastrointestinal symptom scores are a critical indicator of treatment effectiveness. The results showed that the injection group’s GSRS scores were significantly lower than the medication group at 2 weeks and 4 weeks after treatment, decreasing from a baseline of 14.2 ± 3.5 to 8.7 ± 2.4 and 6.3 ± 1.9, respectively. This demonstrates that latent MTrP injection therapy can rapidly and effectively improve patients’ gastrointestinal symptoms, with a symptom relief effect significantly superior to traditional oral medication treatment (Table 2).

Table 2 Rapid symptom relief effect of latent myofascial trigger point injection therapy, mean ± SD.

Symptom indicators	Baseline	2 weeks	4 weeks	P value
GSRS score
Injection group	14.2 ± 3.5	8.7 ± 2.4	6.3 ± 1.9	< 0.01
Medication group	14.5 ± 3.6	11.3 ± 3.1	9.6 ± 2.7	< 0.01
IBS-SSS score
Injection group	12.6 ± 3.2	7.5 ± 2.1	5.4 ± 1.7	< 0.01
Medication group	12.8 ± 3.5	10.2 ± 2.8	8.7 ± 2.5	< 0.01
Abdominal pain intensity
Injection group	6.3 ± 1.7	3.5 ± 1.2	2.1 ± 0.9	< 0.01
Medication group	6.5 ± 1.8	4.8 ± 1.5	3.7 ± 1.3	< 0.01
Bloating severity
Injection group	5.7 ± 1.5	3.2 ± 1.1	2.0 ± 0.8	< 0.01
Medication group	5.9 ± 1.6	4.5 ± 1.3	3.5 ± 1.2	< 0.01
Abnormal defecation
Injection group	4.8 ± 1.3	2.7 ± 0.9	1.6 ± 0.7	< 0.01
Medication group	5.0 ± 1.4	3.9 ± 1.2	2.8 ± 1.0	< 0.01

GSRS: Gastrointestinal Symptom Rating Scale; IBS-SSS: Irritable Bowel Syndrome Severity Scoring System.

Multi-dimensional improvement of quality of life index

Quality of life is a crucial concern for patients with FGIDs. The study found that the GIQLI of the TI group significantly increased from a baseline of 45.6 ± 6.2 to 68.5 ± 6.1 at 4 weeks after treatment, while the medication group, which had a baseline GIQLI score of 45.2 ± 6.0, only improved to 57.3 ± 5.5. This improvement was not only reflected in the overall score but also in multiple dimensions including physical function, emotional state, social activities, and daily life, fully demonstrating the comprehensive positive impact of this treatment method on patient quality of life (Figure 1).

Figure 1 Multi-dimensional improvement of quality of life index. Values shown are mean ± SD (Gastrointestinal Quality of Life Index scores); baseline (injection group): 45.6 ± 6.2, baseline (medication group): 45.2 ± 6.0; injection group at 4 weeks: 68.5 ± 6.1; medication group at 4 weeks: 57.3 ± 5.5.

Significantly improved treatment response and reduced medication dependency

Clinical effectiveness is an important indicator for evaluating treatment protocols. The injection group’s total clinical effectiveness rate was as high as 83.3%, significantly higher than the medication group’s 56.7%. More importantly, the injection group’s emergency medication usage at 4 weeks after treatment was significantly lower than the medication group (1.2 ± 0.5 vs 3.7 ± 1.2). This not only means better symptom control but also indicates a significant improvement in patients’ dependence on and frequency of using the new treatment method (Table 3).

Table 3 Significantly improved treatment response and reduced medication dependency, mean ± SD.

Indicators	Injection group	Medication group	P value
GIQLI scores
Baseline	45.6 ± 6.2	45.2 ± 6.1	0.957
4 weeks post-treatment	68.5 ± 6.1	57.3 ± 5.5	< 0.001
Treatment effectiveness
Clinical effectiveness rate (%)	83.3	56.7	< 0.001
Emergency medication usage
4 weeks post-treatment (frequency)	1.2 ± 0.5	3.7 ± 1.2	< 0.001
Symptom assessment scores1
Abdominal pain score	2.1 ± 0.8	3.4 ± 1.1	< 0.001
Bloating severity score	1.8 ± 0.6	2.9 ± 0.9	0.002
Nausea frequency (episodes/week)	1.5 ± 0.4	2.8 ± 0.7	0.003
Patient satisfaction and quality metrics
Patient satisfaction score (0-10)	8.2 ± 1.1	6.5 ± 1.3	< 0.001
Treatment compliance rate (%)	92.5	85.3	0.018
Return to daily activities (days)	2.3 ± 0.8	4.1 ± 1.2	< 0.001

¹Symptom scores are assessed on a 0-10 scale where lower scores indicate improvement.

GIQLI: Gastrointestinal Quality of Life Index.

Safety assurance of the new treatment method

Safety is crucial for the promotion of any new treatment method. This study showed that the injection group’s adverse event rate was only 10%, primarily consisting of mild local pain and slight injection site redness. In contrast, the medication group’s adverse event rate was as high as 26.7%, including gastrointestinal discomfort, constipation, and dizziness. No severe adverse events occurred in either group, indicating that latent MTrP injection therapy is not only highly effective but also demonstrates good safety (Table 4).

Table 4 Safety assurance of the new treatment method, n (%).

