Usefulness of a pre-procedure ultrasound scanning of the lumbar spine before epidural injection in patients with a presumed difficult puncture: A randomized controlled trial

Abstract

Ultrasound (US) is widely used in rheumatology to study and guide injection of peripheral joints. It can also provide useful information about the anatomy of the lumbar spine. Studies have shown that US examination of the spine was a useful tool to help perform epidural anaesthesia. The purpose of the study was to determine if the selection of the optimum puncture level by US may facilitate epidural steroid injection in case of presumed difficult puncture (BMI>30 kg/m(2), age>60 years or lumbar scoliosis).

Methods: We performed a prospective randomized controlled study. Eighty patients were randomized in two groups: US group (n=40) which underwent a pre-procedure spinal US to determine the optimal lumbar level for injection or control group (n=40) for which the level of injection was determined by palpation. Primary endpoint was the pain during the procedure assessed using the Visual Analogue Scale (VAS).

Results: We found a positive correlation between depth of the epidural space and BMI (P<0.001) and a negative correlation between size of the interspinous spaces and age (P<0.01). Visibility of the epidural space was not altered by obesity or age. We observed a trend toward a reduction in pain intensity during the procedure in the US group compared to the control group with a mean difference at -0.94 [-1.90; 0.02] but the difference was not significant (P=0.054).

Conclusion: US of the lumbar spine was feasible in patients with lumbar conditions even in obese and old ones and allowed the visualization of the epidural space. However, pre-procedure US examination did not reduce pain during the procedure.

Keywords: Difficult puncture; Epidural space; Sciatica; Steroid injection; Ultrasound.