In reviewing techniques for therapeutic local anesthesia of pain spots, it appeared that the common denominator was puncture by the needle and not the anesthetic employed. The present study examines short- and long-term effects of dry needling in the treatment of chronic myofascial pain. 241 patients and 312 pain sites were treated by needling. When the most painful spot was touched by the needle, immediate analgesia without hypesthesia was observed in 86.8% of cases. 

Permanent relief of tenderness in the needled structure was obtained for 92 structures; relief for several months in 58; for several weeks in 63; and for several days in 32 out of 288 pain sites followed up. The effectiveness of treatment was related to the intensity of pain produced at the trigger zone, and to the precision with which the site of maximal tenderness was located by the needle. The immediate analgesia produced by needling the pain spot has been called the “needle effect”.