Electro-acupuncture, also called e-stim or electrical stimulation, is used to provide greater stimulation of acupuncture points. According to Acupuncture Today, a trade journal for acupuncturists:

Classical True Acupuncture and Chinese Herbal Medicine Electro-Acupuncture

"Electroacupuncture is quite similar to traditional acupuncture in that the same points are stimulated during treatment. As with traditional acupuncture, needles are inserted on specific points along the body. The needles are then attached to a device that generates continuous electric pulses using small clips. These devices are used to adjust the frequency and intensity of the impulse being delivered, depending on the condition being treated. Electroacupuncture uses two needles at time so that the impulses can pass from one needle to the other. Several pairs of needles can be stimulated simultaneously, usually for no more than 30 minutes at a time." (Acupuncture Today: Electroacupuncture, Feb. 1, 2004)

The sensation felt is a mild tapping, tingling, or buzzing where the needle is inserted, and electro-acupuncture is considered to be especially useful for conditions in which there is an accumulation of qi, such as in chronic pain syndromes, or in cases where the qi is difficult to stimulate.