Robotic-Assisted Spine Surgery: Role in Training the Next Generation of Spine Surgeons.

OBJECTIVE: This study aimed to assess the degree of interest in robot-assisted spine surgery (RASS) among residents and to investigate the learning curve for beginners performing robotic surgery. METHODS: We conducted a survey to assess awareness and interest in RASS among young neurosurgery residents. Subsequently, we offered a hands-on training program using a dummy to educate one resident. After completing the program, the trained resident performed spinal fusion surgery with robotic assistance under the supervision of a mentor. The clinical outcomes and learning curve associated with robotic surgery were then analyzed. RESULTS: Neurosurgical residents had limited opportunities to participate in spinal surgery during their training. Despite this, there was a significant interest in the emerging field of robotic surgery. A trained resident performed RASS under the supervision of a senior surgeon. A total of 166 screw insertions were attempted in 28 patients, with 2 screws failing due to skiving. According to the Gertzbein-Robbins classification, 85.54% of the screws were rated as grade A, 11.58% as grade B, 0.6% as grade C, and 1.2% as grade D. The clinical acceptance rate was approximately 96.99%, which is comparable to the results reported by senior experts and time per screw statistically significantly decreased as experience was gained. CONCLUSION: RASS can be performed with high accuracy within a relatively short timeframe, if residents receive adequate training.

A Comprehensive Analysis of Potential Complications after OLIF : A Review of Postoperative Magnetic Resonance Scans in Over 400 Cases.

Objective: This study focuses on identifying potential complications following oblique lumbar interbody fusion (OLIF) through routine magnetic resonance (MR) scans. Methods: From 650 patients who underwent OLIF from April 2018 to April 2022, this study included those with MR scans taken one-week post-operatively, and only for indirect decompression patients. The analysis evaluated postoperative MR images for hematoma, cage insertion angles, and indirect decompression efficiency. Patient demographics, post-operatively symptoms, and complications were also evaluated. Results: Out of 401 patients enrolled, most underwent 1- or 2-level OLIF. Common findings included approach site hematoma (65.3%) and contralateral psoas hematoma (19%). The caudal level OLIF was related with less orthogonality and deep insertion of cage. Incomplete indirect decompression occurred in 4.66% of cases but did not require additional surgery. Rare but symptomatic complications included remnant disc rupture (4 cases, 1%) and synovial cyst rupture (4 cases, 1%). Conclusion: This study has identified potential complications associated with OLIF, including approach site hematoma, contralateral psoas hematoma, cage malposition risk at caudal levels, and radiologically insufficient indirect decompression. Additionally, it highlights rare, yet symptomatic complications such as remnant disc rupture and synovial cyst rupture. These findings contribute insights into the relatively under-explored area of OLIF complications.

A Single-Center Experience of Robotic-Assisted Spine Surgery in Korea : Analysis of Screw Accuracy, Potential Risk Factor of Screw Malposition and Learning Curve.

OBJECTIVE: Recently, robotic-assisted spine surgery (RASS) has been considered a minimally invasive and relatively accurate method. In total, 495 robotic-assisted pedicle screw fixation (RAPSF) procedures were attempted on 100 patients during a 14-month period. The current study aimed to analyze the accuracy, potential risk factors, and learning curve of RAPSF. METHODS: This retrospective study evaluated the position of RAPSF using the Gertzbein and Robbins scale (GRS). The accuracy was analyzed using the ratio of the clinically acceptable group (GRS grades A and B), the dissatisfying group (GRS grades C, D, and E), and the Surgical Evaluation Assistant program. The RAPSF was divided into the no-breached group (GRS grade A) and breached group (GRS grades B, C, D, and E), and the potential risk factors of RAPSF were evaluated. The learning curve was analyzed by changes in robot-used time per screw and the occurrence tendency of breached and failed screws according to case accumulation. RESULTS: The clinically acceptable group in RAPSF was 98.12%. In the analysis using the Surgical Evaluation Assistant program, the tip offset was 2.37±1.89 mm, the tail offset was 3.09±1.90 mm, and the angular offset was 3.72°±2.72°. In the analysis of potential risk factors, the difference in screw fixation level (p=0.009) and segmental distance between the tracker and the instrumented level (p=0.001) between the no-breached and breached group were statistically significant, but not for the other factors. The mean difference between the no-breach and breach groups was statistically significant in terms of pedicle width (p<0.001) and tail offset (p=0.042). In the learning curve analysis, the occurrence of breached and failed screws and the robot-used time per screw screws showed a significant decreasing trend. CONCLUSION: In the current study, RAPSF was highly accurate and the specific potential risk factors were not identified. However, pedicle width was presumed to be related to breached screw. Meanwhile, the robot-used time per screw and the incidence of breached and failed screws decreased with the learning curve.

