19 Case Presentations and Surgical Technique: Special Lumbar Cases

• Sagittal and axial magnetic resonance imaging (MRI) showed a left-side high-grade downward-migrated disk herniation at L4-L5 (Fig. 19.1). A computed tomo-graphic (CT) scan also showed a soft disk (Fig. 19.2).

Preoperative Plan

• The safe zone for needle insertion in this case is at the shoulder region of the S1 nerve root. Figure 19.3 shows the intended trajectory and target point for insertion of the needle (caudal to cranial direction).

• A preoperative x-ray shows a wide interlaminar space between L5 and S1, which is beneficial in reaching the downward-migrated disk fragment through the intended trajectory (Fig. 19.4).

Surgical Procedures

1. The needle is inserted in the shoulder region with the needle tip close to the medial aspect of the facet joint (Fig. 19.5A).

2. An upward angle of the needle is required over the disk space (Fig. 19.5B–D).

3. The working cannula is placed over the needle (Fig. 19.6A).

4. The endoscopic forceps are then introduced to grasp the upward-migrated disk fragment (Fig. 19.6B).

Endoscopic Findings

• After inserting the endoscope, epidural fat and the outer surface of the disk fragment are seen (Fig. 19.7A).

• The radiofrequency probe is used to remove the ligamentum flavum (Fig. 19.7B).

• The endoscopic forceps are then used to grasp the upward-migrated disk fragment (Fig. 19.7C).

• After the herniated fragments are completely removed, the posterior longitudinal ligament, L5 nerve root, and L5 vertebral body can be visualized (Fig. 19.7D).

• The preoperative MRI revealed a ruptured disk herniation at the central L4-L5 level. A CT scan also showed a soft disk (Fig. 19.9).

Results

• Postoperative imaging confirmed the complete removal of the downward-migrated disk fragment (Fig. 19.8).

• The expanded dural sac and nerve root are clearly visible on the postoperative MRI after the complete decompression performed in this case.

Tips

• The skin entry point is caudal to the index level for removal of the upper-level downward-migrated disk.

• Performing preoperative diskography with indigo car-mine transforaminally through L4-L5 can be useful in identifying the ruptured fragment.

L4-L5 Level Central Ruptured Disk Herniation

Clinical Findings

• A 58-year-old man presented with left leg pain along the L5 dermatome and low back pain.

• The VAS was 8/10 for back pain and 8 to 9/10 for left leg pain.

• The patient had undergone a previous operation 1 year earlier.

Preoperative Plan

• Axial MRI scans are used to determine the skin entry point, the intended trajectory of the needle, and the distance from the midline. The distance of the skin entry point from the midline is 12.5 cm, and the cranial to caudal angle is 8 degrees (Fig. 19.10).

• The intended position of the needle is shown in Fig. 19.11.

Surgical Procedures

1. There are two main considerations in determining the placement of the needle:

• Site of the annular puncture: For a lower lumbar disk herniation, the annular puncture must be made at the medial pedicular line and not the midpedicular line as in cases involving the upper lumbar disks.

• Inclination of the needle trajectory: The needle is directed downward or upward depending on whether it is a downward- or upward-migrated fragment.

2. The needle tip lies at the posterior vertebral line in the inferior part of the disk space (Fig. 19.12A,B).

3. Diskography is performed to verify the extent of the herniation (Fig. 19.12C). This is especially important in revision cases such as this.

4. After diskography is completed, the working channel is introduced over the needle to the midline as seen on an intraoperative anteroposterior (AP) fluoroscopic view (Fig. 19.12D).

Endoscopic Findings

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