Case 2

Play movie of the case (avi 350*240 pix mepg4 movie)

Fig. 1: To facilitate the procedure, the approach should be visualized on a preprocedural CT scan (or axial MR imaging). The entry point and its distance from the midline (spinous process) can be measured on the preprocedural CT scan or MR films. A paramedian line lateral and parallel to the midline is drawn depending to the measurement done on the previous CT or MR scan (approximately 5 cm for lumbar level).

Fig. 2: The needle is in contact with the inner limit of the ring (pedicle) on anteroposterior projection. However, the posterior wall is not reached on lateral projection. If the course of the needle is not modified, the needle will enter into the spinal canal.

Fig. 3 Right: The needle is too close to the inner limit of the ring on AP projection while the posterior wall is still not reached on lateral projection. The hub notch (bevel face) is in side position, leading the course of the needle medially. The needle pathway must be corrected in order to avoid spinal canal penetration.

Fig. 3 Left: Correction of the needle course. 180° rotation of the needle. The hub notch is in medial position (the bevel face is then in medial position),  leading the course of the needle to the side. After the rotation of the needle hub, AP projection shows that the needle tip is not anymore in contact with the inner limit of the ring (pedicle).

Fig. 4: Hammering, course of needle corrected. Once the needle has reached the posterior wall of the vertebral body on lateral projection, the needle should be still inside the ring.  The spinal canal is avoided and the procedure is monitored under lateral fluoroscopy.

Fig. 5: On the AP projection the needle tip approaches the midline. The needle is placed in the anterior one-third of the vertebral body.

Fig. 6: CT control. The needle is placed in the anterior one-third of the vertebral body.