https://orcid.org/0000-0001-7502-7644
Abstract
The objective of this study was to evaluate the efficacy of electrotherapy and manual therapy for the treatment of women with primary dysmenorrhea.
Systematic searches were conducted in Scopus, Web of Science, PubMed, CINAHL, and MEDLINE. The articles must have been published in the last 10 years, had a sample exclusively of women with primary dysmenorrhea, had a randomized controlled trial design, and used interventions that included some form of manual therapy and/or electrotherapy techniques. Two reviewers independently screened articles for eligibility and extracted data. Difference in mean differences and their 95% CIs were calculated as the between-group difference in means divided by the pooled standard deviation. The I2 statistic was used to determine the degree of heterogeneity.
Twelve selected studies evaluated interventions, with 5 evaluating electrotherapy techniques and 7 evaluating manual therapy techniques. All studies analyzed identified improvements in pain intensity and meta-analysis confirmed their strong effect.
Manual therapy and electrotherapy are effective for the treatment of women with primary dysmenorrhea. Transcutaneous electrical nerve stimulation combined with thermotherapy and effleurage massage stands out for its effects on the intensity and duration of pain with the application of a few sessions and their long-term effects.
Manual therapy techniques and electrotherapy methods reduce the pain intensity of women with primary dysmenorrhea. Quality of life and degree of anxiety improved significantly with manual therapy interventions. Transcutaneous electrical nerve stimulation combined with thermotherapy and effleurage massage are the interventions with which positive effects were achieved with fewer sessions.
Introduction
Dysmenorrhea is a menstrual disorder characterized by suprapubic cramping of uterine origin and pain occurring a few hours before or after the onset of menstruation.1 Dysmenorrhea is classified, according to its pathophysiology, into primary dysmenorrhea, which occurs in the absence of a previous pathology and with regular ovulatory cycles, and secondary dysmenorrhea, which is associated with a recognizable disease or the use of an intrauterine contraceptive device.2,3 Primary dysmenorrhea occurs especially in adolescents and young adult women (aged 16–25 years) and is one of the main causes of pelvic pain.2,4
Patients with primary dysmenorrhea describe pain onset shortly before or at the beginning of bleeding, lasting up to 72 hours. The pain is localized in the suprapubic region and can radiate to the upper thigh or back, or both. Pain intensity typically reaches its peak at 24 to 36 hours from the start of menses, and the duration is seldom longer than a few days.5,6 The pain may spread to areas such as the back and thighs and may be accompanied by systemic symptoms such as vomiting, nausea, diarrhea, and insomnia.1
Currently, the prostaglandin theory is the most widely accepted cause of primary dysmenorrhea,5 whereby these substances cause the blood vessels supplying the uterus to constrict, causing hypercontractility of the myometrium.6 This leads to ischemia and hypoxia of the uterus, as well as increased sensitivity of the nerve endings in this region.3,7,8 Prostaglandins are the primary lipid mediators in animals.9 In particular, prostaglandins F2α and E2 play specific roles in the inflammatory process. PGF2α mediates the constriction of arcuate vessels, leading to local hypoxia of endometrial tissues and stimulating smooth muscle contractions. These contractions, in turn, facilitate menstrual bleeding. The action of PGE2 depends on the type of receptors involved but can include the relaxation of endometrial blood vessels and potentially contribute to increased swelling and the recruitment of leukotrienes.10
When prescribing treatment for primary dysmenorrhea, there are several possible therapeutic options. A previous systematic review concluded that drugs, medicinal plants, and acupressure all seem to alleviate pain by decreasing prostaglandin levels, mediating nitric oxide, increasing beta-endorphin levels, blocking calcium channels, and enhancing circulatory flow through the uterine pathway.11,12 One of the most common treatments is pharmacological treatment with hormonal agents (progestins or estrogen-progestin combinations) and non-steroidal anti-inflammatory drugs.13 These medications alleviate pain by inhibiting the production and release of prostaglandins. However, their use has been linked to side effects such as bronchospasm, dyspepsia, salt retention, damage to gastric mucosa and antiplatelet activity, ulcers, erosion, muscle pain, and nausea.14,15 These effects, which can occur both in the short and long term after usage, must be considered.14,15
As a result, there has been a rise in the allocation of resources for the research and development of non-pharmacological and non-invasive therapeutic alternatives such as therapeutic exercise,16 biofeedback,17 thermotherapy,18 acupoint stimulation,18 electrotherapy,18, and manual therapy.19 In fact, all of them are included as intervention techniques recommended by clinical practice guidelines.5,18 Of these, the latter 2 stand out for the few side effects they entail, the wide variety of techniques and methods they include and their great adaptability to women’s preferences.16,18,19 Manual therapy is the synergistic application of movement-oriented strategies, integrating exercise and manually applied mobilization and manipulation procedures, aimed at modulating pain; enhancing range of motion; minimizing or eliminating soft tissue swelling, inflammation, or limitation; inducing relaxation; improving contractile and non-contractile tissue repair, extensibility, and/or stability; facilitating movement; and enhancing function.20,21 Electrostimulation is a strategy used to modulate the nervous system through electrical stimulation. It capitalizes on the mechanism of neural signaling, utilizing both electrical and chemical means through which action potentials are propagated, neurotransmitters are released, and neurons or target organs (such as muscles) are activated. When an external electrical stimulation is applied to a nerve fiber, it triggers an action potential that travels along the nerve and subsequently activates nearby cells, whether they are neurons or muscle fibers. These attributes enable electrostimulation, or the application of electrical current to a nerve, to be employed for both diagnostic and therapeutic purposes.22 However, there is no consensus on which electrotherapy and manual therapy techniques are most effective.
While systematic reviews on the effectiveness of physical therapist interventions for treating primary dysmenorrhea symptoms have been previously published,2,23–25 the specific impact of electrotherapy and manual therapy has not been assessed yet. Therefore, a systematic review and meta-analysis was considered necessary to evaluate the efficacy of electrotherapy and manual therapy for the treatment of women with primary dysmenorrhea.
Methods
Data Sources and Searches
This systematic review and meta-analysis were prospectively registered on PROSPERO (ID: CRD42022314951) and followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), the recommendations for their implementation in Exercise, Rehabilitation, Sport Medicine, and Sports Science (PERSiST),26 and the reporting guidelines and the recommendations from the Cochrane Collaboration.27 The PICO question was then chosen as follows: the population was women with primary dysmenorrhea; the interventions were electrotherapy and/or manual therapy techniques; the control was no intervention, sham techniques, counseling, or drugs; the outcome was pain-related variables (intensity, frequency, duration, and/or need of drug consumption); and the study designs were randomized controlled trials.
