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Neuroendoscopy and Interventional Pain Medicine is a clinically focused medical monograph series. With contributions from a team of internationally recognized neurosurgeons and spinal surgery specialists, the series aims to illuminate the latest advancements in minimally invasive neurosurgical techniques and pain management. Each volume offers invaluable insights into the future of minimally invasive treatments in this medical subspecialty.
Interventional Pain Surgery is the third of the monograph series. This book comprehensively covers endoscopic techniques for spinal surgery. Topics include interlaminar lumbar endoscopy, transforaminal lumbar discectomy, endoscopic approaches for lumbar spinal canal stenosis, and management of chronic low back pain through rhizotomy and rhiziolysis. The endoscopic treatment of basivertebral neuropathy, cervical foraminotomy, and decompression techniques is explained in dedicated chapters. Finally, the book also addresses endoscopic posterior lumbar interbody fusion and procedures for adjacent segment disease after lumbar fusion.
Key Features
- Covers a wide range of topics in neuroendoscopy and interventional pain medicine
- Emphasizes evidence-based approaches to treatment
- Offers clinical perspectives from expert surgeons
- Includes scientific references for researchers and advanced learners
It is an essential resource for readers who need to enhance their understanding of the latest technological advancements in neuroendoscopy and interventional pain medicine and apply these innovative techniques to improve patient outcomes.
Readership
This book is designed for a broad audience, including interventionalists, surgeons, medical students, healthcare professionals, and policy-makers involved in the care of patients with degenerative conditions of the neuroaxis.
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Veröffentlichungsjahr: 2024
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Direct visualization of abnormal and painful neuroanatomy has become commonplace. The endoscopic surgery technology platform has reached a level of sophistication that makes accessing anatomical compartments in the human body possible in places that hitherto have never been attempted. The intrauterine neuroendoscopy of raphe defects and their concomitant repair is one example of many that are life-changing for patients and their families.
Two developments primarily facilitated the advances. First, pioneers of the field – some of them serve as editors of this textbook – have paved the way with their unconventional approach to surgical pain care by holding their own when criticized for breaking with the traditional protocols, many of which have their foundation in image-based medical necessity criteria rather than a personalized patient-focused approach for treating abnormal or painful pathology of the spine and neuroaxis. These entrepreneur innovator surgeons have mainstreamed endoscopic spine surgery by dedicating their careers to scientific research, education, and training, ultimately leading to the establishment of treatment guidelines, updates in postgraduate surgeon training programs, and the development of credentialing standards.
Second, the technology transfers from aerospace, consumer electronics, and automotive, including automatization, robotics, navigation, artificial intelligence, 3D-printing, regenerative medicine, and above all, systems integration via miniaturization, allows surgeons to rewrite the rule book on the standard of care of many neurological and painful degenerative conditions for which historically there was not much to do because risks from exposure-related collateral damage or medical comorbidities. The ability to safely navigate towards the surgical objective and directly visualize it in great detail on a high-definition video monitor with a well-illuminated and irrigated endoscopic surgery and to intervene simultaneously with custom endoscopic instruments has broadened the indications by making surgical treatments safer and less burdensome to patients. The neuroendoscopic interventions in the brain illustrated in this text are a remarkable example of this trend.
In Neuroendoscopy and Interventional Pain Medicine Vol. 3: Interventional Pain Surgery, the editors have developed a multi-authored and clinically focused medical monograph to give the reader the most up-to-date snapshot of the current state-of-the-art endoscopic clinical practice in neurosurgery and surgical and interventional pain management. The publication is intended for physicians involved in pain management and orthopedic & neurosurgeons interested in treating common painful conditions, including degenerative disc disease, herniated discs, stenosis, peripheral nerve entrapment, tumor, and infection, with minimally invasive endoscopic techniques. A wide array of highly timely and clinically relevant topics have been assembled for this purpose. They range from suitable pain generator-based protocols, patient selection algorithms for endoscopic decompressive and reconstructive procedures, cell- and non-cell-based regenerative strategies, illustrative clinical decision-making scenarios, their respective indications, and clinical outcomes.
The chapters were selected based on contemporary trends in endoscopic surgery applications in neuro- and spinal surgery and modern interventional pain surgeries and procedures. The editors recognize that this trend is based on the need for less costly yet safe and efficient solutions for common congenital and degenerative painful neural axis and spinal conditions. Patients and other stakeholders in the ongoing debate on better value-based health care, including healthcare policymakers and payors, are demanding of surgeons less burdensome and less risky treatments with shorter time to recovery, return to work, and social reintegration. Neuroendoscopy and Interventional Pain Medicine: Vol. 3: Interventional Pain Surgery was written with these goals in mind. The editors hope the readers will find it an informative knowledge resource they will continue to revert to when implementing the endoscopy platform in their practice setting.
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.
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].
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].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 jointCyst of the yellow ligamentOssification of the yellow ligamentForaminal stenosisThere 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 radiographsGrade 2 or higher spondylolisthesis according to the Meyerding criteria [39]Severe degenerative scoliosisInfectionMalignancySimple 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].
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
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.
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 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.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.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.
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.
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.