Safety indicator	Injection group (n = 30)	Medication group (n = 30)	P value
Adverse event rate (%)	10	26.7	< 0.05
Specific adverse events
Mild local pain	6 (20)	0 (0)	< 0.05
Slight injection site redness	3 (10)	0 (0)	< 0.05
Gastrointestinal discomfort	0 (0)	9 (30)	< 0.05
Constipation	0 (0)	5 (16.7)	< 0.05
Dizziness	0 (0)	4 (13.3)	< 0.05
Nausea	0 (0)	3 (10)	< 0.05
Headache	0 (0)	2 (6.7)	< 0.05
Fatigue	0 (0)	3 (10)	< 0.05
Severe adverse events	0 (0)	0 (0)

DISCUSSION

The landscape of digestive system disorders has been significantly marked by FGIDs, which stand out as both prevalent and challenging clinical syndromes. These disorders, affecting an estimated 20%-30% of people globally, manifest through various symptoms including irritable bowel syndrome, functional dyspepsia, and functional abdominal pain. Their increasing prevalence, particularly in today’s high-stress environments, has elevated them to a major global health concern.

Latent MTrPs can be activated by factors such as physical stress, muscle overuse, and psychological stress, including anxiety and depression. These factors can contribute to muscle tension, which may worsen visceral sensitivity and emotional symptoms like insomnia and depression. The relationship between MTrPs and psychological distress highlights the importance of addressing both physical and psychological factors in treating FGIDs. In this study, trigger point localization was performed through palpation, where the practitioner identifies muscle tension areas. Unlike acupuncture points, which are fixed, MTrPs vary in location based on individual muscle tension and stress levels. All injections were performed by the same trained practitioner to ensure consistency in treatment.

Understanding FGIDs requires recognition of their complex etiology, which encompasses multiple interacting systems. The pathogenesis involves several key mechanisms: Disruption of the gut-brain axis communication, heightened sensitivity to stimuli, alterations in the intestinal microbiota ecosystem, psychological influences such as anxiety and depression, and the presence of low-grade chronic inflammation affecting intestinal function[16-18]. While traditional approaches - including pharmacological interventions, psychological support, and lifestyle modifications - have been standard practice, their effectiveness often proves limited and may introduce additional complications, particularly with long-term medication use[19-22].

Within this therapeutic landscape, MTrPs injection therapy has emerged as an innovative minimally invasive approach. These trigger points, characterized as localized tension areas within muscle tissue, exhibit distinct pathophysiological features: Heightened sensitivity in specific muscle regions, sustained local muscle fiber contraction, irregular autonomic nervous system activation, and neuromuscular dysfunction. Recent scientific inquiry has begun exploring their potential role in digestive system disorders, with particular attention to latent MTrPs due to their capacity to influence visceral sensation and function through complex neuromuscular pathways.

Anatomical and neurophysiological investigations have revealed intriguing connections between abdominal muscle trigger points and viscera-visceral reflexes, alongside visceral sensory hypersensitivity. These muscle tension anomalies appear to influence gastrointestinal function through various neurological mechanisms: Visceral pathology can induce changes in body wall muscles, trigger points may stimulate local neurotransmitter release, and persistent muscle tension could alter central pain processing[23-25]. However, comprehensive research into MTrPs’ specific therapeutic value in FGIDs remains limited, with existing studies primarily focusing on pain mechanisms rather than broader symptom improvement.

A groundbreaking study conducted at Qilu Hospital of Shandong University (June 2023 to May 2024) sought to address this knowledge gap. This randomized controlled trial compared MTrP injection therapy with conventional oral medication in 60 FGID patients. The injection protocol involved treating 3-5 trigger points with a specialized drug solution, administered twice over a four-week period, while the control group received standard oral medication. The results proved compelling. The TI group demonstrated superior outcomes in gastrointestinal symptom scores (GSRS and Irritable Bowel Syndrome Severity Scoring System) at both 2 weeks and 4 weeks post-treatment. Quality of life measurements (GIQLI) showed remarkable improvement, rising from 45.6 ± 6.2 to 68.5 ± 6.1, surpassing the medication group’s more modest improvement to 57.3 ± 5.5. The clinical effectiveness rate reached 83.3% in the injection group, substantially exceeding the medication group’s 56.7%. Safety profiles further supported the injection approach, with only 10% experiencing minor adverse events compared to 26.7% in the medication group. These adverse events were primarily limited to mild local reactions, contrasting with the more systemic side effects observed in the medication group.

This innovative treatment approach represents a significant advancement in FGID management, offering rapid symptom relief, comprehensive quality of life improvements, and reduced medication dependency, all while maintaining an excellent safety profile. These findings not only present a promising treatment option but also open new avenues for understanding FGID pathogenesis and treatment.

While this study demonstrates the efficacy of latent MTrP injection therapy in treating FGIDs, several limitations should be noted. The relatively small sample size and single-center design may limit the generalizability of the findings, necessitating larger, multi-center studies. The short follow-up period of 4 weeks prevents assessment of long-term efficacy and sustainability of symptom relief. Additionally, the study did not investigate underlying biological mechanisms, such as inflammatory markers or autonomic nervous system involvement, which could provide deeper insights into the therapy’s mode of action. The absence of a placebo control also makes it difficult to fully exclude psychological or nonspecific effects. Future research should address these limitations by incorporating larger cohorts, extended follow-up, mechanistic analyses, and placebo-controlled designs to validate and optimize this therapeutic approach.

CONCLUSION

The implications of this research extend beyond immediate clinical applications, suggesting potential paradigm shifts in how we approach FGIDs. Future investigations may further elucidate the precise mechanisms of action, optimize treatment protocols, and explore potential applications in related conditions, ultimately advancing our understanding and treatment of these challenging disorders.