Large-Scale Comparative Study Between Microendoscopic Laminectomy and Full-Endoscopic Laminectomy for the Treatment of Single-Level Lumbar Spinal Canal Stenosis.

BACKGROUND: We previously compared the operative outcomes of microendoscopic laminectomy (MEL) and full-endoscopic laminectomy (FEL) for single-level lumbar spinal canal stenosis (LSCS). In this initial report, the operative outcomes of FEL were not inferior to those of MEL. OBJECTIVE: The purpose of this study is to compare the outcomes of MEL and FEL for single-level LSCS on a large scale using widely used multiple evaluation methods. METHODS: MEL was performed using a 16 mm tubular retractor and an endoscope, while FEL was performed using a 6.4 mm working channel endoscope. A retrospective study was performed on patients with LSCS treated with MEL (n = 355) or FEL (n = 154). Patient background and operative data were also collected. The Oswestry Disability Index (ODI), European Quality of Life-5 Dimensions (EQ-5D), and 36-item Short Form Survey (SF-36) scores were recorded preoperatively and 1-year postoperatively. RESULTS: Background data of the two groups and the mean operation time (MEL, 72.1 m; FEL, 74.2 m) were not significant (p>0.2). The mean volumes of intraoperative bleeding (MEL, 25.2 ml; FEL, 10.3 ml) were significantly different (p<0.001). The mean postoperative hospital stays (MEL, 3.9 days; FEL, 2.1 days) were significantly different (p<0.001). Fifteen dural tears (MEL, 11; FEL, 4) and 1 surgical site infection (MEL, 1; FEL, 0) were observed but not significant (p>0.5). Reoperation was required for postoperative hematoma in five patients (MEL, 3; FEL, 2). Although the ODI, EQ-5D, and SF-36 scores improved significantly at one year postoperatively in the MEL and FEL groups (p<0.001), there were no significant differences between the two groups (p>0.1). CONCLUSION: The operative outcomes and minimal invasiveness were no statistical difference between the MEL and FEL groups. Further development of the operative techniques and the instruments of FEL are required to shorten the operation time.

A new surgical method to treat intracanal lumbar disc herniation using the unilateral biportal endoscopic transforaminal approach: patient series.

BACKGROUND: Unilateral biportal endoscopic lumbar discectomy (UBELD) is a new minimally invasive spine surgery. The purpose of this study is to describe a new surgical method to treat intracanal lumbar disc herniation (LDH) using the unilateral biportal endoscopic transforaminal approach (UBE-TFA). The first 15 patients who had undergone UBELD for single-level LDH were included in this study. Operative time, intraoperative blood loss, postoperative stay, and intraoperative complications were recorded. The Oswestry Disability Index (ODI), numeric rating scale (NRS) score for leg pain, and modified MacNab criteria were assessed at 3 months postoperatively. OBSERVATIONS: The mean operative time was 52.0 ± 13.8 minutes. The mean intraoperative blood loss was 10.5 ± 10.2 mL. The mean postoperative stay was 1.1 ± 0.3 days. There were no complications. The postoperative mean ODI was significantly improved from 44.9 ± 14.4 to 7.7 ± 11.2 at the final follow-up (p < 0.001). There was a significant decrease in the postoperative mean NRS score for leg pain, from 6.1 ± 1.9 to 0.8 ± 1.3 at the final follow-up (p < 0.001). Based on the modified MacNab criteria, good to excellent results were obtained in 86.7% of the patients. LESSONS: We considered UBELD-TFA as not only one of the promising surgical methods for UBELD, but also a new surgical implementation of the TFA.

Impact of Intensive Low-Density Lipoprotein Cholesterol-Lowering Therapy on Coronary Artery Plaques in Acute Coronary Syndrome.

