Prevalence and Characteristics of Cervical Ossified Posterior Longitudinal Ligament in the Jewish Population.

BACKGROUND: Numerous studies have demonstrated an association between ethnic identity and the prevalence rate of cervical ossified posterior longitudinal ligament (C-OPLL). To date, its prevalence rate in the Jewish population has not been determined. The aim of this historical prospective study is to evaluate the prevalence and characteristics of C-OPLL in the Jewish population. METHODS: We performed a retrospective evaluation of imaging studies of all adult patients who underwent both cervical computed tomography and magnetic resonance imaging for all clinical indications within a span of 36 months between January 2017 and July 2020 at a single tertiary referral hospital located in central Israel. Identified C-OPLL carriers were interviewed by telephone. All the patients provided informed consent and then were questioned for current symptoms and demographics, including religion, Jewish ethnic identity, birthplace, parental birthplace and ethnic identity, and family history of spinal disorders. RESULTS: Overall, 440 participants were radiographically evaluated. The prevalence of C-OPLL in the Jewish population was 7.5% (33 of 440). The mean age of the C-OPLL carriers was 65.8 years. All the C-OPLL carriers were symptomatic at analysis. The carriers had an increased proportion with a Sephardic Jewish ethnic identity (65.4%), with a significantly high rate of homogeneous parental Jewish identity (92.4%), suggesting a prominent genetic contribution to the development of this condition. CONCLUSIONS: The prevalence of C-OPLL in the Jewish population in central Israel was 7.5%. This rate is significantly higher than that in other previously studied populations. To the best of our knowledge, this is the first study to identify the Jewish population as experiencing an increased prevalence of C-OPLL.

MRI-based detection of cervical ossification of the posterior longitudinal ligament using a novel automated machine learning diagnostic tool.

OBJECTIVE: Currently, CT is considered the gold standard for the diagnosis of ossification of the posterior longitudinal ligament (OPLL). The objective of this study was to develop artificial intelligence (AI) software and a validated model for the identification and representation of cervical OPLL (C-OPLL) on MRI, obviating the need for spine CT. METHODS: A retrospective evaluation was performed of consecutive imaging studies of all adult patients who underwent both cervical CT and MRI for any clinical indication within a span of 36 months (between January 2017 and July 2020) in a single tertiary-care referral hospital. C-OPLL was identified by a panel of neurosurgeons and a neuroradiologist. MATLAB software was then used to create an AI tool for the diagnosis of C-OPLL by using a convolutional neural network method to identify features on MR images. A reader study was performed to compare the performance of the AI model to that of the diagnostic panel using standard test performance metrics. Interobserver variability was assessed using Cohen's kappa score. RESULTS: Nine hundred consecutive patients were found to be eligible for radiological evaluation, yielding 65 identified C-OPLL carriers. The AI model, utilizing MR images, was able to accurately segment the vertebral bodies, PLL, and discoligamentous complex, and detect C-OPLL carriers. The AI model identified 5 additional C-OPLL patients who were not initially detected. The performance of the MRI-based AI model resulted in a sensitivity of 85%, specificity of 98%, negative predictive value of 98%, and positive predictive value of 85%. The overall accuracy of the model was 98%, with a kappa score of 0.917. CONCLUSIONS: The novel AI software developed in this study was highly specific for identifying C-OPLL on MRI, without the use of CT. This model may obviate the need for CT scans while maintaining adequate diagnostic accuracy. With further development, this MRI-based AI model has the potential to aid in the diagnosis of various spinal disorders and its automated layers may lay the foundation for MRI-specific diagnostic criteria for C-OPLL.

The use of a new high-speed shielded curved drill is associated with improved intraoperative and clinical outcomes after cervical corpectomy and fusion procedures: a retrospective case series.