A systematic search of publications was conducted in March 2022 in the following databases: Scopus, Web of Science, PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and MEDLINE. The search strategy included different combinations with the following Medical Subject Headings terms: Dysmenorrhea, Physical therapy specialty, Physical therapy modalities, Manual therapy, and Electric stimulation therapy. The search strategy is presented in the Supplementary Table.
Study Selection
After removing duplicates, 2 reviewers (Á. G.-M. and R. L.-R for independently screened articles for eligibility. In case of disagreement, a third reviewer (P. H.-L.) finally decided whether the study should be included or not. For the selection of results, the inclusion criteria were established as follows: the sample exclusively consisted of women with primary dysmenorrhea (should not demand that the diagnosis be based on specific diagnostic criteria); the study design was a randomized controlled trial; interventions included manual therapy and/or electrotherapy techniques; studies assessed variables related to pain (intensity, frequency, duration, and/or drug consumption); and the control group received placebo techniques or drug treatments. No exclusion criteria were employed. Interrater agreement (kappa score) was calculated for the process of article selection, measuring the level of agreement in the outcomes obtained after applying the inclusion criteria.
After screening the data, extracting, obtaining, and screening the titles and abstracts for inclusion criteria, the selected abstracts were obtained in full texts. Titles and abstracts lacking sufficient information regarding inclusion criteria were also obtained as full texts. Full text articles were selected in case of compliance with inclusion criteria by the 2 reviewers using a data extraction form.
Data Extraction and Quality Assessment
Data from the included studies were independently extracted by the 2 aforementioned reviewers using a customized data extraction table in Microsoft Excel (Microsoft Corp, Redmond, WA, USA). In case of disagreement, both reviewers debated until an agreement was reached.
The data extracted from the included articles for further analysis were: demographic information (title, authors, journal, and year), characteristics of the sample (age, inclusion and exclusion criteria, and number of participants), study-specific parameters (study type, techniques included in the intervention, parameters of its application, duration of the intervention, and duration and frequency of the sessions), follow-up and dropout rates of participants, and results obtained (variables analyzed, instruments used, and results throughout the follow-up). Tables were used to describe both the studies’ characteristics and the extracted data.
Assessment of Risk of Bias
The Physiotherapy Evidence Database (PEDro) scale was used to assess the quality of studies. Included studies were categorized based on PEDro scale scores as excellent (9 or 10), good (6 to 8), or fair (≤5) quality.28 Additionally, the RoB (Risk of Bias) tool was applied to assess bias risk.29 Furthermore, when performing meta-analysis, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was employed to evaluate the quality of evidence.30
The assessment of study quality and bias risk was conducted by 2 independent evaluators (Á. G.-M. and R. L.-R.), with a third evaluator (P. H.-L.) consulted in cases of disagreement.
Data Synthesis and Analysis
A meta-analysis was carried out for the intensity of pain (the other pain-related variables were assessed in such a heterogeneous way that they did not allow meta-analysis). The meta-analysis included subgroup analysis of interventions based on manual therapy and electrotherapy independently. Mean differences (MD) and their 95% CIs were calculated as the difference between the intervention and control group means and the SD of the difference between the means.31 When these data were not available in the study, they were requested via email to the authors (however, none of them responded by providing data and were not included in the meta-analysis). Effect sizes were interpreted using the following MD cutoff values: 0 to 0.2 (very small), 0.2 to 0.5 (small), 0.5 to 0.8 (moderate), and > 0.8 (large).32 The same increments were used for negative values. The significance level was set to P < .05. The I2 statistic was used to determine the degree of heterogeneity, where the percentages quantified the magnitude of heterogeneity: 25% = low, 50% = medium, and 75% = high heterogeneity.33 I2 values higher than 50% were considered as having substantial heterogeneity, and the random-intercepts model was used for analysis of the data. The random-intercepts model θ* is calculated as θ*=|$\frac{\sum{w}_{\ast}^i\kern0em \mathrm{\theta} i\kern0em }{\sum{w}_{\ast}^i\kern0em }$|, where θi is the effect estimate of study i, and |${w}_{\ast}^i$| is the weight of study i.31 The weight is calculated with the formula weight = |$\frac{1}{\mathrm{Var}i+\mathrm{\tau} 2}$|, where Vari is the within-study variance for the i th study, and τ2 is the between-study variance estimated using the method of DerSimonian and Laird.34 The analyses were performed with Comprehensive Meta-Analysis (CMA) V2 software (Biostat, Englewood, NJ, USA).
Results
Characteristics of the Selected Studies
After searching the different databases, a total of 491 results were obtained. Of these, 171 were duplicates, and 307 were eliminated due to the inclusion and exclusion criteria so that 12 articles were finally selected. After the first reading of all candidate full texts, Kappa score for inclusion of the results of reviewers 1 and 2 was 0.97, indicating a very high agreement. The process for the final retrieval of the results is shown in Figure 1.
PRISMA flow diagram.
