Learning Curves during Implementation of Robotic Stereotactic Surgery.

INTRODUCTION: Adoption of robotic techniques is increasing for neurosurgical applications. Common cranial applications include stereoelectroencephalography (sEEG) and deep brain stimulation (DBS). For surgeons to implement robotic techniques in these procedures, realistic learning curves must be anticipated for surgeons to overcome the challenges of integrating new techniques into surgical workflow. One such way of quantifying learning curves in surgery is cumulative sum (CUSUM) analysis. METHODS: Here, the authors present retrospective review of stereotactic cases to perform a CUSUM analysis of operative time for robotic cases at a single institution performed by 2 surgeons. The authors demonstrate learning phase durations of 20 and 16 cases in DBS and sEEG, respectively. RESULTS: After plateauing of operative time, mastery phases started at cases 132 and 72 in DBS and sEEG. A total of 273 cases (188 DBS and 85 sEEG) were included in the study. The authors observed a learning plateau concordant with change of location of surgery after exiting the learning phase. CONCLUSION: This study demonstrates the learning curve of 2 stereotactic workflows when integrating robotics as well as being the first study to examine the robotic learning curve in DBS via CUSUM analysis. This work provides data on what surgeons may expect when integrating this technology into their practice for cranial applications.

Isolated subependymal giant cell astrocytoma (SEGA) in the absence of clinical tuberous sclerosis: two case reports and literature review.

PURPOSE: Subependymal giant cell astrocytoma (SEGA) is a WHO grade I pediatric glioma arising in 5-15% of patients with tuberous sclerosis (TSC). Rare cases of isolated SEGA without TSC have been described. The etiology, genetic mechanisms, natural history, and response to treatment of these lesions are currently unknown. We describe two such cases of isolated SEGA with follow-up. METHODS: Retrospective review was performed at a single institution to describe the clinical course of pathology-confirmed SEGA in patients with germline testing negative for TSC mutations. RESULTS: Two cases of isolated SEGA were identified. Genetic analysis of the tumor specimen was available for one, which revealed an 18 base pair deletion in TSC1. Both cases were managed with surgical resection, one with preoperative embolization. In spite of a gross total resection, one patient experienced recurrence after three years. Treatment with an mTOR inhibitor led to a significant interval reduction of the mass on follow-up MRI. The patient tolerated the medication well for 6 years and is now off of treatment for 2 years with a stable lesion. CONCLUSION: Cases of SEGA outside of the context of TSC are exceedingly rare, with only 48 cases previously described. The genetic mechanisms and treatment response of these lesions are poorly understood. To date, these lesions appear to respond well to mTOR inhibitors and may behave similarly to SEGAs associated with TSC. However, given that experience is extremely limited, these cases should be followed long term to better understand their natural history and treatment response.

Robot-Assisted Minimally Invasive Asleep Single-Stage Deep Brain Stimulation Surgery: Operative Technique and Systematic Review.

BACKGROUND AND OBJECTIVES: Robotic assistance has garnered increased use in neurosurgery. Recently, this has expanded to include deep brain stimulation (DBS). Several studies have reported increased accuracy and improved efficiency with robotic assistance, but these are limited to individual robotic platforms with smaller sample sizes or are broader studies on robotics not specific to DBS. Our objectives are to report our technique for robot-assisted, minimally invasive, asleep, single-stage DBS surgery and to perform a meta-analysis comparing techniques from previous studies. METHODS: We performed a single-center retrospective review of DBS procedures using a floor-mounted robot with a frameless transient fiducial array registration. We compiled accuracy data (radial entry error, radial target error, and 3-dimensional target error) and efficiency data (operative time, setup time, and total procedure time). We then performed a meta-analysis of previous studies and compared these metrics. RESULTS: We analyzed 315 electrodes implanted in 160 patients. The mean radial target error was 0.9 ± 0.5 mm, mean target 3-dimensional error was 1.3 ± 0.7 mm, and mean radial entry error was 1.1 ± 0.8 mm. The mean procedure time (including pulse generator placement) was 182.4 ± 47.8 minutes, and the mean setup time was 132.9 ± 32.0 minutes. The overall complication rate was 8.8% (2.5% hemorrhagic/ischemic, 2.5% infectious, and 0.6% revision). Our meta-analysis showed increased accuracy with floor-mounted over skull-mounted robotic platforms and with fiducial-based registrations over optical registrations. CONCLUSION: Our technique for robot-assisted, minimally invasive, asleep, single-stage DBS surgery is safe, accurate, and efficient. Our data, combined with a meta-analysis of previous studies, demonstrate that robotic assistance can provide similar or increased accuracy and improved efficiency compared with traditional frame-based techniques. Our analysis also suggests that floor-mounted robots and fiducial-based registration methods may be more accurate.