Incidental Ureteral Complication in Single-Center Consecutive Oblique Lateral Interbody Fusion Cases.

Oblique lateral interbody fusion (OLIF) has recently gained widespread use as a minimally invasive surgical procedure for degenerative lumbar disease. OLIF has several advantages but can also lead to several possible complications. For example, although less common, access through the retroperitoneal cavity can cause ureteral injury. Here, we report two cases of ureteral complications that occurred during consecutive OLIF procedures. One involved a 77-year-old female patient who had a double-J catheter inserted due to ureteral injury during surgery, and the other involved a 69-year-old male patient suspected of having a ureteral stricture due to retractor compression. To prevent ureteral complications in OLIF, it is necessary to accurately identify the anatomy of the ureter through preoperative imaging and to pay special attention during surgery.

Mini-Open Intercostal Retroperitoneal Approach for Upper Lumbar Spine Lateral Interbody Fusion.

OBJECTIVE: Conventional oblique lumbar interbody fusion (OLIF) approach is possible from the L2/3 to L4/5 levels. However, obstruction of the lower ribs (10th-12th) makes it difficult to maintain disc parallel maneuvers or orthogonal maneuvers. To overcome these limitations, we proposed an intercostal retroperitoneal (ICRP) approach to access the upper lumbar spine. This method does not expose the parietal pleura or require rib resection and employs a small incision. METHODS: We enrolled patients who underwent a lateral interbody procedure on the upper lumbar spine (L1/2/3). We compared the incidence of endplate injury between conventional OLIF and ICRP approaches. In addition, by measuring the rib line, the difference in endplate injury according to rib location and approach was analyzed. We also analyzed the previous period (2018-2021) and the year 2022, when the ICRP has been actively applied. RESULTS: A total of 121 patients underwent lateral interbody fusion to the upper lumbar spine (OLIF approach, 99 patients; ICRP approach, 22 patients). Endplate injuries occurred in 34 of 99 (34.3%) and 2 of 22 patients (9.1%) during the conventional and ICRP approaches, respectively (p = 0.037; odds ratio, 5.23). When the rib line was located at the L2/3 disc or L3 body, the endplate injury rate was 52.6% (20 of 38) for the OLIF approach but 15.4% (2 of 13) for the ICRP approach. Since 2022, the proportion of OLIF including L1/2/3 levels has increased 2.9-fold. CONCLUSION: The ICRP approach is effective in reducing the incidence of endplate injury in patients with a relatively lower rib line, without pleural exposure or rib resection.

Safety of discontinuing antiplatelet therapy 12-24 months after stent-assisted coil embolization: a multicenter retrospective study.