The selected studies evaluated interventions involving electrotherapy techniques on 6 studies35–39 and manual therapy techniques on the remaining 740–46 (Tab. 1). Out of the 12 analyzed outcomes, 9 of them had 2 sample groups (intervention and control),35,37–41,43,45,46 2 of them had 3 groups (2 for intervention and 1 for control),42,44 and 1 of them had 4 groups (3 for intervention and 1 for control).36
Methodological Characteristics of the Studies Analyzeda
| Authors | Sample Size | Interventions | Duration of Intervention | Number of Sessions (Frequency) | |
|---|---|---|---|---|---|
| Experimental Groups | Control Group | ||||
| Azima et al44 (2015) | 102 | Group 1: effleurage massage with lavender oil in a gentle, clockwise circular motion for 15 min. Group 2: isometric exercises with 7-step protocol. | No intervention | 2 mo | Group 1: 4 (2/mo) Group 2: 40 (5/wk) |
| Bai et al37 (2017) | 122 | TENS on painful abdominal area (2 electrodes, 2–100 Hz at maximum supportable intensity for 30 min). | Sham TENS | 3 mo | 24 maximum (8/mo maximum) |
| Barassi et al43 (2018) | 60 | Neuromuscular therapy in the lumbo-sacral and abdominal area on dysfunctional myofascial structures related to the pelvic and visceral areas (rectus abdominis, diaphragm, iliopsoas, piriformis, quadratus lumborum and the lumbo-ileon, and sacroiliac and sacrotuberous ligaments): stripping, deep longitudinal and transverse friction and rolled clamping (for 30–35 min). | Ibuprofen or naproxen | 1 mo | 8 (2/wk) |
| Lauretti et al39 (2015) | 40 | TENS on abdominal skin dermatomas related to referred uterine pain (2 electrodes, at 85 Hz, at 10–30 mA for 30 min). | Sham TENS | 3 mo | 21 maximum (7/mo maximum) |
| Lee et al38 (2015) | 115 | High frequency TENS (100–110 Hz for 10 min) & thermotherapy (47–18°C for 20 min) on painful lower abdominal region. | Sham TENS & sham thermotherapy | 1 mo | 8 maximum (days with menstrual pain) |
| Machado et al36 (2019) | 88 | Group 1: microwave (5 cm from abdomen with moderate heat for 20 min) & TENS on abdomen (2 electrodes on both sides at T10-T11, 100 Hz, 200 μs at maximum bearable intensity for 30 min). Group 2: placebo TENS & microwave. Group 3: placebo microwave & TENS. | Pacebo microwave & placebo TENS | 1 d | 1 (1/d) |
| Manisha et al35 (2021) | 140 | High frequency TENS at root level L3-L5 (at proximal margin 2 in lumbar region and 2 in gluteal region) with 4 electrodes at 100 Hz, 80 μs at maximum supportable intensity for 20 min. | No intervention | 12 mo | 12 (1/mo) |
| Molins-Cubero et al45 (2014) | 40 | Global manipulation technique of the sacroiliac joints bilaterally. | Sham manipulation | 1 d | 1 (1/d) |
| Özgul et al41 (2018) | 40 | Connective tissue manipulation in sacral, lumbar, anterior pelvic, and lower thoracic areas: long and short strokes (3 reps/stroke according to structures from right to left for 10 min) & counseling (decrease sugar, alcohol, tobacco, and caffeine intake; daily exercises (general stretching 30 min with deep abdominal breathing and moderate aerobic exercise 2.5 h/wk). | Counseling | 2–3 wk | 10–15 (5/wk) |
| Park et al40 (2020) | 30 | Sacroiliac joint manipulation: high-intensity, low-amplitude manipulation technique on both sides of the sacroiliac joints, placing women in lateral recumbency and applying force for less than 200 ms. A maximum of 2 reps/session were performed. | Sham manipulations | 1 d | 1 (1/d) |
| Schwerla et al46 (2014) | 53 | Six osteopathic techniques: manipulation of structures with osteopathic dysfunctions. The therapists chose the techniques they considered appropriate for each participant (direct, indirect, visceral, and cranial). | No intervention | 3 mo | 6 (2/mo) |
| Vagedes et al42 (2019) | 60 | Group 1: rhythmic effleurage massage (without pressure and with circular movements) for 30–40 min + 15–20 min rest at the end. Group 2: visual biofeedback of heart rate variability using Qiu device for 15–20 min. | No intervention | 3 mo | Group 1: 12 (1/wk) Group 2: 90 (1/d) |
| Authors | Sample Size | Interventions | Duration of Intervention | Number of Sessions (Frequency) | |
|---|---|---|---|---|---|
| Experimental Groups | Control Group | ||||
| Azima et al44 (2015) | 102 | Group 1: effleurage massage with lavender oil in a gentle, clockwise circular motion for 15 min. Group 2: isometric exercises with 7-step protocol. | No intervention | 2 mo | Group 1: 4 (2/mo) Group 2: 40 (5/wk) |
| Bai et al37 (2017) | 122 | TENS on painful abdominal area (2 electrodes, 2–100 Hz at maximum supportable intensity for 30 min). | Sham TENS | 3 mo | 24 maximum (8/mo maximum) |
| Barassi et al43 (2018) | 60 | Neuromuscular therapy in the lumbo-sacral and abdominal area on dysfunctional myofascial structures related to the pelvic and visceral areas (rectus abdominis, diaphragm, iliopsoas, piriformis, quadratus lumborum and the lumbo-ileon, and sacroiliac and sacrotuberous ligaments): stripping, deep longitudinal and transverse friction and rolled clamping (for 30–35 min). | Ibuprofen or naproxen | 1 mo | 8 (2/wk) |
| Lauretti et al39 (2015) | 40 | TENS on abdominal skin dermatomas related to referred uterine pain (2 electrodes, at 85 Hz, at 10–30 mA for 30 min). | Sham TENS | 3 mo | 21 maximum (7/mo maximum) |
| Lee et al38 (2015) | 115 | High frequency TENS (100–110 Hz for 10 min) & thermotherapy (47–18°C for 20 min) on painful lower abdominal region. | Sham TENS & sham thermotherapy | 1 mo | 8 maximum (days with menstrual pain) |
| Machado et al36 (2019) | 88 | Group 1: microwave (5 cm from abdomen with moderate heat for 20 min) & TENS on abdomen (2 electrodes on both sides at T10-T11, 100 Hz, 200 μs at maximum bearable intensity for 30 min). Group 2: placebo TENS & microwave. Group 3: placebo microwave & TENS. | Pacebo microwave & placebo TENS | 1 d | 1 (1/d) |
| Manisha et al35 (2021) | 140 | High frequency TENS at root level L3-L5 (at proximal margin 2 in lumbar region and 2 in gluteal region) with 4 electrodes at 100 Hz, 80 μs at maximum supportable intensity for 20 min. | No intervention | 12 mo | 12 (1/mo) |
| Molins-Cubero et al45 (2014) | 40 | Global manipulation technique of the sacroiliac joints bilaterally. | Sham manipulation | 1 d | 1 (1/d) |
| Özgul et al41 (2018) | 40 | Connective tissue manipulation in sacral, lumbar, anterior pelvic, and lower thoracic areas: long and short strokes (3 reps/stroke according to structures from right to left for 10 min) & counseling (decrease sugar, alcohol, tobacco, and caffeine intake; daily exercises (general stretching 30 min with deep abdominal breathing and moderate aerobic exercise 2.5 h/wk). | Counseling | 2–3 wk | 10–15 (5/wk) |
| Park et al40 (2020) | 30 | Sacroiliac joint manipulation: high-intensity, low-amplitude manipulation technique on both sides of the sacroiliac joints, placing women in lateral recumbency and applying force for less than 200 ms. A maximum of 2 reps/session were performed. | Sham manipulations | 1 d | 1 (1/d) |
| Schwerla et al46 (2014) | 53 | Six osteopathic techniques: manipulation of structures with osteopathic dysfunctions. The therapists chose the techniques they considered appropriate for each participant (direct, indirect, visceral, and cranial). | No intervention | 3 mo | 6 (2/mo) |
| Vagedes et al42 (2019) | 60 | Group 1: rhythmic effleurage massage (without pressure and with circular movements) for 30–40 min + 15–20 min rest at the end. Group 2: visual biofeedback of heart rate variability using Qiu device for 15–20 min. | No intervention | 3 mo | Group 1: 12 (1/wk) Group 2: 90 (1/d) |
aTENS = Transcutaneos Electrical Nerve Stimulation.
