Endoscopic Decompression

Abstract

Endoscopic spinal decompressive techniques are rapidly enhancing the minimally invasive care of spinal disorders. The development of full endoscopic surgical tools coupled with enhanced optical visualization and navigation are synergistically advancing endoscopic techniques and indications. Complex spinal pathologies such as extra-foraminal disc herniation, discitis, multifocal disc herniation, and recurrent disc herniations can be endoscopically approached with a significant decrease in morbidity. Endoscopic direct spinal decompression and disc space preparation for spinal fusion done can be performed under regional/local anesthesia thereby enhancing “ultra” minimally invasive surgery and enhanced recovery after surgery principles.

A number of elements are required to result in successful endoscopic decompressive spine surgery. These elements include (1) careful physical examination, (2) a comprehensive knowledge and evaluation of all pertinent radiographic studies, (3) appropriate diagnostic injection testing and interpretation, and (4) phasic surgical training. Surgical training includes didactic, cadaveric, and direct live surgery observation. Unlike traditional open surgery, endoscopic training is phasic with repetitive didactic, cadaveric, and observational training before and after embarking on decompressive surgery, before and after transforaminal decompressive and fusion surgery, and before and after direct posterior and interlaminar decompressive techniques. Appropriate initial needle placement permits targeted decompression for varying disc pathology locations and indications. Lastly, anesthetic considerations are also a critical component of a successful endoscopic spinal surgery. The surgeon and anesthesia team should be comfortable performing surgery utilizing regional/local as well as general anesthesia techniques. Adhering to the above, tenets will help mitigate complications.

Appendices

Quiz Questions

• 1. What are the unique features of a spine endoscope that allow for endoscopic spine surgery techniques?

• 2. What types of disc herniations are most readily approachable using endoscopic techniques?

• 3. What types of disc herniation are not most readily approachable using endoscopic techniques?

• 4. What is meant by targeted needle placement and decompression?

• 5. What are the two types of extra-discal endoscopic approaches?

• 6. What are the two skin markings using the lateral intraoperative X-ray that should be made on all transforaminal approaches?

• 7. What structures are at risk with an endoscopic approach?

• 8. How does one learn endoscopic surgical techniques?

Answers

• 1. High-resolution HD endoscopes with 25-30 degree angled view with working length for posterolateral and lateral transforaminal approach. Optimized ratio of large working channel to outside diameter for minimal invasive access and effective operation. Fluid management optimized by engineered dimensioning of inflow and outflow preventing neural compression by high pressures of the irrigation fluid. Working sleeves with atraumatic distal design to protect neural structures and variety of tip styles for multiple indications.

• 2. Paracentral, foraminal and extra-foraminal disc herniations

• 3. Central disc herniations Extruded disc herniations caudal to the mid pedicle of the distal pedicle or more cephalad to the inferior margin of the proximal pedicle

• 4. Based on the location of the disc herniation and/or goal of the procedure, the initial needle can be positioned within the disc (intra-discal, inside-out) or can be positioned on the most posterior aspect of the disc space (extra-discal) location. By changing the angle of approach, the needle can be positioned in either of these two positions to optimize disc material resection.

• 5. The extra-discal technique is comprised of two distinct approaches: 1. A facet sparing technique and 2. A facet resection transforaminal endoscopic surgical system (TESSYS) technique.

• 6. The first is the posterior facet line and the mid-disc line (The most posterior aspect of the facet complex of interest is identified on the lateral view with endplates parallel and the first line is drawn. The entry point of the needle must never be more anterior to this posterior facet in order to help obviate entry into the retroperitoneal space. The location of the retroperitoneum should be assessed on MRI and/or CT scan to also assist in identifying the angle of needle trajectory and entry starting point. The mid-disc line is used to gain access to the posterior to ½ of the disc space for intra-discal approaches. Needle entry should always be between the mid-disc line and posterior facet line and selected based on disc location and operative goals.

• 7. When performing a posterior lateral lumbar endoscopic approach, the retroperitoneal structures are at risk including the ipsilateral viscous structures and the contra-lateral vascular, ureteral structures, and viscous structures.

• 8. Full spinal endoscopic training requires multimodal learning techniques including didactic lectures and written materials, cadaver trainings, and on-site peer-to-peer case observation. These learning modalities should be repeated as necessary in order to optimize the learning curve for individual types of endoscopic techniques such as postero-lateral lumbar, posterior lumbar, posterior cervical, and others.