OBJECTIVE: Antiplatelet medication is required after stent-assisted coil embolization (SACE) to avoid thromboembolic complications. Currently, there is no consensus on how long the antiplatelet agent should be maintained. The authors investigated clinical outcomes in patients who discontinued their antiplatelet agent 12-24 months after SACE. METHODS: Data were retrieved from a prospective database for 373 consecutive patients with SACE at 6 institutions who discontinued antiplatelet therapy 12-24 months after SACE. Thromboembolic complications associated with discontinuation were defined as neurological or radiographic ischemia that occurred within 6 months after discontinuation of the antiplatelet agent; the lesion had to be correlated with the territory of the stented artery. RESULTS: The mean time until discontinuation of the antiplatelet medication was 15.8 ± 4.7 months after SACE (12-18 months, n = 271; 19-24 months, n = 102). The most common location of treated aneurysms was the internal carotid artery (n = 223, 59.8%). A laser-cut open-cell stent was most commonly applied (n = 236/388, 60.8%), followed by laser-cut closed-cell stents (n = 119, 30.7%) and braided closed-cell (n = 33, 8.5%); double stenting was applied in 15 aneurysms. There were no patients who experienced cerebral ischemia related to discontinuation of antiplatelet medications, except for 1 patient at high risk of ischemia (0.27%, 95% CI 0.01%-1.48%). CONCLUSIONS: These results suggest that it may be safe to discontinue antiplatelet medication after SACE in patients at low risk for ischemia, and that it appears safe to discontinue the agent at approximately 15 months after the procedure. Large cohort-based prospective studies or randomized clinical trials are warranted to confirm these results.

Tailored antiplatelet therapy in stent assisted coiling for unruptured aneurysms: a nationwide registry study.

BACKGROUND: Antiplatelet therapy, where regimens are tailored based on platelet function testing, has been introduced into neurointerventional surgery. This nationwide registry study evaluated the effect and safety of tailored antiplatelet therapy in stent assisted coiling for unruptured aneurysms compared with conventional therapy using a standard regimen. METHODS: This study enrolled 1686 patients in 44 participating centers who received stent assisted coiling for unruptured aneurysms between January 1, 2019 and December 31, 2019. The standard regimen (aspirin and clopidogrel) was used for all patients in the conventional group (924, 19 centers). The regimen was selected based on platelet function testing (standard regimen for clopidogrel responders; adding cilostazol or replacing clopidogrel with other thienopyridines (ticlopidine, prasugrel, or ticagrelor) for clopidogrel non-responders) in the tailored group (762, 25 centers). The primary outcome was thromboembolic events. Secondary outcomes were bleeding and poor outcomes (increase in modified Rankin Scale score). Outcomes within 30 days after coiling were compared using logistic regression analysis. RESULTS: The thromboembolic event rate was lower in the tailored group than in the conventional group (30/762 (3.9%) vs 63/924 (6.8%), adjusted OR 0.560, 95% CI 0.359 to 0.875, P=0.001). The bleeding event rate was not different between the study groups (62/762 (8.1%) vs 73/924 (7.9%), adjusted OR 0.790, 95% CI 0.469 to 1.331, P=0.376). Poor outcomes were less frequent in the tailored group (12/762 (1.6%) vs 34 (3.7%), adjusted OR 0.252, 95% CI 0.112 to 0.568, P=0.001). CONCLUSION: Tailored antiplatelet therapy in stent assisted coiling for unruptured aneurysms reduced thromboembolic events and poor outcomes without increasing bleeding.

Surgical outcome of minimal invasive oblique lateral interbody fusion with percutaneous pedicle screw fixation in the treatment of adult degenerative scoliosis.

Oblique lateral interbody fusion is performed for lumbar spinal restoration and stabilization, without extensive paraspinal muscle damage or massive bleeding. This study aimed to confirm the radiological and clinical outcomes of minimally invasive oblique lateral interbody fusion (OLIF) with percutaneous pedicle screw fixation (PPSF) as treatment for adult degenerative lumbar scoliosis. Medical records of 40 patients with degenerative lumbar spinal deformities who underwent selective OLIF and PPSF at our hospital between April 2018 and February 2021 were retrospectively reviewed. The study population comprised 7 male and 33 female patients aged 55-79 years. Standing radiography was performed, and the coronal cobb angle, distance between the C7 plumb line and central sacral vertical line, sagittal vertical axis, pelvic tilt, lumbar lordosis (LL), pelvic incidence (PI), and difference between PI and LL (PI-LL) were measured. Coronal scoliosis was defined as a lumbar coronal plane curve of > 15°. All patients achieved statistically significant improvements in coronal and sagittal alignment. The coronal cobb angle was corrected from 18.82° to 11.52°, and the central sacral vertical line was reduced from 18.30 mm to 15.47 mm. The sagittal vertical axis was significantly reduced from 45.95 mm to 32.72 mm. In contrast, the pelvic tilt and LL were minimally changed. For subgroup analyses, patients were divided into the convex and concave groups according to the direction of coronal curve correction. Vertebral body rotation was superior in the convex group than in the concave group. Furthermore, we checked for asymmetric facet degeneration at the upper instrumented vertebra (UIV) level at 1 year postoperatively. Of the 22 patients who underwent more than 3 level fusion surgery, 8 patients were confirmed the postoperative asymmetric facet degeneration in above UIV. Minor complications occurred in 16 patients, who recovered without any problems. Revision surgery was not performed in all cases. Minimally invasive OLIF with PPSF has a lower risk of complications and favorable surgical outcomes in patients with adult degenerative lumbar scoliosis. Access from the convex side is advantageous for the correction of the rotated vertebra. Extending the UIV level to the neutral vertebra can reduce the occurrence of postoperative asymmetric facet degeneration.