Case report: Utilizing diffusion-weighted MRI on a patient with chronic low back pain treated with spinal cord stimulation.

Diffusion-weighted magnetic resonance imaging (dwMRI) has increasingly demonstrated greater utility in analyzing neuronal microstructure. In patients with chronic low back pain (cLBP), using dwMRI to observe neuronal microstructure can lead to non-invasive biomarkers which could provide clinicians with an objective quantitative prognostic tool. In this case report, we investigated dwMRI for the development of non-invasive biomarkers by conducting a region-based analysis of a 55-year-old male patient with failed back surgery syndrome (FBSS) treated with spinal cord stimulation (SCS). We hypothesized that dwMRI could safely generate quantitative data reflecting cerebral microstructural alterations driven by neuromodulation. Neuroimaging was performed at 6- and 12- months post-SCS implantation. The quantitative maps generated included diffusion tensor imaging (DTI) parameters; fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD) computed from whole brain tractography. To examine specific areas of the brain, 44 regions of interest (ROIs), collectively representing the pain NeuroMatrix, were extracted and registered to the patient's diffusion space. Average diffusion indices were calculated from the ROIs at both 6- and 12- months. Regions with >10% relative change in at least 3 of the 4 maps were reported. Using this selection criterion, 8 ROIs demonstrated over 10% relative changes. These ROIs were mainly located in the insular gyri. In addition to the quantitative data, a series of questionnaires were administered during the 6- and 12-month visits to assess pain intensity, functional disability, and quality of life. Overall improvements were observed in these components, with the Pain Catastrophizing Scale (PCS) displaying the greatest change. Lastly, we demonstrated the safety of dwMRI for a patient with SCS. In summary, the results from the case report prompt further investigation in applying dwMRI in a larger cohort to better correlate the influence of SCS with brain microstructural alterations, supporting the utility of dwMRI to generate non-invasive biomarkers for prognostication.

Insula in epilepsy - "untying the gordian knot": A systematic review.

PURPOSE: Despite significant advances in epileptology, there are still many uncertainties about the role of the insula in epilepsy. Until recently, most insular onset seizures were wrongly attributed to the temporal lobe. Further, there are no standardised approaches to the diagnosis and treatment of insular onset seizures. This systematic review gathers the available information about insular epilepsy and synthesizes current knowledge as a basis for future research. METHOD: Adhering to the PRISMA guidelines, studies were meticulously extracted from the PubMed database. The empirical data pertaining to the semiology of insular seizures, insular networks in epilepsy, techniques of mapping the insula, and the surgical intricacies of non-lesional insular epilepsy were reviewed from published studies. The corpus of information available was then subjected to a process of concise summarization and astute synthesis. RESULTS: Out of 235 studies identified for full-text review, 86 studies were included in the systematic review. The insula emerges as a brain region with a number of functional subdivisions. The semiology of insular seizures is diverse and depends on the involvement of particular subdivisions. The semiological heterogeneity of insular seizures is explained by the extensive connectivity of the insula and its subdivisions with all four lobes of the brain, deep grey matter structures, and remote brainstem areas. The mainstay of the diagnosis of seizure onset in the insula is stereoelectroencephalography (SEEG). The surgical resection of the insular epileptogenic zone (when possible) is the most effective treatment. Open surgery on the insula is challenging but magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) also holds promise. CONCLUSION: The physiological and functional roles of the insula in epilepsy have remained obfuscated. The dearth of precisely defined diagnostic and therapeutic protocols acts as an impediment to scientific advancement. This review could potentially facilitate forthcoming research endeavours by establishing a foundational framework for uniform data collection protocols, thereby enhancing the feasibility of comparing findings across future studies and promoting progress in this domain.

Minimally Invasive Surgical Decompression without Fusion for the Treatment of Lumbar Synovial Cysts: Feasibility and Long-Term Outcomes.

