Treatment Concept and Technical Considerations of Biportal Endoscopic Spine Surgery for Lumbar Spinal Stenosis.

Decompression is a major component of surgical procedures for degenerative lumbar spinal stenosis (LSS). In addition to sufficient decompression to guarantee the relief of neurological pain, compensating surgical instability after wider laminectomy and foraminotomy and instrumentation with caging and fusion with grafting are performed to secure or restore the foraminal dimension and correct coronal/sagittal imbalance for longer survival of the adjacent segment. Endoscopic spinal surgery (ESS) has been developed under the flag of successful decompression while preserving structural integrity as much as possible with the help of magnification and illumination. ESS provides a technical possibility and feasibility for solving LSS by decompression alone. Recently, many endoscopic trials have been conducted to overcome conventional surgical treatment that requires wider dissection, escape inevitable complications from surgical damage, and compensate for the fusion technique. However, biportal ESS has some technical limitations, including clinical difficulties in accessibility for more moderate to severe stenosis and challenges for complicated conditions with segmental ventral slip, isthmic defect, stenosis combined with foraminal stenosis or foraminal disk rupture, or degenerative segmental scoliosis with disk height collapsing and endplate fatigue fracture. Because decompression alone is a skill for eliminating pathologies, there is no function of preserving degenerative structure or stopping the recurrence of disk degeneration or subsidence. This review of clinical reports investigated the possibility of biportal ESS for treating degenerative lumbar disorders by sufficient decompression and adequate elimination of various pathologies and decreasing technical complications. The results of this study may help develop better innovative spinal surgical techniques in the near future.

Exploring Physical Lumbar Microvascular Geometry Through Endoscopy and Illustrations: Implications for Clinical Interpretation.

STUDY DESIGN: Retrospective Study. OBJECTIVES: Minimally invasive endoscopic spinal surgery is gaining popularity, but our understanding of the lumbar spine's microvascular geometry relies heavily on cadaver studies and textbook illustrations. Additionally, inconsistent nomenclature of vessels in the literature hampers effective communication among surgeons. This study aims to improve the clarity and comprehensibility of the lumbar spinal microvascular geometry under endoscopic view. METHODS: The study included 400 patients who underwent endoscopic spinal surgery for lumbar spinal canal stenosis and foraminal stenosis. The surgeries were performed by an experienced surgeon using either the interlaminar or transforaminal approach. Endoscopic video recordings were further analyzed to map the microvascular geometry and common bleeding foci. The observed results were cross-referenced with existing literature to reconstruct a comprehensive view of the vascular anatomy. RESULTS: The transforaminal approach commonly encounters bleeding foci originating from the major branches of the segmental lumbar artery and the emissary veins within the foramen. The interlaminar approach primarily encounters bleeding foci from the muscle vessels in the dorsal lamina, which are believed to be located near the ends of the three main branches. In the intracanal region, epidural vessels form a rotary loop above the disc, which can contribute to most of the bleeding during discectomy. CONCLUSIONS: This study provides a comprehensive understanding of the microvascular anatomy in the lumbar spine during endoscopic spinal surgery. Recognizing the geometry will help surgeons anticipate and control bleeding, reducing the risk of complications. The findings contribute to the improvement of surgical techniques and patient safety in endoscopic spinal surgery.

Biportal Endoscopic Spine Surgery: Clinical Results for 163 Patients.

BACKGROUND: Biportal endoscopy spine surgery is an endoscopic procedure that uses 2 portals, 1 for the endoscope and 1 for the instruments. It provides an excellent and very versatile field of view, with the advantage of another portal to approach the most common degenerative lumbar pathologies. METHODS: We evaluated a retrospective series of patients who underwent biportal endoscopy with ≥1 year of follow-up. Relevant epidemiological and clinical data, such as the Oswestry disability index and visual analog scale for pain, were also considered. Complications and the effects of the learning curve are also discussed. RESULTS: We included 163 patients treated within a 5-year period with ≥1 year of follow-up available. The main pathologies were disc herniation (53.4%), foraminal stenosis (19%), and central canal stenosis (16.6%). The outcomes regarding disability and pain scores after surgery were very good, with a redistribution of the patient sample to the mild categories of disability. Inferential analysis showed relative and absolute improvements for both disc herniation and canal stenosis in terms of the Oswestry disability index and visual analog scale for pain, especially for disc herniation. The incidence of complications was approximately 7%. The most common approach was interlaminar (89%), and the most common pathology was disc herniation (54.9%). The duration of surgery overall and for the different stages had improved at the end of the learning curve with a reduction of almost 58 minutes. CONCLUSIONS: Biportal endoscopy is a minimally invasive procedure that is safe and effective, with a low rate of complications. It has a reproducible learning curve and provides very good outcomes regarding functionality and pain scores.

Enhancing endoscopic foraminal decompression in adult isthmic spondylolisthesis: the potential influence of lateral recess isthmic spur and our case series of an innovative craniocaudal interlaminar approach via unilateral biportal endoscopic spinal surgery.

