LUMBAR MUSCLE USAGE IN CHRONIC LOW-BACK-PAIN - MAGNETIC-RESONANCE IMAGE EVALUATION

Methods for detecting recruitment patterns of the lumbar muscles durin g exercise in patients with chronic low back pain are limited. This ar ticle discusses the use of magnetic resonance imaging with Roman chair extension exercise to examine lumbar muscle usage in five normal volu nteers, five chronic low back pain patients without surgery, and five chronic low back pain patients with surgery. Changes in signal intensi ties of psoas, multifidus, and longissimus/iliocostalis with graded ex ercise were measured at three lumbar disc levels. At rest, there was a difference between multifidus and longissimus/iliocostalis signal int ensity in chronic low back pain subjects without surgery (P = 0.0162) and in chronic low back pain subjects with surgery (P = 0.0036), but n ot in normal subjects. At peak exercise, there was a difference in sig nal intensities between multifidus and longissimus/iliocostalis in all groups (normal volunteers, P = 0.0069; chronic low back pain patients without surgery, P = 0.0125; chronic low back pain patients with surg ery, P = 0.0060). The exercise response was attenuated in chronic low back pain patients with surgery, Thus, MRI demonstrates static and dyn amic differences in lumbar paraspinal musculature in chronic low back pain subjects compared to normal subjects.