Bone-anchored annular closure device leading to histiocytic-inflammation-induced neuropathy with resolution after removal: a case report.

PURPOSE: To determine and report the underlying cause of local inflammation causing recurrent neuropathy and multiple operations in a patient with a Barricaid® device. METHODS: After removal of this patient's Barricaid® device, we sent local inflammatory tissue to pathology for histochemical analysis. Upon discovery of giant cells formation with polarizable foreign bodies, we performed a literature review regarding the Barricaid® device and its elements. RESULTS: After two previous operations and three trials of conservative management, the presented patient underwent an L5/S1 TLIF with removal of her previously installed Barricaid® device. There were no signs of device instability/failure nor were there obvious signs of infection. Inflamed tissue proximal to the Barricaid® device was discovered, debrided, and sample sent to pathology. Removal of the Barricaid® device led to subsequent and durable relief of her symptoms. During review of this case, we discovered the polyethylene terephthalate (PET) weave used in the Barricaid® device is known to induce foreign body reactions, and this precise finding was seen in the majority of animal data submitted to the FDA for the device's acceptance. CONCLUSION: Given the constellation of this patient's symptoms, imaging, intraoperative, and pathology findings, previously published reports, and pre-approval data submitted to the FDA, we conclude that the inflammatory response to the PET weave in this patient's Barricaid® device was the ultimate cause of her continued neuropathy despite multiple prior surgical interventions.

Single-level awake transforaminal lumbar interbody fusion: a Mayo Clinic institutional experience and national analysis.

OBJECTIVE: Awake transforaminal lumbar interbody fusion (TLIF) is a novel technique for performing spinal fusions in patients under conscious sedation. Whether awake TLIF can reduce operative times and decrease the hospital length of stay (LOS) remains to be shown. In this study, the authors sought to assess the differences in clinical outcomes between patients who underwent awake TLIF and those who underwent TLIF under general anesthesia by using institutional experience at the Mayo Clinic and the National Surgical Quality Improvement Program (NSQIP) database. METHODS: Chart review was performed for a consecutive series of patients who underwent single-level minimally invasive surgery (MIS)-TLIF performed by a single surgeon (K.A.I.) at a single institution. Additionally, the NSQIP database was queried from 2016 to 2019 for patients who underwent awake TLIF as well as propensity score-matched patients who underwent TLIF under general anesthesia. RESULTS: A total of 20 patients at Mayo Clinic underwent awake single-level MIS-TLIF. The mean operative time was 122 ± 16.68 minutes, and the mean estimated blood loss was 39 ± 30.24 ml. No intraoperative complications were reported. A total of 96 patients who underwent TLIF (24 awake and 72 under general anesthesia) were analyzed from the NSQIP database. The mean LOS was less in the awake cohort (1.4 ± 1.381 days) than the general anesthesia cohort (3 ± 2.274 days) (p = 0.002). CONCLUSIONS: Evidence from the authors' institutional experience and national analysis has demonstrated that awake MIS-TLIF is efficient and can reduce hospital LOS.

General Versus Nongeneral Anesthesia for Spinal Surgery: A Comparative National Analysis of Reimbursement Trends Over 10 Years.

