The Correlation between Caudal Epidurogram and Low Back Pain

BACKGROUND The common causes of lower back pain with or without leg pain includes disk disease and spinal stenosis. A definitive diagnosis is usually made by means of magnetic resonance imaging (MRI), but treatment is often difficult because the MRI findings are not consistent with the symptoms of the patient in many cases. The objective of this study was to observe the correlation between the patterns of epidurography performed in patients having lower back pain with or without leg pain and the position or severity of the pain as subjectively described by the patients. METHODS The subjects of this study were 69 outpatients with lower back pain with or without leg pain who visited our clinic and complained of predominant pain on one side. We performed caudal epidural block using an image intensifier. A mixture of the therapeutic drug and the contrast agent (10 ml) was injected to observe the contrast flow pattern. The patients who complained of predominant pain on one side were divided into the left side group and the right side group. A judgment of inconsistency was made if the contrast agent flowed to the side of the pain, while a judgment of consistency was made if the contrast agent flowed to the opposite side of the pain. The degree of the drug distribution was evaluated by counting the number of cells to which the contrast agent's flowed for evaluating the correlation between the contrasted cell and the severity of pain (one group ≤ VAS 7, the other group ≥ VAS 8) the degree of the contrast agent's contrast was evaluated by dividing and counting an image into 15 cells (the left, right, and middle sections at each level of L4, L5, S1, S2, and S3). RESULTS Thirty out of the 69 patients who had laterality in pain, that is, those who complained of predominant pain on one side, showed that the laterality of the pain and the contrast agent flow was consistent, while 39 patients showed that the laterality was inconsistent (P: 0.137). The evaluation of the correlation between the pain and the contrast agent flow showed that the mean number of contrasted cells was 9.0 ± 2.2 for the 46 patients in the group with a VAS of 7 or lower and 6.5 ± 2.0 for the 23 patients in the group with a VAS of 8 or higher, indicating that the former group showed a significantly greater number of contrasted cells (P < 0.001). CONCLUSIONS This study, conducted with patients having lower back pain with or without leg pain, showed that the contrast flow pattern of caudal epidurography had a significant correlation with the severity of the pain but not with the laterality of the pain.