BACKGROUND: Anterior cervical corpectomy and fusion (ACCF) is an effective technique to address multi-level degenerative cervical myelopathy. However, as the number of surgical levels increases, the outcomes worsen with respect to complication rates, range of motion and length of surgery. This study aimed to determine the clinical outcome of ACCF procedures performed using a new distally curved and shielded drilling device. METHODS: A retrospective study was conducted on 43 ACCF procedures in which the device was used for osteophyte removal. Patient files were reviewed to assess the early clinical results and complications following ACCF. Clinical outcomes were evaluated using patient neck and arm pain scores and SF-36 questionnaires. Hospitalization characteristics were compared with historical controls. RESULTS: All procedures were uneventful and without major complications or neurological deterioration. Single-level ACCF procedures required an average of 71 min and followed by an average hospitalization of 3.3 days. Osteophyte removal, verified by intraoperative imaging, was satisfactory. Average neck pain score was improved by 0.9 points (p = 0.24). Average arm pain score was improved by 1.8 points (p = 0.06). SF-36 scores were improved in all domains. CONCLUSIONS: The new curved device enabled safe and efficient removal of osteophytes sparing adjacent vertebral removal in ACCF procedures, thus improving the clinical outcome.

The Evolution of Minimally Invasive Spine Tumor Resection and Stabilization: From K-Wires to Navigated One-Step Screws.

Minimization of the surgical approaches to spinal extradural metastases resection and stabilization was advocated by the 2012 Oncological Guidelines for Spinal Metastases Management. Minimally invasive approaches to spine oncology surgery (MISS) are continually advancing. This paper will describe the evolution of minimally invasive surgical techniques for the resection of metastatic spinal lesions and stabilization in a single institute. A retrospective analysis of patients who underwent minimally invasive extradural spinal metastases resection during the years 2013-2019 by a single surgeon was performed. Medical records, imaging studies, operative reports, rates of screw misplacement, operative time and estimated blood loss were reviewed. Detailed description of the surgical technique is provided. Of 138 patients operated for extradural spinal tumors during the study years, 19 patients were treated in a minimally invasive approach and met the inclusion criteria for this study. The mortality rate was significantly improved over the years with accordance of improve selection criteria to better prognosis patients. The surgical technique has evolved over the study years from fluoroscopy to intraoperative 3D imaging and navigation guidance and from k-wire screw insertion technique to one-step screws. Minimally invasive spinal tumor surgery is an evolving technique. The adoption of assistive devices such as intraoperative 3D imaging and one-step screw insertion systems was safe and efficient. Oncologic patients may particularly benefit from the minimization of surgical decompression and fusion in light of the frailty of this population and the mitigated postoperative outcomes associated with MIS oncological procedures.

Post-operative dysphagia following ventral cervical approach: complication or side-effect? Retrospective analysis and review of the literature.

OBJECTIVE: To ameliorate the clinical decision-making process when debating between a ventral or dorsal cervical approach by elucidating whether post-operative dysphagia be regarded as a complication or a transient side effect. METHODS: A literature review of studies comparing complication rates following ventral and dorsal cervical approaches was performed. A stratified complication rate excluding dysphagia was calculated and discussed. A retrospective cohort of patients operated for degenerative cervical myelopathy in a single institution comprising 665 patients was utilized to analyze complication rates using a uniform definition for dysphagia. RESULTS: Both the ventral and the dorsal approach groups exhibited comparable neurological improvement rates. Since transient dysphagia was not considered a complication, the dorsal approach was associated with higher level of overall complications. CONCLUSIONS AND RELEVANCE: Inconsistencies in the definition of dysphagia following ventral cervical surgery impedes the interpretation of trials comparing dorsal and ventral complication rates. A uniform definition for complications and side effects may enhance the validity of medical trials.

C1 lateral mass screw insertion using cannulated, navigated screws: preliminary results of a novel technique.