Does the COVID-19 Screening Test Affect the Postoperative Prognosis of Patients Who Undergo Emergency Surgery for Cerebral Hemorrhage?

Objective: The coronavirus disease 2019 (COVID-19) pandemic has affected all medical fields, including neurosurgery. Particularly, performing preoperative screening tests has become mandatory, potentially extending the time from admission to the emergency room and operating room, thus possibly affecting patients' prognosis. This study aimed to determine the influence of COVID-19 screening time on patients' postoperative prognosis. Methods: From September 10, 2020, to May 31, 2021, we retrospectively evaluated 54 patients with cerebral hemorrhage who underwent emergency surgery in the emergency room after the screening test. The control group included 89 patients with cerebral hemorrhage who underwent emergency surgery between January 2019 and March 2020, i.e., the period before the COVID-19 pandemic. Prognosis was measured using the Glasgow Coma Scale scores, which were obtained preoperatively, postoperatively, and at discharge, and the modified Rankin Scale (mRS). Additionally, unfavorable outcomes (mRS score 3-6) and in-hospital mortality rates were investigated for postoperative prognostic assessments. Results: No remarkable differences were observed in the time to surgical intervention and prognostic evaluation scores between patients with cerebral hemorrhage who underwent COVID-19 screening tests and subjects in the control group. Conclusion: This study confirmed that patient treatment and prognosis were not significantly affected by additional preoperative screening testing times during the pandemic. We believe that our results are informative for the evaluation and performance of emergency neurosurgery during the pandemic.

Surgical Treatment for Degenerative Lumbar Disease With Neurologic Deficits: Comparison Between Oblique Lumbar Interbody Fusion and Posterior Lumbar Interbody Fusion.

Objective: This study aimed to compare the radiological and clinical outcomes of oblique lumbar interbody fusion (OLIF) and posterior lumbar interbody fusion (PLIF) surgeries and to confirm the effects of additional partial laminectomy on the surgical outcomes of OLIF. Methods: This retrospective study included 130 patients who underwent OLIF or PLIF for single-level fusion. Among them, 42 patients underwent PLIF and open pedicle screw fixation and 88 underwent OLIF and percutaneous pedicle screw fixation. In the OLIF group, 42 patients received additional neural decompression through partial laminectomy and discectomy (direct OLIF), whereas the remaining 46 patients did not (indirect OLIF). To measure the neurological deficits, the clinical outcomes were evaluated using a visual analog scale for back and leg pain and the Oswestry Disability Index. Radiologic outcomes were evaluated based on the disc and foraminal heights as well as the segmental lordotic and lumbar lordotic angles. Results: The improvement in the clinical outcomes did not differ significantly among the 3 groups. Radiologically, the 2 OLIF groups showed statistically significant improvements in the disc and foraminal heights when compared with the PLIF group. The PLIF group showed a significant decrease in the disc height and segmental lordotic angle when compared with the OLIF group in the postoperative 1-year period. Conclusion: Both OLIF and PLIF showed similar clinical outcomes in the single-level lumbar fusion. However, OLIF grafts showed an advantage over PLIF with respect to the radiographic outcomes and complication rates. Additionally, partial laminectomy did not significantly affect the radiological results.

