No drugs are injected through the solid “dry” needle used to penetrate the skin, muscles and tendons, giving the process its name. Hovel locates trigger points, or painful areas in a muscle or tendon, then inserts a monofilament needle, the same kind used for acupuncture, into the tissue until the patient feels a “deep ache” or the muscle twitches. Electrical stimulation from a 9-volt battery is sometimes used to spur the twitching response in muscles.
Dry needling derived from clinical trials in the United States in the 1940s that injected trigger points with corticosteroids, analgesics and saline. In the 1970s, Czechoslovakian Dr. Karel Lewit found that patients showed signs of improvement from just the needling effect, whether or not any drugs were injected.
Canadian physician Dr. Chan Gunn took things a step further. Gunn, widely acknowledged as the innovator of the practice in North America, dubbed the technique “intramuscular stimulation.” He theorized that peripheral nerve pain caused trigger points to tighten and compress, but if pain signals were interrupted by the insertion of a needle, the muscle would return to its natural state.