Endoscopy of the lumbar spine has traditionally found much broader adoption than those endoscopic procedures of other areas of the spine. Initially, a herniated disc was the target of endoscopic spine surgery techniques. Stenosis indications were later identified as technological advancements permitted. Many endoscopic spinal surgeries commenced in the domain of interventional pain management. Lasers and radiofrequency were applied to some of the procedures that nowadays are aided by direct videoendsocopic visualization of the painful pathology. In this chapter, the authors briefly reviewed the history of spinal endoscopy and its key opinion leaders. Giving credit to the most prominent pioneers of this fast-moving field sets the stage for what the reader is about to discover in this most-up-to-date publication: Contemporary Spinal Endoscopy: Lumbar Spine.

Various endoscopic spinal surgery techniques to remove herniated discs in the lumbar spine have gained popularity. The “inside-out” and “outside-in” transforaminal techniques have been employed extensively, and their clinical indications have expanded with the advances in video-imaging and endoscopic optical and surgical equipment. In this chapter, the authors review some of the relevant anatomical considerations the endoscopic spine surgeon should consider when scheduling a patient for endoscopic spinal surgery. The authors also present their most up-to-date knowledge of technological advances and new endoscopic surgery techniques to provide the reader with a snapshot of modern advancements of the established transforaminal “inside-out” and “outside-in” and interlaminar methods. This chapter sets the anatomical stage for many of the following chapters in this volume 2 of the Bentham text series on Contemporary Endoscopic Spinal Surgery.

Uniform use of nomenclature and classification systems appears logical to anyone attempting to systematically study clinical outcomes with new emerging technology applications in spine surgery. At the introduction of spinal endoscopy into routine clinical practice, today's key opinion leaders introduced nomenclature conducive to the description of their innovations at the time. With endoscopy of the spine becoming more mainstream several authors have pushed classification systems for clinical outcome studies. Others have introduced terminology in hopes of them being adopted to further research and health care policy agendas. These nomenclature and classification systems' practicality in routine clinical practice may be debatable and perhaps be considered by some an academic exercise. However, the need for some common language and categorization of descriptors of painful pathology, confounding factors, and their treatments are accepted by most. This chapter summarizes the literature on nomenclature, terminology, and classification systems relevant to clinical outcome research in spinal endoscopy. It was motivated by the desire to formalize its clinical outcome research, bring it up to par with traditional translaminar spine surgery techniques, and, ultimately, incorporate it into clinical treatment and coverage guidelines formulated by spine societies and payors.

The transforaminal spinal surgery technique is the most commonly performed way of endoscopic discectomy. Initial placement of the working cannula may determine the sequence of procedural steps. Commonly applied variations of the technique include the “inside-out” and “outside-in” techniques. In this up-to-date chapter, the authors describe the necessary procedure steps of the transforaminal endoscopic discectomy procedure, focusing on downward migrated disc herniations as these may push the endoscopic spine surgeon to the limits of his or her skill set. Therefore, the authors describe the limitations of the technique and assess adequate neural element decompression in great detail.

 Endoscopic spine surgeries are gradually evolving and being accepted by spine surgeons globally. Transforaminal approach discectomy is one of the initial surgeries done with a fully endoscopic approach. The transforaminal approach has various advantages. Nevertheless, it has certain limitations too, and a high lying iliac crest anatomically impeding access is one of them. An Interlaminar approach for L5-S1 herniated disc exploiting a wide interlaminar window is a phenomenal endoscopic approach to this common clinical problem.

Commonly employed transforaminal decompression techniques may use the “inside-out” and “outside-in” technique, not as a standalone technique, but as a combined technique that considers different surgical philosophies. The inside-out technique calls for an initial emphasis on visualization of the intradiscal cavity with the endoscope by advancing the working cannula inside the lumbar intervertebral disc for intradiscal examination when appropriate. In contrast, the outside-in approach places it initially into the neuroforamen and lateral recess. The authors present an illustrative case series of 411 patients in whom they employed a hybridization of these two techniques because they found it to be more reliable in cases of end-stage degenerative vacuum disc disease. The study group consisted of 192 (46.7%) females and 219 (53.3%) males with an average age of 54.84 ± 16.32. The average follow-up of 43.2 ± 26.53 months. Patients underwent surgery for herniated disc (135/411;32.8%), foraminal spinal stenosis (101/411;24.6%), a combination of the latter two conditions (162/411;39.4%), or low-grade spondylolisthesis (13/411;3.2%). Results of our clinical series showed a significant reduction of preoperative ODI and VAS for leg pain of 49.8 ± 17.65, and 7.9 ± 1.55 to postoperatively 12.2 ± 9.34, and 2.41 ±5 1.55 at final follow-up (p 0.0001), respectively. Macnab outcomes were Excellent in 134 (32.6%), Good in 228 (55.5%), Fair in 40 (9.7%), and Poor in 9 (2.2%) patients, respectively. There was end-stage degenerative vacuum disc disease in 304 (74%) of the 411 patients; 37.5% had Excellent and 50% Good Macnab outcomes.

