PARASPINAL MAPPING - QUANTIFIED NEEDLE ELECTROMYOGRAPHY OF THE PARASPINAL MUSCLES IN PERSONS WITHOUT LOW-BACK-PAIN

Study Design. This was a case series with intervention performed by ma sked investigators. Objectives. To determine values for normal subject s on quantified needle electromyography of the paraspinal muscles comp ared with a previous sample of patients with clear evidence of radicul opathy. Summary of Background Data. Diagnosis of radicular back pain i s difficult, even with modern imaging studies, partly due to the large percentage of imaging abnormalities in asymptomatic persons. Electrom yography has been shown to be as sensitive as imaging studies in diagn osing radicular pain. An electromyographic study of the low back has n ever been done in normal subjects. We have previously anatomically val idated and clinically demonstrated a method of quantitative needle ele ctromyography in the paraspinal muscles called paraspinal mapping. Met hods. Thirty-five subjects free of back pain or polyneuropathy were in termixed with volunteers referred for electromyography of radicular ba ck pain. One electrodiagnostician punctured the skin at five predeterm ined locations and obtained paraspinal mapping scores in one of these. An electromyographer who was masked to the study's nature then perfor med a complete paraspinal mapping study. A total ''sensitivity'' score was compared to scores of previously tested patients who had pain com plaints and clear evidence for radiculopathy on either radiologic or t raditional electromyographic studies. Results. Mean score in normal su bjects was 1.11 (SD 1.49). Mean score for abnormal subjects averaged 1 2.18 (SD 12.03). Differences between examiners were insignificant. Con clusions. Normal persons have few, if any electromyographic abnormalit ies in the paraspinal muscles. This is in contrast to computed tomogra phy, magnetic resonance imaging, or myelographic results in normal sub jects. Persons with radiculopathy have significantly different scores. Needle electromyographic examination of the paraspinal muscles is use ful in distinguishing false-positive radiologic studies.