BACKGROUND: The NASS guideline cannot recommend any of the surgical treatment options toward adult isthmic spondylolisthesis (AIS) since 2014. After the introduction of endoscopic decompression, instead of treating the spondylolysis itself, treatment can specifically target the refractory radicular pain developed during the degeneration progress without devastating the peripheral soft tissue. However, we noticed that endoscopic transforaminal decompression seems to be less effective in AIS compared to other types of degenerative spondylolisthesis. Thus, we came up with a novel craniocaudal interlaminar approach, utilizing the proximal adjacent interlaminar space to perform bilateral decompression and observed the pathoanatomy of pars defect directly and tried to identify the cause of decompression failure. METHODS: From January 2022 to June 2022, 13 patients with AIS underwent endoscopic decompression via the endoscopic craniocaudal interlaminar approach and were followed up for at least 6 months. Visual Analogue Scale, Oswestry Disability Index and MacNab scores were recorded to monitor patients' clinical recovery. All endoscopic procedures were recorded and reviewed to illustrate the pathoanatomy. RESULTS: Four patients required minor revision via the same technique. One of them required it due to incomplete isthmic spur resection, two due to neglected disc protrusion, and the other due to root subpedicular kinking in higher grade anterolisthesis. All patients' clinical condition improved significantly subsequently. After reviewing the endoscopic video, we have observed that the hook-like, ragged spur originating from the isthmic defect extends beyond the region around the foramen. Instead, it extends proximally into the adjacent lateral recess, resulting in impingement along the fracture edge above the index foramen and, in some cases, even in the extraforaminal area. CONCLUSIONS: The broad spanning isthmic spur extending to the proximal adjacent lateral recess might be the reason why the transforaminal approach yielded less satisfactory results due to the incomplete decompression result from approach related restriction. Our study demonstrated an optimistic outcome by applying decompression from the upper level. Therefore, we propose that the craniocaudal interlaminar approach might be a better route for decompression in adult isthmic spondylolisthesis.

Comparison of Primary Versus Revision Lumbar Discectomy Using a Biportal Endoscopic Technique.

STUDY DESIGN: Retrospective study. OBJECTIVE: To compare the clinical outcomes of the biportal endoscopic technique for primary lumbar discectomy (BE-LD) and revision lumbar discectomy (BE-RLD). METHODS: Eighty-one consecutive patients who underwent BE-LD or BE-RLD, and could be followed up for at least 12 months were divided into two groups: Group A (BE-LD; n = 59) and Group B (BE-RLD; n = 22). Clinical outcomes included the visual analog scale (VAS), Oswestry Disability Index (ODI), and modified MacNab's criteria. Perioperative results included operation time (OT), length of hospital stay (LOS), amount of surgical drain, and kinetics of serum creatine phosphokinase (CPK) and C-reactive protein (CRP). Clinical and perioperative outcomes were assessed preoperatively and postoperatively at 2 days and at 3, 6, and 12 months. Postoperative complications were noted. RESULTS: Both groups showed significant improvement in pain (VAS) and disability (ODI) compared to baseline values at postoperative day 2, which lasted until the final follow-up. There were no significant differences in the improvement of the VAS and ODI scores between the groups. According to the modified MacNab's criteria, 88.1 and 90.9% of the patients were excellent or good in groups A and B, respectively. OT, LOS, amount of surgical drain, and kinetics in serum CRP and CPK levels were comparable. Complications in Group A included incidental durotomy (n = 2), epidural hematoma (n = 1), and local recurrence (n = 1) and in Group B incidental durotomy (n = 1) and epidural hematoma (n = 1). CONCLUSION: BE-RLD showed favorable clinical outcomes, less postoperative pain, and early laboratory recovery equivalent to BE-LD.

Unilateral Biportal Endoscopy for Lumbar Spinal Stenosis and Lumbar Disc Herniation.

