Measuring Needle Angle and Depth for Lumbar Medial Branch Block Using Ultrasonography: An Evaluation of Efficiency Compared with Magnetic Resonance Imaging / 대한정형외과학회잡지

ABSTRACT

PURPOSE: The purpose of this study was to compare accuracy of proper needle insertion angle between magnetic resonance imaging (MRI) and ultrasonography during lumbar medial branch nerve block procedure. MATERIALS AND METHODS: Between January 2015 and June 2016, 80 people who underwent MRI in the past 3 months with improved lumbar pain after sono-guided medial branch nerve block were enrolled for analysis (male, 39; female, 41; average age, 63.3 years). The insertion angle and depth between the spinous process and needle at each target points were measured at various levels (superior, inferior segment of each facet joints from L2–3 to L5–S1). The needle was positioned 1 cm apart from both lateral sides of the probe, locating spinous process in the middle. A comparative analysis was performed between an ultrasonography and an MRI. We determined the statistical correlation between the two methods. RESULTS: The average differences with respect to the distance between each level on a sono-guided medial branch nerve block were 1.28±1.07 mm in L2 (7 cases), 1.27±4.26 mm in L3 (25 cases), 1.63±5.89 mm in L4 (93 cases), 1.99±4.12 mm in L5 (141 cases), and 1.51±3.87 mm in S1 (66 cases). The average differences regarding the angle of each level were 1.69°±1.34° in L2 (7 cases), 2.03°±5.35° in L3 (25 cases), 1.49°±3.42° in L4 (93 cases), −1.55°±3.67° in L5 (141 cases), and 1.86°±4.83° in S1 (66 cases). All measurements followed a normal distribution (p < 0.05), showing statistical correlation without significant difference (p < 0.05). CONCLUSION: After measuring each level using an MRI prior to performing the procedure, a sono-guided lumbar medial branch nerve block can be performed with greater safety and efficacy, especially for beginners.