BACKGROUND: Lumbar synovial cysts (LSCs) can cause painful radiculopathy and sensory and/or motor deficits. Historically, first-line surgical treatment has been decompression with fusion. Recently, minimally invasive laminectomy without fusion has shown equal or superior results to traditional decompression and fusion methods. OBJECTIVE: This study investigates the long-term efficacy of minimally invasive laminectomy without fusion in the treatment of LSC as it relates to the rate of subsequent fusion surgery. METHODS: A retrospective review was performed over a 10-year period of patients undergoing minimally invasive laminectomy for symptomatic LSCs. The primary end point was the rate of revision surgery requiring fusion. RESULTS: Eighty-five patients with symptomatic LSCs underwent minimally invasive laminectomy alone January 2010-August 2020 at our institution. The most common location was L4-5 (72%). Preoperative imaging identified spondylolisthesis (grade 1) in 43 patients (57%), none of which was unstable on available dynamic radiographs. Average procedure duration was 93 minutes, with 78% of patients discharged home on the same day of surgery. Over 46 months of mean follow-up, 17 patients (20%) required 19 revision operations. Of those operations, 16 were spinal fusions (17.6%). Median time to fusion surgery was 36 months. There were no identifiable risk factors on multivariate regression analysis that predicted the need for fusion. CONCLUSIONS: Minimally invasive laminectomy is an effective first-line treatment for symptomatic LSCs and avoids the need for fusion in most treated patients. Of our patients, 18% required a fusion over 46 months, suggesting that further studies are required to guide patient selection.

Lateral versus prone robot-assisted percutaneous pedicle screw placement: a CT-based comparative assessment of accuracy.

OBJECTIVE: Single-position lateral lumbar interbody fusion (SP-LLIF) has recently gained significant popularity due to increased operative efficiency, but it remains technically challenging. Robot-assisted percutaneous pedicle screw (RA-PPS) placement can facilitate screw placement in the lateral position. The authors have reported their initial experience with SP-LLIF with RA-PPS placement in the lateral position, and they have compared this accuracy with that of RA-PPS placement in the prone position. METHODS: The authors reviewed prospectively collected data from their first 100 lateral-position RA-PPSs. The authors graded screw accuracy on CT and compared it to the accuracy of all prone-position RA-PPS procedures during the same time period. The authors analyzed the effect of several demographic and perioperative metrics, as a whole and specifically for lateral-position RA-PPS placement. RESULTS: The authors placed 99 lateral-position RA-PPSs by using the ExcelsiusGPS robotic platform in the first 18 consecutive patients who underwent SP-LLIF with postoperative CT imaging; these patients were compared with 346 prone-position RA-PPSs that were placed in the first consecutive 64 patients during the same time period. All screws were placed at L1 to S1. Overall, the lateral group had 14 breaches (14.1%) and the prone group had 25 breaches (7.2%) (p = 0.032). The lateral group had 5 breaches (5.1%) greater than 2 mm (grade C or worse), and the prone group had 4 (1.2%) (p = 0.015). The operative level had an effect on the breach rate, with breach rates (grade C or worse) of 7.1% at L3 and 2.8% at L4. Most breaches were grade B (< 2 mm) and lateral, and no breach had clinical sequelae or required revision. Within the lateral group, multivariate regression analysis demonstrated that BMI and number of levels affected accuracy, but the side that was positioned up or down did not. CONCLUSIONS: RA-PPSs can improve the feasibility of SP-LLIF. Spine surgeons should be cautious and selective with this technique owing to decreased accuracy in the lateral position, particularly in obese patients. Further studies should compare SP-LLIF techniques performed while the patient is in the prone and lateral positions.

IDH-mutated gliomas promote epileptogenesis through d-2-hydroxyglutarate-dependent mTOR hyperactivation.