Acute coronary syndrome (ACS) is associated with a high incidence of unstable plaques beyond the culprit lesion, leading to early recurrence of cardiovascular events. Coronary computed tomography angiography (CCTA) can be used to noninvasively observe plaques throughout the coronary arteries. To evaluate the impact of intensive low-density lipoprotein cholesterol (LDL-C)-lowering therapy on quantitative changes in coronary plaque, assessed using CCTA in a study population with ACS. In total, 81 consecutive patients with ACS who underwent CCTA at discharge and at 1-year follow-up from April 2018 to March 2020 were analyzed. The patients were divided into 2 groups: those who achieved LDL-C <70 mg/100 ml and those who did not. Changes in plaque morphology within and between the 2 groups were compared using CCTA. A total of 198 vessels were analyzed. The calcified plaque volume was significantly increased in the LDL-C <70 group (65.8 ± 80.1 mm3 to 73.6 ± 83.7 mm3, p = 0.007), whereas no significant change was observed in the LDL-C ≥70 group (106.9 ± 161.7 mm3 to 105.7 ± 137.5 mm3, p = 0.552). Percent change in low-attenuation plaque volume in the LDL <70 group was significantly lower than in the LDL-C ≥70 group (17.2 ± 90.9% vs 84.4 ± 162.6%, p = 0.020). Receiver operating characteristic curve analysis demonstrated that the target LDL-C level for low-attenuation plaque volume regression was 64 mg/100 ml. In conclusion, noninvasive CCTA demonstrated that intensive LDL-C lowering in high-risk patients with ACS could potentially lead to plaque stabilization.

A multilocular discal cyst extending from the spinal canal to the extraforaminal region: A case report.

BACKGROUND: Lumbar discal cysts are intraspinal extradural cysts communicating with the intervertebral disc. The usual location and morphology are in the caudal ventrolateral epidural space of the spinal canal, without extension to the neural foramen or crossing the midline and described as a well-defined homogeneous oval or spherical cyst on low and high signal intensities observed in lumbar lesions on T1- and T2-weighted magnetic resonance imaging, respectively. We report an unusual lumbar discal cyst in terms of the lesion location and morphology. CASE PRESENTATION: A 33-year-old-man presented with lower back and right anterior thigh pain. Magnetic resonance imaging revealed multilocular cystic lesions in the cranial ventrolateral epidural space at L2-L3 with low and high signal intensities on T1- and T2-weighted magnetic resonance imaging, respectively. We performed a full-endoscopic transforaminal cystectomy under general anesthesia. CONCLUSION: Lumbar discal cysts should be considered a differential diagnosis for multilocular intraspinal cystic lesion.

Comparison of the Outcomes of Microendoscopic Cervical Foraminotomy versus Full-endoscopic Cervical Foraminotomy for the Treatment of Cervical Radiculopathy.

This study aimed to compare the outcomes of microendoscopic cervical foraminotomy (MECF) versus full-endoscopic cervical foraminotomy (FECF) for treating cervical radiculopathy (CR).A retrospective study was performed on patients with CR treated using MECF (n = 35) or FECF (n = 89). A 16-mm tubular retractor and endoscope was used for MECF, while a 4.1-mm working channel endoscope was used for FECF. Patient background and operative data were collected. The numerical rating scale (NRS) and the Neck Disability Index scores were recorded preoperatively and at 1 year postoperatively. Postoperative subjective satisfaction was also assessed.Although the NRS, and NDI scores, as well as postoperative satisfaction at 1 year considerably improved in both groups, one of the background data (number of operated vertebral level) was significantly different. Therefore, we separately analyzed single- and two-level CR. In single-level CR, operation time, intraoperative bleeding, postoperative stay, NDI after 1 year, and reoperation rate were statistically superior in FECF group. In two-level CR, the postoperative stay was statistically superior in FECF group. Three postoperative hematomas were observed in the MECF group, while none was observed in the FECF group.Operative outcomes did not significantly differ between groups. We did not observe postoperative hematoma in FECF even without placement of a postoperative drain. Therefore, we recommend FECF as the first option for the treatment of CR as it has a better safety profile and is minimally invasive.

Improved Recurrence Plots Compression Distance by Learning Parameter for Video Compression Quality.

