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Brain lesioning is a fundamental technique in the functional neurosurgery world. It has been investigated for decades and presented promising results long before novel pharmacological agents were introduced to treat movement disorders, psychiatric disorders, pain, and epilepsy. Ablative procedures were replaced by effective drugs during the 1950s and by Deep Brain Stimulation (DBS) in the 1990s as a reversible neuromodulation technique. In the last decade, however, the popularity of brain lesioning has increased again with the introduction of magnetic resonance-guided focused ultrasound (MRgFUS). In this review, we will cover the current and emerging role of MRgFUS in functional neurosurgery. Literature review from PubMed and compilation. Investigated since 1930, MRgFUS is a technology enabling targeted energy delivery at the convergence of mechanical sound waves. Based on technological advancements in phased array ultrasound transducers, algorithms accounting for skull penetration by sound waves, and MR imaging for targeting and thermometry, MRgFUS is capable of brain lesioning with sub-millimeter precision and can be used in a variety of clinical indications. MRgFUS is a promising technology evolving as a dominant tool in different functional neurosurgery procedures in movement disorders, psychiatric disorders, epilepsy, among others.

Objective. Holographic mixed reality (HMR) allows for the superimposition of computer-generated virtual objects onto the operator’s view of the world. Innovative solutions can be developed to enable the use of this technology during surgery. The authors developed and iteratively optimized a pipeline to construct, visualize, and register intraoperative holographic models of patient landmarks during spinal fusion surgery. Methods. The study was carried out in two phases. In phase 1, the custom intraoperative pipeline to generate patient-specific holographic models was developed over 7 patients. In phase 2, registration accuracy was optimized iteratively for 6 patients in a real-time operative setting. Results. In phase 1, an intraoperative pipeline was successfully employed to generate and deploy patient-specific holographic models. In phase 2, the registration error with the native hand-gesture registration was 20.2 ± 10.8 mm (n = 7 test points). Custom controller-based registration significantly reduced the mean registration error to 4.18 ± 2.83 mm (n = 24 test points, P < .01). Accuracy improved over time (B = −.69, P < .0001) with the final patient achieving a registration error of 2.30 ± .58 mm. Across both phases, the average model generation time was 18.0 ± 6.1 minutes (n = 6) for isolated spinal hardware and 33.8 ± 8.6 minutes (n = 6) for spinal anatomy. Conclusions. A custom pipeline is described for the generation of intraoperative 3D holographic models during spine surgery. Registration accuracy dramatically improved with iterative optimization of the pipeline and technique. While significant improvements and advancements need to be made to enable clinical utility, HMR demonstrates significant potential as the next frontier of intraoperative visualization.

Hemispheric disconnection in the form of hemispherectomy or hemispherotomy is the most effective way of treating intractable hemispheric epilepsy. Anatomical hemispherectomy approaches have largely been abandoned in most cases due to a higher risk of superficial hemosiderosis, intraoperative blood loss, hydrocephalus, prolonged hospital stay, and mortality compared to the variety of tissue-sparing hemispherotomy techniques. Disconnective hemispherotomy approaches utilize the lateral ventricle as a key component of the surgical corridor. Without a lateral ventricle, disconnective surgery becomes significantly challenging, typically leading to a hemispherectomy. The authors present the case of a patient with severe hemispheric dysplasia without a lateral ventricle on the pathologic side and detail a novel surgical technique for a prone, occipital interhemispheric, tissue-sparing, purely disconnective aventricular hemispherotomy with an excellent surgical outcome.

Background Second Window Indocyanine Green (SWIG) is a novel technique for real-time, intraoperative tumor visualization using a high-dose infusion of indocyanine green (ICG) 24 hours before surgery. Due to pathologic diversity found in the pineal region, tissue diagnosis in patients with pineal region mass is essential to optimize further clinical management. Case Description We present the case of a 75-year-old woman with known pineal region mass for 18 years, who presented with progressive classic signs and symptoms of obstructive hydrocephalus over the past 6 months. Preoperative imaging confirmed a contrast-enhancing pineal region tumor, which appeared to be obstructing the aqueduct of Sylvius, causing proximal obstructive hydrocephalus. We delivered 5 mg/kg of ICG intravenously 24 hours before the surgery. The patient underwent an endoscopic third ventriculostomy and a biopsy of the pineal lesion. The tumor demonstrated clear near-infrared fluorescence, which was distinct from surrounding third ventricle floor and ependyma. The signal-to-background ratio was 2.9. The final pathology report revealed a World Health Organization grade I pineocytoma. Conclusions We report on a novel application of near-infrared fluorescence for tumor identification of pineal region tumors, using the “SWIG technique.”

