The volumetric caudal epidural steroid injection has been advocated to facilitate the delivery
of medications to the lesion site. This study was aimed to examine the actual spreading patterns
of this technique, using epidurogram. A total of 32 patients with chronic low back pain accompanied
by radiculopathy of various causes (degenerative spondylosis, herniated nucleus pulposus,
spondylolisthesis, and spinal stenosis) were included. The volumetric caudal epidural injection
of the 10 mL mixture of contrast medium 5 mL, 0.5% bupivacaine 1 mL, triamcinolone 1.5 mL (60 mg)
and normal saline 25 mL was performed. Immediately after the cessation of the first spread, the
subsequent solution of another 10 mL of contrast medium 5 mL, 0.5% bupivacaine 1 mL and normal
saline 4 mL was injected. This procedure was repeated serially until the total volume to be 50 mL.
Continuous fluoroscopic imaging was obtained after each injection. Average time taken to complete
the study was 37 sec per every 10 mL. The spreading levels of the mixture were distributed mainly
at mid to lower lumbar area in the majority of the patients. During the subsequent injections, the
levels were not changed significantly. This was thought to be due to the minimal resistance in
cephalad direction, anatomic variations and Starling effect of epidural space.
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