BACKGROUND AND OBJECTIVES: Nongeneral anesthesia (non-GA) spine surgery is growing in popularity and has facilitated earlier postoperative recovery, reduced cost, and fewer complications compared with spine surgery under general anesthesia (GA). Changes in reimbursement policies have been demonstrated to correlate with clinical practice; however, they have yet to be studied for GA vs non-GA spine procedures. We aimed to investigate trends in physician reimbursement for GA vs non-GA spine surgery in the United States. METHODS: We queried the ACS-NSQIP for GA and non-GA (regional, epidural, spinal, and anesthesia care/intravenous sedation) spine surgeries during 2011-2020. Work relative value units per operative hour (wRVUs/h) were retrieved for decompression or stabilization of the cervical, thoracic, and lumbar spine. Propensity score matching (1:1) was performed using all baseline variables. RESULTS: We included 474 706 patients who underwent spine decompression or stabilization procedures. GA was used in 472 248 operations, whereas 2458 operations were non-GA. The proportion of non-GA spine operations significantly increased during the study period. Operative times ( P < .001) and length of stays ( P < .001) were shorter in non-GA when compared with GA procedures. Non-GA lumbar procedures had significantly higher wRVUs/h when compared with the same procedures performed under GA (decompression; P < .001 and stabilization; P = .039). However, the same could not be said about cervicothoracic procedures. Lumbar decompression surgeries using non-GA witnessed significant yearly increase in wRVUs/h ( P < .01) contrary to GA ( P = .72). Physician reimbursement remained stable for procedures of the cervical or thoracic spine regardless of the anesthesia. CONCLUSION: Non-GA lumbar decompressions and stabilizations are associated with higher and increasing reimbursement trends (wRVUs/h) compared with those under GA. Reimbursement for cervical and thoracic surgeries was equal regardless of the type of anesthesia and being relatively stable during the study period. The adoption of a non-GA technique relative to the GA increased significantly during the study period.

What Factors Predict the Development of Neurologic Deficits Following Resection of Intramedullary Spinal Cord Tumors: A Multi-Center Study.

BACKGROUND: Intramedullary spinal cord tumors are challenging to resect, and their postoperative neurological outcomes are often difficult to predict, with few studies assessing this outcome. METHODS: We reviewed the medical records of all patients surgically treated for Intramedullary spinal cord tumors at our multisite tertiary care institution (Mayo Clinic Arizona, Mayo Clinic Florida, Mayo Clinic Rochester) between June 2002 and May 2020. Variables that were significant in the univariate analyses were included in a multivariate logistic regression. "MissForest" operating on the Random Forest algorithm, was used for data imputation, and K-prototype was used for data clustering. Heatmaps were added to show correlations between postoperative neurological deficit and all other included variables. Shapley Additive exPlanations were implemented to understand each feature's importance. RESULTS: Our query resulted in 315 patients, with 160 meeting the inclusion criteria. There were 53 patients with astrocytoma, 66 with ependymoma, and 41 with hemangioblastoma. The mean age (standard deviation) was 42.3 (17.5), and 48.1% of patients were women (n = 77/160). Multivariate analysis revealed that pathologic grade >3 (OR = 1.55; CI = [0.67, 3.58], P = 0.046 predicted a new neurological deficit. Random Forest algorithm (supervised machine learning) found age, use of neuromonitoring, histology of the tumor, performing a midline myelotomy, and tumor location to be the most important predictors of new postoperative neurological deficits. CONCLUSIONS: Tumor grade/histology, age, use of neuromonitoring, and myelotomy type appeared to be most predictive of postoperative neurological deficits. These results can be used to better inform patients of perioperative risk.

Reliability of YouTube videos on robotic spine surgery for patient education.

BACKGROUND: Robotic surgical systems developed to improve spine surgery accuracy. Studies have found significant reductions in screw revisions and radiation exposure with robotic assistance compared with open surgery. YouTube is the largest online video platform for medical education. Therefore, there is a need for the continuous critical assessment of healthcare-related YouTube videos. Our objective is to assess the reliability of YouTube videos on robotic spine surgery for patient education. METHODS: In April of 2022, YouTube was queried for the following keywords: "Robotic Spine Surgery". The "Relevance-Based Ranking" filter was applied, and the first 3 result pages were considered. Videos had to be uploaded by universities or hospitals and be in the English. Three independent healthcare personnel evaluated the videos' education quality using the DISCERN tool. RESULTS: Our study found that 33 % of videos analyzed scored above a 3 on the DISCERN scoring scale (considered a ''good" video), with overall mean DISCERN score of 2.8 ± 1.3 (SD). The duration of videos was significantly different between the two groups (Good = 16 min ± 21 vs Unhelpful = 4 min ± 4, p = 0.01). In the helpful group, other characteristics were number of views (16331 ± 31308), likes (88 ± 168) and dislikes (5 ± 8). No statistically significant differences were observed compared to the unhelpful group: number of views (6515 ± 9074; P = 0.20), likes (39 ± 55; P = 0.21) and dislikes (3 ± 4; P = 0.33). CONCLUSION: Our study shows that YouTube videos on robotic spine surgery lack accuracy and have poor educational value. There should be increased institutional oversight to combat the spread of misinformation.