PURPOSE: The upper cervical spine region is densely populated by neural and vascular structures impeding the approach for fusion surgery. Technological advancement simplify the approach to C1-C2 fusion, thus reduce risks. The current paper purpose is to describe initial experience with a novel technique modification for C1 lateral screw insertion that incorporates cannulated-navigated screw system with intra-operative 3D imaging. METHODS: A single-center single surgeon database was reviewed to identify all patients who underwent placement of C1 lateral mass screw insertion using the novel technique modification described below, on 2020. This cohort was retrospectively analyzed and compared with a cohort of patients who were operated on by the same surgeon with non-cannulated, navigated screws with intra-operative 3D imaging (O-arm, Medtronic, USA) between 2011 and 2019. Following navigated starting hole and drilling of the C1 lateral mass, a blunt guide-wire is used to palpate the hole and cannulated screw is advanced to the correct position over the wire. After initial purchase, a navigated screw driver is used for final screw depth position. RESULTS: Twelve C1 lateral mass screws were inserted in six patients using this novel cannulated-navigated screw placement technique and compared to 24 patients operated using navigated non-cannulated screws. Minimal Estimated Blood Loss (EBL) was recorded in five of six cases undergoing the novel cannulated navigated placement of C1 lateral mass screws. Comparison to non-cannulated cohort demonstrated an EBL of 83CC vs. 354CC (Not significant). Mean surgery time was 97min and 118min for the cannulated-navigated and navigated only procedures (p = 0.03, statistically significant) respectively. In the current cohort, all screws were rated in optimal position and no repositioning procedures were performed. CONCLUSION: The new method presented allows for faster and possibly safer and more accurate C1 lateral mass screw insertion.

Post-laminectomy Dorsal Cord Migration Resulting in Immediate Neurologic Deterioration during Ventral Meningioma Resection: Proposed Mechanism of Injury and Prevention Technique.

BACKGROUND: Ventral thoracic meningiomas may pose a technical challenge owing to a limited surgical corridor and the presence of long-standing ventral cord compression. Unopposed dorsal spinal cord migration may occur following a laminectomy resulting in immediate neurologic injury. We discuss the possible mechanism underlying such a phenomenon, suggesting alternative approach to prevent neurologic injury. METHODS: Two patients operated on for ventral thoracic meningioma and sustained neurologic compromise were retrospectively evaluated. Image editing software was used for 3D modeling to simulate the possible underlying mechanism of injury. Cases where ventral thoracic meningiomas were approached via unilateral hemilaminectomy, performed in 2020, were retrospectively analyzed and compared with the laminectomy approach cohort. RESULTS: Two patients sustained postoperative neurologic function decline following resection of ventral thoracic meningioma via the laminectomy approach. Both exhibited permanent abolishment of transcranial motor evoked potentials (MEPs) following laminectomy. Based on the extrapolated 3D models for these two cases, dorsal cord migration was postulated as the cause for the acute neurologic compromise. CONCLUSION: Laminectomy for resection of thoracic ventral meningioma may lead in some cases to dorsal cord migration resulting in grave neurologic deterioration. Unilateral approach to these tumors restricts the dorsal migration and may mitigate neurologic outcomes.

A quantitative and comparative evaluation of stereotactic spine radiosurgery local control: proposing a consistent measurement methodology.

