Dry needle is a form of acupuncture. It was first described in the Chinese medical textbook - Yellow Emperor's Inner Classic over 2000 years ago - it discussed in detail using tender/painful points to treat pain (particularly neuromusculoskeletal system). These "trigger points" are still widely being used by acupuncturists who have unwent proper acupuncture training, which requires a minimum of 2348 hours of theoretical and clinical training (in California).  I strongly against Dry Needling by PT, which only requires 50 hours of training.