Transforaminal Insertion of a Thermocouple on the Posterior Vertebral Wall Combined with Hydrodissection during Lumbar Spinal Radiofrequency Ablation

Representation and principle of the double-oblique approach. A, Drawing from a sagittal perspective. The craniocaudal approach in the sagittal plane enables going through the posterior and inferior parts of the foramen, away from the radicular nerve and vessels. B, Drawing from an oblique axial view (in the axis of the sagittal angulation). The lateromedial approach allows slipping along the facet joint with the 18-ga needle (arrow), away from the nerve and vessels (arrowhead). The 28-ga thermosensor (dotted arrows) can then be advanced into the anterior epidural space toward the posterior wall of the vertebral body.

Fluoroscopic details of the technique of the transforaminal approach. A, The craniocaudal angulation in the sagittal plane is estimated on the lateral projection to point the 18-ga needle (white arrow) used as a landmark on the skin of the patient toward the posterior and inferior parts of the foramen. B, The 35° oblique view (from the anterior-posterior view) is then used to define the distance of the entry point laterally. The 18-ga spinal needle (arrow) should be pointed toward the lateral part of the facet joint (dotted line). C, The needle is advanced in the oblique view toward the foramen. D, Once in the vicinity of the foramen, the lateral view confirms that the needle enters it at its posterior and inferior parts. E, Satisfactory localization of the needle tip (arrow) inside the foramen is confirmed on anterior-posterior projection. F, The 28-ga thermosensor (dotted arrow) is gently advanced into the canal until it reaches the midline (G), where resistance is felt. H, At this point, the tip of the thermometer (dotted arrow) should be located at the middle portion of the vertebral body on the lateral view.