Endoscopic transforaminal lumbar discectomy (ETLD) with trephines represents a minimally invasive surgical procedure for treating lumbar disc herniation. This technique best suits the novice surgeon and offers several advantages over traditional open surgery, including reduced tissue trauma, faster recovery, and improved patient outcomes. It simplifies the placement of the endoscopic working cannula by creating an initial working space under fluoroscopic guidance without the need for an initial foraminoplasty. This chapter delves into the technical and procedural aspects of ETLD with trephines, providing a detailed overview of the procedure, its indications, contraindications, surgical steps, and potential complications. Furthermore, we highlight the advantages and limitations of this innovative technique and discuss its established role in spinal surgery.
Lumbar disc herniations are common in adults and are more relevant in any spine surgeon’s practice [1-4]. The aging population demographic dynamic has shifted the focus of spinal endoscopy from just treating disc herniations to broadening the indication of spinal stenosis, as the two conditions often coincide with the same patient and sometimes even at the same surgical level [5-7]. This degenerative disease process results in the progressive vertical collapse of the spinal motion segment that leads to significant back pain, radiculopathy, and functional disability. While open surgical techniques have long been the gold standard for treatment, they are associated with substantial tissue trauma, postoperative pain,
and extended recovery times [8]. The advent of endoscopic procedures revolutionized the field of spinal surgery, and ETLD has emerged as an up-and- coming minimally invasive alternative.
Earlier versions of the transforaminal decompression procedure involved trephines placed over a guidewire and dilators into the surgical neuroforamen [9]. Sequentially larger trephines are introduced to create a working space. These steps are typically done under fluoroscopic guidance and make an initial working space in the lateral aspect of the facet joint complex at the surgical level. This step dramatically simplifies the placement of the working cannula since no extensive foraminoplasty is required. While the experienced endoscopic spinal surgeon may prefer to perform these initial steps under direct visualization [10], the novice may find placing the endoscopic working cannula under fluoroscopic guidance easier as it simplifies the first few procedural steps quite a bit [11, 12].
In this chapter, the authors give the reader a procedural overview of the endoscopic transforaminal lumbar discectomy with trephines which involves accessing the herniated disc through a small incision near the affected vertebral level with the aid of a tubular retractor system, specialized endoscopic instruments, and real-time imaging guidance, the surgeon navigates through the intervertebral foramen, reaching the herniated disc. Trephines, cylindrical surgical instruments, are then used to remove a targeted portion of the herniated disc material, decompressing the affected nerve root and alleviating the associated symptoms.
1) Indications: ETLD with trephines is suitable for patients with symptomatic lumbar disc herniation causing radicular pain, sciatica, or neurological deficits. Typical indications include but are not limited to persistent pain despite conservative treatment, neurological deficits, severe radiculopathy, and a herniated disc confirmed by imaging studies [13-18].
2) Contraindications: Certain patient characteristics and anatomical factors may contraindicate ETLD with trephines. These include significant instability of the affected vertebral segment, sizeable central disc herniation compressing the spinal canal, prior lumbar surgery, active infection, and severe spinal stenosis [16-18].
1) Advantages: ETLD with trephines offers several advantages over open surgical techniques. These include minimal tissue trauma, reduced blood loss, shorter operative time, preservation of anatomical structures, faster recovery, reduced postoperative pain, decreased hospital stay, and potential cost savings. The procedure's minimally invasive nature also allows for outpatient or short-stay hospitalization, further improving patient satisfaction.
2) Limitations: While ETLD with trephines is generally safe and effective, it has limitations such as challenges such as limited access to the central disc or contralateral foramen, the learning curve for surgeons, the need for specialized training, and the potential for recurrent disc herniation, dural tears, nerve root injury, dysesthesia, bleeding, and transient or persistent neurological deficits and in rare cases require careful consideration.
The transforaminal outside-in endoscopic lumbar technique combines the benefits of easy transforaminal access to the neuroforamen and spinal canal with direct endoscopic visualization, allowing for precise diagnosis and targeted treatment of the painful lumbar pathology [19-24]. The target area is accessed by placing the endoscopic work cannula, typically measuring 8.9 mm in diameter the intervertebral foramen – an existing anatomical structure – to treat herniated discs or foraminal stenosis, with minimal disruption to surrounding tissues by maneuvering within the epidural space, in Kambin’s triangle [25, 26]; a working space between the traversing and exiting nerve root and the inferior pedicle. Most importantly, the transforaminal technique requires less bony resection typically needed in a translaminar procedure and therefore has a lower incidence of iatrogenic instability (Fig. 1).
This technique offers an effective solution for relieving nerve root compression and associated radiculopathy by directly visualizing and decompressing the foraminal space [27-30]. Briefly, the method involves placing a working channel over sequential dilators. The endoscopic working channel is a tubular retractor enabling the insertion of an endoscope and specialized instruments. The working channel may have various tip configurations to facilitate specific procedural steps and objectives, such as safe retraction of the exiting nerve root. In real-time visualization, the surgeon can navigate through the foraminal and epidural space, accurately identify the painful pathology, and perform precise decompression, ablation, or discectomy procedure. In doing so, the surgeon can address foraminal stenosis affecting the exiting nerve root [31] (Figs. 2-6).
Fig. (1)) Shown is the position of the patient (a) for the transforaminal endoscopic decompression procedure, (b) the posterior-anterior fluoroscopy view of the guidewire being placed across the L4/5 intervertebral disc space, (c)) the posterior-anterior fluoroscopy view of the guidewire being placed across the L5/S1 intervertebral disc space, (d) the guide wire being placed in the preferred suprapedicular trajectory to gain transforaminal access to the L4/5 level, (e