Augmented Reality in Minimally Invasive Spinal Surgery: A Narrative Review of Available Technology.

INTRODUCTION: Spine surgery has undergone significant changes in approach and technique. With the adoption of intraoperative navigation, minimally invasive spinal surgery (MISS) has arguably become the gold standard. Augmented reality (AR) has now emerged as a front-runner in anatomical visualization and narrower operative corridors. In effect, AR is poised to revolutionize surgical training and operative outcomes. Our study examines the current literature on AR-assisted MISS, synthesizes findings, and creates a narrative highlighting the history and future of AR in spine surgery. MATERIAL AND METHODS: Relevant literature was gathered using the PubMed (Medline) database from 1975 to 2023. Pedicle screw placement models were the primary intervention in AR. These were compared to the outcomes of traditional MISS RESULTS: We found that AR devices on the market show promising clinical outcomes in preoperative training and intraoperative use. Three prominent systems were as follows: XVision, HoloLens, and ImmersiveTouch. In the studies, surgeons, residents, and medical students had opportunities to operate AR systems, showcasing their educational potential across each phase of learning. Specifically, one facet described training with cadaver models to gauge accuracy in pedicle screw placement. AR-MISS exceeded free-hand methods without unique complications or contraindications. CONCLUSIONS: While still in its infancy, AR has already proven beneficial for educational training and intraoperative MISS applications. We believe that with continued research and advancement of this technology, AR is poised to become a dominant player within the fundamentals of surgical education and MISS operative technique.

Application of Color Doppler Ultrasound to Identify and Repair Postoperative Cerebrospinal Fluid Leak: A Technical Note.

BACKGROUND: Incidental durotomy is a known complication of spinal surgery. Persistent cerebrospinal fluid (CSF) leak after unrecognized durotomy may lead to prolonged hospitalization and significant morbidity. If initial bed rest fails, the surgeon must choose between nontargeted methods such as oversewing the wound and lumbar drain placement or return to the operating room. OBJECTIVE: To report the novel use of color flow doppler (CFD) in conjunction with ultrasound (US) to localize the point of CSF leak, assist with aspiration of the pseudomeningocele, and direct the application of fibrin sealant or epidural blood patch. METHODS: This article includes a description of the technique as a technical note. RESULTS: A 72-year-old man underwent L2-5 laminectomies for spinal stenosis. During the index operation, a durotomy occurred and was repaired primarily. The patient subsequently developed leg weakness, back pain, and bulging of the incision. Using CFD, the site of durotomy was determined. Under direct visualization, 34 mL of CSF was aspirated from the pseudomeningocele and 20 mL of fibrin sealant was placed opposing the durotomy. At 2-month follow-up, CFD confirmed absent flow and MRI demonstrated pseudomeningocele resolution. CONCLUSION: This article represents the first report highlighting the utility of CFD US to guide epidural patch placement for postsurgical CSF leaks. CFD allows localization of the durotomy and direct application of blood or fibrin sealant, potentially increasing the success rate of epidural blood patch in postoperative patients. This approach is less invasive than revision surgery and does not require the prolonged hospitalization of lumbar drainage or other nontargeted interventions.

Interactive Neurosurgery Lecture Series: A Global Education Platform of Tele-Teaching During the Coronavirus Disease 2019 Pandemic and Beyond.

