Effect of epidural corticosteroid injection on magnetic resonance imaging findings

BACKGROUND: Magnetic resonance imaging (MRI) of the spine is the preferred diagnostic tool for pathologic conditions affecting the spine. However, in patients receiving epidural corticosteroid injection (ESI) for treatment of spinal diseases, there is a possibility of misreading of MR images because of air or fluid in the epidural space after the injection. Therefore, we defined the characteristics of abnormal changes in MRI findings following an ESI in patients with low back pain. METHODS: We reviewed the medical records of 133 patients who underwent MRI of the lumbar spine within 7 days after ESI between 2006 and 2015.All patients were administered an ESI using a 22-gauge Tuohy needle at the lumbar spine through the interlaminar approach. The epidural space was identified by the loss of resistance technique with air. RESULTS: The incidences of abnormal changes in MRI findings because of ESI were 54%, 31%, and 25% in patients who underwent MRI at approximately 24 h, and 2 and 3 days after ESI, respectively. Abnormal MRI findings included epidural air or fluid, needle tracks, and soft tissue changes. Epidural air, the most frequent abnormal finding (82%), was observed in 41% of patients who underwent MRI within 3 days after injection. Abnormal findings due to an ESI were not observed in MR images acquired 4 days after ESI or later. CONCLUSIONS: Pain physicians should consider the possibility of abnormal findings in MR images acquired after epidural injection using the interlaminar approach and the loss of resistance technique with air at the lumbar spine.

The comparative study of flow rate between IV extension tube and epidural catheter connected to patient controlled analgesia device / 대한마취과학회지

BACKGROUND: Patient controlled analgesia (PCA) device is known to be an effective method for acute and chronic pain control and the administration route for PCA pump is various. The representative routes are intravenous and epidural space. The aim of this study is to investigate the influence of catheter diameter on flow rate. METHODS: IV extension tube or epidural catheter connected to Mechanical- or balloon-type PCA devices were examined (100 ml, 2 ml/hr). There were four groups each of 5 experiments: Group I: Mechanical-type pump + IV extension tube, Group II: Mechanical-type pump + epidural catheter, Group III: Balloon-type pump + IV extension tube, Group IV: Balloon-type pump + epidural catheter. The flow rate was indirectly measured by the weight change of collecting infusate bottle. Infusion fluid was distilled water. Experiment was carried out in a laboratory room with a constant room temperature of 20-22degrees C. RESULTS: Infusion rate differed significantly among the groups, exhibiting flow rates within +/-15% of their expected rate for 28% (group IV) to 100% (group I) of their infusion duration. The mean Infusion rate in group I was significantly more rapid than that in other groups. The mean flow rate in group III was higher than that in group IV (P<0.05). CONCLUSIONS: These results indicate that the use of an epidural catheter with a small internal diameter could decrease the flow rate of PCA device.