Ultrasound-Guided Lumbar Plexus Injection: A Cadaveric Validation

Ultrasound (US) has gained increasing acceptance for evaluating the axial spine, including the lumbar region. While its accuracy for superficial structures such as facet joints and medial branches has been validated, evidence supporting its use for deeper targets, such as the lumbar plexus, remains limited. This cadaveric study aimed to assess the feasibility of US-guided lumbar plexus injection. A fresh-frozen female cadaver with a body mass index of 23 kg/m², prepared using the "Fix-for-Life" technique, was utilized. Using a 2-5 MHz curved linear transducer (HS30; Samsung Medison, Seoul, Republic of Korea), injections were performed with an in-plane approach under continuous needle visualization. A 20-gauge, 7 cm spinal needle was used to deliver 5 mL of green dye targeting the L3 and L4 nerve roots. Dissection confirmed that L3 injection achieved dye spread to the extraforaminal region, whereas L4 injection demonstrated anterior dye distribution adjacent to the intervertebral foramen. The main limitations included the use of a single specimen and acoustic shadowing from articular processes, which impeded visualization of neural structures. This study demonstrates the feasibility of US-guided lumbar plexus injection and supports its potential application in clinical pain management, although further validation with larger sample sizes is warranted.