Background: Unilateral biportal endoscopy (UBE) is a novel minimally invasive technique for the treatment of lumbar spinal stenosis and lumbar disc herniations. Uniportal endoscopy was utilized prior to the advent of UBE and has been considered the workhorse of endoscopic spine surgery (ESS) for lumbar discectomy and decompressive laminectomy. However, there are theoretical advantages to UBE compared with traditional uniportal endoscopy, including that the procedure utilizes typical spinal equipment that should be readily available, requires less capital cost and optical instrumentation, and provides greater operative flexibility as a result of utilizing both a working and a viewing portal7,8. Description: A 0-degree arthroscope is typically utilized for discectomy and lumbar laminectomies. The use of a radiofrequency ablator is critical to help coagulate osseous and muscle bleeders. For irrigation, gravity or a low-pressure pump, typically <40 mm Hg, can be utilized9,10. Further details regarding irrigation pressure are provided in "Important Tips." The use of a standard powered burr is typical to help osseous decompression, and Kerrison ronguers, pituitaries, osteotomes, and probes utilized in open or tubular cases suffice. Two incisions are made approximately 1 cm lateral to the midline. If working from the left side for a right-handed surgeon, the working portal is typically made at the lower laminar margin of the target level. The camera portal is then made typically 2 to 3 cm cephalad. A lateral radiograph is then utilized to confirm the portal placements. From the right side, the working portal is cephalad and the camera portal is caudal. Because of the switch, the portals may be shifted more distally.The first step is creating a working space because there is no true joint space in the spine. With use of radiofrequency ablation, a working space is created in the interlaminar space. Next, with use of a powered burr or a chiseled osteotomy, the base of the cephalad spinous process is thinned until the insertion of the ligamentum flavum is found. Next, the ipsilateral and contralateral laminae are thinned in a similar fashion. Once the osseous elements are removed, the ligamentum flavum is removed en bloc. The traversing nerve roots are checked under direct high-magnification visualization to ensure that they are decompressed. If a discectomy is necessary, standard nerve-root retractors can be utilized to retract the neural elements. With use of a blunt-tip elevator, the anular defect can be incised and the herniated disc can be removed under direct high-power visualization. In addition, a small curet can be utilized to create a defect in the weakened anulus or membrane covering the extruded disc material in order to help deliver the herniated disc material. Epidural veins are coagulated typically with use of a fine-point bipolar radiofrequency device. Alternatives: Nonoperative treatments include oral anti-inflammatory drugs, physical therapy, and epidural injections; if these fail, alternative surgical treatments include open lumbar laminectomy and/or discectomy, tubular lumbar laminectomy and/or discectomy, and other minimally invasive techniques, such as microendoscopy, uniportal endoscopy, and microscopy-assisted decompression. Rationale: UBE is a minimally invasive surgical procedure that better preserves osseous and muscular structure compared with open and tubular techniques. Conventional lumbar laminectomy involves dissection and retraction of the multifidus muscle from the spinous process to the facet joint. This exposure can damage the delicate posterior dorsal rami. Long retraction time can also lead to pressure-induced muscle atrophy and potentially increased chronic low back pain. Alternatively, smaller incisions and shorter hospital stays are possible with UBE.Similar to UBE, tubular surgery can minimize soft-tissue damage compared with open techniques; however, in a randomized trial assessing techniques for spinal stenosis surgery, Kang et al. found that UBE and tubular surgery had similarly favorable clinical outcomes at 6 months postoperatively but UBE resulted in decreased operative time, drain output, opiate use, and length of hospital stay5.Furthermore, the use of an endoscope in the biportal technique allows ultra-high magnification of the spinal pathology, decreased capital costs, and the ability to use 2 hands with freedom of movement. UBE provides clear visualization of the neural elements while keeping maximal ergonomic efficiency with the surgeon's head looking straight forward, the shoulders relaxed, and the elbows bent to 90°. Continuous irrigation through the endoscope also helps with bleeding and decreasing the risk of infection. Expected Outcomes: Long-term outcomes do not differ substantially between discectomies performed with use of the presently described technique and procedures done with more traditional minimally invasive (i.e., tubular) techniques; however, visual analogue scale scores for back pain may be better in the short term, and there is evidence of a shorter hospital stay with UBE2. Complication rates did not differ from other minimally invasive techniques. When comparing UBE and stenosis, Aygun and Abdulshafi found that UBE was associated with decreased hospital stays, operative time, and blood loss and better clinical outcomes up to 2 years postoperatively compared with tubular laminectomy12. Important Tips: The optimal hydrostatic pressure is 30 to 50 mm Hg. Pressure is determined by the distance between the fluid source and the working space. Because the working space does not change, the height of the bag decides pressure. A simple formula for pressure is calculated by dividing the distance from the working field to the irrigation source by 1.36. A rule of thumb is that if the bag is 50 to 70 cm above the patient's back, the pressure should be adequate. The advantages of using gravity rather than a pressure pump are that excessive fluid solution pressure in the epidural space can cause neurological issues such as nuchal pain, headache, and seizure11. Additionally, if the intertransverse membrane or the lateral margins of the disc are violated, hydroperitoneum can occur unknowingly due to the high-pressure system.Gravity or pump pressure of >40 mm Hg may elevate epidural pressure and mask operative bleeding. When the pump is turned off at the end of the surgical procedure, a postoperative epidural hematoma may occur because the bleeding source may not have been recognized while the pump pressure was on.Excessive pump pressure may lead to an increase in intracranial pressure, causing headache or delayed recovery from general anesthesia with stiff posture and hyperventilation.Make sure fluid is emerging from the working portal and the muscle area is not swelling to prevent soft-tissue fluid extravasation.Epidural veins are coagulated typically with a fine-point bipolar radiofrequency device.Osseous bleeding can be controlled with bone wax or a high-speed burr. Acronyms and Abbreviations: MRI = magnetic resonance imagingRF = radiofrequencyAP = anteroposterior.

Comparison of Minimal Invasive Versus Biportal Endoscopic Transforaminal Lumbar Interbody Fusion for Single-level Lumbar Disease.

