Interventional Pain Surgery

Interlaminar Lumbar Endoscopy

José Antonio Name Guerra¹, Daniel Andrés Castro Prasca², William Omar Contreras López³, *, Kai-Uwe Lewandrowski⁴, ⁵, ⁶

¹ Klinikum Bremen Mitte University of Goettingen, Bremen, Germany

² Universidad del Norte, Barranquilla, Colombia

³ Clínica Foscal Internacional, Autopista Floridablanca - Girón, Km 7, Floridablanca, Santander, Colombia

⁴ Center for Advanced Spine Care of Southern Arizona, Full Professor of Orthopedic Surgery Department of Orthopaedics

⁵ Departmemt of Orthopaedics, Fundación Universitaria Sanitas, Bogotá, D.C., Colombia

⁶ Department of Neurosurgery in the Video-Endoscopic Postgraduate Program at the Universidade Federal do Estado do Rio de Janeiro - UNIRIO, Rio de Janeiro, Brazil

Abstract

This chapter provides a comprehensive overview and technique guide for endoscopic interlaminar lumbar decompression surgery, a minimally invasive surgical technique for managing herniated discs and spinal stenosis. The authors discuss the relevant surgical anatomy of the lumbar spine, the inclusion and exclusion criteria for the surgery, and explain the surgery’s step-by-step choreography by highlighting the use of advanced imaging and endoscopic technology. The authors review their clinical outcomes and discuss common complications and their management. They highlight the limitations of the procedure. This book chapter is a valuable resource for surgeons and healthcare professionals interested in understanding and implementing endoscopic lumbar interlaminar decompression as an effective and minimally invasive approach for managing sciatica-type low back and leg pain.

Keywords: Interlaminar endoscopy, Herniated disc, Spinal stenosis, Sciatica-type low back and leg pain.

* Corresponding author William Omar Contreras López: Clínica Foscal Internacional, Autopista Floridablanca - Girón, Km 7, Floridablanca, Santander, Colombia; Tel: +3116659964; E-mail: [email protected]; Home Page: www.doctorname.co

Introduction

One of the most frequent causes of low back pain is disc pathology, which is painful due to irritation or compression of the surrounding neural structures [1]. Disc pathology can occur in isolation or in combination with spinal canal stenosis, reflecting mixed symptoms, including mechanical pain, neurogenic claudication,

and signs of root stretching [2-6]. The surgical treatment of this type of entity has evolved from open procedures, becoming less and less invasive today, as is the case of the uniportal interlaminar percutaneous endoscopic approach [7-33]. Its efficacy, safety, and cost-effectiveness have been widely described in the literature, highlighting shorter surgical time, less postoperative pain, less intraoperative bleeding, less perioperative infection, minimal incisions, continuous irrigation, and absence of retractor systems; consolidating itself as an ambulatory surgical strategy [34].

Progress in the advancement of percutaneous techniques has brought the development of increasingly specialized endoscopes and endoscopic instruments, thus expanding the spectrum of spinal pathologies treatable by this route. Today, it is possible to perform discectomy and spinal canal decompression with the over the top technique through the interlaminar approach [35]. In the case of discectomy, the endoscopes used are usually long and thin with 4.1 mm working channels to allow delicate retraction of neural structures. In contrast, endoscopes for stenosis are shorter and thicker, with 5.6 mm working channels, and allow the use of more robust instruments such as burs and shavers of different sizes [36]. With the development of the interlaminar approach and improved endoscopic optics and instrumentation, endoscopic spine surgery is applied to a broad spectrum of degenerative lumbar diseases [28-30, 37].

Advantages

Interlaminar endoscopy offers several advantages in minimally invasive spine surgery. Firstly, it affords direct visualization and enhanced magnification and illumination. Additionally, this technique preserves the integrity of the surrounding muscles and ligaments, promoting faster recovery and reducing the risk of complications. Its specific advantages are:

Better exposure of the lumbar spinal microanatomy through a single 8-mm access port.

Minimal trauma to the paraspinal muscles on the ipsilateral side, and sparing of the paraspinal muscles on the contralateral side [8].

Sufficient osteoligamentous decompression, preserving the stabilizing anatomy [9].

Access to disc pathology with minimal manipulation of the neural structures and a lower rate of neurological injury.

Faster postoperative recovery and rehabilitation, and minimal lower back pain at long-term follow-up [33].

Cost-effectiveness due to surgical times being comparable to or shorter than other techniques, allowing for outpatient surgical management [33].