Magnetic resonance image-guided high-intensity focused ultrasound (MRgFUS)-based thermal ablation of the ventral intermediate nucleus of the thalamus (VIM) is a minimally invasive treatment modality for essential tremor (ET). Dentato-rubro-thalamic tractography (DRTT) is becoming increasingly popular for direct targeting of the presumed VIM ablation focus. It is currently unclear if patients with implanted pulse generators (IPGs) can safely undergo MRgFUS ablation and reliably acquire DRTT suitable for direct targeting. We present an 80-year-old male with a spinal cord stimulator (SCS) and an 88-year-old male with a cardiac pacemaker who both underwent MRgFUS for medically refractory ET. Clinical outcomes were measured using the Clinical Rating Scale for Tremor (CRST). DRTT was successfully created and imaging parameter adjustments did not result in any delay in procedural time in either case. In the first case, 7 therapeutic sonications were delivered. The patient improved immediately and durably with a 90% CRST-disability improvement at 6-week follow-up. In our second case, 6 therapeutic sonications were delivered with durable, 75% CRST-disability improvement at 6 weeks. These are the first cases of MRgFUS thalamotomy in patients with IPGs. DRTT targeting and MRgFUS-based thermal ablation can be safely performed in these patients using a 1.5-T MRI.

Background: We present a “Do-It-Yourself” method to build an affordable augmented reality heads-up display system (AR-HUD) capable of displaying intraoperative images. All components are commercially available products, which the surgeons may use in their own practice for educational and research purposes. Methods: Moverio BT 35-E smart glasses were connected to operating room imaging modalities (ie, fluoroscopy and 3D navigation platforms) via a high-definition multimedia interface (HDMI) converter, allowing for continuous high-definition video transmission. The addition of an HDMI transmitter-receiver makes the AR-HUD system wireless. Results: We used our AR-HUD system in 3 patients undergoing instrumented spinal fusion. AR-HUD projected fluoroscopy images onto the surgical field, eliminating shift of surgeon focus and procedure interruption, with only a 40- to 100-ms delay in transmission, which was not clinically impactful. Conclusions: An affordable AR-HUD capable of displaying real-time information into the surgeon9s view can be easily designed, built, and tested in surgical practice. As wearable heads-up display technology continues to evolve rapidly, individual components presented here may be substituted to improve its functionality and usability. Surgeons are in a unique position to conduct clinical testing in the operating room environment to optimize the augmented reality system for surgical use.

BACKGROUND The Management of Myelomeningocele Study (MOMS) demonstrated that fetal myelomeningocele (fMMC) closure results in improved hydrocephalus and hindbrain herniation when compared to postnatal closure. OBJECTIVE To report on the outcomes of a single institution's experience in the post-MOMS era, with regard to hydrocephalus absence and hindbrain herniation resolution. METHODS A single-center retrospective study of a subset of post-MOMS patients who underwent fetal/postnatal myelomeningocele closure was performed. Primary outcomes included cerebrospinal fluid (CSF) diversion status and hindbrain herniation resolution. Families were contacted via telephone for outcome information if care was transitioned to outside institutions. Univariate/multivariable analyses were performed using several prenatal and postnatal variables. RESULTS From January 2011 to May 2016, data were reviewed from families of 62 postnatal and 119 fMMC closure patients. In the postnatal group, 80.6% required CSF diversion compared to 38.7% fetal cases (P