OBJECTIVE: Stereotactic body radiotherapy (SBRT) is a precise and conformal treatment modality used in the management of metastatic spine tumors. Multiple studies have demonstrated its safety and efficacy for pain and tumor control. However, no uniform quantitative imaging methodology exists to evaluate response to treatment in these patients. This study presents radiographic local control rates post-SBRT, systematically compares measurements acquired according to WHO and Response Evaluation Criteria in Solid Tumors (RECIST) criteria, and explores the relationship to patient outcome. METHODS: The authors performed a retrospective review of prospectively obtained data from a cohort of 59 consecutive patients (81 metastatic isocenters) treated with SBRT and followed with serial MRI scans. Measurements were performed by a neuroradiologist blinded to the patients' clinical course. Local control status was determined according to both WHO and RECIST measurements, and agreement between the measuring methodologies was calculated and reported. RESULTS: Eighty-one isocenters (111 vertebral bodies) were treated with SBRT. The mean treatment dose was 13.96 Gy and the median follow-up duration was 10.8 months, during which 408 MRI scans were evaluated with both WHO and RECIST criteria for each scan point. Imaging demonstrated a mean unidimensional size decrease of 0.2 cm (p = 0.14) and a mean area size decrease of 0.99 cm2 (p = 0.03). Although 88% of the case classifications were concordant and the agreement was significant, WHO criteria were found to be more sensitive to tumor size change. The local control rates according to WHO and RECIST were 95% and 98%, respectively. CONCLUSIONS: Although WHO volumetric measurements are admittedly superior for tumor size measurement, RECIST is simpler, reproducible, and for the first time is shown here to be comparable to WHO criteria. Thus, the application of RECIST methodology appears to be a suitable standard for evaluating post-SBRT treatment response. Moreover, using comprehensive and consistent measuring approaches, this study substantiates the efficacy of SBRT in the treatment of spine metastases.

Short-term post-operative complications in 207 patients with multi-level degenerative cervical myelopathy: the effect of surgical approach.

INTRODUCTION: Degenerative cervical myelopathy (DCM) is a common condition often treated by surgical decompression and fusion. The objective of this paper was to compare short-term post-operative complication rates of patients with multi-level DCM treated with decompression and fusion using either an anterior or a posterior cervical approach. MATERIAL AND METHODS: A retrospective evaluation of patients' charts, imaging studies and operative reports of patients operated for multilevel subaxial DCM from 2011 to 2016 at a single institution was performed. Patients who were operated upon for the treatment of three stenosed spinal levels or above and who underwent anterior cervical discectomy and fusion, or anterior cervical corpectomy and fusion, or posterior cervical laminectomy and fusion, were included. Short-term post-operative complications were compared between the anterior and posterior approaches. RESULTS: Overall, 207 patients were included in this study. 156 were operated via an anterior approach and 51 via a posterior approach. The mean number of treated levels was 3.4 and 4.3 for the anterior and posterior approach groups, respectively (p < 0.001). In the posterior approach group, the proportion of stenosed spinal levels within all operated levels was significantly lower than in the anterior approach group (p = 0.025). Early post-operative neurological status change was favourable for both groups. Deep wound infection rate was significantly higher in the posterior approach group (7.8% vs. none; p = 0.001). CONCLUSIONS: Posterior cervical laminectomy and fusion is significantly associated with an increased rate of deep wound infection and wound revision surgery compared to the anterior approach. We recommend the anterior approach as the valid option in treating multi-level DCM.

The XVS System During Open Spinal Fixation Procedures in Patients Requiring Pedicle Screw Placement in the Lumbosacral Spine.

OBJECTIVE: This pilot study was undertaken to evaluate the safety, performance, and usability of the Xvision-Spine (XVS) System (Augmedics, Arlington Heights, IL) during open spinal fixation procedures in patients requiring pedicle screw placement in the lumbosacral spine. METHODS: The XVS System is an augmented reality head-mounted display (HMD) based on a computer navigation system designed to assist surgeons in accurately placing pedicle screws. It uses an HMD-mounted tracking camera to provide optical tracking technology, and provides the surgeon a translucent direct near-eye display of the navigated surgical instrument's location relative to the computed tomographic image. We report the preliminary results of a prospective series of all consecutive patients who underwent augmented reality-assisted pedicle screw placement in the lumbosacral vertebrae at 3 institutions. Clinical accuracy for each pedicle screw was graded with Gertzbein-Robbins scores by 2 independent and blinded neuroradiologists. RESULTS: The 19 study participants included 8 men and 11 women with a mean age of 59.13 ± 12.09 and 59.91 ± 12.89 years, respectively. Seventeen procedures were successfully completed via the XVS System. Two procedures were not completed due to technical issues with the system's intraoperative scanner. A total of 86 screws were inserted. The accuracy of the XVS System was 97.7%. CONCLUSIONS: The XVS System's performance in accurate placement of pedicle screws in the lumbosacral vertebrae had an overall accuracy of 97.7%. These preliminary results were comparable to the accuracy of other manual computer-assisted navigation systems reported in the literature.