OBJECTIVE: To explore the worldwide impact of a virtual neurosurgery-neuroscience lecture series on optimizing neurosurgical education with tele-teaching. METHODS: A retrospective analysis was performed from our Zoom database to collect data from October 15, 2020, to December 14, 2020, and from September 27, 2021, to December 13, 2021. A comparative analysis of participants in the 2 different time frames was performed to investigate the impact of tele-teaching on neurosurgical education worldwide. To evaluate participant satisfaction, the yearly continuing medical education reports of 2020-2021 were analyzed. Data related to the distribution of lectures by subspecialties were also described. RESULTS: Among the 11 lectures of the first period, 257 participants from 17 countries in 4 different continents were recorded, with a mean of 64 (standard deviation = 9.30) participants for each meeting; 342 attendees participated from 19 countries in 5 continents over the 11 lectures of the second part, with an average of 82.8 (standard deviation = 14.04) attendees; a statistically significant increase in participation between the 2 periods was identified (P < 0.001) A total of 19 (2020) and 21 (2021) participants submitted the continuing medical education yearly survey. More than 86.4% of overall responses considered the lectures "excellent." The main topics reported during lectures in 2020-2021 were related to brain tumors (33.7%) and education (22.1%). CONCLUSIONS: The COVID-19 pandemic has increased the need to introduce new educational approaches for teaching novel ways to optimize patient care. Our multidisciplinary Web-based virtual lecture series could represent an innovative tele-teaching platform in neurosurgical training.

Preoperative embolization of the external carotid artery branches as an adjunct to superficial temporal artery-to-middle cerebral artery bypass.

When technically feasible, the preferred revascularization procedure in patients with adult moyamoya disease is a superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass. The caliber of the STA has been reported as a prognostic factor for a successful bypass, with smaller-caliber STA being more likely to fail. We describe a novel approach to this circumstance in which preoperative embolization of external carotid artery (ECA) branches is used to augment blood flow through a small STA as a prelude to bypass surgery. We report 2 cases: a 42-year-old female presenting with symptomatic ischemic and radiographically progressive moyamoya disease and a 23-year-old female presenting with advanced moyamoya disease secondary to diabetes. Preoperative angiography demonstrated small-caliber STAs in each case, and primary revascularization was deemed difficult. Preoperative ECA embolization was undertaken to shunt blood toward the STA, thereby increasing its flow and caliber. In both cases, angiography after embolization demonstrated a 20%-45% increase in STA size, and doppler ultrasound indicated a 14%-50% increase in flow. Subsequently, both patients underwent successful STA-MCA bypass combined with encephalomyosynangiosis without complications. Of 167 STA-MCA bypasses performed by the senior author, embolization was performed in 7 unique patients on 9 sides. ECA embolization may be a beneficial adjunct when considering a direct bypass in the setting of a small STA. It can increase blood flow through the STA, making the operation technically easier and enhancing the patency of the bypass.

Initial Results of Precision Treatment of Postoperative Cerebrospinal Fluid Leak with Ultrasound-Guided Epidural Blood Patch.

BACKGROUND: Incidental durotomy, a known complication of spinal surgery, can lead to persistent cerebrospinal fluid leak and pseudomeningocele if unrecognized or incompletely repaired. We describe the use of ultrasound to visualize the site of durotomy, observe the aspiration of the pseudomeningocele, and guide the precise application of an ultrasound-guided epidural blood patch (US-EBP), under direct visualization in real time. METHODS: A retrospective review was performed to determine demographic, procedural, and outcome characteristics for patients who underwent US-EBP for symptomatic postoperative pseudomeningocele. RESULTS: Overall, 48 patients who underwent 49 unique episodes of care were included. The average age and body mass index were 60.5 (±12.6) years and 27.8 (±4.50) kg/m2, respectively. The most frequent index operation was laminectomy (24.5%), and 36.7% of surgeries were revision operations. Durotomy was intended or recognized in 73.4% of cases, and the median time from surgery to symptom development was 7 (interquartile range 4-16) days. A total of 61 US-EBPs were performed, with 51.0% of patients experiencing resolution of their symptoms after the first US-EBP. An additional 20.4% were successful with multiple US-EBP attempts. Complications occurred in 14.3% of cases, and the median clinical follow-up was 4.3 (interquartile range 2.4-14.5) months. CONCLUSIONS: This manuscript represents the largest series in the literature describing US-EBP for the treatment of postoperative pseudomeningocele. The success rate suggests that routine utilization of US-guided EBP may allow for targeted treatment of pseudomeningoceles, without the prolonged hospitalization associated with lumbar drains or the risks of general anesthesia and impaired wound healing associated with surgical revision.