As the Internet-of-Things is deployed widely, many time-series data are generated everyday. Thus, classifying time-series automatically has become important. Compression-based pattern recognition has attracted attention, because it can analyze various data universally with few model parameters. RPCD (Recurrent Plots Compression Distance) is known as a compression-based time-series classification method. First, RPCD transforms time-series data into an image called "Recurrent Plots (RP)". Then, the distance between two time-series data is determined as the dissimilarity between their RPs. Here, the dissimilarity between two images is computed from the file size, when an MPEG-1 encoder compresses the video, which serializes the two images in order. In this paper, by analyzing the RPCD, we give an important insight that the quality parameter for the MPEG-1 encoding that controls the resolution of compressed videos influences the classification performance very much. We also show that the optimal parameter value depends extremely on the dataset to be classified: Interestingly, the optimal value for one dataset can make the RPCD fall behind a naive random classifier for another dataset. Supported by these insights, we propose an improved version of RPCD named qRPCD, which searches the optimal parameter value by means of cross-validation. Experimentally, qRPCD works superiorly to the original RPCD by about 4% in terms of classification accuracy.

Comparison of the Interlaminar and Transforaminal Approaches for Full-endoscopic Discectomy for the Treatment of L4/5 Lumbar Disc Herniation.

This study aims to compare the outcomes of interlaminar and transforaminal approaches for full-endoscopic discectomy (FED) for treating L4/5 lumbar disc herniation (LDH).A retrospective study of patients with L4/5 LDH treated with interlaminar endoscopic lumbar discectomy (IELD, n = 19) or transforaminal endoscopic lumbar discectomy (TELD, n = 105) was conducted. Patient background, radiological findings, and operative data were collected. Oswestry Disability Index (ODI) and European Quality of Life-5 Dimension (EQ-5D) scores were recorded preoperatively and 1 and 2 years postoperatively.Although ODI and EQ-5D scores 1 and 2 years postoperatively improved statistically in the IELD and TELD groups, there were no statistical differences between the groups. IELD was predominantly performed in patients who were taller and heavier. The mean operative times and the frequency of laminectomy for IELD and TELD were 67.2 and 44.6 min and 63.2 and 17.1%, respectively (P < 0.001). The radiological findings showed that the concave configuration of the L4 lamina, interlaminar space width, and foraminal width were statistically different between the groups. There were no complications in either of the groups. Reoperation was required for recurrence in two and five patients in the IELD and TELD groups (P = 0.29), respectively.Operative outcomes were identical between the two groups. Although the operative time was longer in the IELD group, both approaches were safely and effectively performed. Depending on the patient's physique and preoperative radiological findings, the more suitable approach for L4/5 LDH should be chosen.

Comparison of the Outcomes of Microendoscopic Discectomy Versus Full-Endoscopic Discectomy for the Treatment of L4/5 Lumbar Disc Herniation.

STUDY DESIGN: Retrospective Comparative Study. OBJECTIVES: To compare the outcomes of microendoscopic discectomy (MED) versus full-endoscopic discectomy (FED) for treating L4/5 lumbar disc herniation (LDH). METHODS: A retrospective study was performed on patients with L4/5 LDH treated using MED (n = 249) or FED (n = 124). A 16-mm tubular retractor and endoscope was used for MED, while a 4.1-mm working channel endoscope was used for FED. Patient background and operative data were collected. The Oswestry Disability Index (ODI) and European Quality of Life-5 Dimensions (EQ-5D) scores were recorded preoperatively and at 1 and 2 years postsurgery. RESULTS: The background data of the two groups were similar. The mean operation times for MED and FED were 59.3 and 47.7 min (respectively), and the mean volumes of removed nucleus pulposus were .65 and 1.03 g, respectively. These differences were significant (P < .001). Six dural tears and one postoperative hematoma were observed in the MED group; none were observed in the FED group. During the follow-up period, 16 MED and 7 FED patients required re-operation due to recurrence (P = 1.00). Although the ODI and EQ-5D scores significantly improved at 1 and 2 years postsurgery in both groups, the differences were not statistically significant. CONCLUSIONS: Operative outcomes were almost identical in both groups. We did not observe any operative or postoperative complications in FED. We, therefore, recommend FED as the first option for the treatment of L4/5 LDH since it has a better safety profile and is minimally invasive.