Which factor can predict the effect of indirect decompression using oblique lumbar interbody fusion?

The aim of this study was to investigate the association between various factors of indirect decompression. Previous studies have demonstrated the effectiveness of indirect decompression. There is no consensus regarding the predictive factors for indirect decompression. Facet joint gap (FJG) and bulging disc thickness (BDT) have never been considered as factors in other studies. We retrospectively reviewed 62 patients who underwent OLIF L4/5 between April 2018 and September 2020. The relationships between cross-sectional area (CSA) change, CSA change ratio, spinal stenosis grade, and various factors were studied. Various factors related to indirect decompression, such as ligament flavum thickness (LFT), foraminal area (FA), disc height (DH), bulging disc thickness(BDT), and facet joint gap (FJG), were measured. CSA increased from 69.72 mm2 preoperatively to 115.95 mm2 postoperatively (P < .001). BDT decreased from 4.97 mm preoperatively to 2.56 mm postoperatively (P < .001). FJG (Right) increased from 2.99 mm preoperatively to 4.38 mm postoperatively (P < .001). FJG (Left) increased from 2.95 mm preoperatively to 4.52 mm postoperatively (P < .001). The improvement of spinal stenosis grade was as follows: 1 point up group, 38 patients; 2 point up groups, 19 patients; and 3 point up groups, 3 patients. The correlation factors were prespinal stenosis grade (0.723, P < .00), CSA change (0.490, P < .00), and FJG change ratio (left, 0.336, P < .008). FJG showed statistical significance with indirect decompression. Indirect decompression principles might be utilized in patients with severe spinal canal stenosis (even grade 4).

The Effect of Hounsfield Unit Value with Conventional Computed Tomography and Intraoperative Distraction on Postoperative Intervertebral Height Reduction in Patients Following Stand-Alone Anterior Cervical Discectomy and Fusion.

OBJECTIVE: The most common complication of anterior cervical discectomy and fusion (ACDF) is cage subsidence and maintenance of disc height affects postoperative clinical outcomes. We considered cage subsidence as an inappropriate indicator for evaluating preservation of disc height. Thus, this study aimed to consider patients with complications such as reduced total disc height compared to that before surgery and evaluate the relevance of several factors before ACDF. METHODS: We retrospectively reviewed the medical records of 40 patients who underwent stand-alone single-level ACDF using a polyetheretherketone (PEEK) cage at our institution between January 2012 and December 2018. Our study population comprised 19 male and 21 female patients aged 24-70 years. The minimum follow-up period was 1 year. Twenty-seven patients had preoperative bone mineral density (BMD) data on dual-energy X-ray absorptiometry. Clinical parameters included sex, age, body mass index, smoking history, and prior medical history. Radiologic parameters included the C2-7 cobb angle, segmental angle, sagittal vertical axis, disc height, and total intervertebral height (TIH) at the preoperative and postoperative periods. Cage decrement was defined as the reduction in TIH at the 6-month follow-up compared to preoperative TIH. To evaluate the bone quality, Hounsfield unit (HU) value was calculated in the axial and sagittal images of conventional computed tomography. RESULTS: Lumbar BMD values and cervical HU values were significantly correlated (r=0.733, p<0.001). We divided the patients into two groups based on cage decrement, and 47.5% of the total patients were regarded as cage decrement. There were statistically significant differences in the parameters of measuring the HU value of the vertebra and intraoperative distraction between the two groups. Using these identified factors, we performed a receiver operating characteristic (ROC) curve analysis. Based on the ROC curve, the cut-off point was 530 at the HU value of the upper cortical and cancellous vertebrae (p=0.014; area under the curve [AUC], 0.727; sensitivity, 94.7%; specificity, 42.9%) and 22.41 at intraoperative distraction (p=0.017; AUC, 0.722; sensitivity, 85.7%; specificity, 57.9%). Using this value, we converted these parameters into a bifurcated variable and assessed the multinomial regression analysis to evaluate the risk factors for cage decrement in ACDF. Intraoperative distraction and HU value of the upper vertebral body were independent factors of postoperative subsidence. CONCLUSION: Insufficient intraoperative distraction and low HU value showed a strong relationship with postoperative intervertebral height reduction following single stand-alone PEEK cage ACDF.