MRI blind zone: A proposed novel index for spinal implants artifacts.

BACKGROUND: To advocate the formulation of a new index termed MRI Blind Zone, designated to predict the dimensions of the magnetic resonance metallic artifact caused by specific spinal implants. The index may also specify the obscured organs of interest. METHODS: A retrospective evaluation of post-operative MR images of patients operated for spinal instrumentation with various implants from different materials, in our institution, was performed. The MRI blind zone was described for each product, and the related obscured region of interest was discussed. A proposed 3D model was created as an example for suggested future reporting by the implants' industry. RESULTS: Seven implant types are presented. The post-operative MR artifacts were detailed, and the clinical implications were discussed. Material type, processing methods and individual anatomical traits have a dramatic effect on the MRI blind zone and the obscured regions. CONCLUSION: MRI artifact is multifactorial and is influenced in part by the implant's shape, size, material and processing method. Individual products affect post-operative MR artifacts to different extents, and may carry clinical implications when post-operative imaging is required. A standardized index displaying the predicted post-operative artifact is warranted. For the manufacturers to accurately report the data to the surgeons, a parametric standardization should be performed. MRI blind zone index will allow surgeons to compare between different implants efficiently, and improve the informed decision-making process of implant selection.

Comparison of Frame-Based Versus Frameless Image-Guided Intracranial Stereotactic Brain Biopsy: A Retrospective Analysis of Safety and Efficacy.

BACKGROUND: A definitive diagnosis of brain lesions not amenable to surgery is mainly made by stereotactic needle biopsy. The diagnostic yield and safety of the frameless versus frame-based image-guided stereotactic techniques is unclear. Our objective was to evaluate the safety and accuracy of frameless versus frame-based stereotactic brain biopsy techniques. METHODS: A total of 278 patients (153 men; mean age: 65.5 years) with intra-axial brain lesions underwent frame-based (n = 148) or frameless image-guided stereotactic brain biopsy (n = 130) using a minimally invasive twist drill technique during 2010-2016 at Sheba Medical Center. Demographic, imaging, and clinical data were retrospectively analyzed. RESULTS: The diagnostic yield (>90%) did not differ significantly between groups. Overall morbidity (6.8% vs. 8.5%), incidence of permanent neurologic deficits (2.1% vs. 1.6%), mortality rate (0.7% vs. 0.8%), and postoperative computed tomography-detected asymptomatic (14.2% vs. 16.1%) and symptomatic (2.0% vs. 1.6%) bleeding also did not differ significantly between the frame-based and frameless cohorts, respectively. The diagnostic yield and complication rates related to the biopsy technique were not significantly associated with sex, age, entry angle to the skull and skull thickness, lesion location or depth, or radiologic characteristics. Diagnostic yield was significantly associated with the mean lesion volume. Smaller lesions were less diagnostic than larger lesions in both techniques (P = 0.043 frame-based and P = 0.048 frameless). CONCLUSIONS: The frameless biopsy technique is as efficient as the frame-based brain biopsy technique with a low complication rate. Lesion volume was the only predictive factor of diagnostic yield. The minimally invasive twist drill technique is safe and efficient.

Potential neurotoxicity of titanium implants: Prospective, in-vivo and in-vitro study.

