Measurements of Multifidus Signal Intensity in Magnetic Resonance Imaging of the Patients with Unilateral Lumbar Radiculopathy

ABSTRACT

OBJECTIVE: To quantitatively evaluate the side- and level-specific change of the multifidus muscle in unilateral radicular pain caused by lumbar disc herniation using magnetic resonance imaging (MRI).METHOD: Sixty-nine patients with L4-5 disc herniation who underwent electrodiagnostic study and spine MRI were enrolled and divided into the radiculopathy group (n=30) and the control group (n=39) according to the presence of L5 radiculopathy. The radiculopathy group was subdivided into the paraspinalis group (n=12) and the limb group (n=18) according to whether or not paraspinalis muscle was denervated. The cross-sectional area (CSA) and signal intensity (SI) of the multifidus muscle were measured bilaterally at L4-5 and L5-S1 middle intervertebral levels on axial T2-weighted MRI.RESULTS: There was no significant difference in the CSA of the multifidus muscle between the radiculopathy group and the control group. In the radiculopathy group, multifidus SI was greater than the control group on the affected side and below the level of herniation (p=0.015). In the subgroup comparison, affected side L5-S1 multifidus SI was significantly different between the paraspinalis group and the control group (p=0.001), but not between the limb group and the control group (p>0.05).CONCLUSION: Our findings suggest that quantitative measurement of multifidus SI may be indicative of the location of nerve root compromise through side- and level- specific changes.