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To characterize lateral lumbar interbody fusion surgical learning curve and investigate changes in perioperative and postoperative clinical parameters associated with increased operative experience.In a case series, surgical learning curve was defined using 3-parameter asymptotic regression and piecewise linear regression, yielding learning phase (patients 1-53) and proficient phase (patients 54-179) cohorts. Using a 5-point grading scale, ipsilateral iliopsoas (hip-flexion) and quadriceps (knee-extension) muscle strength and thigh and groin sensory disturbances were compared for differences preoperatively versus postoperatively using χThe proficient phase cohort demonstrated significantly reduced operative time, estimated blood loss, postoperative length of stay, and narcotic consumption on postoperative days 0 and 1. The proficient phase cohort displayed decreased disability at 6 weeks and 6 months and demonstrated significant improvement at all time points for disability, pain, and physical function except for 6 weeks and 2 years for physical function, whereas the learning phase cohort demonstrated improvement in disability beginning at 6 months, leg pain at all time points, and back pain through 6 months. Ipsilateral groin and thigh sensory disturbances and iliopsoas and quadriceps weakness improved with increasing operative experience.The proficient phase cohort demonstrated significantly improved perioperative profile, reduced complication rate, and reduced rates of iliopsoas and quadriceps weakness. While the proficient phase cohort demonstrated earlier improvement in disability and physical function scores compared with the learning phase cohort, 2-year outcome measures did not differ. Long-term clinical outcomes suggest that patient safety and quality of life are not compromised during the learning phase, but patients may be particularly susceptible to femoral nerve injury early in a surgeon's practice.

Distal transradial access (dTRA) has several advantages compared with proximal transradial access (pTRA) for cerebral angiography. The learning curve for transitioning from pTRA to dTRA has not been described.Retrospective analysis of the first 75 diagnostic cerebral angiograms performed with dTRA by a single operator was performed. Outcomes included time for sheath insertion, sheath to first vessel time, procedure duration, fluoroscopy time, radiation dose, and contrast volume. Their associations with procedure number were evaluated with multivariate linear regressions, segmented linear regression, and locally weighted regression (LOESS).The mean age of patients was 56.1 years and 61.3% were female. Seventy-four of 75 angiograms were successfully completed with dTRA. There were 3 minor and no major complications. After adjusting for covariates, sheath to first vessel time (β = -0.50, P0.001) and procedure duration (β = -0.26, P = 0.002) were associated with procedure number. Time for sheath insertion, fluoroscopy time, radiation dose, and contrast volume were not associated with procedure number. Segmented linear regression identified break-points of 33 for sheath to first vessel time and 11 for procedure duration, which corresponded to the procedure number after which these outcomes trended down. LOESS models for time to sheath placement, procedure duration, fluoroscopy time, and radiation dose predicted minimum values between procedures 40-50.Transitioning from pTRA to dTRA for diagnostic cerebral angiography is feasible and safe. The learning curve is overcome between procedures 11 and 33, and further refinement in performance occurs through procedures 40-50.

Objective This study aims to examine the risk factors that can cause intraoperative rupture (IOR), and especially, the role of surgical experience. To our knowledge, this is the first study to analyze the effect of the surgeon's experience on the IOR rate in 2 different perspectives. Methods A total of 1000 aneurysms in 775 patients were operated on by a single neurosurgeon. The clinical and radiologic data and intraoperative video recordings of all patients were retrospectively analyzed. To evaluate the role of the surgeon's experience on the IOR rate, the aneurysms were divided chronologically into both 5-year periods and each 100 aneurysms. Number, stage, severity, location, management of IORs, and patients' outcomes were determined. Results IOR occurred in 55 aneurysms (5.5% per aneurysm). The incidence of IOR decreased gradually in the first 2 groups of 5-year periods (11.4% and 5.9%, respectively). However, in the last 3 groups, the decline remained stable (4%–5%). Considering all groups, this decrease was statistically significant (P = 0.037). When this evaluation was made for each group of 100 aneurysms, similar results were obtained. Mortality also gradually decreased over the years (P = 0.035). Of 8 possible risk factors, rupture status was found to be the only independent predictor for IOR (OR, 8.68; 95% confidence interval, 3.69–20.47; P Conclusions Increased surgical experience reduces the IOR rate from 10%–11% to 4%–5% after an average of 250 aneurysm operations. However, this rate does not decrease further with more experience. To our knowledge, a learning curve regarding IOR is presented for the first time in the literature.

To provide data about surgical workflow, accuracy, complications, radiation exposure, and learning curve effect in patients who underwent minimally invasive (MIS) transforaminal lumbar interbody fusion with navigation coupled with mobile intraoperative computed tomography.A retrospective analysis was performed of data from consecutive patients who underwent single- or double-level MIS transforaminal lumbar interbody fusion at a single institution; mobile intraoperative computed tomography combined with a navigation system was used as the sole intraoperative imaging method to place pedicular screws; decompression and interbody fusion were performed through a 22-mm tubular retractor. Clinical data, perioperative complications, accuracy of pedicular screw placement, and radiation exposure were analyzed. A learning curve effect on surgical time and accuracy was assessed.A total of 408 screws in 100 patients were analyzed. In all cases, spinal navigation allowed for identification of pedicular trajectories and greatly facilitated nerve root decompression through the MIS approach. Overall accuracy according to Heary classification was 95.3%. Nineteen screws (4.7%) presented a minor lateral breach (2 mm), not clinically significant. Surgical time, blood loss, and patient radiation exposure compared favorably with reported values from other series using three-dimensional navigation. A learning curve effect on surgical time, but not on screw accuracy, was identified.MIS transforaminal lumbar interbody fusion can now be performed without any radiation exposure to the surgeon and operating room staff, with almost absolute accuracy during screw positioning and tubular decompression. A learning curve effect on surgical time, but not on overall screw accuracy, may be expected.