Comparison of Outcomes of Lumbar Interbody Fusion and Full-endoscopic Laminectomy for L5 Radiculopathy Caused by Lumbar Foraminal Stenosis.

This study compared the outcomes of microendoscopy-assisted lumbar interbody fusion (ME-LIF) and uniportal full-endoscopic laminectomy (FEL) for L5 radiculopathy caused by lumbar foraminal stenosis (LFS). ME-LIF was performed using an 18- to 20-mm tubular retractor and endoscope, and FEL via the translaminar approach (TLA) was performed at the dorsal part of the foramen using a 4.1-mm working channel endoscope. Patients with LFS treated using ME-LIF (n = 39) or FEL-TLA (n = 30) were retrospectively evaluated. Patients' background and operative data were collected. The 36-item Short Form Survey (SF-36), Oswestry Disability Index (ODI), and European Quality of Life-5 Dimension (EQ-5D) scores were recorded preoperatively and 2 years postoperatively. The background data of the two groups (ME-LIF and FEL-TLA) were similar. The mean operation times for ME-LIF and FEL-TLA were 110.7 and 65.2 min, respectively, and the mean length of hospital stay were 10.3 and 1.5 days, respectively. Reoperation was required for surgical site infection, and percutaneous pedicle screw malposition in three patients was treated using ME-LIF. During follow-up, second FEL-TLA and LIF were performed for recurrent L5 radiculopathy in one and three patients in the FEL-TLA group, respectively. Although the SF-36, ODI, and EQ-5D scores 2 years postoperatively improved in both groups, improvement in ODI scores was lower following FEL-TLA than following ME-LIF. FEL-TLA can be performed to treat patients with L5 radiculopathy caused by LFS. Although the ODI score improvement following FEL-TLA was unremarkable, FEL-TLA might be considered because of its better safety profile and minimal invasiveness than ME-LIF.

Efficacy of catheter ablation from the noncoronary aortic cusp of verapamil-sensitive atrial tachycardia arising near the atrioventricular node.

BACKGROUND: The efficacy of catheter ablation from the noncoronary aortic cusp (NCC) of verapamil-sensitive atrial tachycardia arising near the atrioventricular node (AVN-AT) has yet to be fully clarified. OBJECTIVE: We elucidated the determinant of an effective AVN-AT ablation from the NCC. METHODS: After identifying the earliest atrial activation site (EAAS) during tachycardia, the direction of the slow conduction zone (SCZ) of the reentry circuit was identified by demonstrating manifest entrainment in 26 patients with AVN-AT. Catheter ablation was initially performed from the NCC irrespective of the local activation time. If NCC ablation was ineffective, catheter ablation was performed targeting the SCZ entrance. Then the anatomical relationship between the SCZ and the successful ablation site was elucidated. RESULTS: NCC catheter ablation terminated AVN-AT in 14 patients (NCC group) but not in 12 (non-NCC group). Catheter ablation targeting the SCZ entrance terminated all non-NCC group ATs. The local activation time at the NCC relative to the EAAS did not differ between the NCC and non-NCC groups (10.1 ± 6.5 ms vs 11.2 ± 4.8 ms; P = .6333). The direction of the SCZ was posterior to the EAAS in all NCC group patients; however, it was posterolateral (n = 5) and lateral (n = 7) to the EAAS in the non-NCC group, suggesting that the SCZ existed in the direction of the NCC in the NCC group but was away from the NCC in the non-NCC group. CONCLUSION: A close proximity between the NCC and the SCZ of the reentry circuit, but not the local activation time at the NCC, determined the efficacy of NCC catheter ablation in AVN-ATs.