STUDY DESIGN: Retrospective study. OBJECTIVE: The authors aimed to compare the clinical outcomes of biportal endoscopic transforaminal lumbar interbody fusion (BE-TLIF) with those of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) using a microscope. SUMMARY OF BACKGROUND DATA: Lumbar spinal fusion has been widely performed for various lumbar spinal pathologies. Minimally invasive transforaminal interbody fusion using a tubular retractor under a microscope is a method of achieving fusion while reducing soft tissue injury. Recently, several studies have reported minimally invasive techniques for lumbar discectomy, decompression, and interbody fusion using biportal endoscopic spinal surgery. MATERIALS AND METHODS: This retrospective study included 87 patients who underwent single-level TLIF for degenerative or isthmic spondylolisthesis between 2015 and 2018. Thirty-two and 55 patients underwent BE-TLIF (group A) and MI-TLIF (group B), respectively. Visual Analogue Scale scores of the back and leg and Oswestry Disability Index were collected perioperatively.Further, data regarding perioperative complications, including length of hospital stay, time to ambulation, and fusion rate, were collected. RESULTS: The Visual Analogue Scale score at 2 weeks and 2 months postoperatively was significantly lower in group A (P=0.001). All other clinical scores showed improvement with no significant difference between the 2 groups (P>0.05). The difference in the fusion rates between group A (93.7%) and group B (92.7%) were not significant (P=0.43). CONCLUSIONS: Because BE-TLIF yieldeds lesser early postoperative back pain than did MI-TLIF, it may allow early ambulation and a shorter hospitalization period. BE-TLIF may be a viable alternative to MI-TLIF in patients with degenerative or isthmic spondylolisthesis with superior clinical results in the early postoperative period.

Learning Curve and Clinical Outcome of Biportal Endoscopic-Assisted Lumbar Interbody Fusion.

Interbody fusion is a common surgical technique for diseases of the lumbar spine. Biportal endoscopic-assisted lumbar interbody fusion (BE-LIF) is a novel minimally invasive technique that has a long learning curve, which can be a barrier for surgeons. Therefore, we analyzed the learning curve in terms of operative time and evaluated the outcomes of BE-LIF. A retrospective study of fifty-seven consecutive patients who underwent BE-LIF for degenerative lumbar disease by a single surgeon from January 2017 to December 2018 was performed. Fifty patients underwent a single-level procedure, and 7 underwent surgery at two levels. The mean follow-up period was 24 months (range, 14-38). Total operative time, postoperative drainage volume, time to ambulation, and complications were analyzed. Clinical outcome was measured using the Oswestry Disability Index (ODI), Visual Analog Scale (VAS) score for back and leg pain, and modified Macnab criteria. The learning curve was evaluated by a nonparametric regression locally weighted scatterplot smoothing curve. Cases before the stable point on the curve were designated as group A, and those after the stable point were designated group B. Operative time decreased as the number of cases increased. A stable point was noticed on the 400th day and the 34th case after the first BE-LIF was performed. All cases showed improved ODI and VAS scores at the final follow-up. Overall mean operative time was 171.74 ± 35.1 min. Mean operative time was significantly lower in group B (139.7 ± 11.6 min) compared to group A (193.4 ± 28.3 min). Time to ambulation was significantly lower in group B compared to group A. VAS and ODI scores did not differ between the two groups. BE-LIF is an effective minimally invasive technique for lumbar degenerative disease. In our case series, this technique required approximately 34 cases to reach an adequate performance level.

Clinical outcome of biportal endoscopic revisional lumbar discectomy for recurrent lumbar disc herniation.

BACKGROUND: Although literature provides evidence regarding the superiority of surgery over conservative treatment in patients with lumbar disc herniation, recurrent lumbar disc herniation (RLDH) was the indication for reoperation in 62% of the cases. The major problem with revisional lumbar discectomy (RLD) is that the epidural scar tissue is not clearly isolated from the boundaries of the dura matter and nerve roots; therefore, unintended durotomy and nerve root injury may occur. The biportal endoscopic (BE) technique is a newly emerging minimally invasive spine surgical modality. However, clinical evidence regarding BE-RLD remains limited. We aimed to compare the clinical outcomes after performing open microscopic (OM)-RLD and BE-RLD to evaluate the feasibility of BE-RLD. METHODS: This retrospective study included 36 patients who were diagnosed with RLDH and underwent OM-RLD and BE-RLD. RLDH is defined as the presence of herniated disc material at the level previously operated upon in patients who have experienced a pain-free phase for more than 6 months. BE-RLD was performed as follows: two independent surgical ports were made inside the medial pedicular line of the target segment and on the intact upper and lower laminas. Peeling off the soft tissue from the vertebral lamina helps to easily identify the traversing nerve root and the recurrent disc material without dealing with the fibrotic scar tissue. Clinical outcomes were obtained using a visual analog scale (VAS) and the modified Macnab criteria before and at 2 days, 2 and 6 weeks, and 3, 6, and 12 months after surgery. RESULTS: The data of 20 and 16 patients who underwent OM-RLD and BE-RLD, respectively, were evaluated. The demographic and perioperative data were comparable between the groups. During the year following the surgery, in the BE-RLD group, the VAS scores at each point were significantly improved over the baseline and remained improved up to 2 weeks after surgery (p < 0.05); however, no statistical difference between the two groups was observed after 6 weeks of surgery (p > 0.05). According to the modified Macnab criteria on the follow-up, the excellent or good satisfaction rates reported at 2 weeks, 6 weeks, 6 months, and 12 months after surgery were 81.25%, 81.25%, 75%, and 81.25%, respectively, in the BE-RLD group, and 50%, 75%, 75%, and 80%, respectively, in the OM-RLD group. CONCLUSION: BE-RLD yielded similar outcomes to OM-RLD, including pain improvement, functional improvement, and patient satisfaction, at 1 year after surgery. However, faster pain relief, earlier functional recovery, and better patient satisfaction were observed when applying BE-LRD. TRIAL REGISTRATION: Retrospectively registered.