Objectives Accurate placement of the pedicle screw is requisite for any successful spinal instrumentation procedure. Screw insertion can be achieved using free-hand and fluoroscopic- or navigation-guided techniques. We sought to assess the variation in accuracy between fluoroscopic- and navigation-guided techniques, which are both used in Sheffield Teaching Hospitals National Health Service Trust, a tertiary spine referral center. Methods Using a retrospective study design, we assessed all the pedicle screws placed between 2013 and 2018. Radiographic and clinical assessment of all cases was performed. Results We studied 176 spinal instrumented cases, with a total of 831 screws implanted, out of which 296 (35.6%) were navigated and 535 (64.4%) were fluoroscopic guided. Pathology treated included spinal stenosis, spondylolisthesis, tumors, and trauma. Suboptimal screw position was identified in 2.03% (n = 6) of the navigation-guided series and 4.11% (n = 22) of the fluoroscopic-guided series with an overall screw misplacement rate of 3.4%. Evaluating surgeons’ individual accuracy rates revealed that suboptimal screw placement registered a higher variation for the fluoroscopy-guided technique, and the misplacement rate was higher for surgeons with a lower volume of cases. Conclusions Use of navigation during spinal instrumentation helps lower the rate of screw misplacement for spinal surgeons who are at the beginning of their learning curve or do not frequently perform this kind of procedure. Navigation-guided spinal instrumentation is more accurate compared with fluoroscopic-guided techniques and appears to have a lower complication rate.

Minimally invasive spine surgery (MISS) has continued to evolve over the past few decades, with significant advancements in technology and technical skills. From endonasal cervical approaches to extreme lateral lumbar interbody fusions, MISS has showcased its usefulness across all practice areas of the spine, with unique points of access to avoid pertinent neurovascular structures. Adult spine deformity has also recognized the importance of minimally invasive techniques in its ability to limit complications and to provide adequate sagittal alignment correction and improvements in patients' functional status. Although MISS has continued to make significant progress clinically, consideration must also be given to its economic impact and the learning curve surgeons experience in adding these procedures to their armamentarium. This review examines current innovations in MISS, as well as the economic impact and future directions of the field.

Objective External ventricular drain (EVD) placement is a life-saving procedure performed frequently by neurosurgical residents. The July effect is a theoretic decline in quality of health care sometimes perceived in teaching hospitals at the start of an academic year. We sought to quantify the learning curve of ventriculostomy drain placement in teaching hospitals and determine its impact on patient outcomes, health care utilization, and cost. Methods The National Inpatient Sample was queried for patients admitted nonelectively between 2012 and 2015 requiring EVD placement at a teaching hospital determined by using International Classification of Diseases, Ninth Revision codes. Rates of multiple EVD placements per admission, infection and hemorrhage, mortality, length and cost of hospital stay, and discharge disposition were compared between admissions in the first quarter (Q1) of an academic year (July–September) versus those in Q4 (April–June). Results A total of 7783 admissions met inclusion criteria (3901 in Q1 and 3882 in Q4). The odds ratios (OR) for all combined complications, mortality, and long-term care disposition were similar between Q1 and Q4 groups. There was a significant reduction in the OR of wound and infectious complications in Q1 versus Q4 (1.60% vs. 2.31%; OR, 0.66; P = 0.01). The impact of Q1 EVD placement on total hospital charge and number of EVD codes was not statistically significant. However, there was a statistically significant reduction in length of stay in Q1 compared with Q4 (β = −0.04 days; P Conclusions There was no evidence of a July effect on EVD complication rates in outcomes for patients admitted in the beginning of an academic year versus the end.

There are few reports on the robot-assisted percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures (OVCF), and we aimed to explore the learning curve of the robot-assisted PKP for treating OVCF.A total of 44 patients (71 vertebral fractures) with OVCF treated with robot-assisted PKP were divided into 4 groups, namely groups 1, 2, 3, and 4, according to the date of operation, with 11 cases in each group. Another 11 patients (18 vertebral fractures) treated with PKP without robot assistance were included in group 5. The success rate of robot-assisted puncture, total operation time, robot-assisted operation time, PKP operation time, and complications were analyzed.All patients underwent operation successfully. The success rates of puncture in the robot-assisted groups were 92.9%, 94.4%, 94.7%, and 100%, respectively, with no statistical difference (P0.05). The success rate of puncture in group 5 was 63.2%, with a statistical difference (P0.05) compared with groups 1-4. The total operation time and robotic operation time reduced significantly and remained relatively stable since the third group, and groups 1 and 2 showed a statistical significance compared with groups 3 and 4 (P0.05), but there was no difference among groups 3, 4, and 5 (P0.05). The main intraoperative complication was leakage of bone cement in the anterior vertebral space and intervertebral space, with an incidence of 8.5% in the robot-assisted groups and 26.3% in group 5.The puncture accuracy of robot-assisted PKP for treating OVCF does not change with the increase in the number of operations. The total operation time and robotic-assisted operation time decreases with the increase in the number of cases.