Verification of Coronary Computed Tomography-Derived Fractional Flow Reserve Measurement Site for Detection of Significant Coronary Artery Disease.

Background: The optimal site for measuring computed tomography (CT)-derived fractional flow reserve (FFRCT) to detect significant coronary artery disease (CAD) remains unknown. We investigated how diagnostic performance changes with FFRCT measurement site. Methods and Results: The diagnostic performance of FFRCT, measured 1-2 cm distal to the stenosis vs. a far-distal site, in detecting significant CAD with invasive fractional flow reserve ≤0.8 was evaluated in 254 diseased vessels from 146 patients with stable or suspected CAD diagnosed by coronary CT angiography. Receiver operating characteristic curve analysis revealed a significantly larger area under the curve for FFRCT measured 1-2 cm distal to the stenosis than at a far-distal site (0.829 vs. 0.791, respectively; P=0.0305). The rate of reclassification of positive FFRCT was 19% for measurements made 1-2 cm distal to the stenosis, and diagnostic accuracy for FFRCT 0.71-0.80 improved from 36% to 58% (P=0.0052). Vessel-based diagnostic accuracy of FFRCT 1-2 cm distal to the stenosis and at a far-distal site was 75% and 65%, respectively (P<0.0001), with corresponding sensitivity of 87% and 94% (P=0.0039), specificity of 60% and 29% (P<0.0001), a positive predictive value of 73% and 62% (P=0.028), and a negative predictive value of 78% and 79% (P=0.958). Conclusions: Our data suggest measuring FFRCT 1-2 cm distal to the stenosis has better diagnostic performance for detecting physiologically significant CAD.

Comparison of Diagnostic Performance of Fractional Flow Reserve Derived from Coronary Computed Tomographic Angiography Versus Single-Photon Emission Computed Tomographic Myocardial Perfusion Imaging.

Fraction flow reserve (FFR) derived from computed tomography (FFRCT) has been proposed to be an effective gatekeeper for invasive angiographic referral. The purpose of the present study is to examine the real-world diagnostic performance of FFRCT and myocardial perfusion imaging as well as to assess the utility of FFRCT as a gatekeeper for invasive coronary angiography in patients suspected of having obstructive coronary artery disease. Total of 146 consecutive patients underwent both single-photon emission computed tomography (SPECT) and invasive FFR were evaluated. An FFRCT value 1 to 2 cm distal to a stenosis ≤0.80 was defined as positive for ischemia and a summed stress score ≥2 or transient ischemic dilatation ≥1.2 were positive for ischemia with the invasive FFR value of <0.80 serving as the gold standard. The patient-based sensitivity of FFRCT was significantly higher than SPECT (91 vs 52%, p <0.001) and exhibited similar positive predictive value (82 vs 82%, p = 0.91). These trends were observed even in patients with multivessel and left main trunk disease and those with severe coronary calcification. In conclusion, our data suggest that FFRCT has higher diagnostic performance characteristics than SPECT and details the superior FFRCT analysis in detecting patients with hemodynamically significant coronary artery disease. Our results support the clinical utility of FFRCT analysis as a gatekeeper for invasive coronary angiography in clinical practice.

Clinical Evaluation of Microendoscopy-Assisted Oblique Lateral Interbody Fusion.

