Indication
- Adult patients (>19 years old).
- Clinical and radiologic signs of low back pain without paresis.
- Provided informed consent to participate in the study.
- Had a current CT or MR scan of the lumbar spine available.
Contraindication (Soft)
- Allergy to steroids or local anesthetics.
- Body mass index ≥ 35 kg/m².
- Spinal infection or any local/systemic infection elsewhere in the body.
- Pregnancy.
- Diabetes.
- Spinal tumors.
- Ongoing anticoagulation therapy or uncorrectable coagulopathy.
Surgical technique
- Patient position
- Position patient prone with cushion under abdomen to reduce lumbar lordosis
- Apply sterile ultrasound gel to the skin.
- Use a broadband curved array transducer
- 2-5 MHz
- Set image gain to maximum penetration to visualize bony surfaces
- Place transducer 90 degree to skin
Anatomy identfication
- Perform a midline sagittal scan along the spinous processes to identify the transition from S1 to L5, then count cephalad to localize the target lumbar level.
- Move the transducer laterally from midline into a paravertebral parasagittal orientation toward the junction of the vertebral arch and zygapophyseal joint.
- Advance the transducer further laterally until the transverse processes are visualized, then move slightly back toward midline until the edge of the zygapophyseal joint is seen, defining the pararadicular aditus plane (PAP).
- In this PAP, identify the intertransverse ligament as a thin hyperechoic band between adjacent transverse processes, with the pararadicular compartment just deep to it.
Needle Insertion Technique
- Insert a 21G, 80‑mm spinal needle using an in‑plane technique, advancing strictly parallel to the long axis of the transducer at about 45 degrees to allow real‑time visualization of the entire needle path.
- Paramedian Sagittal Approach:
- Position transducer perpendicularly over skin
- Insert bent needle using in-plane technique at approximately 45° angle
- Advance needle parallel to long axis of transducer for real-time visualization
- Paramedian Sagittal Oblique Approach:
- Tilt transducer 20-25° toward pararadicular aditus plane
- Advance needle using in-plane technique
Needle Advancement and Injection
- Advance needle until intertransverse ligament is punctured
- Proceed very slowly when approaching neuroforamen under transverse processes
- Patient may experience slight paresthesia along nerve root territory (clinical confirmation)
- Slightly withdraw needle when paresthesia occurs, then deliver medication
- Can use fluoroscopic guidance to confirm contrast media injection