Nonpharmacologic treatments provide alternatives to medication for issues ranging from chronic insomnia1 to hypertension.2 Among nonpharmacologic treatments are those involving electrical stimulation, which is administered to treat soft-tissue injuries,3 cardiac arrest4 and a variety of other health conditions. The field of anesthesiology includes such electrical stimulation in the form of electroanalgesia for acute and chronic pain relief.5 Articles from the 1970s cite electrical stimulation to treat chronic6 or postoperative7 pain, but the use of electroanalgesia began centuries ago.5 Renewed interest in electrical stimulation for analgesia is due to interest in understanding the physiological bases of pain perception and transmission, as well as in finding alternatives to traditional analgesic drugs.5 Anesthesia providers should familiarize themselves with the history, mechanisms and usefulness of electroanalgesia in order to provide their patients with a nonpharmacologic alternative.
In 1965, Melzack and Wall proposed the Gate Control Theory, which states that pain perception is due to large-diameter afferent (i.e., sensory) fibers in the dorsal column of the spinal cord, and analgesia is considered “closing the gate.”8 Based on this theory, Shealy et al.’s 1967 study first reported use of an implantable device for direct spinal cord stimulation (SCS) to provide analgesia.9 The efficacy of SCS, which is posited to modulate pain perception, is controversial to this day.5 However, it is currently used to treat a variety of chronic pain syndromes.5 Throughout the years, research has approached pain management techniques such as deep brain stimulation (DBS), peripheral nerve stimulation (PNS), percutaneous electrical nerve stimulation (PENS), percutaneous neuromodulation therapy (PNT), transcutaneous electrical nerve stimulation (TENS), transcutaneous acupoint electrical stimulation (TAES), H-wave therapy (HWT), interferential current therapy (ICT), Piezo-electric current therapy (PECT) and electroacupuncture (EA), all with varying degrees of success.5 The history of electroanalgesia is long and complex, and it has contributed to the numerous electroanalgesic techniques used today.
Because there are so many kinds of electroanalgesia, the mechanisms of each type are varied. Some electroanalgesics, such as SCS, DBS and transcranial magnetic stimulation target pain perception in the central nervous system.5 For example, DBS is administered to the periventricular and periaqueductal gray matter in the mesencephalic-diencephalic transition zone, ventroposterolateral-medial nucleus of the thalamus, internal capsule and motor cortex of the brain.5 The supposed mechanism of action of DBS, like SCS, is decreasing pain transmission along sensory pathways, and it is also believed to release endogenous endorphins.5 Other electroanalgesia techniques, including PNS, PENS, PNT, TENS, TAES, HWT, ICT, PECT and EA, target the peripheral nervous system and localized pain areas to electrically “massage” nerves and tissues and reduce pain at the site.5 Anesthesia providers may use electroanalgesia that either changes the patient’s pain perception or targets painful areas directly depending on type of pain and length of treatment.
The most important issue for an anesthesiology practitioner considering electroanalgesia is its clinical efficacy. For one, a widely used nonpharmacologic treatment for chronic pain, radiofrequency ablation therapy, was recently reported to have no clinical benefit.10 On the other hand, some evidence shows that ultrasound-guided PENS may serve as useful alternatives to nerve block medications, without the limited duration of action, potential for infection or risk of dislodgement.11 EA has also been reported to effectively trigger neuronal firing, as well as the release of neurotransmitters and endogenous opioids within the central nervous system.10 The concrete pain-reducing effects of EA and TENS was found in a clinical study by Eriksson and Sjölund.12 Yet this study was published in 1976, and most recent studies on EA use animal models such as rats13,14 and horses.15 Clearly, the literature on the usefulness of electroanalgesia is lacking.
In the throes of the opioid epidemic, nonmedication, nonaddictive alternatives for pain management are appealing to anesthesia providers.16 Electroanalgesia has been used and studied for centuries, and it can affect a patient’s pain perception or provide relief to a painful area. However, data are limited on the effectiveness of various electroanalgesia techniques. More high-powered human studies are needed to warrant the integration of electroanalgesia into the practice of anesthesiology.
1. Morin CM, Hauri PJ, Espie CA, Spielman AJ, Buysse DJ, Bootzin RR. Nonpharmacologic Treatment of Chronic Insomnia. Sleep. 1999;22(8):1134–1156.
2. Meles E, Giannattasio C, Failla M, Gentile G, Capra A, Mancia G. Nonpharmacologic treatment of hypertension by respiratory exercise in the home setting. American Journal of Hypertension. 2004;17(4):370–374.
3. Wilson DH. Treatment of Soft-tissue Injuries by Pulsed Electrical Energy. British Medical Journal. 1972;2(5808):269–270.
4. Hopps JA, Bigelow WG. Electrical treatment of cardiac arrest: A cardiac stimulator-defibrillator. Surgery. 1954;36(4):833–849.
5. White PF, Li S, Chiu JW. Electroanalgesia: Its Role in Acute and Chronic Pain Management. Anesthesia & Analgesia. 2001;92(2):505–513.
6. Long DM. External electrical stimulation as a treatment of chronic pain. Minnesota Medicine. 1974;57(3):195–198.
7. VanderArk GD, McGrath KA. Transcutaneous electrical stimulation in treatment of postoperative pain. The American Journal of Surgery. 1975;130(3):338–340.
8. Melzack R, Wall PD. Pain mechanisms: A new theory. Science (New York, N.Y.). 1965;150(3699):971–979.
9. Shealy CN, Mortimer JT, Reswick JB. Electrical Inhibition of Pain by Stimulation of the Dorsal Columns: Preliminary Clinical Report. Anesthesia & Analgesia. 1967;46(4):489–491.
10. White PF, Elvir Lazo OL, Galeas L, Cao X. Use of electroanalgesia and laser therapies as alternatives to opioids for acute and chronic pain management. F1000Res. 2017;6:2161.
11. Gabriel RA, Ilfeld BM. Percutaneous peripheral nerve stimulation and other alternatives for perineural catheters for postoperative analgesia. Best Practice & Research Clinical Anaesthesiology. 2019;33(1):37–46.
12. Eriksson M, Sjölund B. Acupuncturelike Electroanalgesia in TNS-Resistant Chronic Pain. In: Zotterman Y, ed. Sensory Functions of the Skin in Primates: Pergamon; 1976:575-581.
13. Qi D, Wu S, Zhang Y, Li W. Electroacupuncture analgesia with different frequencies is mediated via different opioid pathways in acute visceral hyperalgesia rats. Life Sciences. 2016;160:64–71.
14. Wang J, Gao Y, Chen S, et al. The Effect of Repeated Electroacupuncture Analgesia on Neurotrophic and Cytokine Factors in Neuropathic Pain Rats. Evidence-Based Complementary and Alternative Medicine. 2016;2016:11.
15. Sheta E, Ragab S, Farghali H, El-Sherif A. Successful Practice of Electroacupuncture Analgesia in Equine Surgery. Journal of Acupuncture and Meridian Studies. 2015;8(1):30–39.
16. White PF. An Alternative Approach to Solving the Opioid Epidemic: Expanding the Use of Non-Pharmacologic Techniques for Acute and Chronic Pain Management. Journal of Molecular Biology and Methods. 2018;1(1).