To evaluate MRI findings of lateral lumbar disc herniations (LLDHs) and to determine whether those correlate with clinical symptoms.

The study included 105 patients with LLDHs that were diagnosed by MRI. The distribution and location of the LLDHs (foraminal, extraforaminal, and foraminal and extraforaminal), the displacement of adjacent nerves, and the detection rate of LLDHs from axial and sagittal images were reviewed retrospectively by two radiologists. 36 patients were included in evaluating whether location of LLDHs and displacement of adjacent nerve correlate with radiculopathy.

The distributions of the LLDHs were 3.4% at L1-2, 14.4% at L2-3, 33% at L3-4, 33% at L4-5, and 16.9% at L5-S1. The locations were foraminal in 38.6% of cases, extraforaminal in 45.4% of cases, and foraminal and extraforaminal in 16% of cases. In addition, 77.3% of the diagnosed LLDH cases displaced the adjacent nerve. The detection rates of LLDHs in the axial and sagittal images were 100% and 77.3%, respectively. In 36 patients, 47.4% had radiculopathy related to LLDHs. Location of LLDHs and displacement of adjacent nerve had no statistically significant difference between patients with or without radiculopathy.

MRI is an effective method for evaluating the location of LLDHs and their influence on adjacent nerves. The axial image is more important than the sagittal image in diagnosing LLDHs. The location of LLDHs and the displacement of adjacent nerve were not found to be related to radiculopathy.