Aj. Haig et al., PARASPINAL MAPPING - QUANTIFIED NEEDLE ELECTROMYOGRAPHY OF THE PARASPINAL MUSCLES IN PERSONS WITHOUT LOW-BACK-PAIN, Spine (Philadelphia, Pa. 1976), 20(6), 1995, pp. 715-721
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.