Initiation of a Robotic Program in Spinal Surgery: Experience at a Three-Site Medical Center.

OBJECTIVE: To highlight the early experience of implementing a robotic spine surgery program at a three-site medical center, evaluating the impact of increasing experience on the operative time and number of procedures performed. PATIENTS AND METHODS: A retrospective chart review of patients undergoing robotic screw placement between September 4, 2018, and October 16, 2019, was conducted. Baseline characteristics as well as intraoperative and post-operative outcomes were obtained. RESULTS: For a total of 77 patients, the mean age (SD) was 55.7 years (11.5) and 49.4% (n=38) were female. A total of 402 screws were placed (384 pedicle screws, 18 cortical screws) using robotic guidance with a median of two operative levels (interquartile range [IQR], 1 to 2). Median (IQR) estimated blood loss was 100 mL (50 to 200 mL) and the median (IQR) operative time was 224 minutes (193 to 307 minutes). With accrual of surgical experience, operative time declined significantly (R=-0.39; P<.001) whereas the number of procedures performed per week increased (R=0.30; P=.05) throughout the study period. Median (IQR) length of hospital stay following surgery was 2 days (IQR, 2 to 3 days). There were two screws requiring revision intraoperatively. No postoperative revisions were required, and no complications were encountered related to screw placement. CONCLUSION: Early experience at our institution using a spinal robot has demonstrated no requirement for postoperative screw revisions and no complications related to screw malposition. The increased operative times were reduced as the frequency of procedures increased. Moreover, procedural times diminished over a short period with a weekly increasing number of procedures.

Neurosurgical Interactive Teaching Series: Multidisciplinary Educational Approach.

OBJECTIVE: The goal of this manuscript is to investigate the effects of a multidisciplinary multinational web-based teaching conference on trainee education, research, and patient care. METHODS: We present the structure, case selection, and presentation of our educational lectures. We retrospectively reviewed our database to gather data on the number of presentations, type of presentation, and the pathology diagnosis from November 11, 2016 until February 28, 2020. To investigate attendee satisfaction, we analyzed our yearly continuing medical education evaluation survey results to report the impact that this series may have had on our attendees. We assigned a numeric value to the answers, and the mean overall scores were compared through an analysis of variance. Further analysis on specific questions was performed with a Fisher exact test. RESULTS: We have hosted 150 lectures, in which we have presented 208 neurosurgical cases corresponding to 133 general session, 59 pituitary, and 16 spine cases, as well as 28 distinct lectures by guest speakers from institutions across the globe. We received 61 responses to our yearly continuing medical education evaluations over the course of 3 years. On these evaluations, we have maintained an excellent overall rating from 2017-2019 (two-sided P > 0.05) and received significantly less suggestions to improve the series comparing 2017 with 2019 (two-sided, P= 0.04). CONCLUSIONS: As the world of medicine is constantly changing, we are in need of developing new tools to enhance our ability to relay knowledge through accredited and validated methods onto physicians in training, such as the implementation of structured, multidisciplinary, case-based lectures as presented in this manuscript.

Atlantooccipital Synovial Cyst with Isolated Hypoglossal Nerve Palsy: Case Report of Nonfusion Surgical Approach and Review of Literature.