Flow Diverter Devices for the Treatment of Unruptured Vertebral Artery Dissecting Aneurysm.

OBJECTIVE: Vertebral artery dissecting aneurysm (VADA) is a very rare subtype of intracranial aneurysms; when ruptured, it is associated with significantly high rates of morbidity and mortality. Despite several discussions and debates, the optimal treatment for VADA has not yet been established. In the last 10 years, flow diverter devices (FDD) have emerged as a challenging and new treatment method, and various clinical and radiological results have been reported about their safety and effectiveness. The aim of our study was to evaluate the clinical and radiological results with the use of FDD in the treatment of unruptured VADA. METHODS: We retrospectively evaluated the data of all patients with unruptured VADA treated with FDD between January 2018 and February 2021 at our hybrid operating room. Nine patients with unruptured VADA, deemed hemodynamically unstable, were treated with FDD. Among other parameters, the technical feasibility of the procedure, procedure-related complications, angiographic results, and clinical outcomes were evaluated. RESULTS: Successful FDD deployment was achieved in all cases, and the immediate follow-up angiography showed intra-aneurysmal contrast stasis with parent artery preservation. A temporary episode of facial numbness and palsy was noted in one patient; however, the symptoms had completely disappeared when followed up at the outpatient clinic 2 weeks after the procedure. The 3-6 months follow-up angiography (n=9) demonstrated complete/near-complete obliteration of the aneurysm in seven patients, and partial obliteration and segmental occlusion in one patient each. In the patient who achieved only partial obliteration, there was a sac 13 mm in size, and there was no change in the 1-year follow-up angiography. In the patient with segmental occlusion, the cause could not be determined. The clinical outcome was modified Rankin Scale 0 in all patients. CONCLUSION: Our preliminary study using FDD to treat hemodynamically unstable unruptured VADA showed that FDD is safe and effective. Our study has limitations in that the number of cases is small, and it is not a prospective study. However, we believe that the study contributes to evidence regarding the safety and effectiveness of FDD in the treatment of unruptured VADA.

A case of an unruptured duplicated middle cerebral artery aneurysm-An unusual presentation of the distal internal carotid artery aneurysm.

The duplicated middle cerebral artery (DMCA) is an anatomic variation that arises from the distal internal carotid artery (ICA) and supplies blood to the middle cerebral artery (MCA) territory. Aneurysms of the DMCA have been reported in 36 cases in 2020. We also report a case of a 3.7 mm saccular aneurysm originating from the DMCA. A 52-year-old woman visited our hospital with worsening headache. She had no neurological abnormalities. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) revealed a right distal ICA aneurysm at the anterior choroidal artery. Cerebral angiography was performed to confirm the shape and the size of the aneurysm. Cerebral angiography revealed that the vessel that was originally identified as the anterior choroidal artery by the MRA was actually the duplicated MCA that was originating from the aneurysm neck and was supplying the MCA territory. The patient's aneurysm was clipped using a transsylvian approach and she recovered without any neurological symptoms. DMCAs are rare and often associated with aneurysms and require preoperative evaluation to confirm the vascular status, aneurysm characteristics, and the shape of the parent artery.

Learning Curve and Complications Experience of Oblique Lateral Interbody Fusion : A Single-Center 143 Consecutive Cases.

