Transcutaneous Electrical Nerve Stimulation (TENS) for Primary Dysmenorrhea: An Overview

Figures & data

Table 1 Characteristics of Pulse and Current Parameters, Electrode Application, and Treatment Position

Characteristic	Recommendation	Important Considerations
Pulse and current parameters
Pulse waveform	Biphasic waveform	Sensory level transcutaneous electrical nerve stimulation (TENS) is applied by biphasic or monophasic waveforms or bursts in different shapes.^Citation27
Pulse frequency (Hz)	50 to 120 Hz (100 Hz is most common)	High-frequency (HF) sensory-level TENS stimulation frequencies are broadly classified as HF (>50 Hz), low frequency (LF) (1 Hz to 4 Hz), or burst (bursts of HF stimulation applied at a much lower frequency).^Citation23 HF TENS - patient experiences an intense, comfortable, nonpainful paresthesia. LF TENS - experienced as an intense, painful pulsating sensation often accompanied by muscle twitching. Most patients typically find higher frequencies more comfortable.^Citation23
Phase duration (µs)	100 µsec^Citation24,Citation26	Most frequent setting in previous studies on patients affected by primary dysmenorrhea (PD) was 100 µsec.^Citation3,Citation6^–^Citation10,Citation17^–^Citation20,Citation24,Citation26
Current amplitudes	The highest tolerable intensity with continuous adjustment of the current amplitude so that an intense sensation is felt throughout the entire treatment process. Maintaining the same level of sensation by continually increasing the current amplitude.	Dose-response effect: higher intensities (strong, nonpainful, at sensory threshold) produce greater and longer-lasting decreases in pain and nociceptive response, whereas TENS delivered at or below the sensory threshold (or placebo) was ineffective.^Citation24,Citation25 LF TENS applied typically at higher intensities.^Citation22 Continuous increase throughout TENS produced greater analgesia compared to the case at which the intensity was maintained at the initial level.^Citation26 Higher currents activate deeper tissue afferents allowing greater analgesia, in addition to the activation of more sensory afferents.^Citation34
TENS treatment dosage: Duration, number of treatments and frequency	Using the device whenever severe pain is felt	A consistent clinical dosage of TENS is lacking.^Citation26
Habituation/repeated use	Use a fixed high frequency, increase the current intensity continually up to the instance at which anintense, maximum tolerated sensation is felt.	Rational: decrease in habituation effect. Repeated application of the same dose (frequency, intensity, duration) of TENS daily over a period of five days results in analgesic tolerance in healthy women.^Citation16 Resolve the conflict between the cumulative effects and tolerance may be in the mode of application. It is suggested that for chronic pain, a cumulative effect is achieved if the intensity is increased during treatment until the patient describes the sensation as “intense, but comfortable.” Patients likely become more comfortable with TENS over time, and are able to tolerate higher intensities.^Citation39 Animal studies show that increasing the intensity by 10% on a daily basis, delays the onset of analgesic tolerance.
Electrode application and treatment position
Skin preparation	Ensure intact skin area. Cleanse skin prior to application.	Skin breakdown will result in extreme discomfort.^Citation27 Cleansing reduces skin impedance.^Citation27