Safety Evaluation of Biportal Endoscopic Lumbar Discectomy: Assessment of Cervical Epidural Pressure During Surgery.

STUDY DESIGN: A prospective study. OBJECTIVE: To evaluate the change in cervical epidural pressure (CEP) during biportal endoscopic lumbar discectomy (BELD). SUMMARY OF BACKGROUND DATA: In percutaneous uniportal endoscopic lumbar discectomy, irrigation fluid (IF) introduced into the spinal canal during surgery can compress the thecal sac, and act as a potential risk for neurological complications by disturbing cerebrospinal fluid (CSF) circulation and increasing intracranial pressure. METHODS: Thirty consecutive patients, who underwent BELD, which was performed under automated pump system, an infusion pressure of 30 mmHg were enrolled. The change in CEP on C7-T1 level was measured. CEP was measured in each of the five phases of the procedure (1st phase-making surgical portals; 2nd phase-creating a workspace; 3rd phase-performing neural decompression and discectomy; 4th phase-factitious increase of pressure by clogging the outflow; 5th phase-dismission from fluid irrigation system). Neurological complications and independent risk factors were evaluated. RESULTS: In the final 27 patients, changes in CEP during surgery were similar. The baseline CEP was 14.8 ±â€Š2.8 mmHg, and the mean CEP in the 3rd phase 18.8 ±â€Š5.1 mmHg was not significantly higher. In the 4th phase, however, the CEPs rose with linear correlation as the pressure increased. In the 5th phase, the elevated CEP returned to baseline in 2.5 ±â€Š5.6 minutes. No patient had neurological complications. No statistically significant risk factors were observed. CONCLUSION: In BELD, which is performed to allow continuous lavage with infusion pressure set to 30 mmHg, CEP does not increase beyond the physiological range. Therefore, BELD may be considered as a potentially safe technique. LEVEL OF EVIDENCE: 4.

Effectiveness of Gelatin-Thrombin Matrix Sealants (Floseal®) on Postoperative Spinal Epidural Hematoma during Single-Level Lumbar Decompression Using Biportal Endoscopic Spine Surgery: Clinical and Magnetic Resonance Image Study.

BACKGROUND: Symptomatic postoperative spinal epidural hematoma (PSEH) is a devastating complication that could develop after lumbar decompression surgery. PSEH can also develop after biportal endoscopic spine surgery (BESS), one of the recently introduced minimally invasive spine surgery techniques. Gelatin-thrombin matrix sealant (GTMS) is commonly used to prevent PSEH. This study aimed at analyzing the clinical and radiological effects of GTMS use during BESS. METHODS: A total of 206 patients with spinal stenosis who underwent decompression by BESS through a posterior interlaminar approach from October 2015 to September 2018 were enrolled in this study. Postoperative magnetic resonance imaging (MRI) was performed in all patients for evaluation of PSEH. Patients in whom GTMS was not used during surgery were assigned to Group A, and those in whom GTMS was used were classified as Group B. In the clinical evaluation, the visual analog scale (VAS) of the leg and back, Oswestry Disability Index (ODI), and modified MacNab criteria were used. The incidence rate and degree of dural compression of PSEH on postoperative MRI were measured. RESULTS: The average age of the patients was 68.1 ± 11.2 (42-89) years. The overall incidence rate of PSEH was 20.9% (43/206). The incidence rates in Groups A and B were 26.4% and 13.6%, respectively, showing a significant difference (p = 0.023). The VAS-leg and ODI improvement was significantly different depending on the intraoperative use of GTMS. However, there was no statistically significant difference between the two groups in terms of the VAS-back improvement. Groups A and B showed "good" and "excellent" rates according to the modified MacNab criteria in 79.4% and 87.6% of patients, respectively, showing statistically significant difference (p = 0.049). In Group A, two patients underwent revision surgery due to PSEH, while none in Group B had such event. CONCLUSION: Intraoperative use of GTMS during BESS may be related to reduction in the occurrence rate of PSEH. Specifically, patients with GTMS appliance showed marked decrease in the occurrence of PSEH and had better clinical outcomes.

Risk Factors and Options of Management for an Incidental Dural Tear in Biportal Endoscopic Spine Surgery.

