Contribution of Low-Dose Computerized Tomography With Digital Multiplanar Reconstructions in Thoracic Epidurography and Correlation With Sensory Block in Postoperative Analgesia

BACKGROUND The level of sensory block in postoperative epidural analgesia has been correlated with conventional contrast epidurography in only one study, while low-dose CT scan epidurography with multiplanar reconstruction may be a better tool for this purpose. OBJECTIVES The primary objective of this study was to evaluate, by CT imaging and digital multiplanar reconstruction, the spread and distribution of contrast medium injected into the epidural space through a catheter inserted in a low thoracic position for postoperative analgesia. MATERIALS AND METHODS Ten patients undergoing major abdominal cancer surgery with effective epidural analgesia were prospectively included at postoperative day three. Two consecutive boluses of 5 mL of a mixture of ropivacaine and contrast medium were injected at 15 minutes intervals into the epidural space. Multislice low-dose CT scan epidurography and an assessment of the sensory block were performed before and after injection of the second bolus. The primary objective was to assess the contribution of CT scan epidurography to predict a correlation between the level of sensory block and the spread of the contrast medium in the epidural space; the secondary objective was to determine the agreement between the two methods. RESULTS The spread of contrast material and the clinical sensory block significantly increased after the second injection (32%; P < 0.05). However, no highly significant correlation was observed between the two methods. A gap of two spinal segments of CT opacification was observed in two patients and was confirmed by clinical assessment. CONCLUSIONS CT epidurography is not closely correlated with a clinical assessment of epidural block; thus, a clinical assessment of the sensory block is mandatory. The use of opioid analgesia in combination with local anesthetics may compensate for the lack of efficacy of local anesthetics alone.