Methodological Characteristics of the Studies Analyzeda
| Authors | Sample Size | Interventions | Duration of Intervention | Number of Sessions (Frequency) | |
|---|---|---|---|---|---|
| Experimental Groups | Control Group | ||||
| Azima et al44 (2015) | 102 | Group 1: effleurage massage with lavender oil in a gentle, clockwise circular motion for 15 min. Group 2: isometric exercises with 7-step protocol. | No intervention | 2 mo | Group 1: 4 (2/mo) Group 2: 40 (5/wk) |
| Bai et al37 (2017) | 122 | TENS on painful abdominal area (2 electrodes, 2–100 Hz at maximum supportable intensity for 30 min). | Sham TENS | 3 mo | 24 maximum (8/mo maximum) |
| Barassi et al43 (2018) | 60 | Neuromuscular therapy in the lumbo-sacral and abdominal area on dysfunctional myofascial structures related to the pelvic and visceral areas (rectus abdominis, diaphragm, iliopsoas, piriformis, quadratus lumborum and the lumbo-ileon, and sacroiliac and sacrotuberous ligaments): stripping, deep longitudinal and transverse friction and rolled clamping (for 30–35 min). | Ibuprofen or naproxen | 1 mo | 8 (2/wk) |
| Lauretti et al39 (2015) | 40 | TENS on abdominal skin dermatomas related to referred uterine pain (2 electrodes, at 85 Hz, at 10–30 mA for 30 min). | Sham TENS | 3 mo | 21 maximum (7/mo maximum) |
| Lee et al38 (2015) | 115 | High frequency TENS (100–110 Hz for 10 min) & thermotherapy (47–18°C for 20 min) on painful lower abdominal region. | Sham TENS & sham thermotherapy | 1 mo | 8 maximum (days with menstrual pain) |
| Machado et al36 (2019) | 88 | Group 1: microwave (5 cm from abdomen with moderate heat for 20 min) & TENS on abdomen (2 electrodes on both sides at T10-T11, 100 Hz, 200 μs at maximum bearable intensity for 30 min). Group 2: placebo TENS & microwave. Group 3: placebo microwave & TENS. | Pacebo microwave & placebo TENS | 1 d | 1 (1/d) |
| Manisha et al35 (2021) | 140 | High frequency TENS at root level L3-L5 (at proximal margin 2 in lumbar region and 2 in gluteal region) with 4 electrodes at 100 Hz, 80 μs at maximum supportable intensity for 20 min. | No intervention | 12 mo | 12 (1/mo) |
| Molins-Cubero et al45 (2014) | 40 | Global manipulation technique of the sacroiliac joints bilaterally. | Sham manipulation | 1 d | 1 (1/d) |
| Özgul et al41 (2018) | 40 | Connective tissue manipulation in sacral, lumbar, anterior pelvic, and lower thoracic areas: long and short strokes (3 reps/stroke according to structures from right to left for 10 min) & counseling (decrease sugar, alcohol, tobacco, and caffeine intake; daily exercises (general stretching 30 min with deep abdominal breathing and moderate aerobic exercise 2.5 h/wk). | Counseling | 2–3 wk | 10–15 (5/wk) |
| Park et al40 (2020) | 30 | Sacroiliac joint manipulation: high-intensity, low-amplitude manipulation technique on both sides of the sacroiliac joints, placing women in lateral recumbency and applying force for less than 200 ms. A maximum of 2 reps/session were performed. | Sham manipulations | 1 d | 1 (1/d) |
| Schwerla et al46 (2014) | 53 | Six osteopathic techniques: manipulation of structures with osteopathic dysfunctions. The therapists chose the techniques they considered appropriate for each participant (direct, indirect, visceral, and cranial). | No intervention | 3 mo | 6 (2/mo) |
| Vagedes et al42 (2019) | 60 | Group 1: rhythmic effleurage massage (without pressure and with circular movements) for 30–40 min + 15–20 min rest at the end. Group 2: visual biofeedback of heart rate variability using Qiu device for 15–20 min. | No intervention | 3 mo | Group 1: 12 (1/wk) Group 2: 90 (1/d) |
| Authors | Sample Size | Interventions | Duration of Intervention | Number of Sessions (Frequency) | |
|---|---|---|---|---|---|
| Experimental Groups | Control Group | ||||
| Azima et al44 (2015) | 102 | Group 1: effleurage massage with lavender oil in a gentle, clockwise circular motion for 15 min. Group 2: isometric exercises with 7-step protocol. | No intervention | 2 mo | Group 1: 4 (2/mo) Group 2: 40 (5/wk) |
| Bai et al37 (2017) | 122 | TENS on painful abdominal area (2 electrodes, 2–100 Hz at maximum supportable intensity for 30 min). | Sham TENS | 3 mo | 24 maximum (8/mo maximum) |
| Barassi et al43 (2018) | 60 | Neuromuscular therapy in the lumbo-sacral and abdominal area on dysfunctional myofascial structures related to the pelvic and visceral areas (rectus abdominis, diaphragm, iliopsoas, piriformis, quadratus lumborum and the lumbo-ileon, and sacroiliac and sacrotuberous ligaments): stripping, deep longitudinal and transverse friction and rolled clamping (for 30–35 min). | Ibuprofen or naproxen | 1 mo | 8 (2/wk) |
| Lauretti et al39 (2015) | 40 | TENS on abdominal skin dermatomas related to referred uterine pain (2 electrodes, at 85 Hz, at 10–30 mA for 30 min). | Sham TENS | 3 mo | 21 maximum (7/mo maximum) |
| Lee et al38 (2015) | 115 | High frequency TENS (100–110 Hz for 10 min) & thermotherapy (47–18°C for 20 min) on painful lower abdominal region. | Sham TENS & sham thermotherapy | 1 mo | 8 maximum (days with menstrual pain) |
