Electroacupuncture
Electroacupuncture is a form of acupuncture in which acupuncture needles are attached to a device that generates continuous electric pulses, generating a small electric current that flows between pairs of needles.  Another term is Percutaneous Electrical Nerve Stimulation (PENS).
According to some acupuncturists, this practice augments the use of regular acupuncture, can restore health and well-being, and is particularly good for treating pain.  For the most part, there is insufficient scientific evidence regarding the safety or efficacy of electroacupuncture, although there is evidence for its efficacy in treating post-chemotherapy vomiting.

# Use by acupuncturists
According to Acupuncture Today, a trade journal for acupuncturists:
That article adds:
Electroacupuncture is also variously termed EA, electro-acupuncture or incorprated under the generic term electrotherapy.
Needless to say, the above description does not reflect the scope of practice nor application of electroacupuncture as used by many contemporary acupuncturists and traditional Chinese medicine practitioners.  While application of electrical currents to specific acupuncture points is used as an alternative to stimulating these areas of the body (instead of using manual manipulation techniques), practitioners also apply electroacupuncture using a neurophysiological model.  In this approach, the same practitioners that use traditional acupuncture points, will also incorporate mapping of neuronal pathways, cutaneous and spinal distributions, to bring about a therapuetic response.  For example, the application of high frequencies electroacupuncture result in quick acting analagesia using segmental gate theory so blocking pain signals reaching the mind.  Low frequencies are also applied for analgesia, but the analgesic effect is long-acting, causing enkephalins and beta-endorphins to be released.  In this way, the practitioner is attempting to harness the body's own mechanism for the control and relief of pain.  In addition to pain, electroacupuncture is commonly used in the treatment of musculoskeletal trauma and muscle dysfunction, where it used for the treatment of over-use injuries (tendonitis or RSI), spasms, sprains and dysfunction.  There is also strong RCT evidence to support electroacupuncture's use as a frontline treatment of osteoarthritis of the knee.

# Scientific research
The Cochrane Collaboration, a group of evidence-based medicine (EBM) reviewers, reviewed eleven randomized controlled trials on the use of electroacupuncture at the P6 acupuncture point to control chemotherapy-induced nausea or vomiting.  The reviewers found that electroacupuncture applied along with anti-vomiting drugs reduced first-day vomiting after chemotherapy more effective than anti-vomiting drugs alone.  However, the drugs given were not the most modern drugs available, so the reviewers stated that further research with state-of-the-art drugs was needed to determine clinical relevance.  The reviewers concluded:
The Cochrane Collaboration also reviewed acupuncture and electroacupuncture for the treatment of rheumatoid arthritis.  Due to the small number and poor quality of studies, they found no evidence to recommend its use for this condition.  The reviewers concluded:
Several recent RCTs (Randomised Clinical Trials) are summarized below:
A study by Ghoname et al utilized percutaneous electrical nerve stimulation (PENS) acupuncture, a contemporary neuroanatomic style of acupuncture utilizing trigger points and electric stimulation.(13) Ghoname et al demonstrated PENS acupuncture to be more effective in decreasing visual analog scale (VAS) pain score compared to sham, transcutaneous electrical nerve stimulation (TENS), and exercise. Additional benefits included decreased medication use and improved physical activity, quality of sleep, and sense of well-being (P < 0.05 for each). A weakness of the study is that the patients (n = 60) were divided into four groups leaving a small number of subjects for each treatment arm.
In a study published in 2004, Sator-Katzenschlager et al compared auricular acupuncture and auricular electro-acupuncture. Although both groups showed improvement during the observation period, the pain relief was significantly better in the auricular electro-acupuncture group than in the conventional auricular acupuncture group (P < 0.001). In addition, psychological well-being, physical activity, and quality of sleep during the six-week acupuncture treatment and follow-up were significantly improved in the auricular electro-acupuncture group compared to the conventional auricular acupuncture group (P < 0.05).
In another study, Meng et al compared medical treatment with acupuncture. The acupuncture group showed significant improvement in the Roland Disability Questionnaire (P = 0.001). Effects were maintained for up to four weeks after treatment (P = 0.007). Kerr et al conducted a similarly designed study comparing TENS and acupuncture. The result showed overall improvement of back pain in both groups; however, no differences between the two groups were observed. Both studies failed to control for potential placebo response resulting from needle insertion (by using sham acupuncture, for example). The fact that both acupuncture and TENS benefited back pain patients and no difference was observed between groups means both may be acceptable for treating back pain. Other studies document similar findings.
Gadsby and Flowerdew concluded that electro-acupuncture and TENS reduce pain and improve range of motion in chronic back pain patients in their Cochrane Database System Review. Carlsson and Sjolund conducted a RCT comparing acupuncture and mock TENS, concluding that a significant decrease in pain intensities occurred at one and three months in the acupuncture group compared with the mock TENS group.(22)

# Safety
Researchers at the FDA Center for Devices and Radiological Health (Rockville, Maryland, USA) evaluated three representative devices intended for electrostimulation of acupuncture needles. The abstract at PubMed summarizes their findings:

# Criticism
Clinical use of electroacupuncture frequently relies on the conceptual framework of Traditional Chinese Medicine (TCM), which some scholars have characterized as pseudoscientific.  Proponents reply that TCM is a prescientific system that continues to have practical relevance.  Yet, practitioners also incorprate biomedical and neurophysiological principles in using EA, for which it possibly has better suitability.  See Acupuncture: Criticism of TCM theory.