Electromyographic techniques for multifidus muscle examination : A cadaveric study

Abstract

3 ELECTROMYOGRAPHIC TECHNIQUES FOR MULTIFIDUS MUSCLE EXAMINATION: A CADAVERIC STUDY B.J. Kim; E.S. Date; R. Derby*; S.H. Lee*; K.S. Seo*; K.J. Oh; M.J. Kim (Stanford, CA; Daly City, CA*) Introduction: The multifidus muscle permits determination of the involved root level without examination of additional muscles. Techniques for multifidus electromyography, however, have been largely subjective. Objectives: To verify and compare established techniques for needle localization in the mulifidus muscle and explore more practical techniques. Methods: A 22-gauge needle was inserted into the multifidus muscle fascicle of 6 fresh human cadavers utilizing two different techniques which have described previously in the electrodiagnostic literature by Haig and colleagues and Stein and colleagues. Fluoroscopic guidance was employed to increase the accuracy of needle angulation. A mixture of colored latex and contrast dyes (0.1 cc) was injected bilaterally into each fascicle at levels L1-L5. Two electrodiagnostic consultants performed injections into 60 targeted muscles, affording 120 insertions total. To determine dye position, separate investigators dissected the muscles. An injection was judged to be correct if dye was located in a fascicle originated from the spinous process directly above it. Results: A total of 88 (73%) and 79 (66%) injections were successfully delivered to the targeted mulitifidus muscles using the Haig and Stein techniques, respectively. For the Haig method, 22 injections (18%) were delivered to different superficial muscles. For the Stein method, 29 injections were delivered to a common tendon and 3 injections were delivered to the spinal canal. Conclusions: This study demonstrates the non-optimizing accuracy of previous techniques for multifidus needle EMG. A modified method with less acute needle angulation relative to the skin surface and closer insertion from the midline may increase accuracy and safety. Byung Jo Kim, MD, PhD Junior Member Recognition Award Recipient of the 2004 President’s Research Initiative Award