Background Spinal anesthesia (SA) is routinely used in obstetrics and orthopedic surgery but has not been widely adopted in lumbar spine surgery (LSS). One perceived barrier is the learning curve for the neurosurgical and anesthesia team associated with managing a patient in the prone position under SA. Methods A retrospective cohort of 34 LSS cases under SA at our institution was examined. Operative time, corrected operative time per level, and complications were analyzed. The learning curve was assessed using a curve-fit regression analysis. Results Of patients, 62% were female, with mean (SD) age and body mass index of 60.7 (10.8) years and 29.9 (4.6) kg/m2, respectively. The mean (SD) for each time segment was operating room arrival to incision 35.7 (8.1) minutes, total surgical time 100.4 (35.8) minutes, and procedure finish to operating room exit 3.4 (2.5) minutes. When the times were normalized to procedure type and analyzed sequentially, the mean (SD) slope of all trendlines was 0.003 (0.005) with correlation coefficients of R2 = 0.0002–0.01, indicating no appreciable learning curve. Normalized postanesthesia care unit time was significantly shorter for overnight stay versus same-day discharge (0.64 vs. 1.36, P = 0.0005). Conclusions Our data demonstrate the lack of a learning curve when SA is implemented in LSS cases by an anesthetic team already familiar with SA techniques for other procedures. Importantly, the surgical team was already familiar with the minimally invasive surgery approaches used in conjunction with SA. This study highlights that the barriers to transitioning to SA for LSS may be fewer than perceived.

The purpose of this study was to determine the number of cases needed to achieve the level of competence for percutaneous endoscopic lumbar diskectomy (PELD) via the bi-needle technique using the cumulative summation test for learning curve (LC-CUSUM).A retrospective design was used. We included 60 patients who underwent a single-level PELD via the bi-needle technique performed by a single surgeon. The surgeon had 5 years of experience in open surgery including the transforaminal endoscopic spine system and Yeung endoscopic spine system but no experience in the bi-needle technique. Surgery success was defined as an operative time60 minutes, and the acceptable procedure was completed within 3 times of C-arm fluoroscopies. The LC-CUSUM was used to analyze the data.The average operative time for PELD via the bi-needle technique was 58.3 ± 12.4 minutes. The mean operative time was 65.7 ± 12.1 minutes in the early learning period (30 cases) and 51.0 ± 7.5 minutes in the late learning period (30 cases) (P0.05). On the basis of the evaluation indexes of the operative time and radioactive exposure, the LC-CUSUM signaled proficiency for the bi-needle technique at the 50th-54th operation. Seven cases of complications were observed during the whole learning process, with 6 in the early period and 1 in the late period (P0.05).The novel bi-needle technique is safe and effective for PELD with appropriate patients, and the learning curve is acceptable. A substantial learning period (50-54 cases) is needed before a spine surgeon can master the bi-needle technique.

Objective Until now, there were few studies on the safety analysis of oblique lumbar interbody fusion (OLIF) and extreme lateral interbody fusion (XLIF) in the initial stage of learning curve. The purpose of this study was to find out the safety differences between the 2 minimally invasive fusion methods in the initial stage of learning curve and to provide reference for beginners. Methods We retrospectively collected the first 30 cases of lumbar degenerative disease with OLIF or XLIF in our center since June 2014. Patients were divided into group OLIF and group XLIF according to different operative methods. The clinical efficacy and complications of the 2 groups were compared. A P Results Group XLIF were aged 37–74 years (mean 58.4 years) and group OLIF were aged 39–71 years (mean 56.1 years). There were no significant differences between the 2 groups in age, sex, operation time, intraoperative bleeding volume, operation segment, and follow-up time. The incidence of complications in group XLIF was significantly lower than that in group OLIF (10% vs. 33.3%; P = 0.028). Conclusions OLIF has a higher risk of neurovascular injury in the initial stage of learning. By contrast, the XLIF approach is simple and the incidence of complications is relatively low. Therefore, we believed that XLIF is more acceptable in the initial stage of anterolateral lumbar interbody fusion.

Interlaminar endoscopic lumbar discectomy (IELD) is an efficient surgical treatment for lumbar disc herniation. However, this minimally invasive procedure requires a considerable learning curve that has not yet been standardized. This review aimed to evaluate the learning curve's characteristics, including the cutoff point required to achieve technical proficiency and to discuss appropriate training methods.We systematically searched the core databases (PubMed, Embase, and Cochrane Library) for clinical studies that evaluated the learning curve using quantitative data. We performed a quality assessment using the Newcastle-Ottawa scale. We also compared descriptive statistics, including operative time and other variables before and after the cutoff point.Six studies reporting 302 cases of IELD were selected from 7188 screened articles. The cutoff point was randomly set in 3 studies and determined as the curve's asymptote in 3 studies. The mean value for the cutoff point was 22.17 ± 12.40 cases (range: 10-43 cases) and mainly determined based on the operative time, which was shorter in the late group than that in the early group (P0.05). The cutoff points were not significant for patient outcome parameters such as pain score, functional result, surgical failure, or complications.The evidence of published studies regarding the learning curve for the IELD technique is insufficient. The reported cutoff points may be significant only for task efficiency. Moreover, they may not represent the asymptote of the curve. Future studies should evaluate the actual plateau points using patient outcome data.