OBJECTIVE: Oblique lateral interbody fusion (OLIF) is becoming the preferred treatment for degenerative lumbar diseases. As beginners, we performed 143 surgeries over 19 months. In these consecutive cases, we analyzed the learning curve and reviewed the complications in our experience. METHODS: This was a retrospective study; however, complications that were well known in the previous literature were strictly recorded prospectively. We followed up the changes in estimated blood loss (EBL), operation time, and transient psoas paresis according to case accumulation to analyze the learning curve. RESULTS: Complication-free patients accounted for 43.6% (12.9%, early stage 70 patients and 74.3%, late stage 70 patients). The most common complication was transient psoas paresis (n=52). Most of these complications occurred in the early stages of learning. C-reactive protein normalization was delayed in seven patients (4.89%). The operation time showed a decreasing trend with the cases; however, EBL did not show any significant change. Notable operation-induced complications were cage malposition, vertebral body fracture, injury to the ureter, and injury to the lumbar vein. CONCLUSION: According to the learning curve, the operation time and psoas paresis decreased. It is important to select an appropriately sized cage along with clear dissection of the anterior border of the psoas muscle to prevent OLIF-specific complications.

Preoperative Radiological Parameters to Predict Clinical and Radiological Outcomes after Laminoplasty.

Many studies have focused on pre-operative sagittal alignment parameters which could predict poor clinical or radiological outcomes after laminoplasty. However, the influx of too many new factors causes confusion. This study reviewed sagittal alignment parameters, predictive of clinical or radiological outcomes, in the literature. Preoperative kyphotic alignment was initially proposed as a predictor of clinical outcomes. The clinical significance of the K-line and K-line variants also has been studied. Sagittal vertical axis, T1 slope (T1s), T1s-cervical lordosis (CL), anterolisthesis, local kyphosis, the longitudinal distance index, and range of motion were proposed to have relationships with clinical outcomes. The relationship between loss of cervical lordosis (LCL) and T1s has been widely studied, but controversy remains. Extension function, the ratio of CL to T1s (CL/T1s), and Sharma classification were recently proposed as LCL predictors. In predicting postoperative kyphosis, T1s cannot predict postoperative kyphosis, but a low CL/T1s ratio was associated with postoperative kyphosis.

Quality improvement of general anteroposterior radiographic image of vertebral body according to optimum angle of incidence.

OBJECTIVE: In this study, we present an appropriate angle of incidence to reduce the distortions in images of L4 and L5 during a general anteroposterior radiograph examination. METHOD: We selected 170 patients who had normal radiological findings among those who underwent anteroposterior and lateral examination for lumbar vertebrae. An optimum angle of incidence wa suggested through the statistical analysis by measuring the lumbar lordosis angle and the intervertebral disc angle in these 170 patients. RESULT: We suggested the incident angle (10.28°) of L4 and the incident angle (23.49°) of L5. We compared the distorted area ratios when the incident angle was 0°, 10°, and 23.5° using the ATOM® phantom. The ratio for the L4 decreased from 14.90% to 12.11% and that of the L5 decreased from 15.25% to 13.72% after applying the angle of incidence. We determined the incident angle (9.34°) of L4 and (21.26°) of L5 below 30° of LLA. Thus, we determined the incident angle (11.21°) of L4 and (25.73°) of L5 above 30° of LLA. CONCLUSION: When you apply the optimum angle of incidence, the distortion of image was minimized and an image between the joints adjacent to the anteroposterior vertebral image with an accurate structure was obtained. As a result, we were able to improve the quality of the image and enhance diagnostic information.

Validation of Gamma Knife Perfexion Dose Profile Distribution by a Modified Variable Ellipsoid Modeling Technique.

OBJECTIVE: High precision and accuracy are expected in gamma knife radiosurgery treatment. Because of the requirement of clinically applying complex radiation and dose gradients together with a rapid radiation decline, a dedicated quality assurance program is required to maintain the radiation dosimetry and geometric accuracy and to reduce all associated risk factors. This study investigates the validity of Leksell Gamma plan (LGP)10.1.1 system of 5th generation Gamma Knife Perfexion as modified variable ellipsoid modeling technique (VEMT) method. METHODS: To verify LGP10.1.1 system, we compare the treatment plan program system of the Gamma Knife Perfexion, that is, the LGP, with the calculated value of the proposed modified VEMT program. To verify a modified VEMT method, we compare the distributions of the dose of Gamma Knife Perfexion measured by Gafchromic EBT3 and EBT-XD films. For verification, the center of an 80 mm radius solid water phantom is placed in the center of all sectors positioned at 16 mm, 4 mm and 8 mm; that is, the dose distribution is similar to the method used in the x, y, and z directions by the VEMT. The dose distribution in the axial direction is compared and analyzed based on Full-Width-of-Half-Maximum (FWHM) evaluation. RESULTS: The dose profile distribution was evaluated by FWHM, and it showed an average difference of 0.104 mm for the LGP value and 0.130 mm for the EBT-XD film. CONCLUSION: The modified VEMT yielded consistent results in the two processes. The use of the modified VEMT as a verification tool can enable the system to stably test and operate the Gamma Knife Perfexion treatment planning system.