Background and objectives: Oblique Lateral Interbody Fusion (OLIF) is a widely performed, minimally invasive technique to achieve lumbar lateral interbody fusion. However, some complications can arise due to constraints posed by the limited surgical space and visual field. The purpose of this study was to assess the short-term postoperative clinical outcomes of microendoscopy-assisted OLIF (ME-OLIF) compared to conventional OLIF. Materials and Methods: We retrospectively investigated 75 consecutive patients who underwent OLIF or ME-OLIF. The age, sex, diagnosis, and number of fused levels were obtained from medical records. Operation time, estimated blood loss (EBL), and intraoperative complications were also collected. Operation time and EBL were only measured per level required for the lateral procedure, excluding the posterior fixation surgery. The primary outcome measure was assessed using the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ). The secondary outcome measure was assessed using the Oswestry Disability Index (ODI) and the European Quality of Life-5 Dimensions (EQ-5D), measured preoperatively and 1-year postoperatively. Results: This case series consisted of 14 patients in the OLIF group and 61 patients in the ME-OLIF group. There was no significant difference between the two groups in terms of the mean operative time and EBL (p = 0.90 and p = 0.50, respectively). The perioperative complication rate was 21.4% in the OLIF group and 21.3% in the ME-OLIF group (p = 0.99). In both groups, the postoperative JOABPEQ, EQ-5D, and ODI scores improved significantly (p < 0.001). Conclusions: Although there was no significant difference in clinical results between the two surgical methods, the results suggest that both are safe surgical methods and that microendoscopy-assisted OLIF could serve as a potential alternative to the conventional OLIF procedure.

Comparison of the catheter ablation outcome in patients between targeting the entrance and exit of the reentry circuit in verapamil-sensitive atrial tachycardia originating from the atrioventricular-node vicinity.

Verapamil-sensitive atrial tachycardia originating from the atrioventricular node vicinity (AVN-AT) can be eliminated with radiofrequency energy (RF) deliveries targeting either the entrance or exit of its reentry circuit. However, the outcome of these different approaches has not been clarified well. Thus, we compared the catheter ablation outcome targeting the entrance of reentry circuit, identified by the entrainment method (Ent-Group; 21 patients) with that targeting the earliest atrial activation site (EAAS) during AT (Exit-Group; 16 patients). There was no significant difference in the tachycardia cycle length (441.4 ± 87.4 vs. 392.8 ± 64.8 ms, p = 0.0704) or distance from the His bundle (HB) site to the EAAS (6.5 ± 2.0 vs. 7.6 ± 1.8 mm, p = 0.0822) between the Ent- and Exit-Groups. However, distance from the successful ablation site to the HB site in the Ent-Group was significantly longer than that in the Exit-Group (13.4 ± 3.1 vs. 7.6 ± 1.8 mm, p < 0.0001), resulting in more frequent transient atrioventricular block episodes in the Exit-Group than Ent-Group (31.3 vs. 0%, p < 0.01). Initial ATs (AT1s) were terminated in all patients in both Groups. However, ATs accompanied by shifting in the EAAS (AT2) were induced more frequently in the Exit-Group than Ent-Group (50.0 vs. 14.3%, p < 0.02) after eliminating AT1. RF deliveries to the EAAS eliminated all AT2s. The number of RF deliveries was greater in the Exit-Group than Ent-Group (6.9 ± 3.3 vs. 3.9 ± 1.6, p < 0.001). In conclusion, RF ablation targeting the entrance sites can avoid AVN injury and is superior in reducing the number of RF deliveries and occurrence of different ATs than targeting the exit sites in the AVN-AT.

The Diagnostic Value of Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for the Detection of Surgical Site Infection after Spine Surgery.

STUDY DESIGN: Retrospective case series. OBJECTIVE: The purpose of this study was to assess the diagnostic yield of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) for surgical site infection (SSI) after spine surgery. SUMMARY OF BACKGROUND DATA: Diagnosis of SSI in the spine based on F-18 FDG PET/CT requires experienced nuclear medical physicians for a detailed analysis of F-18 FDG distribution pattern. It has also been reported that increases in the maximal standardized uptake values of F-18 FDG (SUVmax) closely correlated with SSI, suggesting potential of more objective and quantitative diagnosis. METHODS: We assessed the diagnostic yield of F-18 FDG PET/CT (pattern-based diagnosis by nuclear medical physicians and SUVmax-based diagnosis) for SSI in 52 subjects who underwent spine surgery. The 52 subjects included 11 nonimplant and 41 implant cases. F-18 FDG PET/CT was performed in 33 and 19 cases in early (≤12 weeks after the surgery) and late (>12 weeks) phases, respectively. The final diagnosis of SSI was based on the results of pathogen identification, plain radiography, and CT and/or magnetic resonance imaging or response to antibiotics and/or reoperation. RESULTS: SUVmax-based diagnosis was performed with a cut off value of 5.0 as determined by receiver operating characteristic analysis. Both pattern-based and SUVmax-based diagnoses demonstrated excellent diagnostic yields with high sensitivity (97% and 90%), specificity (100% and 100%), and accuracy (98% and 94%). High diagnostic yields (accuracy of ≥90%) were consistently observed irrespective of presence or absence of implantation or interval between surgery and F-18 FDG PET/CT. CONCLUSION: F-18 FDG PET/CT can be the procedure of choice for investigation of SSI in the spine when other imaging fails to provide a definitive diagnosis.Level of Evidence: 4.