| Machado et al36 (2019) | 88 | Group 1: microwave (5 cm from abdomen with moderate heat for 20 min) & TENS on abdomen (2 electrodes on both sides at T10-T11, 100 Hz, 200 μs at maximum bearable intensity for 30 min). Group 2: placebo TENS & microwave. Group 3: placebo microwave & TENS. | Pacebo microwave & placebo TENS | 1 d | 1 (1/d) |
| Manisha et al35 (2021) | 140 | High frequency TENS at root level L3-L5 (at proximal margin 2 in lumbar region and 2 in gluteal region) with 4 electrodes at 100 Hz, 80 μs at maximum supportable intensity for 20 min. | No intervention | 12 mo | 12 (1/mo) |
| Molins-Cubero et al45 (2014) | 40 | Global manipulation technique of the sacroiliac joints bilaterally. | Sham manipulation | 1 d | 1 (1/d) |
| Özgul et al41 (2018) | 40 | Connective tissue manipulation in sacral, lumbar, anterior pelvic, and lower thoracic areas: long and short strokes (3 reps/stroke according to structures from right to left for 10 min) & counseling (decrease sugar, alcohol, tobacco, and caffeine intake; daily exercises (general stretching 30 min with deep abdominal breathing and moderate aerobic exercise 2.5 h/wk). | Counseling | 2–3 wk | 10–15 (5/wk) |
| Park et al40 (2020) | 30 | Sacroiliac joint manipulation: high-intensity, low-amplitude manipulation technique on both sides of the sacroiliac joints, placing women in lateral recumbency and applying force for less than 200 ms. A maximum of 2 reps/session were performed. | Sham manipulations | 1 d | 1 (1/d) |
| Schwerla et al46 (2014) | 53 | Six osteopathic techniques: manipulation of structures with osteopathic dysfunctions. The therapists chose the techniques they considered appropriate for each participant (direct, indirect, visceral, and cranial). | No intervention | 3 mo | 6 (2/mo) |
| Vagedes et al42 (2019) | 60 | Group 1: rhythmic effleurage massage (without pressure and with circular movements) for 30–40 min + 15–20 min rest at the end. Group 2: visual biofeedback of heart rate variability using Qiu device for 15–20 min. | No intervention | 3 mo | Group 1: 12 (1/wk) Group 2: 90 (1/d) |
aTENS = Transcutaneos Electrical Nerve Stimulation.
On the PEDro scale, 41.7% of the investigations obtained a score equal to or higher than 8 points36–39,45 (Tab. 2).
PEDro Scale Scoresa
| 1b | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | Score | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | ✓ | ✓ | X | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 6 |
| Bai et al37 (2017) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Barassi et al43 (2018) | ✓ | ✓ | X | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 7 |
| Lauretti et al39 (2015) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | X | ✓ | ✓ | ✓ | 8 |
| Lee et al38 (2015) | ✓ | ✓ | ✓ | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 8 |
| Machado et al36 (2019) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Manisha et al35 (2021) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Molins-Cubero et al45 (2014) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Özgul et al41 (2018) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Park et al40 (2020) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Schwerla et al46 (2014) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Vagedes et al42 (2019) | ✓ | ✓ | X | ✓ | X | X | X | X | ✓ | ✓ | ✓ | 5 |
| 1b | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | Score | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | ✓ | ✓ | X | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 6 |
| Bai et al37 (2017) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Barassi et al43 (2018) | ✓ | ✓ | X | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 7 |
| Lauretti et al39 (2015) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | X | ✓ | ✓ | ✓ | 8 |
| Lee et al38 (2015) | ✓ | ✓ | ✓ | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 8 |
| Machado et al36 (2019) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Manisha et al35 (2021) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Molins-Cubero et al45 (2014) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Özgul et al41 (2018) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Park et al40 (2020) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Schwerla et al46 (2014) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Vagedes et al42 (2019) | ✓ | ✓ | X | ✓ | X | X | X | X | ✓ | ✓ | ✓ | 5 |
a(1) Choice criteria specified (not to be used for scoring). (2) Subjects randomly assigned into groups. (3) Assignment blinded. (4) Groups are similar at baseline with respect to the most important prognostic factors. (5) All subjects were blinded. (6) Therapists were blinded. (7) Evaluators who measured at least 1 key outcome were blinded. (8) Measures of at least 1 of the key outcomes were obtained from more than 85% of the subjects initially assigned to the groups. (9) Results were presented for all subjects who received treatment or were assigned to the control group. (10) Results of statistical comparisons between groups were reported for at least 1 key outcome. (11) Point and variability measures for at least one key outcome. PEDro = the Physiotherapy Evidence Database.
bThis item is not used to calculate the PEDro score.