Type of electrodes	Self-adhesive. Dual-channel devices using four large-sized electrodes corresponding to the painful area(s).	Self-adhesive electrodes are easy to apply and less cumbersome but are costlier as they are disposable.^Citation27 Other types require conductive material at the electrode–skin interphase (eg, gel, water-saturated material) and additional use of Velcro belts, or tight-fitting clothing to hold the electrode in place. Advantages include the facts that they are not disposable and can be used in several patients. Few studies investigated the effects of different types of electrodes on the analgesic effect of TENS.^Citation25,Citation26 However, no prior study provided a clear answer as to which of the two types is better. Accordingly, each woman will require her own electrode set.
Size and location of electrodes	Adjust specifically to each woman according to thetypical area of her pain. Education and training should emphasize the fact that the electrode should not be fixed to the same point and should be adjusted to the actual area of pain experienced in each menstrual cycle.	The choice of electrode size and location depends on the TENS type (HF versus LF), the size of the painful area and the pathophysiology of the condition.^Citation26 Focus on HF TENS and apply TENS over nonacupuncture points. The electrode placement is based on the rationale that the HF TENS operates via a segmental mechanism, and the pain pattern usually covers a large area and more than one location (eg, lower back and upper leg). Two suggested options includetheapplication of the electrodes over the thoracic spine in areas related to the spinal nerve roots that receive nociceptive information from the uterus. Alternatively, place them on dermatomes corresponding to the referred uterine pain (on the lower pelvis, medially, at the suprapubic region in the lower abdominal quadrants).^Citation23
Position	Use TENS during an activity that is typically interrupted by PD pain.	Rational: previous studies indicated that TENS is more effective for reducing pain during movement compared to resting conditions.^Citation39 Given thatup to 20% of women may have severe painsthatinterfere with daily activities, it is suggested that they use the dynamic mode. The TENS apparatusis small and lightweight and can be attached to clothing.
Treatment setting	Self-use of TENS at home in accordance with the appearance of PD symptoms.	Major advantages of TENS equipment include the facts that they are practical, relatively inexpensive, and easy to use. TENS machines are portable, battery-operated devices.^Citation9 Home use of the TENS was evaluated in four studies during menstrual cycles.^Citation6,Citation17,Citation8,Citation10 However, no study compared the effectiveness of TENS between clinical and home settings. It is impractical and time-consuming to use TENS for PD in a clinical setting and an unnecessary utilization of healthcare services, as the symptoms appears for a limited time period (hours to days) every month in young women. The therapist should be aware that some patients are not suitable for HF TENS, as they cannot tolerate higher intensities.^Citation6,Citation19
Adverse effect	A safe treatment modality.	Pay attention to the skin status and increased menstrual flow. Caution should be exercised to ensure that TENS is used correctly by the patient. Only two studies reported adverse effects associated with treatment.^Citation18,Citation10 Dawood et al^Citation18 reported that 4/32 women using HF TENS experienced muscle vibrations, tightness, and headaches, as well as slight redness or burning of the skin after use. Wang et al^Citation10 reported that 1/13 women experienced increased menstrual flow during TENS stimulation. The clinical importance of these minor yet adverse effects is unclear.^Citation18 Nevertheless, TENS has fewer side effects than pharmacological agents do.

