WRITTEN TRANSCRIPT
0:08 Case Presentation
I am presenting the case of a 63-year-old male patient who experienced severe radiating pain in the left buttock and leg with numbness in the left dorsal foot and weakness in the left foot and ankle. This individual was a runner for 25 years and he was unable to continue running after developing these symptoms. He had temporary relief of the pain with physical therapy and an epidural steroid injection. However, after the effect of the epidural steroid injection had diminished, the pain was worse than before. Upon neurological examination, the patient demonstrated a 4/5 motor grade weakness in the left tibialis anterior and extensor hallucis longus muscles.
0:48 Preoperative X-ray
The preoperative anterior-posterior (AP) and lateral lumbar x-ray reveal L5–S1 disc degeneration, disc space narrowing, and neuroforaminal narrowing. Additionally, there are no signs of instability with flexion and extension views.
1:01 Preoperative Magnetic Resonance Imaging
The preoperative T2 axial and sagittal images revealed bilateral foraminal stenosis at L5–S1 level that is worse on the left side. This pathology correlated with the patient’s constellation of pain and symptoms, as well as his neurological examination.
1:18 Surgical Planning
For this patient, we decided to do a right-sided L5–S1 unilateral biportal endoscopy (UBE) laminotomy, contralateral sublaminar approach for a left-sided foraminotomy to directly visualize and decompress the contralateral foramen. For the UBE procedure, 2 distinct portals are created: an endoscopic viewing portal and working portal.
The steps of this procedure closely resemble those of traditional “over-the-top” laminotomy and foraminotomy but done with endoscopically.
1:45 Patient Positioning
The patient is positioned in the prone position. A Wilson frame can be used to reduce lumbar lordosis, which leads to a larger interlaminar window. The procedure is performed with the patient under general endotracheal anesthesia.
1:59 Starting Points
With the aid of C-arm fluoroscopy, 2 portals are created. First, we mark the midline and the medial pedicle line on the skin using the AP view. The working portal incision site is determined at the S1 pedicle and is caudal to the L5–S1 disc in the lateral fluoroscopy. An endoscopic viewing portal is created approximately 2–3 cm cephalad to the working portal and is cephalad to the L5–S1 disc.
2:25 Portals
The working portal incision is made and with the aid of a soft tissue dissector, the soft tissue over the caudal edge of the L5 lamina is dissected and the working space is created. This step is followed by the introduction of serial dilators to dilate the thoracolumbar fascia. An outflow cannula is placed in the working portal to secure continuous and efficient drainage of irrigation throughout the procedure and assist with the insertion of the surgical instruments. Next, the viewing portal incision is made and the endoscopic trocar is gently inserted through the thoracolumbar fascia heading toward the disc space. The endoscope is inserted into the trochar and is triangulated with the radiofrequency wand that is inserted into the working portal.
3:33 L5–S1 Laminotomy
The radiofrequency wand is used to remove any loose adventitia that was dissected off the L5 lamina. A 3-mm diamond matchstick burr is then used to perform the laminotomy. The laminotomy is performed at the junction of the spinous process and lamina extending toward the base of the L5 spinous process. The laminotomy is performed until the ligamentum flavum is exposed. Then, a curette is used to detach the ligamentum flavum from the inner laminar attachments and a Kerrison rongeur is used to remove the remaining bone, fully exposing the yellow ligament.
4:20 L5 Sublaminar Approach
The inner cortex of the lamina under the base of the spinous process is removed with a Kerrison rongeur. This creates a larger working space towards the contralateral side and allows enhanced visibility and exposure of the contralateral structures.
4:35 Ligamentum Flavum Resection
As the contralateral ligamentum flavum is completely detached from its insertion under the L5 lamina, it is then removed starting at the midline raphe and progressing towards the contralateral side. The dural sac, left L5 nerve root and L5–S1 left facet joint are now exposed.
5:29 Left L5–S1 Foraminotomy
As we gain access to the contralateral side, the partial medial facetectomy is performed, resecting the tip of the left S1 SAP. This can be performed with a curved Kerrison or small osteotome. This is followed by removal of the residual ligamentum flavum and facet capsule occupying the region surrounding the nerve root.
5:57 Verifying the Decompression
The decompression is verified by palpating the L5 and S1 pedicles, as well as the neuroforamen. The probe passes easily through the neuroforamen.The L5 exiting nerve root is visualized and the left L5 neuroforamen is now well decompressed.
6:13 Hemostasis
As the surgery is concluded, a rigorous examination of the surgical area is performed searching and coagulating any bleeding epidural vessels with the radiofrequency probe. In order to avoid epidural hematoma, an epidural drainage catheter is inserted. The procedure took around 75 minutes with nonquantifiable minimal bleeding.
6:33 Postoperative Course and Conclusion
After waking up from the anesthesia, the patient described complete resolution of the radicular pain. The sublaminar procedure resembles the traditional over-the-top laminotomy and foraminotomy. The approach can be effectively used to decompress a contralateral stenotic foramen. It was useful to alleviate radicular pain generated by compression of the contralateral exiting nerve root.
6:57 Discussion
The contralateral sublaminar approach in the lumbar spine with UBE allows for enhanced visualization of the spinal anatomy and effective decompression of the exiting nerve root and the neuroforamen. The magnification and high definition images by the 4-mm endoscope allows access to areas of the spine that was previously difficult to access using traditional techniques [1,2]. The endoscopic approach minimizes soft tissue, muscular, and bony damage [3], which can lead to less postoperative pain with faster and smoother surgical recovery for the patient. Tranexamic acid can be used intraoperatively to reduce intraoperative blood loss, as well as reduce the risk of epidural hematoma [4]. Although the sublaminar procedure is similar to the traditional over-the-top laminotomy and foraminotomy, there is still a learning curve with the UBE technique that must be considered prior to performing this procedure. Sufficient experience is required with UBE prior to performing the sublaminar approach [5].
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