• - Sciatic pain due to radicular impairment inside the spinal canal
• - Symptomatic spinal stenosis
• - Acute low back pain of discogenic origin and resistant to conservative medical treatment

Target: Epidural space, between ligamentum flavum, facet joint, dural sac and symptomatic nerve root

Procedure:

• - Patient in prone position
• - Axial scan to locate target slice and chek concordance between symptoms and radiological findings
• - Paramedian posterior approach
• - CT-fluoroscopy guided puncture from skin to the anterior aspect of the ligamentum flavum with a 20 or 22 gauge needle. Sharp feeling is necessary for crossing of the ligamentum flavum, in order to feel loss of resistance when passing to its anterior aspect
• - Injection of 0.3mL of purified air to confirm extradural needle tip positioning and to drive back the dural sac. If the dura is perforated, there is an immediate wash out of the injected air. Needle must than be pulled back slightly and checked by aspiration for CSF.
• - Steroid injection.

Danger:

• - Dural perforation: always turn the needle tip bevel towards the midline for ligamentum flavum crossing. In the case of induced headache, consider blood patch
• - Rarely : puncture of nerve root, epidural vein, facet joint