BACKGROUND: Uncontrolled seizures in patients with gliomas have a significant impact on quality of life and morbidity, yet the mechanisms through which these tumors cause seizures remain unknown. Here, we hypothesize that the active metabolite d-2-hydroxyglutarate (d-2-HG) produced by the IDH-mutant enzyme leads to metabolic disruptions in surrounding cortical neurons that consequently promote seizures. METHODS: We use a complementary study of in vitro neuron-glial cultures and electrographically sorted human cortical tissue from patients with IDH-mutant gliomas to test this hypothesis. We utilize micro-electrode arrays for in vitro electrophysiological studies in combination with pharmacological manipulations and biochemical studies to better elucidate the impact of d-2-HG on cortical metabolism and neuronal spiking activity. RESULTS: We demonstrate that d-2-HG leads to increased neuronal spiking activity and promotes a distinct metabolic profile in surrounding neurons, evidenced by distinct metabolomic shifts and increased LDHA expression, as well as upregulation of mTOR signaling. The increases in neuronal activity are induced by mTOR activation and reversed with mTOR inhibition. CONCLUSION: Together, our data suggest that metabolic disruptions in the surrounding cortex due to d-2-HG may be a driving event for epileptogenesis in patients with IDH-mutant gliomas.

Minimally invasive surgery for intradural extramedullary spinal cord pathologies: A case series and technical note.

BACKGROUND: Intradural spinal cord pathologies have traditionally been managed with open surgical procedures and require the completion of a durotomy. Minimally invasive techniques are emerging as alternative procedures with the goal of reducing complications, but often require specialized equipment with additional training. METHODS: We conduct a single institution retrospective review from 2016 to 2019 of patients undergoing minimally invasive durotomy closure for intradural extramedullary pathologies using a novel technique that utilizes standard operating room equipment. This cohort is compared to a cohort of patients treated with a traditional open approach. RESULTS: Patients treated with minimally invasive surgery (MIS) had no statistically significant differences in baseline characteristics compared to patients treated with open procedures. Patients treated with MIS had decreases in complication rates, estimated blood loss, and length of stay in the hospital compared to the patients treated with open procedures, but these differences did not reach levels of statistical significance. CONCLUSIONS: Our novel MIS technique for intradural extramedullary pathologies appears to be safe and effective in creating a watertight dural closure using standard operating room equipment, while avoiding the costs and training associated with specialized equipment and possibly improving surgical outcome measures when compared to open approaches.

Does the Modified Arrhenius Model Reliably Predict Area of Tissue Ablation After Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Pediatric Lesional Epilepsy?

BACKGROUND: Commercial magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) systems utilize a generalized Arrhenius model to estimate the area of tissue damage based on the power and time of ablation. However, the reliability of these estimates in Vivo remains unclear. OBJECTIVE: To determine the accuracy and precision of the thermal damage estimate (TDE) calculated by commercially available MRgLITT systems using the generalized Arrhenius model. METHODS: A single-center retrospective review of pediatric patients undergoing MRgLITT for lesional epilepsy was performed. The area of each lesion was measured on both TDE and intraoperative postablation, postcontrast T1 magnetic resonance images using ImageJ. Lesions requiring multiple ablations were excluded. The strength of the correlation between TDE and postlesioning measurements was assessed via linear regression. RESULTS: A total of 32 lesions were identified in 19 patients. After exclusion, 13 pairs were available for analysis. Linear regression demonstrated a strong correlation between estimated and actual ablation areas (R2 = .97, P < .00001). The TDE underestimated the area of ablation by an average of 3.92% overall (standard error (SE) = 4.57%), but this varied depending on the type of pathologic tissue involved. TDE accuracy and precision were highest in tubers (n = 3), with average underestimation of 2.33% (SE = 0.33%). TDE underestimated the lesioning of the single hypothalamic hamartoma in our series by 52%. In periventricular nodular heterotopias, TDE overestimated ablation areas by an average of 13% (n = 2). CONCLUSION: TDE reliability is variably consistent across tissue types, particularly in smaller or periventricular lesions. Further investigation is needed to understand the accuracy of this emerging minimally invasive technique.