PEDro Scale Scoresa
| 1b | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | Score | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | ✓ | ✓ | X | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 6 |
| Bai et al37 (2017) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Barassi et al43 (2018) | ✓ | ✓ | X | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 7 |
| Lauretti et al39 (2015) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | X | ✓ | ✓ | ✓ | 8 |
| Lee et al38 (2015) | ✓ | ✓ | ✓ | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 8 |
| Machado et al36 (2019) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Manisha et al35 (2021) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Molins-Cubero et al45 (2014) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Özgul et al41 (2018) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Park et al40 (2020) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Schwerla et al46 (2014) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Vagedes et al42 (2019) | ✓ | ✓ | X | ✓ | X | X | X | X | ✓ | ✓ | ✓ | 5 |
| 1b | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | Score | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | ✓ | ✓ | X | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 6 |
| Bai et al37 (2017) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Barassi et al43 (2018) | ✓ | ✓ | X | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 7 |
| Lauretti et al39 (2015) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | X | ✓ | ✓ | ✓ | 8 |
| Lee et al38 (2015) | ✓ | ✓ | ✓ | ✓ | X | X | ✓ | ✓ | ✓ | ✓ | ✓ | 8 |
| Machado et al36 (2019) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Manisha et al35 (2021) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Molins-Cubero et al45 (2014) | ✓ | ✓ | ✓ | ✓ | ✓ | X | ✓ | ✓ | ✓ | ✓ | ✓ | 9 |
| Özgul et al41 (2018) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Park et al40 (2020) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Schwerla et al46 (2014) | ✓ | ✓ | ✓ | ✓ | X | X | X | ✓ | ✓ | ✓ | ✓ | 7 |
| Vagedes et al42 (2019) | ✓ | ✓ | X | ✓ | X | X | X | X | ✓ | ✓ | ✓ | 5 |
a(1) Choice criteria specified (not to be used for scoring). (2) Subjects randomly assigned into groups. (3) Assignment blinded. (4) Groups are similar at baseline with respect to the most important prognostic factors. (5) All subjects were blinded. (6) Therapists were blinded. (7) Evaluators who measured at least 1 key outcome were blinded. (8) Measures of at least 1 of the key outcomes were obtained from more than 85% of the subjects initially assigned to the groups. (9) Results were presented for all subjects who received treatment or were assigned to the control group. (10) Results of statistical comparisons between groups were reported for at least 1 key outcome. (11) Point and variability measures for at least one key outcome. PEDro = the Physiotherapy Evidence Database.
bThis item is not used to calculate the PEDro score.
Interventions Analyzed
Five studies aimed to assess the effect of Transcutaneous Electrical Nerve Stimulation (TENS)35–39: 3 of them applied it in isolation35,37,39 (one of them, additionally, applied at home39) and 2 investigations combined TENS with diathermy (microwave)36 or with thermotherapy (simultaneously applied using the I-Rune I-200 L device from Medirune Co, Weonju, South Korea).38
The manual therapy interventions40–46 evaluated the impact of effleurage massage,42,44 neuromuscular therapy,43 connective tissue manipulation41, and manipulations.40,45,46 Specifically, these manipulations were applied on the sacroiliac joints40,45 or included different combinations of direct techniques such as indirect, visceral, and/or cranial (depending on the individual patient).46
The diverse control groups included in the study received placebo treatment,36–40,45 drug treatment (naproxen or ibuprofen),43 counseling41, or no intervention.35,42,44,46
Effects on Variables Related to Pain
The application of TENS (both individually35,37,39 and in combination with diathermy36 or thermotherapy38) led to significant reductions in local35–39 and referred35 pain intensity and duration,37,38 as well as in drug consumption37,39 within the intervention groups when compared with their respective controls. Moreover, Manisha et al35 reported that pain relief was sustained up to 1 year after the intervention.
The reduction of pain intensity was statistically superior in participants who received the combined or isolated diathermy intervention compared with those who received TENS alone.36 However, the thermotherapy in isolation intervention failed to reduce the medication use.38
Effleurage massage,42,44 manipulations,40,45,46 neuromuscular therapy,43, and connective tissue manipulation41 significantly decreased pain duration,43,44,46 frequency,46, and intensity40–46 (although neuromuscular therapy in a similar manner to pharmacological treatment43) as well as medication consumption.41,42,46 Furthermore, the reduction in pain intensity caused by effleurage massage was significantly greater than that achieved by an exercise program.44
Other Analyzed Variables
The application of TENS led to significant decreases in systolic and diastolic blood pressure within the intervention group compared with their control.35 Additionally, when TENS was combined with diathermy36 and sacroiliac joints manipulations45 there was a significant increase in pain thresholds to pressure in the abdomen.36,45
Regarding quality of life, Bai et al37 did not identify any changes with the application of TENS, while Lauretti et al39 did observe changes, specifically in terms of improved sleep quality, ability to get out of bed, and food and drink intake. The isolated thermotherapy intervention did not result in an improvement in the impact of pain on daily life and quality of life.38 The various combinations of manipulations46 and effleurage massage42 significantly increased the physical component of quality of life,46 but they did not improve bleeding characteristics such as duration and intensity.46
Interventions involving effleurage massage44 and connective tissue manipulation41 significantly reduce anxiety44 and pain catastrophizing,41 respectively. Additionally, Özgül et al41 evaluated participants’ attitudes toward menstruation and observed an increase in the perception that menstruation is a natural event. However, the results of the other subscales of the Menstrual Attitude Questionnaire remained unchanged.
Lastly, sacroiliac joint manipulation significantly reduced heart rate variability40 whereas the effleurage massage intervention42 did not.
The only study that recorded potential adverse treatment events did not identify their occurrence.37
Effects on Pain Intensity
Ten studies35,36,38–43,45,46 were included in the meta-analysis with a total sample size of 687 participants. Analysis was divided into 2 subgroups: electrotherapy and manual therapy. The analysis in the electrotherapy group indicated a statistically significant decreased pain score with MD = −2.68 (95% CI = −3.67 to −1.69; P < .001; I2 = 95%). Also, analysis in the second subgroup indicated a statistically significant decreased pain score in manual therapy group than control group with MD = −2.34 (95% CI = −3.32 to −1.35; P < .001; I2 = 65%). Finally, the results indicated a statistically significant decreased pain score in overall therapy group than control group with MD = −2.5 (95% CI = −3.2 to −1.81; P < .001; I2 = 93%). The forest plot can be seen in Figure 2.
Forest plot for pain intensity. BTP = bilateral thigh pain; ET = electrotherapy; G1 = group 1; G2 = group 2; G3 = group 3; LAP = lower abdominal pain; LBP = low back pain; MT = manual therapy; NI = non-intervention; PB = placebo.
Risk of Bias for Individual Studies
The risk of bias within individual studies was determined to be critical in 7 studies (58.3%)35,38,40,42,44–46 while 4 studies had a low risk of bias (33.3%)36,37,39,41 (Tab. 3).