BACKGROUND: Isolated hypoglossal nerve palsy caused by an atlantooccipital synovial cyst is a rare lesion, with fewer than 5 cases reported in the literature. CASE DESCRIPTION: Our patient presented with acute hypoglossal nerve dysfunction. Our differential included neoplasm, trauma, stroke, multiple sclerosis, or other inflammatory/infectious etiology. Imaging revealed a peripherally enhancing, extradural focus in the left premedullary cistern, most likely consistent with a synovial cyst. CONCLUSIONS: A left suboccipital craniectomy was performed in the region of the left hypoglossal canal, in which a cystic structure was noted at the occipital condyle and C1 vertebral junction. The nerve was adequately decompressed via aspiration of the cyst. Postoperatively, the patient substantially improved. Although rare, synovial cysts must be included in the differential diagnosis of atlantooccipital lesions.

A Feasibility Study for the Production of Three-dimensional-printed Spine Models Using Simultaneously Extruded Thermoplastic Polymers.

Background Medical simulation is an emerging field for resident training. Three-dimensional printing has accelerated the development of models for spine surgical simulation. Previous models have utilized augmented infill ratios to simulate the density difference between cortical and cancellous bone; however, this does not fully account for differences in the material properties of these components of human vertebrae. In order to replicate the differences in both density and material characteristics for realistic spinal simulation, we created a three-dimensional model composed of multiple thermoplastic polymers. Materials and methods Three lumbar vertebrae and 20 C2 vertebrae models using an experimental dual material fabrication method were printed on an Ultimaker S5 3D printer. Assessment of model integrity during instrumentation as well as user tactile feedback were points of interest to determine prototype viability for educational and biomechanical use. The experimental cohort was compared with a control cohort consisting of a single material print, resin print, and polyurethane mold. Results Based on tactile feedback, the experimental dual material print (polylactic acid [PLA]/polyvinyl alcohol [PVA]) more accurately represented the sensation of in vivo instrumentation during pedicle probing, pedicle tapping, and screw placement. There were no instrumentation or material failures in the PLA/PVA experimental model cohort. Conclusions This feasibility study indicates that multiple material printing using PLA and PVA is a viable method to replicate the cortico-cancellous interface in vertebral models. This concept and design using our unique infill algorithm have not been yet reported in the medical literature. Further educational and biomechanical testing on our design is currently underway to establish this printing method as a new standard for spinal biomimetic modeling.

Troubleshooting a Rare Anatomic Variation with Intraoperative Navigation in a Patient with Bilateral C2 Pars Fractures.

C2 pars fractures occur most commonly after traumatic hyperextension injuries. Although a significant number of cases may heal with conservative measures, some require surgical intervention. Anatomical variations of the V3 segment of the vertebral artery are not uncommon and may present an obstacle to safe instrumentation. Intraoperative CT-guided navigation is a useful tool in these cases, but the limitations of accuracy in the upper cervical spine especially in the context of unstable injuries must be understood to avoid complication. In this case we present a rare anatomic variation of the vertebral artery size and position in conjunction with bilateral C2 pars fractures treated successfully by surgical fixation. This article highlights the important technical details of the posterior instrumentation of unstable atlas pars fractures with the aid of intraoperative navigation.

Prognostic factors and survival in low grade gliomas of the spinal cord: A population-based analysis from 2006 to 2012.

PURPOSE: Primary spinal cord tumors are rare, and evidence-based management of these patients remains a source of controversy. This study used a large cohort of low-grade spinal cord astrocytomas to determine the effectiveness of prognostic factors and survival. METHODS: The Surveillance, Epidemiology, and End Results (SEER) cancer registry was used to identify patients with WHO grade I-II primary spinal cord astrocytomas from 1973 to 2012; however, patients before 2006 were excluded due to ambiguity diagnosis. Univariate and multivariate Cox proportional hazard models were created to compare survival across covariates and summarized using the Kaplan-Meier method. RESULTS: A total of 561 patients with low-grade glioma (astrocytoma) were identified. Among these, 15.5% of patients received a gross total resection (GTR), 26.1% subtotal resection (STR), and 46.2% unidentified extent of resection. 59.4% did not receive any radiation therapy at any point of the treatment course, while 40.6% underwent radiation therapy. In our cohort, only patients with GTR demonstrated statistically improved survival (HR: 0.22, P < 0.001). Patients with STR had nearly identical survival compared to patients with no surgery (HR: 0.98), and radiotherapy was associated with increased odds of mortality (HR: 1.47, P < 0.001). Multivariate analysis demonstrated a significant survival benefit among patients with younger age, GTR and absence of radiotherapy. Histologic grade did not statistically impact survival. CONCLUSION: Our study suggests that GTR results in improved survival among patients with low-grade gliomas within the spinal cord. Future, considerable data research efforts will aim to better define the role of radiotherapy and tumor grading in this patient population.

