The definition of Iontophoresis according to About.com is: A medical treatment used to deliver medication across the skin to deeper tissues by the use of electrical polarity.
Physical therapists are using this treatment as a way to deliver steroid medication to inflammation and swelling of the muscles and more recently is being used as a way to treat Carpal Tunnel Syndrome.
More info may be found here: http://www.ehow.com/how_2088372_use-iontophoresis-carpal-tunnel-syndrome.html
http://physicaltherapy.about.com/od/abbreviationsandterms/g/iontophoresis.htm