Lower incidence of infection, bleeding, and lumbar spine instability [38].

Indications

Interlaminar spinal endoscopy is indicated in lumbar disc herniation that causes unrelenting pain that is unresponsive to conservative care. This technique is also beneficial for managing spinal stenosis, particularly in the central canal. Its translaminar surgical access corridor to the spinal canal makes this minimally invasive technique a versatile option for a range of painful spinal pathologies, offering patients a faster recovery and improved quality of life. The authors consider the following to be acceptable indications for interlaminar lumbar endoscopy [15]:

Intervertebral disc herniations causing unrelenting pain.

Cranial or caudal far-migrated disc herniations.

Stenosis of the central spinal canal and lateral recess.

Combined central and paracentral disc herniation with facet hypertrophy and hypertrophy of the ligamentum flavum.

Other pathologies that compress the spinal cord or spinal roots including:

Cyst of the facet joint

Cyst of the yellow ligament

Ossification of the yellow ligament

Foraminal stenosis

Contraindications

There are specific contraindications to consider when employing the interlaminar spinal endoscopy technique. It may not be suitable for patients with severe spinal instability, as the procedure involves accessing the spinal canal through the interlaminar space. Individuals with active infections, significant spinal deformities, and prior spinal surgery that has resulted in extensive scar tissue formation may also be unsuitable for the interlaminar technique. There may be some relative contraindications that vary from surgeon to surgeon based on skill level and experience; however, the authors consider the following to be absolute contraindications to the interlaminar endoscopy:

Segmental instability evident on dynamic radiographs

Grade 2 or higher spondylolisthesis according to the Meyerding criteria [39]

Severe degenerative scoliosis

Infection

Malignancy

Preoperative Planning and Imaging

Simple radiographic studies in the posterior-anterior and lateral projections are helpful in screening the patient for curvature of the spine. Dynamic extension/flexion views should also be routinely obtained to determine whether the patient has segmental instability. For surgical planning, a PA radiography allows evaluation of the size of the interlaminar window, which is reduced in the majority of cases of spinal canal stenosis, and the width of the cranial and caudal laminae and isthmus are visualized for safe bone decompression. Magnetic resonance imaging (MRI) allows us to evaluate the hypertrophy of the ligamentum flavum and its subarticular and sublaminar extension. The MRI should also indicate the affected root or the extent or migration of the herniated disc [40]. Its diagnostic value is at its best when combined with the patient’s clinical manifestations and diagnostic injections [41].

Surgical Instruments

Interlaminar spinal endoscopy requires a specialized set of instruments to perform the procedure effectively. The most critical instruments include an endoscope, a camera attachment, a light source, and an optional irrigation pump. A gravity-fed system may also suffice [42]. Various tools such as graspers, forceps, power drills, and curettes are utilized for tissue removal, bone decompression, and nerve manipulation. Radiofrequency probes and laser fibers may be used for targeted ablation or coagulation of tissues. These instruments and fluoroscopic guidance enable surgeons to perform precise and minimally invasive interlaminar spinal endoscopy procedures. The following instruments are the bare-bone minimum a surgeon should have at his or her disposal for the interlaminar lumbar endoscopy (Fig. 1):

Radiolucent angular surgical table with thoracopelvic supports.

8 mm outer diameter working cannula and a 25-degree endoscope with 7.9 mm outer diameter and 4.1 mm working channel (herniated disc endoscope).

10.5 mm outer diameter working cannula and a 20-degree endoscope with 9.3 mm diameter and 5.6 mm working channel (stenosis endoscope).

Standard instruments for endoscopy: video tower with high-definition screen, camera, light source, and irrigation system.

Electric motor with cutting and diamond burs from 2.5 to 4 mm in diameter.

Radiofrequency generator with angular electrodes.

Standard instruments for spinal endoscopy: dilator, Kerrison forceps, alligator forceps, scissors, and trephine, among others (Img 1).

Diagnostic image intensifier, C-arm.

Fig. (1))

Standard instrumentation for spinal endoscopy. (1) Hernia endoscope working cannula. (2) Hernia endoscope dilator (3) Hernia endoscope (4 -5) Kerrison forceps (6) Grasper forceps (7) Scissors (8) Stenosis endoscope working cannula (9) Stenosis endoscope dilator (10) Stenosis endoscope (11).

Cutting drill

Surgical Steps

The surgical technique with an endoscopic interlaminar approach is explained using the following exemplary case of right-sided L4/5 lateral recess stenosis with disc herniation (Fig. 2).