Open Versus Minimally Invasive Surgery for Extraforaminal Lumbar Disk Herniation: A Systematic Review and Meta-Analysis.

INTRODUCTION: Extraforaminal disk herniation (EDH) accounts for 3%-11% of all disk herniations. Despite the heterogeneity of spinal procedures, there is a paucity of literature comparing the outcomes from different surgical approaches. METHODS: We performed a systematic review and meta-analysis of available literature on EDHs. We compared patients undergoing open surgery (OS) with those undergoing minimally invasive surgery (MIS) approaches, including tubular microscopic, percutaneous endoscopic, and microendoscopic. RESULTS: A total of 41 studies with 1813 patients (1239 OS, 574 MIS) were included our analysis. The MIS group showed no significant difference from OS group in the incidence of complications (MIS: 0.01 vs. OS: 0.01, P = 0.971) or reoperation (OS: 0.04, MIS: 0.03; P = 0.382). There was an increased incidence of poor patient satisfaction according to the Macnab criteria for the OS group compared with the MIS group, but the difference was not statistically significant (OS: 0.14 vs. MIS: 0.06; P = 0.237). The OS group had greater estimated blood loss (mean difference [MD]: 38.6 mL), slightly longer operation time (MD: 12.2 minutes), longer hospital stay (MD: 30.3 hours), and longer return to work time (MD: 3.3 weeks). Tubular microscopic procedures had a lower incidence of reoperation than both percutaneous endoscopic (0.01 vs. 0.06, P = 0.01) and microendoscopic procedures (0.01 vs. 0.05, P = 0.03). CONCLUSIONS: Minimally invasive procedures for EDHs are associated with a similar incidence of complications and reoperation but lower estimated blood loss, shorter operative time, shorter hospital stay, and faster return to work time compared to OS. Tubular microscopic have the lowest reoperation rate of MIS procedures.

Meningiomas With Rhabdoid Features Lacking Other Histologic Features of Malignancy: A Study of 44 Cases and Review of the Literature.

The behavior of rhabdoid meningiomas otherwise lacking malignant features remains unknown as most of the originally reported aggressive cases showed anaplastic histologic features independently of rhabdoid phenotype. We studied 44 patients with rhabdoid meningiomas lacking anaplastic features. Median age at diagnosis was 48.6 years (range 10-79). Location was supratentorial in 28 (63.6%), skull base in 15 (34.1%), and spinal in 1 (2.3%). Tumor grade was otherwise World Health Organization grade I (n = 22, 50%) or II (n = 22, 50%). Rhabdoid cells represented <20% of the tumor in 12 cases (27.3%), 20% to 50% in 18 (40.9%), and >50% in 14 (31.8%). Median clinical follow-up, available for 38 patients, was 5.0 years (range 0.17-14.2). Recurrence occurred in 9 patients (5-year recurrence-free survival, 73.7%) with a significantly higher risk in subtotally resected tumors (p = 0.043). Rhabdoid cell percentage was not associated with recurrence. Six patients died (4 of disease, 2 of unclear causes); 5-year overall survival was 86.7%, a mortality in excess of that expected in grade I-II meningiomas but much lower than originally reported. Review of 50 similar previously reported cases confirmed our findings. We suggest that rhabdoid meningiomas be graded analogously to nonrhabdoid tumors, with caution that some may still behave aggressively and close follow-up is recommended.