Comparative Study between Full-Endoscopic Discectomy and Microendoscopic Discectomy for the Treatment of Lumbar Disc Herniation.

Background and objectives: Lumbar disc herniation (LDH) is a common disease in the meridian of life. Although surgical discectomy is commonly used to treat LDH, there are several different strategies. We compared the outcomes of uniportal full-endoscopic discectomy (FED) with those of microendoscopic discectomy (MED) in treating LDH. Materials and Methods: FED was performed using a 4.1-mm working channel endoscope, and MED was performed using a 16-mm diameter tubular retractor and endoscope. Data of patients with LDH treated with FED (n = 39) or MED (n = 27) by the single surgeon were retrospectively reviewed. Patient background information and operative data were collected. Pre- and postoperative low back and leg pain were evaluated using the numerical rating scale (NRS) score. Pre- and postoperative disc height index (DHI) values were calculated from plain radiographs, and the disc height loss was evaluated using the ratio (DHI ratio); Results: The median (interquartile range (IQR) Q25-75) operation times for FED and MED were 42 (33-61) and 43 (33-50) minutes, respectively. The median (IQR Q25-75) pre- and postoperative NRS scores for low back pain were 5 (2-7) and 1 (0-4), respectively, for FED and 6 (3-8) and 1 (0-2), respectively, for MED. The median (IQR Q25-75) pre- and postoperative NRS scores for leg pain were 7 (5-8) and 0 (0-2), respectively, for FED and 6 (5-8) and 0 (0-2), respectively, for MED. These data were not different between the FED and MED groups. The median (IQR Q25-75) DHI ratios of FED and MED were 0.94 (0.89-1.03) and 0.90 (0.79-0.95), respectively. The DHI ratio was significantly higher (p < 0.05) in the FED group than in the MED group, and there was less blood loss; Conclusions: The pain-relieving effect of FED in treating LDH was almost identical to that of MED. However, FED was superior to MED in preventing disc height loss, which is one of the indicators of postoperative disc degeneration.

Microendoscopic Posterior Decompression for Treating Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum: Case Series.

Background and Objectives: Ossification of the ligamentum flavum (OLF) is a relatively common cause of thoracic myelopathy. Surgical treatment is recommended for patients with myelopathy. Generally, open posterior decompression, with or without fusion, is selected to treat OLF. We performed minimally invasive posterior decompression using a microendoscope and investigated the efficacy of this approach in treating limited type of thoracic OLF. Materials and Methods: Microendoscopic posterior decompression was performed for 19 patients (15 men and four women) with thoracic OLF with myelopathy aged between 35 to 81 years (mean age, 61.9 years). Neurological examination and preoperative magnetic resonance imaging (MRI) and computed tomography (CT) were used to identify the location and morphology of OLF. The surgery was performed using a midline approach or a unilateral paramedian approach depending on whether the surgeon used a combination of a tubular retractor and endoscope. The numerical rating scale (NRS) and modified Japanese Orthopedic Association (mJOA) scores were compared pre- and postoperatively. Perioperative complications and the presence of other spine surgeries before and after thoracic OLF surgery were also investigated. Results: Four midline and 15 unilateral paramedian approaches were performed. The average operative time per level was 99 min, with minor blood loss. Nine patients had a history of cervical or lumbar spine surgery before or after thoracic spine surgery. The mean pre- and postoperative NRS scores were 6.6 and 5.3, respectively. The mean recovery rate as per the mJOA score was 33.1% (mean follow-up period, 17.8 months), the recovery rates were significantly different between patients who underwent thoracic spine surgery alone (50.5%) and patients who underwent additional spine surgeries (13.7%). Regarding adverse events, one patient experienced dural tear, another experienced postoperative hematoma, and one other underwent reoperation for adjacent thoracic stenosis. Conclusion: Microendoscopic posterior decompression was applicable in limited type of thoracic OLF surgery including beak-shaped type and multi vertebral levels. However, whole spine evaluation is important to avoid missing other combined stenoses that may affect outcomes.