Risk of Bias for Included Studies (RoB Tool Results)a
| Authors | Random Sequence (Selection Bias) | Allocation Concealment (Selection Bias) | Blinding of Participants and Personnel (Performance Bias) | Blinding of Outcome Assessment (Detection Bias) | Incomplete Outcome Data (Attrition Bias) | Selective Reporting (Reporting Bias) | Other Bias | Overall |
|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | Low | Low | Moderate | High | High | Low | Low | High |
| Bai et al37 (2017) | Low | Low | Low | Low | Low | Low | Low | Low |
| Barassi et al43 (2018) | Low | Low | Moderate | Low | Moderate | Low | Low | Moderate |
| Lauretti et al39 (2015) | Low | Low | Low | Low | Low | Low | Low | Low |
| Lee et al38 (2015) | Low | Low | Low | High | Low | Low | Low | High |
| Machado et al36 (2019) | Low | Low | Low | Low | Low | Low | Low | Low |
| Manisha et al35 (2021) | Low | Low | High | High | High | Low | Low | High |
| Molins-Cubero et al45 (2014) | Low | Low | High | High | Low | Low | Low | High |
| Özgul et al41 (2018) | Low | Low | Moderate | Low | Low | Low | Low | Low |
| Park et al40 (2020) | Low | Low | High | High | Low | Low | Low | High |
| Schwerla et al46 (2014) | Low | Low | Moderate | High | Moderate | Low | Low | High |
| Vagedes et al42 (2019) | Low | Low | Moderate | High | Moderate | Low | Low | High |
| Authors | Random Sequence (Selection Bias) | Allocation Concealment (Selection Bias) | Blinding of Participants and Personnel (Performance Bias) | Blinding of Outcome Assessment (Detection Bias) | Incomplete Outcome Data (Attrition Bias) | Selective Reporting (Reporting Bias) | Other Bias | Overall |
|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | Low | Low | Moderate | High | High | Low | Low | High |
| Bai et al37 (2017) | Low | Low | Low | Low | Low | Low | Low | Low |
| Barassi et al43 (2018) | Low | Low | Moderate | Low | Moderate | Low | Low | Moderate |
| Lauretti et al39 (2015) | Low | Low | Low | Low | Low | Low | Low | Low |
| Lee et al38 (2015) | Low | Low | Low | High | Low | Low | Low | High |
| Machado et al36 (2019) | Low | Low | Low | Low | Low | Low | Low | Low |
| Manisha et al35 (2021) | Low | Low | High | High | High | Low | Low | High |
| Molins-Cubero et al45 (2014) | Low | Low | High | High | Low | Low | Low | High |
| Özgul et al41 (2018) | Low | Low | Moderate | Low | Low | Low | Low | Low |
| Park et al40 (2020) | Low | Low | High | High | Low | Low | Low | High |
| Schwerla et al46 (2014) | Low | Low | Moderate | High | Moderate | Low | Low | High |
| Vagedes et al42 (2019) | Low | Low | Moderate | High | Moderate | Low | Low | High |
aRoB = Risk of Bias.
Risk of Bias for Included Studies (RoB Tool Results)a
| Authors | Random Sequence (Selection Bias) | Allocation Concealment (Selection Bias) | Blinding of Participants and Personnel (Performance Bias) | Blinding of Outcome Assessment (Detection Bias) | Incomplete Outcome Data (Attrition Bias) | Selective Reporting (Reporting Bias) | Other Bias | Overall |
|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | Low | Low | Moderate | High | High | Low | Low | High |
| Bai et al37 (2017) | Low | Low | Low | Low | Low | Low | Low | Low |
| Barassi et al43 (2018) | Low | Low | Moderate | Low | Moderate | Low | Low | Moderate |
| Lauretti et al39 (2015) | Low | Low | Low | Low | Low | Low | Low | Low |
| Lee et al38 (2015) | Low | Low | Low | High | Low | Low | Low | High |
| Machado et al36 (2019) | Low | Low | Low | Low | Low | Low | Low | Low |
| Manisha et al35 (2021) | Low | Low | High | High | High | Low | Low | High |
| Molins-Cubero et al45 (2014) | Low | Low | High | High | Low | Low | Low | High |
| Özgul et al41 (2018) | Low | Low | Moderate | Low | Low | Low | Low | Low |
| Park et al40 (2020) | Low | Low | High | High | Low | Low | Low | High |
| Schwerla et al46 (2014) | Low | Low | Moderate | High | Moderate | Low | Low | High |
| Vagedes et al42 (2019) | Low | Low | Moderate | High | Moderate | Low | Low | High |
| Authors | Random Sequence (Selection Bias) | Allocation Concealment (Selection Bias) | Blinding of Participants and Personnel (Performance Bias) | Blinding of Outcome Assessment (Detection Bias) | Incomplete Outcome Data (Attrition Bias) | Selective Reporting (Reporting Bias) | Other Bias | Overall |
|---|---|---|---|---|---|---|---|---|
| Azima et al44 (2015) | Low | Low | Moderate | High | High | Low | Low | High |
| Bai et al37 (2017) | Low | Low | Low | Low | Low | Low | Low | Low |
| Barassi et al43 (2018) | Low | Low | Moderate | Low | Moderate | Low | Low | Moderate |
| Lauretti et al39 (2015) | Low | Low | Low | Low | Low | Low | Low | Low |
| Lee et al38 (2015) | Low | Low | Low | High | Low | Low | Low | High |
| Machado et al36 (2019) | Low | Low | Low | Low | Low | Low | Low | Low |
| Manisha et al35 (2021) | Low | Low | High | High | High | Low | Low | High |
| Molins-Cubero et al45 (2014) | Low | Low | High | High | Low | Low | Low | High |
| Özgul et al41 (2018) | Low | Low | Moderate | Low | Low | Low | Low | Low |
| Park et al40 (2020) | Low | Low | High | High | Low | Low | Low | High |
| Schwerla et al46 (2014) | Low | Low | Moderate | High | Moderate | Low | Low | High |
| Vagedes et al42 (2019) | Low | Low | Moderate | High | Moderate | Low | Low | High |
aRoB = Risk of Bias.
Additionally, the certainty of the evidence obtained was assessed as moderate for the variable of ventricular ejection fraction and E/A waveforms and high for the Global longitudinal strain (Tab. 4).
Certainty of the Evidence (GRADE)a
| Outcome | Number of Participants (Studies) | Risk of Biasb | Inconsistencyc | Indirectness | Imprecision | Other Considerations | Certainty of the Evidence (GRADE) |
|---|---|---|---|---|---|---|---|
| Pain intensity | 687 (10 RCTs) | High | High | Low | Low | None | |$\oplus\oplus\bigcirc\bigcirc $| Moderate |
| Outcome | Number of Participants (Studies) | Risk of Biasb | Inconsistencyc | Indirectness | Imprecision | Other Considerations | Certainty of the Evidence (GRADE) |
|---|---|---|---|---|---|---|---|
| Pain intensity | 687 (10 RCTs) | High | High | Low | Low | None | |$\oplus\oplus\bigcirc\bigcirc $| Moderate |
aGRADE = Grading of Recommendations Assessment, Development and Evaluation; RCT = randomized clinical trial.
bThe average risk of bias of the studies according to the Risk of Bias (RoB) tool.
cLow methodological and statistical heterogeneity among trials (I2 > 25%).