Titanium dioxide (TiO2) is a frequently used biomaterial, particularly in orthopedic and dental implants, and it is considered an inert and benign compound. This has resulted in toxicological scrutiny for TiO2 in the past decade, with numerus studies showing potential pathologic downstream effects. Herein we describe case report of a 77-year-old male with subacute CNS dysfunction, secondary to breakdown of a titanium-based carotid stent and leading to blood levels 1000 times higher (3 ppm) than the reported normal. We prospectively collected tissues adjacent to orthopedic implants and found a positive correlation between titanium concentration and time of implant in the body (r = 0.67, p < 0.02). Rats bearing titanium implants or intravascularly treated with TiO2 nanoparticles (TiNP) exhibited memory impairments. A human blood-brain barrier (BBB) in-vitro model exposed to TiNP showed paracellular leakiness, which was corroborated in-vivo with the decrease of key BBB transcripts in isolated blood vessels from hippocampi harvested from TiNP-treated mice. Titanium particles rapidly internalized into brain-like endothelial cells via caveolae-mediated endocytosis and macropinocytosis and induced pro-inflammatory reaction with increased expression of pro-inflammatory genes and proteins. Immune reaction was mediated partially by IL-1R and IL-6. In summary, we show that high levels of titanium accumulate in humans adjacent to orthopedic implants, and our in-vivo and in-vitro studies suggest it may be neurotoxic.

Delayed variations in the diagnostic accuracy of intraoperative neuromonitoring in the resection of intramedullary spinal cord tumors.

OBJECTIVE: The use of intraoperative neuromonitoring (IONM) has become an imperative adjunct to the resection of intramedullary spinal cord tumors (IMSCTs). While the diagnostic utility of IONM during the immediate postoperative period has been previously studied, its long-term diagnostic accuracy has seldom been thoroughly assessed. The aim of this study was to evaluate long-term variations in the diagnostic accuracy of transcranial motor evoked potentials (tcMEPs), somatosensory evoked potentials (SSEPs), and D-wave recordings during IMSCT excision. METHODS: The authors performed a retrospective evaluation of imaging studies, patient charts, operative reports, and IONM recordings of patients who were operated on for gross-total or subtotal resection of IMSCTs at a single institution between 2012 and 2018. Variations in the specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) for postoperative functional outcome (McCormick Scale) were analyzed at postoperative day 1 (POD1), 6 weeks postoperatively (PO-6 weeks), and at the latest follow-up. RESULTS: Overall, 28 patients were included. The mean length of follow-up was 19 ± 23.4 months. Persistent motor attenuations occurred in 71.4% of the cohort. MEP was the most sensitive modality (78.6%, 87.5%, and 85.7% sensitivity at POD1, PO-6 weeks, and last follow-up, respectively). The specificity of the D-wave was the most consistent over time (100%, 83.35%, and 90% specificity at the aforementioned time points). The PPV of motor recordings decreased over time (58% vs 33% and 100% vs 0 for tcMEP and D-wave at POD1 and last follow-up, respectively), while their NPV consistently increased (67% vs 89% and 70% vs 100% for tcMEP and D-wave at POD1 and last follow-up, respectively). CONCLUSIONS: The diagnostic accuracy of IONM in the resection of IMSCTs varies during the postoperative period. The decrease in the PPV of motor recordings over time suggests that this method is more predictive of short-term rather than long-term neurological deficits. The increasing NPV of motor recordings indicates a higher diagnostic accuracy in the identification of patients who preserve neurological function, albeit with an increased proportion of false-negative alarms for the immediate postoperative period. These variations should be considered in the surgical decision-making process when weighing the risk of resection-associated neurological injury against the implications of incomplete tumor resection.

Utility of the Polestar N30 low-field MRI system for resecting non-enhancing intra-axial brain lesions.