Background Transforaminal percutaneous endoscopic lumbar discectomy (TPELD) has become an alternative and minimally invasive surgical technique for soft lumbar disc herniation. However, the learning curve has been relatively long and difficult. In the present study, we have summarized the characteristics of the learning curve of TPELD, including the number of cases required to achieve technical proficiency, and discussed the strategies to improve the learning curve. Methods The PubMed, Embase, Cochrane Library, and KoreaMed databases were searched for reports describing the learning curve for TPELD. Clinical studies involving human patients and evaluating the learning curve of TPELD with quantitative data were included. A strict quality assessment was completed, and descriptive statistics were calculated. Results Of the 6884 screened titles and abstracts, 10 full-text reports, including 958 cases, were included in the analysis. All were cohort studies, which were grouped into early and late groups according to surgeon experience with TPELD. The most commonly used cutoff to differentiate between these groups was 20 (mean, 24.70 ± 18.99 cases; range, 10–72 cases). The most widely used measure was the operative time. Although most studies had reported better results in the operative time or pain scores in the late group, only 1 study had proposed a bona fide learning curve. Conclusions We found insufficient evidence to support a cutoff point of 20 or other numbers of cases for determining when the learning curve has reached a plateau. Therefore, these numbers should be interpreted with great care, and high-quality prospective studies evaluating the actual learning curve are required.

Objective To determine the amount of screws needed to achieve an adequate skill level for pedicle screw placement (PSP) via the freehand technique in the nondeformed thoracolumbar spine using the cumulative summation test for learning curve (LC-CUSUM) analysis. Methods This study includes the first 85 patients who underwent pedicle screw installation in the thoracic and lumbar spine by a single orthopedic surgeon. The surgeon had 1 years' experience of fellowship training in a tertiary teaching hospital. The learning curve of freehand PSP was investigated using the LC-CUSUM analysis. Procedure success was defined as acceptable accuracy of PSP, which was divided into group 1 (the screw breaches the pedicle's cortex by less than 2 mm) and group 2 (the screw is completely within the pedicle). Results A total of 52 cases and 313 pedicle screws were included and analyzed in this study. The LC-CUSUM analysis signaled competency for freehand PSP at the 115th pedicle screw (17th case) in group 1 and at the 312th pedicle screw (52nd case) in group 2. This means that a trainee with no experience with freehand PSP reached an adequate accuracy level of PSP with less than 2 mm pedicle breaches at the 115th screw and completely within the pedicle at the 312th screw. There were no major complications, such as neurovascular injury, and life-threatening complications. Conclusions In this study, the learning curve analysis demonstrated that a substantial learning period may be necessary before an adequate level of performance is achieved for freehand PSP in the nondeformed thoracolumbar spine.

To investigate the value of 3-dimensional (3D)-printed models with pathologic entities in enhancing the learning curve of surgery of tuberculum sellae meningioma.We printed 4 models of tuberculum sellae meningiomas based on radiologic data using a 3D printer. Participants were allocated to the 3D group and the atlas group. In the 3D group, participants learned surgery with the assistance of 3D models. In the atlas group, participants used only 2-dimensional materials to assist their learning. All participants undertook a pre-test and post-test. The scores were used to identify the difference in learning efficiency between the 2 groups.A total of 42 new trainees were recruited, of whom 22 were in the 3D group and 20 in the atlas group. The baseline data were not significantly different. The difference of pre-test score was not significant, either. However, the post-test score was significantly greater in the 3D group (P = 0.005), and the change in score was also significantly greater in the 3D group (P0.001). In accordance with the objective test, the subjective survey through a questionnaire from participants in the 3D group showed that 3D models significantly promoted the learning curve of this kind of complex skull base surgery.3D-printed models can assist in improving the learning curve of surgery of tuberculum sellae meningiomas. It particularly aids in memorization and spatial construction, improves understanding of surgical view, and arouses interest on the part of the trainee. We recommend using it in the education of complex skull base surgery.

Objective The outcomes of recent endoscopic surgery of nonfunctioning pituitary adenomas (NFPAs) are controversial when compared with traditional microscopic surgery. We aimed to assess the outcomes of endoscopic transsphenoidal surgeries performed by 1 surgeon with 7 years of experience and elucidate the predictive factors for surgical outcomes for NFPAs. Methods We included 331 patients (155 men and 176 women) with clinical NFPAs who underwent transsphenoidal surgery because of visual symptoms by a single surgeon in Seoul National University Hospital from March 2010 to May 2016. We assessed the tumor removal rate, hormonal outcomes, visual outcomes, and complications. Results The gross total resection rate of endoscopic transsphenoidal surgery for NFPAs by a single surgeon was 74.9%. Cavernous sinus invasion, a high Knosp grade, large tumor size, previous surgery, and lack of surgical experience in the neurosurgeon elevated the risk for residual tumors. Visual deficits were improved in 73.4% of the patients, which was associated with tumor size, preoperative visual impairment score, previous radiation, and surgical experience. Hormonal status was improved in 15.4% and aggravated in 32.9% after surgery. There were no predictors for hormonal recovery. Transient diabetes insipidus (DI) was the most common complication (9.1%), and among these patients, 3.0% had persistent DI. Conclusions Endoscopic transsphenoidal surgery by a well-experienced surgeon was an effective and safe treatment for NFPAs, but the hormonal outcomes were not changed compared with previous reports of microscopic surgery. Large tumor size and cavernous sinus invasion were still the barriers for achieving total resection.