Comparison of Clinical and Radiographic Outcomes After Standalone Versus Cage and Plate Constructs for Anterior Cervical Discectomy and Fusion.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) has conventionally been performed using an allograft cage with a plate-and-screw construct. Recently, standalone cages have gained popularity due to theorized decreases in operative time and postoperative dysphagia. Few studies have compared these outcomes. Here, we directly compare the outcomes of plated versus standalone ACDF constructs. METHODS: A single-center retrospective review of patients undergoing ACDF after June 2011 with at least 6 months of follow up was conducted. Clinical outcomes were analyzed and compared between standalone and plated constructs. Multivariate regression analysis of the primary outcome, need for revision surgery, as well as several secondary outcomes, procedure duration, estimated blood loss (EBL), length of hospital stay, disposition, and incidence of dysphagia, hoarseness, or surgical site infection, was completed. RESULTS: A total of 321 patients underwent ACDF and met inclusion-exclusion criteria, with mean follow-up duration of 20 months. Forty-six (14.3%) patients received standalone constructs, while 275 (85.7%) received plated constructs. Fourteen (4.4%) total revisions were necessary, 4 in the standalone group and 10 in the plated group, yielding revision rates of 8.7% and 3.6%, respectively (P = .125). Mean EBL was 98 mL in the standalone group and 63 mL in the plated group (P = .001). Mean procedure duration was 147 minutes in the standalone group and 151 minutes in the plated group (P = .800). Mean hospital stay was 3.6 days in the standalone group and 2.5 days in the plated group (P = .270). There was no significant difference in incidence of dysphagia (P = .700) or hoarseness (P = .700). CONCLUSIONS: Standalone ACDF demonstrates higher, but not statistically significant, revision rates than plate-and-screw constructs, without the hypothesized decreased incidence of dysphagia or hoarseness and without decreased procedure duration or EBL. Surgeons may consider limiting use of these constructs to cases of adjacent segment disease. Larger studies with longer follow up are necessary to make more definitive conclusions. LEVEL OF EVIDENCE: 4. CLINICAL RELEVANCE: This study will help spine surgeons decide between using standalone or cage-and-plate constructs for ACDF.

Robot-assisted revision of sacroiliac joint fusion using a triangular titanium implant in an S2-alar-iliac trajectory: illustrative case.

BACKGROUND: Sacroiliac joint (SIJ) dysfunction can lead to significant pain and disability, greatly impairing quality of life. Arthrodesis may take up to 1 year to occur, after which revision can be considered. There is a need for highly accurate and reproducible techniques for revision that allow for purchase through undisturbed bone to prevent prolonged pain and disability. Moreover, a minimally invasive technique for revision would be favorable for recovery, particularly in elderly patients. OBSERVATIONS: An 84-year-old man with a prior history of lumbar fusion presented with severe buttock pain limiting ambulation and sitting because of the failure of arthrodesis after SIJ fusion 1 year earlier. He underwent revision using a triangular titanium implant (TTI) in an S2-alar-iliac (S2-AI) trajectory under robotic guidance, which is a novel technique not yet described in the literature. The patient's pain largely resolved, he was able to ambulate independently, and his quality of life improved tremendously. There were no complications of surgery. LESSONS: Placement of a TTI using an S2-AI trajectory is a safe and effective method for revision that can be considered for elderly patients. Robot-assisted navigation can be used to facilitate an accurate and reproducible approach using a minimally invasive approach.

JET 7 XTRA Flex reperfusion catheter related complications during endovascular thrombectomy.

Endovascular thrombectomy has revolutionized the management of acute ischemic stroke from emergent large vessel occlusion. Continued technological advancement in the field, as evidenced by successive introduction of large bore aspiration catheters with enhanced trackability and large inner diameter, has played a major role in achieving fast and robust recanalization and improved clinical outcome. Here, we present three patients with intraprocedural device malfunction related to the JET 7 XTRA Flex reperfusion catheter.

An Initial Cost-Effectiveness Analysis of Magnetic Resonance-Guided Laser Interstitial Thermal Therapy in Pediatric Epilepsy Surgery.

INTRODUCTION: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a new technology that provides a clinically efficacious and minimally invasive alternative to conventional microsurgical resection. However, little data exist on how costs compare to traditional open surgery. The goal of this paper is to investigate the cost-effectiveness of MRgLITT in the treatment of pediatric epilepsy. METHODS: We retrospectively analyzed the medical records of pediatric patients who underwent MRgLITT via the Visualase® thermal therapy system (Medtronic, Inc., Minneapolis, MN, USA) between December 2013 and September 2017. Direct costs associated with preoperative, operative, and follow-up care were extracted. Benefit was calculated in quality-adjusted life years (QALYs), and the cost-effectiveness was derived from the discounted total direct costs over QALY. Sensitivity analysis on 4 variables was utilized to assess the validity of our results. RESULTS: Twelve consecutive pediatric patients with medically refractory epilepsy underwent MRgLITT procedures. At the last postoperative follow-up, 8 patients were seizure free (Engel I, 66.7%), 2 demonstrated significant improvement (Engel II, 16.7%), and 2 patients showed worthwhile improvement (Engel III, 16.7%). The average cumulative discounted QALY was 2.11 over the lifetime of a patient. Adjusting for inflation, MRgLITT procedures had a cost-effectiveness of USD 22,211 per QALY. Our sensitivity analysis of cost variables is robust and supports the procedure to be cost--effective. CONCLUSION: Our data suggests that MRgLITT may be a cost-effective alternative to traditional surgical resection in pediatric epilepsy surgery.

