Magnetic resonance imaging findings in intervertebral disc herniation: Comparison of canal compromise and canal size in patients with and without cauda equina syndrome

BACKGROUND: Surgical decompressions are typically warranted in patients with magnetic resonance (MR) and clinical evidence of cauda equina syndromes (CESs). However, it is still unclear what MR findings best correlate with such CES. Here, we compared MR-documented canal size and level/extent of compromise in 52 patients with and 56 others without CES attributed to lumbar disc herniation. METHODS: This was a retrospective study of 52 patients with and 56 patients without CES attributed to MR- documented lumbar disc herniations (IDHs). The anteroposterior diameters of the spinal canal and the levels of maximal compression were documented and compared utilizing MR scans from both groups. RESULTS: The 52 patients with CES had more extensive narrowing of the canal diameters at the L4-L5 and L5- S1 levels and higher mean canal compression ratios versus 56 patients without CES. The mean percentage of compression in the CES group at L4-L5 and L5-S1 levels (70% and 67.5%, respectively) was less versus L2-L3 and L3-L4 levels (89.7% and 81.8%, respectively). CONCLUSION: The 52 patients with CES due to IDH had greater canal compromise versus 56 without CES. Further, the percentage of canal compromise was less at L4-L5 and L5-S1 levels compared to other levels in patients with CES.