Certainty of the Evidence (GRADE)a
| Outcome | Number of Participants (Studies) | Risk of Biasb | Inconsistencyc | Indirectness | Imprecision | Other Considerations | Certainty of the Evidence (GRADE) |
|---|---|---|---|---|---|---|---|
| Pain intensity | 687 (10 RCTs) | High | High | Low | Low | None | |$\oplus\oplus\bigcirc\bigcirc $| Moderate |
| Outcome | Number of Participants (Studies) | Risk of Biasb | Inconsistencyc | Indirectness | Imprecision | Other Considerations | Certainty of the Evidence (GRADE) |
|---|---|---|---|---|---|---|---|
| Pain intensity | 687 (10 RCTs) | High | High | Low | Low | None | |$\oplus\oplus\bigcirc\bigcirc $| Moderate |
aGRADE = Grading of Recommendations Assessment, Development and Evaluation; RCT = randomized clinical trial.
bThe average risk of bias of the studies according to the Risk of Bias (RoB) tool.
cLow methodological and statistical heterogeneity among trials (I2 > 25%).
Discussion
This systematic review with meta-analysis aimed to assess the efficacy of manual therapy and electrotherapy in women with primary dysmenorrhea. After analyzing the results, it can be confirmed that both treatment methods are effective in relieving pain in these patients in comparison with placebo interventions or drugs.
All the studies analyzed identified improvements in pain intensity which, after meta-analysis, were confirmed to have a strong effect on this variable. As for electrotherapy interventions, TENS alone35–37,39 or in combination with thermotherapy38 or microwave38 managed to reduce the intensity of the pain. It should be noted, however, that the combination of TENS with thermotherapy did not result in additional benefits compared with TENS alone.38 This could be due to the fact that TENS stimulates the sensory nerve fibers47 and thereby causes pain modulation.48 As a result, these effects would be achieved through activation of central descending inhibitory mechanisms and reduction of excitatory signals in the posterior medullary horn.49 On the other hand, Machado et al38 tested the efficacy of microwaves in reducing pain compared with TENS or placebo. This type of high-frequency current causes tissue heating without causing neuromuscular excitation.50 Specifically, microwaves seem to cause a reduction in inflammation, pain, and muscle spasm and an increase in tissue metabolism and tissue flexibility.51 In this way, and due to the depth at which the microwave acts, its beneficial effects compared with TENS could be justified.
Although all manual therapy interventions were successful in reducing the pain of the participating patients, pelvic manipulations40,45 and effleurage massage44 were successful in reducing pain with only 1 and 2 sessions, respectively. This could be justified by the fact that massage improves both blood and lymphatic flow, as well as relaxing the musculature and reducing stress levels.52 In addition, the effleurage technique was the only one reevaluated in the long term (up to 3 months after the intervention42). Finally, it should be noted that neuromuscular therapy achieved similar effects to non-steroidal anti-inflammatory drugs,43 and that this could be due to the ability of this method to reduce local tensions and pain-related symptoms.53 In addition, long-term reevaluation confirmed that the effectiveness of this technique is maintained over time, in contrast to non-steroidal anti-inflammatory drugs. Taking into account their adverse effects (eg, nausea, indigestion, drowsiness, headache) and the temporary nature of their benefits,54 neuromuscular therapy appears to be a better therapeutic alternative.
On the other hand, several studies have looked at changes in pain duration37,38,43,44,46 and achieved significant reductions in pain. Notably, TENS combined with thermotherapy achieved significant changes with an intervention of only one menstrual cycle.38 In contrast, only effleurage massage showed that its benefits remained for up to 2 months after the intervention.44
In terms of quality of life, only one of the investigations assessing TENS showed significant changes.39 This might be due to the mode of assessment of this variable: Lauretti et al39 used 4 items related to routine daily life, in contrast to the other trials in which the (WHOQHOL)-BREF scale was used with no changes after the interventions.37,38 In contrast, the 2 investigations using manual therapy42,46 showed improvement in the physical component of quality of life. Faster effects were obtained after osteopathic techniques (with only one session46), although it was only effleurage massage that showed long-term effects (after 3 months).42
Limitations
The authors must recognize the main limitations of this research as those directly related to its methodology: the use of other databases and/or other inclusion criteria could modify the results obtained. Additionally, the authors must highlight the following limitations of this review: therapists were not blinded to the active and control interventions. It’s important to note that the diagnostic criteria for primary dysmenorrhea used in each of the studies were not assessed during the outcome selection process. Moreover, only a subset of the included articles considered long-term effects.36,42,43 The variable included in the meta-analysis, although widely used in the clinical field, is an indirect measure.55 However, it’s worth noting that within the analyzed studies, this review stands as the only systematic one to date on the treatment of primary dysmenorrhea using manual and/or electrotherapy.
In conclusion, this systematic review has verified that both manual therapy and electrotherapy are effective physical therapist techniques for the treatment of women with primary dysmenorrhea in comparison with placebo interventions, drugs treatment, counseling, or no intervention. All the trials showed the benefits of the techniques applied in relation to the intensity and duration of pain, with TENS combined with thermotherapy and effleurage massage standing out, whose positive effects are obtained in a few sessions and remain in the long term. Quality of life and degree of anxiety improved significantly with manual therapy interventions (effleurage massage, manipulations, and neuromuscular therapy).
These results should be taken into account by women’s health professionals in order to be able to advise, refer, and treat these patients as effectively as possible using evidence-based procedures.
Author Contributions
Á.G.-M., R.L.-R., and P.H.-L. conceptualized and designed the study, drafted the initial manuscript, designed the data collection instruments, collected data, carried out the initial analyses, and critically reviewed the manuscript for important intellectual content. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Systematic Review Registration
This systematic review and meta-analysis were prospectively registered on PROSPERO (CRD42022314951).
Disclosure
The authors completed the ICMJE Form for Disclosure of Potential Conflicts of Interest and reported no conflicts of interest.
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