BACKGROUND: Residents' lives are hectic-it is hard to find a place and time for training basic and advanced microsurgical skills. Surgical instruments and sutures can be purchased (or loaned from another department), but the most expensive and space-occupying device is the microscope. In developing countries, microscopes are used where they are needed most, in operating rooms. Furthermore, a conventional microscope is not portable. For all of these reasons, the availability of microscopes for training microsurgery is limited. METHOD: We used a coffee cup and smartphone (CCS) as a training device instead of a microscope. The coffee cup was the base, and the smartphone functioned to magnify, illuminate, and visualize objects. We measured 2 residents' performance on end-to-end artificial bypass before and after 5 days of CCS-based training. RESULTS: We were able to quickly set up the environment for practicing microsurgical skills in any surrounding. After 5 days of training with CCS we could see significant development of microsurgical performance with a conventional microscope as well. The learning curve was dependent on baseline performance. CONCLUSION: CCS is efficient, mobile, and easy to set up. Even though our smartphone-based training was in 2 dimensions, we could improve our microsurgical performance with conventional microscopes, which have 3-dimensional capability. CCS also provides an easy method to record one's microsurgical training. CCS improved both of the subjects' microsurgical performance, making it a good alternative for a traditional microscope.

Recent biotechnological advances, including three-dimensional microscopy and endoscopy, virtual reality, surgical simulation, surgical robotics, and advanced neuroimaging, have continued to mold the surgeon-computer relationship. For developing neurosurgeons, such tools can reduce the learning curve, improve conceptual understanding of complex anatomy, and enhance visuospatial skills. We explore the current and future roles and application of virtual reality and simulation in neurosurgical training.

Quality of neurosurgical care and patient outcomes are inextricably linked to surgical and technical proficiency and a thorough working knowledge of microsurgical anatomy. Neurosurgical laboratory-based cadaveric training is essential for the development and refinement of technical skills before their use on a living patient. Recent biotechnological advances including 3-dimensional (3D) microscopy and endoscopy, 3D printing, virtual reality, surgical simulation, surgical robotics, and advanced neuroimaging have proved to reduce the learning curve, improve conceptual understanding of complex anatomy, and enhance visuospatial skills in neurosurgical training. Until recently, few means have allowed surgeons to obtain integrated surgical and technological training in an operating room setting. We report on a new model, currently in use at our institution, for technologically integrated surgical training and innovation using a next-generation microneurosurgery skull base laboratory designed to recreate the setting of a working operating room. Each workstation is equipped with a 3D surgical microscope, 3D endoscope, surgical drills, operating table with a Mayfield head holder, and a complete set of microsurgical tools. The laboratory also houses a neuronavigation system, a surgical robotic, a surgical planning system, 3D visualization, virtual reality, and computerized simulation for training of surgical procedures and visuospatial skills. In addition, the laboratory is equipped with neurophysiological monitoring equipment in order to conduct research into human factors in surgery and the respective roles of workload and fatigue on surgeons' performance.

Background Intraventricular tumors present difficult challenges to the neurosurgeon. Neurosurgeons have begun to explore the possibilities of using the endoscope in the radical resection of solid intraventricular lesions. There is a steep learning curve when dealing with such lesions with an endoscope. Objective The aim of this study was to create a laboratory training model for neuroendoscopic surgery of intraventricular lesions guided by the navigation system. We believe this technique is more reliable than the traditional approach using contrast injection with C-arm x-ray guidance. Materials and Methods Five formalin-fixated, latex-injected cadaveric heads were used. The arterial system was injected with red latex through the common carotid arteries, and the venous system was injected with blue latex through the internal jugular veins at the C6 vertebral level. The contrast-enhancing tumor polymer, Stratathane resin ST-504-derived polymer (SRSDP), was injected into the lateral ventricle via Frazier's point under direct endoscopic visualization and real-time neuronavigation guidance. When navigation was used for trajectory planning, the peel-away sheath was registered using a frameless navigational system (BrainLAB, Feldkirchen, Germany). A questionnaire was distributed to all participants in an endoscopic cadaveric course in which the models were used to evaluate the endoscopic tumor model. Results Neurosurgeons participating in the course performed an endoscopic approach to resect the intraventricular tumor model through an ipsilateral frontal burr hole. The properties of the SRSDP mixture could be manipulated through varying concentrations of the materials used, in order to reach the desired consistency of a nodular solid lesion and possibility for piecemeal resection. The tumor model allowed participants to compare between normal and pathologic endoscopic anatomy in the same cadaveric head. Conclusion This injectable tumor model with the combination of neuroendoscopy and navigation can improve the accuracy of the endoscopic approach and minimize the risk of cadaveric brain specimen damage that in return augments the feeling of lifelike conditions. Using this endoscopic injectable tumor model technique can assist neurosurgeons' preparation for the challenges associated with an endoscopic piecemeal resection of a solid lesion in the lateral or third ventricle.