Fig. (2))

Magnetic resonance imaging of the simple lumbar spine, where L4/5 stenosis is evidenced due to hypertrophy of the ligamentum flavum associated with a herniated disc, predominantly on the right. The patient exhibits right sciatica and claudication while walking..

1. Under general anesthesia, the patient is placed in the prone position, taking care of pressure areas with gel positioners for the pelvic and shoulder girdles. It is critical in positioning to allow the abdomen to remain free of compression, in that any increase in intra-abdominal pressure is transmitted to the Batson venous plexus, which leads to more significant bleeding during surgery; while good flexion widens the interlaminar window.

2. Using anteroposterior fluoroscopic guidance, the interlaminar space to be operated on is located to subsequently make an 8-mm incision in the skin 1 cm from the midline on the ipsilateral side of the desired level, subcutaneous cell tissue, and lumbar fascia. The dilator is introduced up to the interlaminar space, and its position is confirmed by anteroposterior and lateral fluoroscopy (Fig. 3).

Fig. (3))

(A) Location of the interlaminar space at the surgical L4/5 level (red line) corresponds to the midline (B) AP radiograph of the interlaminar level to be operated on (L4L5) (C) Illustration of incision at previously marked level (D) Dilator placement through incision (E) AP radiograph with dilator in interlaminar space, the widest part of the dilator corresponds to the deepest part (F) Illustration with dilator located at the L4-L5 interlaminar level. Source: RIWOSPINE, reproduced with permission..

3. The working cannula of 10.5 mm in outer diameter with an opening bevel towards the midline is introduced. The 20° stenosis endoscope with a 9.3 mm diameter and 5.6 mm working channel is introduced through it. All this with continuous irrigation with a sterile solution at 70 mmHg pressure (Fig. 4).

4. The ligamentum flavum is exposed by radiofrequency coagulation and resection of the surrounding connective tissue. The bony margins of the interlaminar space are identified and exposed, finding the lower border of the L4 lamina in the cephalad direction, laterally the medial border of the descending articular process, and the upper border of the L5 lamina in the caudal direction.

5. The lateral border of the ligamentum flavum is dissected by detaching its superficial layer from the descending facet. Once the medial edge of the tip of the descending articular process has been exposed, a 4-6 mm resection is performed laterally, making bloc movements with the work cannula the endoscope, and the shaver system with a protected tip cutting bur. Bone decompression is performed along the facet joint's medial aspect, preserving the descending facet's attachment to the superior lamina. Bone hemorrhages can be controlled with a diamond bur or radiofrequency probe (Fig. 5).

Fig. (4))

(A) Introduction of the working cannula through the dilator. (B) Lateral X-ray showing a working cannula at the L4-L5 level (red dot), corresponding to a radiofrequency probe. (C) Endoscope with working cannula and grasper forceps. Source: RIWOSPINE, reproduced with permission..

Fig. (5))

Detachment of the ligament flavum from the tip of the descending articular process (Top image). Superior and inferior articular processes, corresponding joint space (blue dot; bottom image). Translaminar reaming removes the medial edge of the descending articular process. Source: RIWOSPINE S. Ruetten 2013, reproduced with permission..

6. By resecting the medial edge of the descending articular process, the ascending articular process of L5 is exposed, deep to it. Resection of its medial edge is also critical for adequate decompression of the neural canal. It can be performed with a sharp or diamond bur until its thickness is thinned and subsequently resected with Kerrison forceps. It is essential to consider that the emerging root is located above the tip of the ascending articular process (Fig. 6).

Fig. (6))

The medial edge of the inferior articular process is resected with a Kerrison rongeur, with exposure of the ascending articular process which must also be drilled. Source: RIWOSPINE S. Ruetten 2013, reproduced with permission..

7. Once the bony resection is complete, the ligamentum flavum is exposed to its most lateral border. This ligament presents a particular endoscopic anatomy made up of two layers: a superficial one inserted on the medial border of the descending facet and a deep one inserted on the medial border of the ascending facet. The endoscope cannula is used as a dissector to tighten the ligament and facilitate scissor cutting. For the protection of underlying neural structures, it is helpful to allow irrigation to enter through the ligament to repel the dural sac deep, thus facilitating the passage of the scissors. Flavectomy is performed laterally, and it is advisable to avoid cutting the most lateral segment of the ligament to keep the cut edges under tension. It is vital to advance the endoscope cannula to maintain ligament stretch to avoid funnel cuts with blind spots where inadvertent dural sac injury can occur. At this point, over-the-top contralateral ligament decompression can be performed (Fig. 7).

