Influence of needle-insertion depth on epidural spread and clinical outcomes in caudal epidural injections: a randomized clinical trial

BACKGROUND: A caudal epidural steroid injection (CESI) is a commonly used method to improve symptoms of lumbosacral pain. We compared the achievement of successful epidurograms and patient-reported clinical outcomes following different needle-insertion depths during CESI. METHODS: For the conventional method group, the needle was advanced into the sacral canal. For the alternative method group, the needle was positioned immediately after penetration of the sacrococcygeal ligament. Epidural filling patterns and vascular uptake during fluoroscopy were determined to verify successful epidural injection. Procedural pain scores were investigated immediately after the procedure. Pain scores and patient global impression of symptom change were evaluated at 1-month follow-up. RESULTS: Assessments were completed by 127 patients (conventional method, n=64; alternative method, n=63). The incidence of intravascular injection was significantly lower in the alternative method group than in the conventional method group (3.2% vs 20.3%, P=0.005). Procedural pain during needle insertion was significantly lower in the alternative method group (3.7±1.3 vs 5.3±1.2, P<0.001). Epidural contrast filling patterns were similar in both groups. One-month follow-up pain scores and patient global impression of symptom change were comparable in both groups. CONCLUSION: Compared with the conventional method, the alternative method for CESI could achieve similar epidural spread and symptom improvement. The alternative technique exhibited clinical benefits of a lower rate of intravascular injection and less procedural pain.