Objectives To describe the learning curve of pedicle screw placement using robot-assisted spine surgery of an experienced neurosurgeon and 2 supervised neurosurgical fellows. Methods The first 120 cases of robot-assisted spine surgery at our institution were assessed. Patient variables included age, body mass index, and indication for surgery. Intraoperative variables included the vertebral level of screw placement, number of screws placed by each operator, intraoperative blood loss, and operative time. Postoperative variables included length of stay, discharge disposition, 30-day readmissions, wound complications, and hardware revisions. Screw accuracy was determined with image overlay analysis comparing planned screw trajectory on the navigation software with the intraoperative computed tomography scan with final screw placement. Two-dimensional accuracy was determined for the tip of the screw, tail of the screw, and angle at the screw was placed. The supervising physician and first fellow began utilizing the robot concurrently upon its arrival, and the second fellow began using the robot after the system had been in place for 7 months. Results Both experienced surgeon and first fellow displayed a learning curve and achieved statistically significant improvement of accuracy after 30 screws. The second fellow had significantly better accuracy than the experienced surgeon in his first 30 screws. There were no complications from hardware placement in either group. There were no returns to the operating room for hardware issues. Conclusions Robot-assisted spine surgery is a safe, accurate method of pedicle screw instrumentation. Our data show similar learning adaptation rates for the first fellow and the experienced surgeon. Techniques learned by the attending surgeon were immediately transferable to a new learner, who was able to achieve a faster learning curve than both the first fellow and the experienced surgeon.

Objective We describe the setup and use of different 3-dimensional (3-D) recording modalities (macroscopic, endoscopic, and microsurgical) in our laboratory and operating room and discuss their implications in neurosurgical research and didactics. We also highlight the utility of 3-D images in providing depth perception and discernment of structures compared with 2-dimensional (2-D) images. Methods The technical details for equipment and laboratory setup for obtaining 3-D images were described. The stereoscopic pair of images was obtained using a modified "shoot-shift-shoot" method and later converged to a 3-D image. For microsurgical procedures, 3-D images were obtained using an integrated 3-D video camera coupled to the surgical microscope in both the laboratory and the operating room. Illustrative cases were used to compare 2-D and 3-D images. Results Side-by-side comparisons of 2-D and 3-D images obtained using all modalities revealed that 3-D imaging was superior to 2-D imaging in providing depth perception and structure identification. Conclusions This is the first report in the literature of the methodology for obtaining 3-D endoscopic endonasal images using the 2-D endoscope. The use of 3-D imaging is invaluable in neurosurgical research and education, as it provides immediate depth perception (third dimension), allowing efficient understanding of key spatial relationships. Integration of 3-D imaging in neurosurgical residency programs may increase learning efficiency and shorten learning curves. However, use of 3-D imaging should not replace direct hands-on practice.

The purpose of the present study was to determine the learning curve for biportal endoscopic spinal surgery (BESS) for decompressive laminectomy in lumbar spinal stenosis using a learning curve cumulative summation test (LC-CUSUM).The surgeon was proficient in open and microscopic decompressive laminectomy in lumbar spinal stenosis but did not have any experience with BESS or other endoscopic surgery techniques. The learning curve of BESS was investigated using LC-CUSUM analysis. Procedure success was defined as an operative time75 minutes, the mean operative time with microscopic decompression laminectomy.The present study included the first 60 patients who had undergone single-level decompressive laminectomy using BESS by a single orthopedic surgeon. The mean operative time for decompressive laminectomy by BESS was 83.8 ± 37.9 minutes. The mean operative time in the early learning period (≤30 cases) and late learning period (second 30 cases) was 105.3 ± 39.7 minutes and 62.4 ± 19.9 minutes, respectively. The overall complication rate was ∼10%. The LC-CUSUM signaled competency for surgery at the 58th operation, indicating that sufficient evidence had accumulated to prove that the surgeon was competent. Thus, a trainee with no experience with BESS had reached adequate performance at 58 cases.The results of the present study have demonstrated that a substantial learning period could be needed before adequate performance can be achieved with lumbar decompressive laminectomy using BESS.

Background The evolution of minimally invasive endovascular approaches and training paradigms has reduced open neurovascular case exposure for neurosurgical residents. There are no published estimates of open neurovascular case volumes during residency or Committee on Advanced Subspecialty Training (CAST) accredited fellowships. Methods Case volumes from residency programs submitting data for CAST accredited fellowship applications were collected and analyzed. The study period covered the academic years of 2013–2016. Case index volumes were calculated to provide an estimate of total volume of cases each trainee participated in a given year. The case index volume was defined as the total volume of cases per year divided by the total training complement. Results Over the study period, institutional data from 46 programs were available. Of those programs, 9 programs had CAST accredited open cerebrovascular fellowships. Across all 46 programs, the median number of vascular cases was 246 (interquartile range [IQR]: 148–340), whereas the median number of open vascular cases was 105 (IQR: 67–152). The median number of open aneurysm cases among programs with CAST cerebrovascular fellowships was 80 (IQR: 54–103) and among programs without CAST cerebrovascular fellowships was 34 (IQR: 24–63). The median open aneurysm case index volume for trainees at programs with and without CAST cerebrovascular fellowships was 23 (IQR: 14–29) and 19 (IQR: 11–24). Conclusions Strong neurovascular training can be obtained through dedication and planning. Completion of a CAST accredited cerebrovascular fellowship will often more than double aneurysm case exposure of trainees.