OBJECTIVEEpilepsy is one of the most common neurological disorders, yet its global surgical burden has yet to be characterized. The authors sought to compile the most current epidemiological data to quantify global prevalence and incidence, and estimate global surgically treatable epilepsy. Understanding regional and global epilepsy trends and potential surgical volume is crucial for future policy efforts and resource allocation.METHODSThe authors performed a systematic literature review and meta-analysis to determine the global incidence, lifetime prevalence, and active prevalence of epilepsy; to estimate surgically treatable epilepsy volume; and to evaluate regional trends by WHO regions and World Bank income levels. Data were extracted from all population-based studies with prespecified methodological quality across all countries and demographics, performed between 1990 and 2016 and indexed on PubMed, EMBASE, and Cochrane. The current and annual new case volumes for surgically treatable epilepsy were derived from global epilepsy prevalence and incidence.RESULTSThis systematic review yielded 167 articles, across all WHO regions and income levels. Meta-analysis showed a raw global prevalence of lifetime epilepsy of 1099 per 100,000 people, whereas active epilepsy prevalence is slightly lower at 690 per 100,000 people. Global incidence was found to be 62 cases per 100,000 person-years. The meta-analysis predicted 4.6 million new cases of epilepsy annually worldwide, a prevalence of 51.7 million active epilepsy cases, and 82.3 million people with any lifetime epilepsy diagnosis. Differences across WHO regions and country incomes were significant. The authors estimate that currently 10.1 million patients with epilepsy may be surgical treatment candidates, and 1.4 million new surgically treatable epilepsy cases arise annually. The highest prevalences are found in Africa and Latin America, although the highest incidences are reported in the Middle East and Latin America. These regions are primarily low- and middle-income countries; as expected, the highest disease burden falls disproportionately on regions with the fewest healthcare resources.CONCLUSIONSUnderstanding of the global epilepsy burden has evolved as more regions have been studied. This up-to-date worldwide analysis provides the first estimate of surgical epilepsy volume and an updated comprehensive overview of current epidemiological trends. The disproportionate burden of epilepsy on low- and middle-income countries will require targeted diagnostic and treatment efforts to reduce the global disparities in care and cost. Quantifying global epilepsy provides the first step toward restructuring the allocation of healthcare resources as part of global healthcare system strengthening.

Freehand bedside ventriculostomy placement can result in catheter malfunction requiring a revision procedure and cause significant patient morbidity. We performed a single-center retrospective review to assess factors related to this complication.Using an administrative database and chart review, we identified 101 first-time external ventricular drain placements performed at the bedside. We collected data regarding demographics, medical comorbidities, complications, and catheter tip location. We performed univariate and multivariate statistical analyses using MATLAB. We corrected for multiple comparisons using the false discovery rate (FDR) procedure.Multivariate regression analyses revealed that revision procedures were more likely to occur after drain blockage (odds ratio [OR] 17.9) and hemorrhage (OR 10.3, FDR-corrected P values0.01, 0.05, respectively). Drain blockage was less frequent after placement in an "optimal location" (ipsilateral ventricle or near foramen of Monroe; OR 0.09, P = 0.009, FDR-corrected P0.03) but was more likely to occur after placement in third ventricle (post-hoc P values0.015). Primary diagnoses included subarachnoid hemorrhage (n = 30, 29.7%), intraparenchymal hemorrhage with intraventricular extravasation (n = 24, 23.7%), tumor (n = 20, 19.8%), and trauma (n = 17, 16.8%). Most common complications included drain blockage (n = 12, 11.8%) and hemorrhage (n = 8, 7.9%). In total, 16 patients underwent at least 1 revision procedure (15.8%).Bedside external ventricular drain placement is associated with a 15% rate of revision, that typically occurred after drain blockage and postprocedure hemorrhage. Optimal placement within the ipsilateral frontal horn or foramen of Monroe was associated with a reduced rate of drain blockage.

Objective To model the financial impact of policies governing the scheduling of overlapping surgeries, and to identify optimal solutions that maximize operating efficiency that satisfy the fiduciary duty to patients. Background Hospitals depend on procedural revenue to maintain financial health as the recent pandemic has revealed. Proposed policies governing the scheduling of overlapping surgeries may dramatically impact hospital revenue. To date, the potential financial impact has not been modeled. Methods A linear forecasting model based on a logic matrix decision tree enabled an analysis of surgeon productivity annualized over a fiscal year. The model applies procedural and operational variables to policy constraints limiting surgical scheduling. Model outputs included case and financial metrics modeled over 1000-surgeon-year simulations. Case metrics included annual case volume, case mix, operating room (OR) utilization, surgeon utilization, idle time and staff overtime hours. Financial outputs included annual revenue, expenses and contribution margin. Results The model was validated against surgical data. Case and financial metrics decreased as a function of increasingly restrictive scheduling scenarios, with the greatest contribution margin loses ($1,650,000 per surgeon-year) realized with the introduction of policies mandating that a second patient could not enter the OR until the critical portion of the first surgery was completed. We identify an optimal scheduling scenario that maximizes surgeon efficiency, minimizes OR idle time and revenue loses, and satisfies ethical obligations to patients. Conclusions Hospitals may expect significant financial loses with the introduction of policies restricting OR scheduling. We identify an optimal solution that maximizes efficiency while satisfying ethical duty to patients. This forecast is immediately relevant to any hospital system that depends upon procedural revenue.