Patients without vacuum discs had Excellent and Good 18.7% and 71.% of the time. With our hybridized technique, patients with end-stage degenerative vacuum disc disease did very well with the endoscopic decompression procedure. Improved clinical outcomes may be obtained with the direct visualization of pain generators in the epidural- and intradiscal space. It is the authors’ preferred transforaminal decompression technique

Foraminal stenosis is often underestimated due to difficulties in approaching the region surgically. The evolution of the transforaminal approach allowed safe surgical exploration of foraminal pathology under direct vision. Postoperative Dysesthesia (POD) due to irritation of the dorsal root ganglion (DRG) of lumbar nerve roots at the surgical level is a common sequela associated with the transforaminal approach. Minimal dorsal root ganglion (DRG) retraction is critical to prevent POD. Full endoscopic interlaminar contra-lateral lumbar foraminotomy consists of a sublaminar approach or translaminar approach. It is followed by contralateral foraminotomy and extraforaminal decompression. The contralateral approach's principle is to create a safe path to the contralateral foramen, preserving the ipsilateral anatomy. It allows simultaneous lateral recess, contra-lateral foramen, and extraforaminal decompression along the nerve root with minimal nerve root manipulation in the foramen. However, the learning curve for the technique is steep compared to the transforaminal technique

Downward migrated lumbar disc herniation can present a challenge to any spine surgeon. Open spine surgery requires an aggressive decompression of the posterior bony elements, which ultimately may lead to postlaminectomy syndrome and instability – both of which have been associated with higher reoperation rates. The interlaminar endoscopic approach is a reasonable alternative to open translaminar surgery but still carries the risk of dural tear and does not afford the ability for an intradiscal discectomy. The authors offer a modification of the outside-in transforaminal approach - the suprapedicular circumferential opening technique (SCOT) to gain better access to downward- and far-migrated extruded lumbar disc herniations.

A systematic review of contemporary lumbar endoscopic decompression techniques shows that the lion’s share of lumbar endoscopic decompressions is done via the transforaminal and interlaminar approach. Many modifications and diverse applications for the more complex clinical applications have been described. Clinical outcomes in well-trained, experienced hands suggest that these modified endoscopic procedures are genuine advances. However, from the point of view of the communitybased or academic traditionally trained spine surgeon adoption of these complex endoscopic procedures may still seem either impractical or out of reach when these endoscopic procedures are considered for each individual patient. The surgeon will have to figure out how to implement these procedures into their routine clinical operations by replacing the well-tried, time-proven and reliable open or other forms of minimally invasive spine surgeries. Recognizing a surgical technique's clinical advantages over another is one thing, but transforming one's practice is much more complex and depends not only on one's training or comfort level, but in most cases, the actual experience for each surgeon that will evolve due to the feedback from their patients. In patients who have experienced both the transforaminal and translaminar endoscopic approach, each surgeon will likely use the approach that gives the safest, most cost-effective, as well as the approach chosen by the surgeon for each anatomically based and guided approach. Many additional factors could potentially impede endoscopic spine surgery implementation, most of which will evolve, as the surgeon circle around the anatomic limitations of each approach. The availability or lack of equipment, trained staff, and support system also plays a role.
 
The institutionalized spine surgeons may encounter additional hurdles since endoscopic spine surgery's disparate nature may disrupt well-established revenue cycles, making its implementation difficult. The surgeon's institutions may have to shoulder the burden of capital equipment purchases while facing lower reimbursement. To aid the prospective endoscopic spine surgeons in overcoming these implementation hurdles, the authors aimed to provide a systematic step-by-step comparison of the lumbar endoscopic overthe-top versus the transforaminal decompression techniques to illustrate their various technical aspects and clinical indications to aid the reader in selecting a “preferred” endoscopic technique

Cysts associated with degeneration of the lumbar facet joints are commonly encountered during routine lumbar endoscopy. They can be difficult to dissect and may heighten the risk of nerve root injury when they are fibrotically attached. Many of these cysts are extradural. Because of their highly inflammatory nature, they may be associated with radicular symptoms even without associated mechanical compression of the traversing or exiting nerve root of the symptomatic surgical level. These synovial cysts may be acutely painful. Their related symptoms may be difficult to distinguish from those caused by lumbar disc herniation or stenosis in the lateral spinal canal on clinical examination. The endoscopic spine surgeon is often forced to deal with them to complete the neural element decompression. What is less clear is what to do with patients with sizeable isolated facet joint based cysts without much other clinical pathology. The surgical indications and prognosticators of favorable clinical outcomes with endoscopic surgery are less well understood. Therefore, the authors performed a systematic analysis of their clinical series of patients they identified to have had synovial cysts either on preoperative advanced imaging studies or on those they found serendipitously during routine lumbar endoscopy. In total, 48 were identified in whom removal of the extradural cyst was performed during routine transforaminal and interlaminar endoscopy. The primary indication for surgery in these patients was painful foraminal and lateral recess stenosis. The patients were divided into 26 females and 22 males. The L4/5 level was the most frequent site of facet based cysts. It was found in 26 patients (72.2%). The second most common site was the L5/S1 level in 8 patients (22.2%), followed by two patients (5.6%) at the L3/4 level. A single patient had endoscopic decompression at the T9/10 level. Outcome analysis showed clinical improvements in all patients. According to the modified Macnab criteria, 19/48 (39.6%) patients had excellent outcomes. Good and fair results were achieved in 18/48 (37.5%) and 11/48 (22.9%) patients, respectively. The observed VAS leg pain score reductions were substantial and statistically significant (p < 0.000) from preoperative 8.06 ± 1.57 to postoperative 1.92 ± 1.49, and 1.77 ± 1.32 at final follow-up. One patient had a recurrent disc herniation, and another patient did not improve. Two patients underwent fusion during the follow-up period. Patients with Fair outcomes had a statistically significant association (p < 0.001) with facet instability as suggested by axial T2-weighted MRI imaging findings of thickened ligamentum flavum, facet joint hypertrophy, and a bright white fluid-filled joint gap of > 2 mm. Endoscopic resection of extradural spinal cysts that nearly exclusively stem from degenerated lumbar facet joints in skilled hands is feasible. Instability was one of the prognosticators of Fair Macnab outcomes.