Background Minimally invasive surgery has become popular in recent times and has proved more advantageous than conventional open surgery methods, in terms of maximal preservation of natural anatomy and minimal postoperative complications. However, these advancements require a longer learning curve for inexperienced surgeons. Overview The learning curve in minimally invasive spine surgery is complex and difficult to measure, and therefore operating times, conversion to open procedures, visual analog scale, and periods of hospital stay are used. In assessing complications as a measure of the learning curve, it was noted that nearly all the complications had been documented previously and became minimum after the 30th consecutive case. As surgical experience increases, perioperative parameters (e.g., operative time and length of hospitalization) improve. The downside of minimally invasive spine surgery is starting unfamiliar procedures without tactile sensation, working in a narrow restricted surgical field, and using endoscopes via two-dimensional imaging. Conclusions Appropriate instruments, a trained team, and an adept radiographer are important assets for a smooth transition during the learning period. Structured training with cadavers and lots of practice, preferably while working under the guidance of experienced surgeons, is helpful. The learning curve can be shortened when a proficient surgeon gains relevant knowledge, understands three-dimensional anatomy, and has surgical aptitude along with manual dexterity.

Objective To characterize the learning curve for a single surgeon during his initial phases of performing minimally invasive surgery oblique lumbar interbody fusion. Methods This was a prospective analysis of 49 consecutive patients who underwent a single-level minimally invasive surgery oblique lumbar interbody fusion performed by a single surgeon. Patients were divided into group A (first 24 patients) and group B (25 patients after initial 24 patients). The following data were compared between the 2 groups: surgical time, estimated blood loss, radiograph exposure time, clinical and radiographic results, and intraoperative and postoperative complications. The learning curve was assessed using a logarithmic curve-fit regression analysis. Results Average operative time was significantly longer in group A compared with group B. Compared with group B, group A had significantly more x-ray exposure time. Perioperative complications included thigh numbness and pain in 8 cases, psoas and quadriceps weakness in 3 cases, sympathetic nerve injury in 2 cases, and paralytic ileus in 1 case. All complications were transient and resolved within 3 months. The incidence of complications was 37.5% in group A and 20.0% in group B. Clinical and radiographic outcomes were basically identical in the 2 groups at last follow-up. Conclusions Minimally invasive surgery oblique lumbar interbody fusion presents a learning curve to the practicing spine surgeon with regard to operative time, x-ray exposure time, and intraoperative and postoperative complications. Close attention to detail can minimize complications that may be associated with the learning curve.

Tubular microdiscectomy has become a staple technique among spine surgeons. Yet the associated learning curve, especially its later stages, has not been extensively studied. With studies reporting a higher rate of recurrent herniation using tubular microdiscectomy, surgeons' level of experience becomes of primary importance for the interpretation of such findings. We aimed to analyze possible improvements in the later stages of the learning curve and to identify factors independently associated with recurrent herniation.A retrospective study was conducted using prospectively collected data from a consecutive cohort of all 1241 patients operated for single-level lumbar disc herniation with tubular microdiscectomy by a single surgeon who already had extensive experience with this technique. We collected demographic and perioperative data and consequently tracked all complications, recurrent herniations, and other reoperations. In addition, 495 patients (40%) provided complete outcome scores on a numeric rating scale for back and leg pain and the Oswestry Disability Index at baseline, 6 weeks, and 12 months postoperatively.A decrease in surgical time (P0.001) and recurrent herniations was observed (P = 0.012) over time. Increased leg pain at 6 weeks was independently associated with recurrent herniation (P = 0.01). Fifty-six patients (4.5%) experienced ipsilateral recurrent herniation.Relevant improvements in clinical results were seen even after the surgeon had already accumulated extensive experience. Any future studies should unambiguously report the level of experience of the participating surgeons, possibly including the number of cases previously treated using a particular technique.

Objective To present a large series of patients and examine the learning curve of the endonasal endoscopic transplanum, transtuberculum approach for primarily suprasellar or sellar-suprasellar tumors. Methods We identified 122 patients who underwent 126 surgeries using the transplanum, transtuberculum approach. Extent of resection was determined with volumetric analysis of magnetic resonance imagings. Results concerning vision, endocrine function, and complications were noted. Results Average tumor volume was 14 cm 3 . The most frequent pathologies were pituitary macroadenoma (51.6%), craniopharyngioma (20.6%), and meningioma (15.9%). A total of 73% patients presented with visual compromise. Rates of gross total resection (GTR) and near total resection for the group as a whole were 58.1% and 13.7%, and for the patients in whom GTR was intended ( n = 90), rates of GTR and near total resection were 77.5% and 12.5% for a total of 90%. Extent of resection in this group was 97.6%. Vision improved in 52.4% and deteriorated in 4.8%. Favorable endocrine outcome occurred in 63.5%. The cerebrospinal fluid leak rate was 3.1% for the series as a whole. It improved from 6.3% in the first half of the series to 0 in the second half. Leak rates varied with technique from 11% (fat graft only) to 4.2% (gasket seal only) to 1.8% (fat plus nasoseptal flap) to 0 (gasket plus nasoseptal flap). The rate of other complications was 14.3% in the first half of the series and 1.6% in the second half. There was one infection (0.8%). Conclusions The endonasal endoscopic transtuberculum transplanum approach is a safe and effective minimal access approach to midline pathology in the suprasellar cistern.