Clinical Efficacy and Safety of Silicone Elastomer Sheet during Decompressive Craniectomy: Anti-Adhesive Role in Cranioplasty.

(1) Background: Cranioplasty is a surgery to repair a skull bone defect after decompressive craniectomy (DC). If the process of dissection of the epidural adhesion tissue is not performed properly, it can cause many complications. We reviewed the effect of a silicone elastomer sheet designed to prevent adhesion. (2) Methods: We retrospectively reviewed 81 consecutive patients who underwent DC and subsequent cranioplasty at our institution between January 2015 and December 2019. We then divided the patients into two groups, one not using the silicone elastomer sheet (n = 50) and the other using the silicone elastomer sheet (n = 31), and compared the surgical outcomes. (3) Results: We found that the use of the sheet shortened the operation time by 24% and reduced the estimated blood loss (EBL) by 43% compared to the control group. Moreover, the complication rate of epidural fluid collection (EFC) in the group using the sheet was 16.7%, which was lower than that in the control group (41.7%, p < 0.023). Multivariate logistic regression analysis showed the sheet (OR 0.294, 95% CI 0.093-0.934, p = 0.039) to be significantly related to EFC. (4) Conclusions: The technique using the silicone elastomer sheet allows surgeons to easily dissect the surgical plane during cranioplasty, which shortens the operation time, reduces EBL, and minimizes complications of EFC.

The experience of surgery and endovascular procedure of cerebrovascular disease in the hybrid operating room; Multi-axis robotic C-arm DSA system.

OBJECTIVE: To report on combined surgical and/or endovascular procedures for cerebrovascular disease in a hybrid operating room (OR). METHODS: Between October 2016 and June 2020, 1832 neurosurgical procedures were performed in a hybrid OR. Our institution's hybrid OR consists of a multi-axis robotic C-arm monoplane digital subtraction angiography (DSA) system with an operating table, 3D-rotational DSA, cone-beam computed tomography (dyna CT), and real-time navigation software. Procedures were categorized into six categories according to purpose (1) simple diagnosis and follow-up, (2) simple endovascular procedure, (3) combination of surgery and endovascular procedures, (4) rescue surgery after endovascular procedures, (5) frameless stereotactic procedure, and (6) other surgeries requiring C-arm. RESULTS: Of 1832 neurosurgical procedures in the hybrid OR, 1430 were simple diagnosis and follow-up cases, 330 simple endovascular procedures, 8 combination of surgery and endovascular procedures, 15 rescue after endovascular procedure, 40 frameless stereotactic procedures, and 9 other surgeries. Eight cases of combination of surgery and endovascular procedures, safely performed without wasting time on patient transfer, were performed in seven bypass end endovascular procedures and one case of bow-hunter syndrome in complex cerebrovascular disease. After embolization, craniotomy (or craniectomy) and intracerebral hemorrhage removal were performed in eight patients in-situ. Of the 40 frameless stereotactic procedure, 37 were extraventricular drainage before/after coil embolization in subarachnoid hemorrhage patients. They all mounted conduits in their planned locations. CONCLUSIONS: A hybrid OR for combined endovascular and surgical procedures represents a safe and useful strategy for cerebrovascular disease. In hybrid ORs various neurosurgical procedures can be safely and conveniently performed. Hybrid OR will pioneer a new era in neurosurgical procedures.