STUDY DESIGN: Here we perform a retrospective analysis regarding an incidental dural tear (IDT) during biportal endoscopic spinal surgery (BESS). PURPOSE: This study investigates the causes of IDT specifically related to technical procedures of BESS with the aim of lowering its risk during training. OVERVIEW OF LITERATURE: The incidence of dural tear is reported 0.5%-18% in open spinal surgery and 1.7%-4.3% during endoscopic spinal surgery. Because conversion to open surgery for direct repair could become necessary during endoscopic spinal surgery, prevention of this complication is essential. METHODS: We have retrospectively studied IDTs by four surgeons during 1 or 2 years after starting BESS for lumbar degenerative diseases and analyzed the locations, sizes, and specific endoscopic conditions specific to each. RESULTS: Twenty-five cases (1.6%) of IDTs among 1,551 cases of BESS occurred; 13 cases (52%) of these were within the first 6 months. The locations were dorsal midline in 12 cases, ipsilateral side in 11 cases, and contralateral side in two cases. The tear sizes were <10 mm in 20 cases and ≥10 mm in five cases. IDT commonly occurred due to injury of central dural folding during flavectomy under turbid surgical fields due to small bleeds under water. Twenty cases with IDTs of <10 mm were treated well with the patch technique. Among five cases of ≥10 mm, three underwent open repair within a few days, and two of these which failed to conservative management required a delayed revision operation due to pseudomeningocele. No cases progressed to surgical site infection or infectious spondylitis. CONCLUSIONS: IDTs of <10 mm can be successfully treated with the patch technique. To prevent IDT during the early learning period, maintaining clear visibility by securing fluent saline outflow and meticulous hemostasis of small bleeding from exposed cancellous bone and epidural vessels is essential with caution not to injure the central dural folding during midline flavectomy.

Pseudomeningocele after biportal endoscopic spine surgery: A case report.

BACKGROUND: Biportal endoscopic spinal surgery (BESS) was recently introduced and became prevalent fast. Incidental dural tear (IDT) could happen as one of the common complications even in endoscopic spine surgery. CASE DESCRIPTION: A 45-year old male underwent discectomy by BESS. IDT sized about 15mm at the dorsal surface of dura occurred during the laminotomy procedure with an osteotome. Revision surgery was planned for assuming that the IDT is small enough to be sealed with a patch. CONCLUSION: Revision surgery using BESS for a small-sized IDT could be reasonable alternative treatment to preserve the soft tissue, the primary purpose of MISS.

Clinical and radiological outcomes between biportal endoscopic decompression and microscopic decompression in lumbar spinal stenosis.

BACKGROUND CONTEXT: Numerous minimal invasive techniques treating lumbar spinal stenosis have been introduced. Clinical results using biportal endoscopic spinal surgery has recently been introduced as a treatment option for lumbar spinal stenosis. The purpose of this study was to compare the clinical and radiologic outcome between microscopic unilateral laminotomy bilateral decompression and biportal endoscopic unilateral laminotomy bilateral decompression in patients with degenerative lumbar spinal stenosis. METHOD: A total of 89 patients were evaluated for this study. Only single-level patients were enrolled for accurate comparison. Patients that underwent biportal endoscopic surgery were assigned to Group A, and patients that underwent microscopic surgery were designated Group B. Clinical outcomes were evaluated using modified Macnab criteria, Oswestry Disability Index, and Visual Analog Scale. Postoperative complications were checked until final follow up. Plain radiographs before and after surgery were compared to analyze the change of alignment. RESULT: There was a significant difference between Group A and B in VAS of back on postoperative 2 months. Other clinical measurements except for postoperative 2 months VAS of back showed no significant difference. There were no significant differences between Group A and Group B regarding preoperative and postoperative radiological findings. CONCLUSION: Two different decompression techniques preserve the spinal structure and exhibit a favorable clinical outcome and have the advantage of not causing postoperative instability in the short term follow up. Biportal endoscopic surgery may leads to less postoperative back pain than microscopic surgery, which may allow early ambulation and shorter hospitalization period.

Risk Factors of Postoperative Spinal Epidural Hematoma After Biportal Endoscopic Spinal Surgery.

BACKGROUND: Although postoperative spinal epidural hematoma is a rare complication, it can cause severe neurologic complications. Studies regarding biportal endoscopic spinal surgery, a type of minimally invasive spinal surgery technique, have been recently reported. The purpose of our study is to report the incidence and risk factors of postoperative hematoma after biportal endoscopic spinal surgery. METHODS: The subjects included 310 patients that underwent biportal endoscopic spinal surgery from 2015 to 2017. Magnetic resonance imaging (MRI) was performed in all patients before surgery, and also after surgery to identify epidural hematoma. Using electronic medical records, perioperative factors such as age, sex, operation name, operation level, water infusion pump usage, thrombin-containing hemostatic agent, and anticoagulant medication were statistically analyzed in the aspect of postoperative hematoma. RESULTS: The overall occurrence rate of postoperative hematoma was 23.6% (n = 94). A total of 304 levels (76.4%) were without hematoma according to the postoperative MRI among the total 398 levels. Six patients underwent revision surgery of hematoma evacuation. Female sex, old age (>70 years), preoperative anticoagulation medication, and usage of intraoperative water infusion pump were significantly correlated to the occurrence of postoperative hematoma. CONCLUSIONS: Although symptomatic postoperative hematoma was extremely rare at 1.9%, radiologic hematoma confirmed by postoperative MRI was higher at 23.6%. The perioperative risk factors of postoperative hematoma after biportal endoscopic spinal surgery include female sex, older age (>70 years), preoperative anticoagulation medication, usage of intraoperative water infusion pump, and surgery requiring more bone work (laminectomy or interbody fusion).