Robot-Assisted Percutaneous Pedicle Screw Placement: Evaluation of Accuracy of the First 100 Screws and Comparison with Cohort of Fluoroscopy-guided Screws.

OBJECTIVE: Percutaneous pedicle screws (PPS) are used to stabilize the spine after interbody fusion in minimally invasive approaches. Recently, robotic assistance has been developed to improve the accuracy of PPS. We report our initial experience with ExcelsiusGPS and compare its accuracy with our historical cohort of fluoroscopy-guided PPS. METHODS: We reviewed prospectively collected data from our first 100 robot-assisted PPS. We graded accuracy of screws on computed tomography imaging and compared it with a previous cohort of 90 PPS placed using fluoroscopy. We also analyzed the effect of various demographic and perioperative metrics on accuracy. RESULTS: We placed 103 PPS in the first 20 consecutive patients with postoperative computed tomography imaging using ExcelsiusGPS. All screws were placed at L2 to S1. Our robot-assisted cohort had 6 breaches, with only 2 breaches >2 mm, yielding an overall breach rate of 5.8% and a significant breach rate of 1.9%. In comparison, our fluoroscopy-guided cohort had a breach rate of 3.3% and a significant breach rate of 1.1%, which was not significantly different. More breaches occurred in the first half of cases, suggesting a learning curve with robotic assistance. No demographic or perioperative metrics had a significant effect on accuracy. CONCLUSIONS: Our breach rates with ExcelsiusGPS were low and consistent with others reported in the literature, as well as with other robotic systems. Our series shows equivalent accuracy of placement of PPS with this robotic platform compared with fluoroscopic guidance and suggests a relatively short learning curve.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for the Treatment of Nonlesional Insular Epilepsy in Pediatric Patients: Technical Considerations.

INTRODUCTION: The insula presents anatomic challenges to surgical exploration and intervention. Open neurosurgical intervention is associated with high rates of complications despite improved seizure control. Minimally invasive techniques using novel energy delivery methods have gained popularity due to their relative safety and ability to overcome access-related barriers. The goal of this paper is to present an operative technical report and methodological considerations on the application of magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) for the treatment of nonlesional, medically refractory, insular epilepsy in pediatric patients. METHODS: Visualase laser probe(s) were implanted using ROSA robotic stereotactic guidance into the insula using a parasagittal trajectory. After confirmation of placement using intraoperative MRI, thermal energy was delivered under real-time MR guidance. Laser wire pullback was performed when the initial dose of thermal energy was insufficient to ablate the target in its entirety. Thermal ablation within the intended target was confirmed using gadolinium-enhanced brain MRI. Following removal of laser wires, a final T1-weighted axial brain MRI was performed to confirm no evidence of hemorrhage. RESULTS: Three patients underwent MRgLITT of nonlesional insular epilepsy over an 11-month period. The epileptogenic focus was localized to the insula using stereoelectroencephalography. The anterior and middle portions of the insula were accessed using a parasagittal trajectory. Laser ablation was performed for up to 3 min using an output of 10.5 W. No complications were encountered, and all patients were discharged within 24 h after the surgery. At the most recent follow-up, all patients had an Engel I outcome without any new neurologic deficits. CONCLUSION: This small cohort shows that insular ablation can be achieved safely with promising seizure outcomes in the short term.

Microsurgical Resection of an Intramedullary Ependymoma at the Cervicomedullary Junction: A Two-Dimensional Operative Video.