Background No clear consensus yet defines the endpoints for operative learning curves in the transition to minimally invasive endoscopic techniques. This retrospective review of our first 202 patients who underwent endoscopic pituitary resection examines the statistical learning curve related to operative times—a measure of our surgical team's efficiency and complication rate, a reflection of surgical skill and maturity. Methods Retrospective chart review included patient demographic data, tumor type, operative time, complications, and follow-up. During the 5-year study period, surgeries were performed by an otolaryngology-neurosurgery team. Statistical analysis by Pearson's correlation delineated a learning curve for operative time and complications. Results Our learning curve showed comparable plateaus: 120 cases (48% males, 52% females) for operative time (mean, 134 minutes; range, 62–307 minutes) and 100 cases for incidence of cerebrospinal fluid (CSF) leak. The risk of CSF leak declined significantly with the surgeon's increasing experience. Complication rates were as follows: temporary nasal obstruction, 9.9%; CSF leak, 8.4%; postoperative epistaxis, 7%; sinusitis, 4.5%; septal osteomyelitis, 2.4%; postoperative sellar hematoma, 1.5%; anosmia, 0.5%; and septal perforation, 0.5%. The overall CSF leak rate included 5.5% intraoperative and 2.9% postoperative; most cases resolved with a lumbar drain. Four patients (2%) underwent postoperative surgical repair and lumbar drainage. Conclusion Our learning curve–defined endpoints for 2 measures, operative time and complication rates, support improved outcomes for reduced CSF leaks, the most common complication, with increasing operative experience. We will continue to examine the implications related to safety, efficacy, and the need for subspecialization in this minimally invasive surgery.

Objective The transition from microscopic to fully endoscopic transsphenoidal surgery requires a surgeon to assess how the change in technique will affect the extent of tumor resection (EOR), outcomes, and complications. We compared a single surgeon's experience transitioning from one technique to the other and examined the operative outcomes and EOR between microscopic versus endoscopic transsphenoidal surgery. Methods Retrospective data analysis of adult patients who were treated surgically for a pituitary adenoma between August 2005 and May 2015 by a single neurosurgeon, who was originally trained and practiced in the microscopic transsphenoidal approach. Patient demographics, perioperative conditions, tumor characteristics, operative times, volumetric EOR, postoperative outcome, and the endoscopic learning curve were evaluated. Results One hundred and nine patients underwent microscopic transsphenoidal surgery and 275 patients underwent a fully endoscopic approach. The patient characteristics were similar in the 2 groups. Operative room time was significantly shorter in the endoscopic group than in the microscopic group (180.2 vs. 215.6 minutes; P P = 0.371) as well as residual tumor volume (1.06 cm 3 vs. 1.15 cm 3 ; P = 0.765). The mean length of hospital stay was 2.4 days in the endoscopic group and 3.2 days in the microscopic group ( P = 0.03). Conclusions During the transition from the microscopic to the endoscopic approach, similar surgical outcomes and EOR were achieved in the 2 cohorts. In our experience, the endoscopic approach offers the advantage of shorter operative times and lengths of hospital stays after the surgeon has developed more experience with the technique.

Background Use of traditional two-dimensional (2-D) neuroendoscopy is limited by lack of depth perception. The advent of next-generation three-dimensional (3-D) endoscopes potentially compensates for this limitation. The aim of this study was to objectively compare the 2 modalities in a controlled laboratory environment. Methods Using 2-D and 3-D endoscopes, 8 participants performed simple and complex motor tasks. Participants were divided into 3 groups: novice ( n = 3), beginner ( n = 4), and expert ( n = 1), based on prior neuroendoscopy training. Efficiency of completing simple motor tasks in an allocated time and time to complete complex motor tasks were recorded for both visualization methods with demerits for inaccuracy. Results Inaccuracy was reduced with increasing experience in the use of the 3-D endoscope for simple motor tasks such as spiral drawing ( P = 0.04), but there was no statistical difference in completion time for complex motor tasks pertaining to depth perception among the groups ( P > 0.05) or within groups for simple or complex tasks. To assess the impact on the learning curve, we analyzed the performance improvement in use of the other endoscope based on which endoscope each participant used first. There was marked improvement in accuracy and efficiency of 2-D scope use in the "3-D first" group for performing simple motor tasks such as dotted-line drawing ( P = 0.002), but no benefit was observed for complex motor tasks. Conclusions Our data do not support the superiority of the 3-D endoscope over its conventional 2-D congener, although its use may shorten the learning curve associated with neuroendoscopy, regardless of subjects' prior experience with neuroendoscopy.

Previously considered the domain of the otolaryngologists, the endoscopy is now a common part of the armamentarium of a neurosurgeon. Neuroendoscopy or endoscope-assisted microsurgery is now being used in almost all routine procedures performed in the neurosurgical operating room. Hands-on training has become essential to learn the basics of neuroendoscopy, even for neurosurgeons well accustomed to the use of microscopes. To decrease the slope of the learning curve of residents during their training and reduce complications of procedures, most neurosurgery training programs around the world have incorporated laboratory or dissection programs in their curricula. Preconference workshops held during annual meetings are also an excellent tool to aid in the transition of surgeons from being a resident under the umbrella of an attending neurosurgeon to being a neurosurgeon able to operate independently and with confidence. In this "tech-savvy era," various cadaver or synthetic models are readily available for endoscopy training in a virtually simulated environment. In accord with the results of a surveys conducted by individual groups and societies, the authors firmly believe that incorporation of endoscopy in the neurosurgical curriculum would add a new dimension to the existing protocol. There is an urgent need for dedicated endoscopy training programs similar to postresidency fellowships in addition to translational research and establishment of dedicated societies to formulate guidelines for such research and monitor its progress.