Paraspinal electromyography that compares concentric with monopolar needles: a blinded study.

ABSTRACT

OBJECTIVE: To establish interrater reliability for paraspinal muscle needle electromyography study with both monopolar and concentric needles in symptomatic and asymptomatic persons and to further establish normative data for paraspinal needle study. DESIGN: At a university spine center, participants with and without radiating low back pain were evaluated with the mini-paraspinal mapping paraspinal needle technique by an unblinded and a blinded electromyographer. RESULTS: In the symptomatic group, the intraclass correlation coefficient between concentric and monopolar needles was 0.793; between monopolar needles, it was 0.876; and between concentric needles, it was 0.966. In the asymptomatic group, the mean total score was 0.25. CONCLUSIONS: The good interrater reliability with the same needle type helps support the validity of the needle electromyography study of the paraspinal muscles. The good correlation between the concentric and monopolar needles shows the data published using monopolar needle data also apply to studies using paraspinal needle electromyography with concentric needles. The low score with the asymptomatic group reaffirms that using a cutoff score of >2 as abnormal has a false-positive rate of <5%.