BACKGROUND: To determine the utility of an intraoperative magnetic resonance imaging (iMRI) system, the Polestar N30, for enhancing the resection control of non-enhancing intra-axial brain lesions. MATERIALS AND METHODS: Seventy-three patients (60 males [83.3%], mean age 37 years) with intra-axial brain lesions underwent resection at Sheba Medical Centre using the Polestar between February 2012 and the end of August 2018. Demographic and imaging data were retrospectively analysed. Thirty-five patients had a non-enhancing lesion (48%). RESULTS: Complete resection was planned for 60/73 cases after preoperative imaging. Complete resection was achieved in 59/60 (98.3%) cases. After iMRI, additional resection was performed in 24/73 (32.8%) cases, and complete resection was performed in 17/60 (28.8%) cases in which a complete resection was intended. In 6/13 (46%) patients for whom incomplete resection was intended, further resection was performed. The extent of resection was extended mainly for non-enhancing lesions: 16/35 (46%) as opposed to only 8/38 (21%) for enhancing lesions. Further resection was not significantly associated with sex, age, intended resection, recurrence, or affected side. Univariate analysis revealed non-eloquent area, intended complete resection, and enhancing lesions to be predictive factors for complete resection, and non-enhancing lesions and scan time to be predictive factors for an extended resection. Non-enhancement was the only independent factor for extended resection. CONCLUSIONS: The Polestar N30 is useful for evaluating residual non-enhancing intra-axial brain lesions and achieving maximal resection.

Area-specific thalamocortical synchronization underlies the transition from motor planning to execution.

We studied correlated firing between motor thalamic and cortical cells in monkeys performing a delayed-response reaching task. Simultaneous recording of thalamocortical activity revealed that around movement onset, thalamic cells were positively correlated with cell activity in the primary motor cortex but negatively correlated with the activity of the premotor cortex. The differences in the correlation contrasted with the average neural responses, which were similar in all three areas. Neuronal correlations reveal functional cooperation and opposition between the motor thalamus and distinct motor cortical areas with specific roles in planning vs. performing movements. Thus, by enhancing and suppressing motor and premotor firing, the motor thalamus can facilitate the transition from a motor plan to execution.

One-step insertion of navigated pedicle screws in minimally invasive transforaminal lumbar interbody fusion (MITLIF): preliminary results of a novel technique.

OBJECTIVE: To describe a novel technique modification and evaluate initial results of pedicle screw insertion in minimally invasive transforaminal lumbar interbody fusion (MITLIF), using self-drilling self-tapping one-step screws. PATIENTS AND METHODS: All patients who were operated for MITLIF using the one-step technique over the last 6 months period at a single institute, were retrospectively identified. The surgical technique is described and depicted. Outcome evaluation was performed, including screw misplacement, screw insertion time, and post-operative complications. RESULTS: We describe a novel technique modification in which self-drilling self-tapping navigated screws incorporate an embedded K-wire that enables a one-step insertion which obviates the need for instrument exchange. The first four patients in whom this technique was implemented were included (mean age was 55). All patients had been previously operated at the fused level. The mean surgical duration was 142 minutes and the calculated mean screw insertion time was 8.2 minutes. The mean estimated blood loss was 66 cc. An intraoperative 3D scan demonstrated no screw pedicle breach. There were no neurological complications or wound healing disturbances. The clinical course was uneventful for all patients. CONCLUSION: To our knowledge, the use of one-step navigation-assisted self-drilling self-tapping pedicle screws with an embedded K-wire has not been previously described. Our initial experience with this novel technique modification was efficient and safe. Navigated surgery allows for newer and safer techniques to be incorporated into the surgeon's toolbox. Further studies should be performed to thoroughly evaluate this technique.

Surgical Management of Failed Endovascular Treatment for Spinal Dural Arteriovenous Fistulas.