Neurogenic claudication due to a herniated disc, spinal stenosis, instability, or deformity is typical in the elderly. When conservative management fails, and the patient’s disability prevents a healthy lifestyle, surgery is often recommended. There are multiple concerns with open spine surgery in the geriatric patient population, including medical comorbidities and fewer overall reserves to tolerate aggressive operations with high blood loss and long operating times. Endoscopic foraminal decompression has gained popularity and is now openly competing with open decompression and fusion operations by focusing the treatment on validated pain generators. Such simplified treatments often consist of targeted single-level and unilateral neuroforaminal decompressions. It is evident that appropriate patient selection and a diagnostic workup employing validated prognosticators of a favorable outcome are necessary to make such an endoscopic spinal surgery program work in the elderly. In this chapter, the authors describe their patient selection algorithms and preferred surgical techniques. In their experience, high patient satisfaction may be achieved when employing their clinical protocols. 

Lumbar spinal facet joints may be a significant source of chronic low back pain, with a reported prevalence of 7.7 to 75%. The clinical entity has been called facet joint syndrome. However, this syndrome and its therapies remain controversial as the clinical evidence for its treatment has been graded as weak. Intra- or periarticular injections have found acceptance as a diagnostic tool. Its etiology may be multifactorial, with degeneration of the joints’ cartilage being the likely leading cause. This process incites an inflammatory response involving the synthesis of proinflammatory cytokines and metalloproteinases. Hence, local injections of glucocorticoids into the affected joint has become an accepted short-term treatment option but with weak long-term benefit. In this chapter, the authors review their clinical experience with the endoscopic rhizotomy when treating chronic low back pain due to facet syndrome. Its safety and effectiveness were evaluated in 84 patients, including 48 females and 36 males with a mean age of 65, ranging from 52 to 82. Patients were included in the study if they reported greater than 80% pain relief with lumbar medial branch blocks using ropivacaine on two separate occasions. Primary clinical outcome measures were the VAS BACK score and the Oswestry Disability Index (ODI). There were no adverse events and complications except one patient with a postoperative hematoma, which resolved with conservative care. At the final six months follow-up, the VAS scores were significantly lower (postop VAS 2.3; range 0 - 4) than before endoscopic rhizotomy (preop VAS mean 6.4; range 4-7; p < 0.05). The postoperative ODI of 24 (range 12 - 48) was significantly lower than its preoperative value 52 (range 42-67). The authors conclude that dorsal endoscopic rhizotomy is safe and effective for facet-related low back pain.

Chronic discogenic back pain is a leading cause of disability in man. Degenerative disc disease and its associated pathological neurotization of the sinuvertebral and basivertebral nerve are some of the mechanisms that lead to lower back pain. The use of radiofrequency ablation to denervate pathological sensitized sinuvertebral and basivertebral nerve has been described to decrease pain in patients with degenerative disc disease. Radiofrequency energy system can be introduced into the region of sinuvertebral and basivertebral nerve via inside out and outside in technique through fluoroscopic and/or endoscopic guidance. This chapter discusses the methods of outside-in-endoscopic guided radiofrequency ablation of sinuvertebral and basivertebral nerves.

 Surgical treatment of benign tumors of the spine when required is still aggressive compared to the lack of malignancy of the underlying disease process. While such lesions rarely cause systemic problems, grow slowly, and rarely degenerate into the malignant lesions or metastasize, their open surgical treatment rivals that done for malignant lesions causing tremendous exposure-related collateral damage from tissue dissections, blood loss, and scarring of the surgical corridor. Endoscopic spinal surgery techniques offer an attractive alternative to gain access and visualize areas deep to the spine that ordinarily would require complicated anterior, posterior, or even combined approaches to decompress and stabilize iatrogenic instability. In this chapter, the authors present an exemplary case of applying endoscopy to treating benign nerve sheath tumors of the lumbar spine – a schwannoma.