Fig. (7))

(A) Yellow ligament opening sequence. Both layers of the ligament are opened with cuts from medial to lateral, always stretching the ligament with the endoscope cannula. (B) Contralateral ligament decompression over the top technique. Source: RIWOSPINE S. Ruetten 2013, reproduced with permission..

8. Once the ligamentum flavum has been removed, the dural sac and the descending nerve root, in this case, L5, are exposed. This last structure is seen to be severely compressed due to the conflict with a herniated disc. At this point, the caliber of the stenosis endoscope is unfavorable for reaching the level of the intervertebral disc and for rejecting the descending root medially by rotating the working cannula, potentially injuring it.

9. The stenosis endoscope is removed, leaving the working cannula safe without resting on neural structures. Through this, the dilator is inserted until it rests on a bone structure, thus minimizing its movement. The 10.5 mm work shirt is removed, and using the dilator as a guide, the 8 mm work shirt is inserted until it rests on the bone repair. Subsequently, the decompression endoscope is introduced, 25°, with an external diameter of 7.9 mm and a working channel of 4.1 mm.

10. Having positioned the decompression scope, the cannula is advanced to disc level and rotated to displace the compressed root medially. This maneuver exposes the herniated disc, and the hernia is resected with grasper forceps of different calibers (Fig. 8).

Fig. (8))

Sequence of rotation of the endoscope at the disc level. The cannula is rotated medially, displacing the root and exposing the herniated disc to be removed. Source: RIWOSPINE S. Ruetten 2013, reproduced with permission..

11. Once the nucleotomy is complete, the endoscope cannula is rotated, allowing the descending root to occupy its usual position. Visible dural sac and spinal root pulsations indicate complete and sufficient decompression (Figs. 9 & 10).

Fig. (9))

Once the hernia is removed, the free nerve root is evident both in the shoulder and in the axilla. Source: RIWOSPINE S. Ruetten 2013, reproduced with permission..

Fig. (10))

Dura matter and spinal root free after decompression in an interlaminar approach, Picture provided by the authors..

12. Hemostasis is verified before withdrawing the endoscope. Finally, the working cannula is withdrawn, and the skin incision is closed with an absorbable suture.

Complications and Management

Lumbar interlaminar endoscopy carries certain risks and potential complications [43, 44]. Possible complications include infection, bleeding, or hematoma formation at the surgical site. Nerve injury or irritation may occur during the insertion or manipulation of instruments, leading to sensory or motor deficits. Dural tears or cerebrospinal fluid leaks can occur in rare cases [45], requiring additional intervention [42]. Moreover, there is a risk of incomplete decompression or inadequate symptom relief, necessitating further treatment. From the authors' point of view, every endoscopic spine surgeon should be able to handle the following complications:

Intraoperative bleeding: Preemptive control of bleeding is a solution to prevent intraoperative bleeding. The surgeon should consider coagulating visible vessels before they are severed. When unsure of the origin of the bleeding, check the source of bleeding outside the working cannula. When visibility is poor because of bleeding, bring the endoscope camera closer to the structures. Attempt to coagulate it with a radiofrequency probe. In the case of bone bleeding, there are several alternatives to radiofrequency coagulation if it should fail. If the bleeding continues, a mini-fracture of the bone trabeculae could be performed with the help of a dissector or endoscopic osteotome to stop the bleeding. Another option would be to use a high-speed diamond bur to obstruct the bony bleeding site with debris created by the fine diamond burr.

Dural tear: This is the most frequent intraoperative complication, and commonly occurs during the revision due to adherence of the dura mater to the yellow ligament, as well as a lesion caused by forceps in the case in which the visualization of the tip of the forceps is not taken into account. This complication could lead to a lesion of the dural sac, and should be avoided by the use of an endoscopic reamer with protective sleeves in place of blind closure of endoscopic forceps and punches. In case of a dural tear, small fibrin patches can be used.

Injury to neural structures: Prevention is the best way to manage neural injury. Endoscopic vision should always be clear, which can be achieved by momentarily increasing fluid pressure and adequate hemostasis. A safe dissection plane must be acquired between the neural structures and nearby structures, which can be achieved by rotating the beveled tip of the working cannula against the neural structures.