BACKGROUND: Spinal dural arteriovenous fistulas (SDAVFs) are rare vascular malformations. Digital subtraction angiography is the modality of choice to demonstrate the malformation before endovascular embolization or open surgical repair. Angiographically occult SDAVFs have been previously reported. Surgical considerations in SDAVFs with misleading angiography findings have not yet been assessed. METHODS: A retrospective evaluation of charts and imaging files of patients operated on for SDAVF in 2018-2019 at a single institution was performed. All patients were referred to surgery following failure of endovascular embolization or owing to clinical and radiographic deterioration in the presence of an angiographically occult lesion. Cases were comprehensively reviewed and evaluated for surgical considerations in these lesions. RESULTS: This case series included 4 cases. Two patients underwent embolization before surgical repair but continued to deteriorate neurologically, and 2 patients had a failed embolization attempt owing to a torturous vascular network. In all 4 patients, exploration was successful, yielding either improvement or stabilization of neurological status. Indocyanine green injection for microscopically integrated fluorescent angiography contributed to the identification of the supplying vessels and confirmed the SDAVF closure. CONCLUSIONS: SDAVFs should be treated promptly after diagnosis. In cases with high suspicion for SDAVF with occult or misleading angiography findings, spinal exploration should be pursued with no delay. Indocyanine green-assisted microscopic angiography may contribute to exploratory spine surgery for SDAVF closure.

Minimally Invasive Spine Surgery: The Learning Curve of a Single Surgeon.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: The learning curve associated with the implementation of minimally invasive spinal surgery (MIS) has been the center of attention in numerous publications. So far, these studies referred to a single MIS procedure. In our view, minimally invasive surgical skills are acquired simultaneously through a variety of procedures that share common features. The aim of this study was to analyze the skills progression of a single surgeon implementing diverse minimally invasive techniques. METHODS: We retrospectively collected all patients who underwent spinal surgery for thoracic or lumbar pathology by a single surgeon between 2012 and 2015 at a single institute. Both minimally invasive as well as open surgical techniques were analyzed; these groups were compared on the basis of surgical indications and outcomes. Skills progression analysis in reference to minimally invasive technique was performed. RESULTS: A total of 230 patients met the inclusion criteria for this study. MIS group included higher percentage of lumbar discectomy and the open-surgery group included higher percentage of tumor resection surgery. Learning curve evaluation demonstrated increased surgical complexity, evaluated by number of levels treated, over the 4-year period, which corresponded with decreased complication rates. DISCUSSION: A gradual increase in surgical complexity over 4 years, together with careful patient selection, enables the surgeon to maintain the rate of complication within acceptable limits. The main challenge facing the MIS community is constructing an education program for MIS surgeons in order to reduce the learning curve-induced complications. CONCLUSION: Advancement of educational aids for MIS surgical skill improvement, including spine models, virtual and augmented reality aids and surgical simulators may reduce the learning curve of spine surgeons.

Integrity of the tectorial membrane is a favorable prognostic factor in atlanto-occipital dislocation.

Objective: Atlanto-occipital dislocation is usually considered to be a fatal injury or one that leaves the victim with serious neurological deficits. The aim of this study is to illustrate a novel positive prognostic factor for atlanto-occipital dislocation, based on cervical MRI studies of patients who suffered this injury.Methods: Over the course of the past year, the authors have treated three consecutive patients with atlanto-occipital dislocation who attained an excellent clinical outcome. We retrospectively evaluated clinical, surgical and radiographic parameters in search of a common denominator to explain the excellent outcome of these patients.Results: All patients presented with severe polytrauma that required urgent surgical intervention including two laparotomies and a thoracotomy. The patients were subsequently treated with an occipitocervical fusion. No patient developed neurological deficits on long-term follow-up. The cervical MRI studies of all patients were notable for a having a preserved tectorial membrane, while other primary stabilizers of the craniocervical junction such as the apical, alar and cruciate ligaments were shown to be severely disrupted. We consider this anatomical distinction to account for their benign clinical course.Conclusion: A preserved tectorial membrane appears to be an important favorable prognostic factor in atlanto-occipital dislocation and may serve to mitigate neurological outcome in such injuries. To determine the integrity of the ligament and consequently affect clinical management, expeditious MRI of the cranio-cervical junction should be considered routinely in such injuries in addition to cervical CT scans.