Multifidus Muscle Changes After Biportal Endoscopic Spinal Surgery: Magnetic Resonance Imaging Evaluation.

OBJECTIVE: We used magnetic resonance imaging (MRI) to assess the radiological status of the multifidus muscles (MFMs) after biportal endoscopic spinal surgery (BESS) and evaluated the extent of MFM injury and atrophy. METHODS: A total of 88 patients who had met the inclusion and exclusion criteria were enrolled in the present study. T2-weighted signal intensity MRI was performed 3 times: preoperatively, immediately postoperatively, and at the final follow-up examination. We measured the cross-sectional area of the MFM on both sides (ipsilaterally and contralaterally) and recorded the operative times. The association between the interval from surgery to the final follow-up MRI and changes in the MFMs and between the operative time and changes in the MFMs were analyzed. For the group comparisons, the patients were divided into 3 groups according to the follow-up interval. Group 1 was followed up within 2 weeks, group 2 within 2-4 weeks, and group 3 after 4 weeks. The MFM changes were recorded. RESULTS: The operative time correlated significantly with the percentage of change in the T2-weighted signal intensity ratio (SIR) for both sides (P < 0.01). At the final follow-up examination, the SIR of the ipsilateral side had decreased in group 3 (P = 0.002). The percentage of change in the SIR was smallest in group 3 (P = 0.004). CONCLUSIONS: The MFM change on MRI after BESS became significant on both sides as the operative time increased. However, the change showed a tendency to reverse within several months, and no substantial change in the MFM cross-sectional area was found. We have concluded that MFM changes after BESS might correlate with an increased operative time but will resolve over time.

Biportal Endoscopic Spinal Surgery for Lumbar Spinal Stenosis.

Biportal endoscopic spinal surgery (BESS) is a minimally invasive spinal surgery, which is basically similar to microscopic spinal surgery in terms of the use of floating technique and technically similar to conventional percutaneous endoscopic spinal surgery in terms of the use of endoscopic or arthroscopic instruments. Using two independent portals (viewing and working) and maintaining a certain distance from the bony and neural structures allow closer access to the target lesion through a panoramic view by free handling of the scope and instruments rather than through a fixed view by docking into the Kambin's triangle. Minimally invasive surgery allows for reduced dissection and inevitable muscle injury, preserving stability and reducing risks of restabilization. The purpose of fusion surgery is the same as that of the three surgical techniques stated above. Its wider range of view helps to overcome limitations of conventional endoscopic spinal surgery and to supplement the weak points of microscopic spinal surgery, such as limited working space in a tubular retractor and difficulty in accessing the contralateral area. This technique provides an alternative to unilateral or bilateral decompression of lumbar central spinal stenosis, foraminal stenosis, low-grade spondylolisthesis, and adjacent segment degeneration. Early clinical outcomes are promising despite potential for complications, such as dural tearing and postoperative epidural hematoma, similar to other procedures. Merits of BESS include decreased postoperative infection rate due to continuous irrigation throughout the procedure and decreased need for fusion surgery for one- or two-level lumbar stenosis by wide sublaminar and foraminal decompression with minimal sacrifice of stabilizing structures.

Efficacy of Biportal Endoscopic Spine Surgery for Lumbar Spinal Stenosis.

BACKGROUND: Biportal endoscopic spine surgery (BESS) is a recent addition to minimally invasive spine surgery treatments. It boasts excellent magnification and fine discrimination of neural structures. Selective decompression with preservation of facet joints for structural stability is also feasible owing to access to the spinal canal and foramen deeper inside. This study has a purpose to investigate clinical benefits of BESS for spinal stenosis in comparison to the other common surgical treatments such as microscopic decompression-only (DO) and fusion and instrumentation (FI). METHODS: From December 2013 to March 2015, 30 cases of DO, 48 cases of FI, and 66 consecutive cases of BESS for lumbar spinal stenosis (LSS) were enrolled to evaluate the relative clinical efficacy of BESS. Visual analog scale (VAS) for back pain and leg pain, postoperative hemoglobin, C-reactive protein (CRP) changes, transfusion, and postoperative complications were examined. RESULTS: All the patients were followed up until 6 months, and 98 patients (86.7%) for 2 years. At the 6-month follow-up, VAS for back pain improved from 6.8 to 2.8, 6.8 to 3.2, and 6.8 to 2.8 (p = 0.078) for BESS, DO, and FI, respectively; VAS for leg pain improved from 6.3 to 2.2, 7.0 to 2.5, and 7.2 to 2.5 (p = 0.291), respectively. Two cases in the BESS group underwent additional foraminal decompression, but no fusion surgery was performed. Postoperative hemoglobin changes for BESS, DO, and FI were -2.5, -2.4, and -1.3 mL, respectively. The BESS group had no transfusion cases, whereas 10 cases (33.3%) in DO and 41 cases (85.4%) in FI had transfusion (p = 0.000). CRP changes for BESS, DO, and FI were 0.32, 6.53, and 6.00, respectively, at day 2 postoperatively (p = 0.000); the complication rate for each group was 8.6% (two dural tears and one root injury), 6.7% (two dural tears), and 8.3% (two dural tears and two wound infections), respectively. CONCLUSIONS: BESS for LSS showed clinical results not inferior to those of the other open surgery methods in the short-term. Stable hemodynamic changes with no need for blood transfusion and minimal changes in CRP were thought to cause less injury to the back muscles with minimal bleeding. Foraminal stenosis decompression should be simultaneously conducted with central decompression to avoid an additional surgery.