Abbreviations: TENS, Transcutaneous electrical nerve stimulation; PD, primary dysmenorrhea; HF, high frequency; LF, low frequency.

Figure 1 Summary of recommendations for transcutaneous electrical nerve stimulation (TENS) in primary dysmenorrhea.

Robinson AJ. Clinical Electrophysiology: Electrotherapy and Electrophysiologic Testing. Lippincott Williams & Wilkins; 2008.

 Google Scholar

Sluka KA, Walsh D. Transcutaneous electrical nerve stimulation: basic science mechanisms and clinical effectiveness. J Pain. 2003;4(3):109–121. doi:10.1054/jpai.2003.434

 PubMed Web of Science ®Google Scholar

Bjordal JM, Johnson MI, Ljunggreen AE. Transcutaneous electrical nerve stimulation (TENS) can reduce postoperative analgesic consumption. A meta-analysis with assessment of optimal treatment parameters for postoperative pain. Eur J Pain. 2003;7(2):181–188. doi:10.1016/S1090-3801(02)00098-8

 PubMed Web of Science ®Google Scholar

Cameron MH. Physical Agents in Rehabilitation: From Research to Practice. Elsevier Health Sciences; 2012.

 Google Scholar

Milsom I, Hedner N, Mannheimer C. A comparative study of the effect of high-intensity transcutaneous nerve stimulation and oral naproxen on intrauterine pressure and menstrual pain in patients with primary dysmenorrhea. Am J Obstet Gynecol. 1994;170(1):123–129. doi:10.1016/s0002-9378(94)70396-5

 Web of Science ®Google Scholar

Lauretti GR, Oliveira R, Parada F, Mattos AL. The new portable transcutaneous electrical nerve stimulation device was efficacious in the control of primary dysmenorrhea cramp pain. Neuromodulation. 2015;18(6):522–527. doi:10.1111/ner.12269

 Web of Science ®Google Scholar

Wang SF, Lee JP, Hwa HL. Effect of transcutaneous electrical nerve stimulation on primary dysmenorrhea. Neuromodulation. 2009;12(4):302–309. doi:10.1111/j.1525-1403.2009.00226.x

 PubMed Web of Science ®Google Scholar

Mannheimer JS, Whalen EC. The efficacy of transcutaneous electrical nerve stimulation in dysmenorrhea. Clin J Pain. 1985;1(2):75–84. doi:10.1097/00002508-198501020-00004

 Google Scholar

Neighbors LE, Clelland J, Jackson JR, Bergman J, Orr JJ. Transcutaneous electrical nerve stimulation for pain relief in primary dysmenorrhea. Clin J Pain. 1987;3(1):17–22. doi:10.1097/00002508-198703010-00004

 Google Scholar

Moran F, Leonard T, Hawthorne S, et al. Hypoalgesia in response to transcutaneous electrical nerve stimulation (TENS) depends on stimulation intensity. J Pain. 2011;12(8):929–935. doi:10.1016/j.jpain.2011.02.352

 PubMed Web of Science ®Google Scholar

Kitchen S, Bazin S, Bellis E. Electrotherapy: Evidence-Based Practice. 11th ed. London, UK: Churchill Livingstone; 2002.

 Google Scholar

Fishbain DA, Chabal C, Abbott A, Heine LW, Cutler R. Transcutaneous electrical nerve stimulation (TENS) treatment outcome in long-term users. Clin J Pain. 1996;12(3):201–214. doi:10.1097/00002508-199609000-00008

 Web of Science ®Google Scholar

Lewers D, Clelland JA, Jackson JR, Varner RE, Bergman J. Transcutaneous electrical nerve stimulation in the relief of primary dysmenorrhea. Phys Ther. 1989;69(1):3–9. doi:10.1093/ptj/69.1.3

 Web of Science ®Google Scholar

Dailey DL, Rakel BA, Vance CG, et al. Transcutaneous electrical nerve stimulation reduces pain, fatigue and hyperalgesia while restoring central inhibition in primary fibromyalgia. PAIN®. 2013;154(11):2554–2562. doi:10.1016/j.pain.2013.07.043

 PubMed Web of Science ®Google Scholar

Tugay N, Akbayrak T, Demirtürk F, et al. Effectiveness of transcutaneous electrical nerve stimulation and interferential current in primary dysmenorrhea. Pain Med. 2007;8(4):295–300. doi:10.1111/j.1526-4637.2007.00308.x

 PubMed Web of Science ®Google Scholar

Schiøtz H, Jettestad M, Al-Heeti D. Treatment of dysmenorrhoea with a new TENS device (OVA). J Obstet Gynaecol. 2007;27(7):726–728. doi:10.1080/01443610701612805

 Google Scholar

Lundeberg T, Bondesson L, Lundströom V. Relief of primary dysmenorrhea by transcutaneous electrical nerve stimulation. Acta Obstet Gynecol Scand. 1985;64(6):491–497. doi:10.3109/00016348509156727

 Web of Science ®Google Scholar

Dawood MY, Ramos J. Transcutaneous electrical nerve stimulation (TENS) for the treatment of primary dysmenorrhea: a randomized crossover comparison with placebo TENS and ibuprofen. Obstet Gynecol. 1990;75(4):656–660.

 Web of Science ®Google Scholar