Chemonucleolysis with Chondroitin Sulfate ABC Endolyase for Treating Lumbar Disc Herniation: Exploration of Prognostic Factors for Good or Poor Clinical Outcomes.

Background and Objectives: Chondroitin sulfate ABC endolyase (condoliase) was launched as a new drug for chemonucleolysis in 2018. Few studies assessed its clinical outcomes, and many important factors remain unclear. This study aimed to clarify the preoperative conditions in which condoliase could be highly effective. Materials and Methods: Of 47 patients who received condoliase, 34 were enrolled in this study. The mean age of the patients was 33 years. The average duration since the onset of disease was 8.6 months. We evaluated patients' low back and leg pain using a numerical rating scale (NRS) score at two time points (before therapy and 3 months after therapy). We divided the patients into two groups (good group (G): NRS score improvement ≥ 50%, poor group (P): NRS score improvement < 50%). The parameters evaluated were age, disease duration, body mass index (BMI), and positive or negative straight leg raising test results. In addition, the loss of disc height and preoperative radiological findings were evaluated. Results: In terms of low back and leg pain, the G group included 9/34 (26.5%) and 21/34 (61.8%) patients, respectively. Patients' age (low back pain G/P, 21/36.5 years) was significantly lower in the G group for low back pain (p = 0.001). High-intensity change in the protruded nucleus pulposus (NP) and spinal canal occupancy by the NP ≥ 40% were significantly high in those with leg pain in the G groups (14/21, p = 0.04; and 13/21, p = 0.03, respectively). Conclusions: The efficacy of improvement in leg pain was significantly correlated with high-intensity change and size of the protruded NP. Condoliase was not significantly effective for low back pain but could have an effect on younger patients.

A Comparative Study on the Minimal Invasiveness of Full-Endoscopic and Microendoscopic Cervical Foraminotomy Using Intraoperative Motor Evoked Potential Monitoring.

Background and Objectives: Full-endoscopic cervical foraminotomy (FECF) and microendoscopic cervical foraminotomy (MECF) are effective surgeries for cervical radiculopathy and are considered minimally invasive in terms of damage to paraspinal soft tissue. However, no studies have quantitatively compared FECF and MECF in terms of neurological invasiveness. The aim of this study was to compare the neurological invasiveness of FECF and MECF using intraoperative motor evoked potential (MEP) monitoring. Materials and Methods: A chart review was conducted of 224 patients with cervical radiculopathy who underwent FECF or MECF between April 2014 and March 2020. Patients were 37 women and 187 men, with a mean age of 51 (range, 21-86) years. FECF was performed in 143 cases and MECF was performed in 81 cases. Results: Average MEP amplitude significantly increased from 292 mV before to 677 mV after nerve root decompression in patients who underwent the FECF. The average improvement rate was 273%. In patients who underwent the MECF, average MEP amplitude significantly increased from 306 mV before to 432 mV after nerve root decompression. The average improvement rate was 130%. The improvement rate was significantly higher for FECF compared with MECF. Conclusions: MEP amplitude increased after nerve root decompression in both FECF and MECF, but the improvement rate was higher in FECF. These results suggest that FECF might be more minimally invasive than MECF in terms of neurological aspects.