Vertical Small-Needle Caudal Epidural Injection Technique

BACKGROUND: Anecdotal evidence suggests that a vertical small-needle injection method enters the caudal epidural space with comparable efficacy to cephalad-directed methods, with less intravascular injection. OBJECTIVES: Assess the success rate of vertical caudal epidural injection using epidurography and the frequency of intravascular injection using a vertical small-needle approach. PATIENTS AND METHODS: Participants had chronic generalized non-surgical low back pain and either gluteal and/or leg pain and were enrolled in a simultaneous clinical trial assessing the analgesic effect of 5% dextrose epidural injection. A 25 gauge 3.7 cm hypodermic needle was placed at the sacral hiatus using a fingertip-guided vertical technique without imaging assistance, followed by fluoroscopic epidurography. Minimal needle redirection was allowed up to 10 degrees from the vertical plane if the initial epidurogram showed an extradural pattern, followed by repeat epidurography. RESULTS: First needle placement without imaging resulted in blood return in 1/199 participants and positive epidurography in 179/199 (90%). Minimal needle repositioning resulted in a positive epidurogram in the remaining 19 attempts. No intravascular injection patterns were observed. CONCLUSIONS: This compares favorably to published success rates of fluoroscopically-guided technique and was well tolerated. Vertical caudal epidural injection may be suitable for combination with ultrasound-guided methods with Doppler flow monitoring.