Ependymomas are the most common adult intramedullary spinal tumors.1 Although uncommon in the brainstem, ependymomas make up a large proportion of tumors of this location.2-8 We present an operative video case report of an intrinsic ependymoma at the cervicomedullary junction. The purpose of this report is to present the clinical picture, operative setup, and surgical technique involved in resection of an intramedullary tumor of this region. For best outcome for intramedullary ependymomas, the goal should be gross total resection.1,9,10 These tumors have a relatively distinct plane between tumor and normal parenchyma, making a gross total resection more probable than cases of infiltrative intramedullary astrocytomas.11 Despite this, significant morbidity can be associated with treatment.1 Proper microsurgical technique with use of operative adjuncts can maximize resection while minimizing neurologic injury to optimize outcomes in patients. We present the case of a 42-year-old man presenting with neck and shoulder pain, upper extremity paresthesias, and gait instability. Magnetic resonance imaging of the neuroaxis revealed a heterogeneously enhancing expansile lesion in the lower medulla and multiple lesions in the thecal sac, representing drop metastases. Due to symptoms and mass effect from the lesion, the patient underwent a suboccipital craniotomy for tumor resection. We highlight operative techniques in our case, including use of neurophysiologic monitoring, intraoperative ultrasound, ultrasonic aspirator, and dissection with microcottonoid pledgets and bimanual technique. Pathology revealed a World Health Organization grade II ependymoma. Postoperative magnetic resonance imaging revealed a small amount of residual. He underwent full craniospinal proton beam therapy with boost to the residual and metastases with good outcome. Patient provided consent for this report.

Initial Report of an Intradural Extramedullary Metastasis of a Pancreatic Neuroendocrine Tumor to the Cervical Spine: A Case Report and Review of the Literature.

BACKGROUND: Pancreatic neuroendocrine tumors (pNETs) are known to frequently metastasize to the liver and lymphatics; however, metastasis to the spine is exceedingly rare. We report the first case of an intradural, extramedullary pNET metastasis to the upper cervical spine. CASE DESCRIPTION: A 75-year-old Hispanic male patient with history of stage IV pNET with metastasis to the liver and lymph nodes and new-onset lymphadenopathy seen on CT of the chest was found on positron emission tomography scan to have a lesion in the cervical spine. The patient was neurologically intact on physical examination, yet given the patient's medical history, magnetic resonance imaging of the cervical spine was performed, revealing a right-sided intradural, extramedullary mass at the C1-C2 level with associated mass effect on the spinal cord, likely representing a schwannoma. Due to the tumor size, mass effect, and the need for definitive tissue diagnosis, a partial C1-C2 laminectomy with intradural resection of the tumor was performed. The histology was consistent with the patient's known pNET. CONCLUSIONS: As treatment for pNETs has evolved, there has been a surge in unique presentations of systemic well-differentiated pNETs being reported. It is vital that patients diagnosed with pNET be monitored for metastases, and when discovered, treated promptly.

Crossing the Cervicothoracic Junction During Posterior Cervical Decompression and Fusion: Is It Necessary?

BACKGROUND: Posterior cervical fusion (PCF) is performed to treat cervical myelopathy, radiculopathy, and/or deformity. Constructs ending at the cervicothoracic junction (CTJ) may lead to higher rates of adjacent segment disease, and much debate exists regarding crossing the CTJ due to paucity of data in the literature. OBJECTIVE: To determine whether extension of PCF constructs across the CTJ decreases incidence of adjacent segment disease and need for revision surgery. METHODS: A single-center retrospective case series of patients undergoing multilevel PCFs since 2011 with at least 6-mo follow-up was conducted. Outcomes were analyzed and compared based on caudal extent of instrumentation via multivariate regression. RESULTS: A total of 149 patients underwent PCF, with a mean follow-up of 18.9 mo. A total of 15 (10.1%) revisions were performed, 7 (4.7%) of which were related to the construct. Five (8.3%) revisions were performed for constructs ending at C6, 1 (5.3%) at C7, 1 (2.6%) at T1, and none (0%) at T2 (P = .035). Mean procedure duration was 215 min at C6, 214 min at C7, 239 min at T1, and 343 min at T2 (P = .001). Mean estimated blood loss was 224 mL at C6, 178 mL at C7, 308 mL at T1, and 575 mL at T2 (P = .001). There was no difference in length of stay, disposition, surgical site infection, or radiographic parameters. CONCLUSION: Extension of PCFs across the CTJ leads to lower early revision rates, but also to increased procedure duration and estimated blood loss. As such, decisions regarding caudal extent of instrumentation must weigh the risk of pseudarthrosis against that of longer procedures with higher blood loss.