Postoperative Rehabilitation

Postoperative rehabilitation initially focuses on pain management, using prescribed medications as needed. Early mobilization begins on postoperative day one, and gentle exercises are gradually introduced to promote a range of motion and prevent muscle stiffness. Patients are typically advised to avoid heavy lifting and strenuous activities for two to four weeks to allow the surgical site to heal. The authors recommend a follow-up visit with the surgeon within two weeks to monitor the patient's progress and make any necessary adjustments to the rehabilitation plan. The postoperative rehabilitation program is tailored to each individual's specific needs, and may vary based on factors such as the extent of the procedure and the patient's medical comorbidities. Specifically, the authors recommend:

Immediate mobilization of lower limbs according to anesthetic effect.

Return to regular activity 3 days after surgery.

Return to light exercise 7 days after surgery.

Oral analgesia for 2 to 3 days.

Stitch on the seventh postoperative day.

Limitations

One limitation is the learning curve associated with the procedure, as it requires dedicated training. Considering the contraindications listed earlier in this chapter, not all patients and spinal conditions are suitable for interlaminar endoscopy [46]. Severe spinal instability or significant spinal deformities may make the procedure technically challenging or contraindicated. The size of the surgical instruments used in endoscopy may limit the amount of tissue that can be removed or the extent of decompression that can be achieved compared to open surgery. Therefore, some patients may experience persistent symptoms due to incomplete decompression, as some pathology may be beyond the reach of the endoscope from the interlaminar approach. Careful patient selection and case-by-case evaluation are essential to manage patients effectively [47]. From the author's point of view, the following limitations are relevant to the novice endoscopic spine surgeon:

The procedure is technically demanding, and has a long and steep learning curve [48].

Access to the endoscope, supporting equipment, and advanced decompression instruments and accessories.

Smaller instruments and, therefore, a more complex and difficult decompression procedure than with traditional microsurgical procedures.

Durotomies are difficult to repair through the endoscope.

Clinical Series

The authors of this chapter enrolled patients consisting of 186 (54.7%) males and 154 (45.3%) females with a mean age of 42 ± 15.3 years. 22 patients (6.5%) had had previous lumbar spine surgery. There were 20 postoperative complications (5.8%): postoperative hematoma drained by endoscopy (20%), postoperative instability requiring instrumentation (15%), wound infection (15%), wound dehiscence (25%), dural lesion which did not require intervention (25%). At six months of follow-up, 328 patients (96.4%) reported improvement in radicular pain caused by a herniated disc. The numerical rating score (NRS) for sciatica leg pain reduced from 9.3 ± 0.4 preoperatively to 3.3 ± 0.8 postoperatively at final follow-up. The average preoperative Oswestry Disability Index (ODI) score was 8.7 ± 1.5 and reduced to 2.4 ± 1.9 postoperatively at final follow-up.

DISCUSSION

Interlaminar lumbar endoscopy has emerged as a minimally invasive technique for diagnosing and treating various spinal conditions. It is indicated for herniated disc, central, and lateral canal stenosis, and foraminal stenosis. It depends on a sizable interlaminar window, for which reason it is frequently done at the L5/S1 level [49], where alternative approaches such as the transforaminal approach may be difficult to execute because of a high-riding ilium, transitional anatomy, degenerative vertical collapse, and other obstructive anatomy. Therefore, careful patient selection is critical, as factors such as severe spinal instability or significant deformities may further limit the suitability of interlaminar endoscopy.

Numerous studies have reported favorable outcomes following interlaminar lumbar endoscopy. The procedure offers advantages such as reduced postoperative pain, minimal blood loss, and shorter hospital stays compared to traditional open surgery. Direct visualization provided by the endoscope enhances surgical precision and enables targeted treatment of specific spinal pathologies. Preserving surrounding muscles and ligaments may contribute to faster recovery and a decreased risk of complications. This endoscopic surgery is technically demanding, with a learning curve that affects surgical outcomes. Surgeons must acquire specialized training and experience to master the technique effectively. The learning curve involves proficiency in endoscope handling, accurate anatomical identification, and safe instrument manipulation within the limited working space [48]. The necessary eye-hand coordination is a skill that not every surgeon will be able to master. The training process ideally involves a series of cases under the guidance of experienced mentors. Studies have suggested that improved patient outcomes, shorter operating times, and reduced complication rates are observed as surgeons progress along the learning curve.

CONCLUSION

The interlaminar approach for managing spinal pathologies provides a safe and effective method for managing pathologies of the spinal canal, the central canal, and the lateral recess. The advantages of the techniques are noted in terms of less intraoperative blood loss, minimal soft tissue damage, and early postoperative recovery with preservation of spinal stability at long-term follow-up. The technique has a long operating time and a steep learning curve.

References