Evaluation of Postoperative Spinal Epidural Hematoma After Biportal Endoscopic Spine Surgery for Single-Level Lumbar Spinal Stenosis: Clinical and Magnetic Resonance Imaging Study.

BACKGROUND: Symptomatic postoperative spinal epidural hematoma is a serious complication that may occur after lumbar spine surgery. We analyzed epidural hematoma using postoperative magnetic resonance imaging (MRI) after biportal endoscopic spinal surgery and its impact on clinical outcome. METHODS: The subjects of this study were 158 patients who underwent single-level decompression using the biportal endoscopic spinal surgery technique from 2015 to 2017. MRI was performed in all patients before and after surgery, and postoperative MRI was used to identify epidural hematoma. The preoperative and postoperative visual analog scale (VAS) score for leg and back pain, Oswestry Disability Index (ODI), and modified Macnab criteria were recorded for evaluation of clinical outcome. The group with postoperative spinal epidural hematoma (group A) and without hematoma (group B) were comparatively analyzed, both radiologically and clinically. RESULTS: The mean age of the patients was 67.9 ± 11.1 years (range, 49-89). The total number with grade 0 (no hematoma) was 119 levels patients (75.3%) on the T2 axial image of postoperative MRI. The total number of patients with hematoma was 39 (24.7%) according to T2-weighted axial postoperative MRI. Two patients underwent revision surgery because of hematoma-related symptoms. The improvement of clinical outcome measures including VAS leg, VAS back, and ODI was significantly different between group A and B (P < 0.05). CONCLUSIONS: The incidence of postoperative spinal epidural hematoma after biportal endoscopic spinal surgery according to postoperative MRI was higher than expected, regardless of the patients' postoperative symptoms. Postoperative hematoma has a decisive influence on postoperative results, and revision surgery might be necessary if canal encroachment is >50% with concomitant symptoms.

Clinical and Radiological Outcomes of Foraminal Decompression Using Unilateral Biportal Endoscopic Spine Surgery for Lumbar Foraminal Stenosis.

BACKGROUND: Since open Wiltse approach allows limited visualization for foraminal stenosis leading to an incomplete decompression, we report the short-term clinical and radiological results of unilateral biportal endoscopic foraminal decompression using 0° or 30° endoscopy with better visualization. METHODS: We examined 31 patients that underwent surgery for neurological symptoms due to lumbar foraminal stenosis which was refractory to 6 weeks of conservative treatment. All 31 patients underwent unilateral biportal endoscopic far-lateral decompression (UBEFLD). One portal was used for viewing purpose, and the other was for surgical instruments. Unilateral foraminotomy was performed under guidance of 0° or 30° endoscopy. Clinical outcomes were analyzed using the modified Macnab criteria, Oswestry disability index, and visual analogue scale. Plain radiographs obtained preoperatively and 1 year postoperatively were compared to analyze the intervertebral angle (IVA), dynamic IVA, percentage of slip, dynamic percentage of slip (gap between the percentage of slip on flexion and extension views), slip angle, disc height index (DHI), and foraminal height index (FHI). RESULTS: The IVA significantly increased from 6.24° ± 4.27° to 6.96° ± 3.58° at 1 year postoperatively (p = 0.306). The dynamic IVA slightly decreased from 6.27° ± 3.12° to 6.04° ± 2.41°, but the difference was not statistically significant (p = 0.375). The percentage of slip was 3.41% ± 5.24% preoperatively and 6.01% ± 1.43% at 1-year follow-up (p = 0.227), showing no significant difference. The preoperative dynamic percentage of slip was 2.90% ± 3.37%; at 1 year postoperatively, it was 3.13% ± 4.11% (p = 0.720), showing no significant difference. The DHI changed from 34.78% ± 9.54% preoperatively to 35.05% ± 8.83% postoperatively, which was not statistically significant (p = 0.837). In addition, the FHI slightly decreased from 55.15% ± 9.45% preoperatively to 54.56% ± 9.86% postoperatively, but the results were not statistically significant (p = 0.705). CONCLUSIONS: UBEFLD using endoscopy showed a satisfactory clinical outcome after 1-year follow-up and did not induce postoperative segmental spinal instability. It could be a feasible alternative to conventional open decompression or fusion surgery for lumbar foraminal stenosis.