Electroacupuncture (EA) is a technique in which two needles are inserted into the body of the patient, acting aselectrodes, allowing the passage of an electrical current. At least one of the needles is inserted into an acupuncture point. Although EA is becoming more popular, manual acupuncture (MA) is still the most commonly used technique. MA consists of inserting
thin needles into acupuncture points, followed by manipulation such as twisting or lifting and pushing the needle.16 17 One of the main advantages of using EA in clinical practice or research is the ability to objectively and quantifiably set the stimulation frequency and the intensity of the current.18 Low-frequency EA (2 Hz) induces the release of enkephalins, β-endorphins and endorphins that activate the m- and δ-opioid receptors. High-frequency EA (100 Hz) induces the release of dynorphins, which activate κ-opioid receptors.19 20 Clinical studies suggest that EA is effective for treating many types of pain.19–21