Primary dysmenorrhea is a common gynecological condition characterized by painful menstrual cramps that can negatively affect daily activities and quality of life. Non-invasive neuromodulation techniques, including Transcutaneous Tibial Nerve Stimulation (TTNS) and Transcutaneous Auricular Vagus Nerve Stimulation (taVNS), have shown potential for pain management and modulation of autonomic nervous system function. However, limited evidence exists regarding the comparative and combined effects of these interventions. This randomized controlled trial aims to evaluate the comparative and combined effects of TTNS and taVNS on pain, autonomic function, menstrual symptoms, and NSAID consumption in females with primary dysmenorrhea. Eligible participants will be randomly assigned to one of four groups: TTNS, taVNS, combined TTNS + taVNS, or sham stimulation. Outcome measures will be assessed before and after the intervention period by a blinded assessor.
Primary dysmenorrhea is one of the most prevalent menstrual disorders among young females and is associated with significant pain, functional limitations, absenteeism, and increased use of analgesic medications. Current management primarily relies on non-steroidal anti-inflammatory drugs (NSAIDs), which may not provide adequate relief for all individuals and can produce adverse effects with repeated use. Therefore, effective non-pharmacological interventions are needed. Transcutaneous Tibial Nerve Stimulation (TTNS) and Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) are non-invasive neuromodulation techniques that have demonstrated promising effects in reducing pain and regulating autonomic nervous system activity. While each intervention has been investigated separately for various pain conditions, evidence regarding their comparative effectiveness and the potential benefit of combining both interventions in females with primary dysmenorrhea remains limited. This study is a randomized, parallel-group, assessor-blinded controlled trial. Approximately 66 participants with primary dysmenorrhea will be recruited using consecutive sampling and randomly allocated using computer-generated block randomization into one of four groups: TTNS group, taVNS group, Combined TTNS + taVNS group Sham stimulation group Participants will receive their allocated intervention according to standardized treatment protocols. The assessor responsible for outcome measurements will remain blinded to group allocation. The primary outcomes are pain intensity and autonomic function. Secondary outcomes include menstrual symptoms and NSAID consumption. Outcome assessments will be conducted at baseline and after completion of the intervention period. The findings of this study are expected to provide evidence regarding the effectiveness of TTNS, taVNS, and their combined application as safe, non-invasive treatment options for the management of primary dysmenorrhea and may contribute to improving conservative physiotherapy management of this condition.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
66
Electrical stimulation will be delivered through a TENS device using surface electrodes placed over the posterior tibial nerve for 30 mins according to the study protocol for the management of primary dysmenorrhea. The intervention will be applied for 5 consecutive days, including 2 days before and 3 days during the mensturation period.
Electrical stimulation delivered through a TENS device using surface electrodes placed on the auricular branch of the vagus nerve for 30 mins according to the study protocol for the management of primary dysmenorrhea. The intervention will be applied for 5 consecutive days, including 2 days before and 3 days during the mensturation period.
Electrical stimulation delivered through a TENS device to both the posterior tibial nerve and the auricular branch of the vagus nerve sequentially according to the study protocol. The intervention will be applied for 5 consecutive days, including 2 days before and 3 days during the mensturation period.
Sham stimulation delivered using the same TENS device and electrode placement as the active intervention but without therapeutic electrical stimulation. The intervention will be applied for 5 consecutive days, including 2 days before and 3 days during the mensturation period.
Dysmenorrhea Severity - WaLIDD Score
Dysmenorrhea severity will be assessed using the WaLIDD score. The WaLIDD score is a multidimensional assessment of dysmenorrhea severity based on the number of pain days, pain intensity, work/activities affected, and history of dysmenorrhea. The total score ranges from 0 to 12, with higher scores indicating greater dysmenorrhea severity.
Time frame: Baseline, 4th Week, 8th Week , and 12th Week
Pain Intensity - Numeric Pain Rating Scale (NPRS)
Pain intensity will be assessed using the Numeric Pain Rating Scale (NPRS), ranging from 0 (no pain) to 10 (worst possible pain). NPRS will be recorded immediately before and immediately after each treatment session during the 5-day intervention period of each menstrual cycle.
Time frame: Baseline, 4th Week, 8th Week , and 12th Week
Autonomic Function - Heart Rate Variability (RMSSD)
Autonomic function will be assessed using the root mean square of successive differences (RMSSD) derived from heart rate variability. RMSSD will be reported in milliseconds (ms), with changes from pre-treatment to post-treatment used to evaluate autonomic response.
Time frame: Baseline, 4th Week, 8th Week , and 12th Week
Autonomic Function - Heart Rate Variability (LF/HF Ratio)
Autonomic function will be assessed using the low-frequency to high-frequency (LF/HF) ratio derived from heart rate variability. The LF/HF ratio will be used to evaluate changes in cardiac autonomic activity in response to the intervention.
Time frame: Baseline, 4th Week, 8th Week , and 12th Week
Menstrual Symptoms - Menstrual Distress Questionnaire (MEDI-Q) Score
Menstrual-related symptoms will be assessed using the Menstrual Distress Questionnaire (MDQ). The questionnaire evaluates the severity of menstrual symptoms across multiple symptom categories. Higher scores indicate greater menstrual symptom severity.
Time frame: Baseline, Week 4, Week 8 and Week 12
NSAID Consumption
NSAID consumption will be assessed using a participant diary/log to record the frequency and quantity of NSAID use during each menstrual cycle.
Time frame: Baseline, Week 4, Week 8 and Week 12.
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