Background In deep brain stimulation (DBS) for essential tremor, the primary target ventrointermedius (VIM) nucleus cannot be clearly visualized with structural imaging. As such, there has been much interest in the dentatorubrothalamic tract (DRTT) for target localization, but evidence for the DRTT as a putative stimulation target in tremor suppression is lacking. We evaluated proximity of the DRTT in relation to DBS stimulation parameters. Methods This is a retrospective analysis of 26 consecutive patients who underwent DBS with microelectrode recordings (46 leads). Fiber tracking was performed with a published deterministic technique. Clinically optimized stimulation parameters were obtained in all patients at the time of most recent follow-up (6.2 months). Volume of tissue activated (VTA) around contacts was calculated from a published model. Results Tremor severity was reduced in all treated hemispheres, with 70% improvement in the treated hand score of the Clinical Rating Scale for Tremor. At the level of the active contact (2.9 ± 2.0 mm superior to the commissural plane), the center of the DRTT was lateral to the contacts (5.1 ± 2.1 mm). The nearest fibers of the DRTT were 2.4 ± 1.7 mm from the contacts, whereas the radius of the VTA was 2.9 ± 0.7 mm. The VTA overlapped with the DRTT in 77% of active contacts. The distance from active contact to the DRTT was positively correlated with stimulation voltage requirements (Kendall τ = 0.33, P = 0.006), whereas distance to the atlas-based VIM coordinates was not. Conclusions Active contacts in proximity to the DRTT had lower voltage requirements. Data from a large cohort provide support for the DRTT as an effective stimulation target for tremor control.

A potential application of near-infrared (NIR) fluorescence imaging using second-window indocyanine green (SWIG) is demonstrated. We hypothesized that because the pituitary lacks a blood-brain barrier, we might visualize the pituitary stalk using SWIG. A 52-year-old, right-handed man presented to our clinic for evaluation of progressive loss of vision. Physical examination was significant for loss of right peripheral vision and near-complete loss of left field vision. Prolactin was high-normal at 16.2 mg/dL. Brain magnetic resonance imaging demonstrated a 36-mm sellar mass extending superiorly and laterally crossing the intracranial left internal carotid artery, consistent with a nonfunctional pituitary macroadenoma. We elected to pursue left pterional craniotomy for resection. The patient was eligible for our SWIG clinical trial and consented to the study. SWIG is a novel, investigational technique using Food and Drug Administration-approved indocyanine green to enhance visualization of neoplastic tissue intraoperatively.1-7 The patient received 2.5 mg/kg of indocyanine green intravenously approximately 24 hours preoperatively. Intraoperatively, under white-light microscopy, the tumor was easily identified and distinguished from the optic nerves and internal carotid artery. After debulking of the gross tumor, NIR visualization using a laser-equipped endoscope8 demonstrated strong NIR fluorescence in the pituitary stalk. Despite the distorted anatomy, this technique enabled us to confidently identify and preserve the pituitary stalk. Postoperatively, the patient had persistently high urine output that normalized in 24 hours without desmopressin (sodium 139-140 mmol/L); after uneventful recovery, he was discharged with mild improvement in visual function. This case demonstrated a potential use of our SWIG protocol. As the stalk demonstrates strong NIR fluorescence after high-dose indocyanine green administration, surgeons may be able to better localize and preserve the stalk even in complex skull base tumor cases where the anatomy may be significantly distorted.

OBJECTIVECraniopharyngioma represents up to 10% of pediatric brain tumors. Although these lesions are benign, attempts at gross-total resection (GTR) can lead to serious complications. More conservative approaches have emerged but require adjuvant radiation. Endoscopic endonasal surgery (EES) aimed at GTR has the potential to result in fewer complications, but there has been limited comparison to open surgery. The authors performed a review of these two approaches within their institution to elucidate potential benefits and complication differences.METHODSThe authors performed a retrospective review of pediatric patients undergoing resection of craniopharyngioma at their institution between 2001 and 2017. Volumetric analysis of tumor size and postoperative ischemic injury was performed. Charts were reviewed for a number of outcome measures.RESULTSA total of 43 patients with an average age of 8.2 years were identified. Open surgery was the initial intervention in 15 and EES in 28. EES was performed in patients 3–17 years of age. EES has been the only approach used since 2011. In the entire cohort, GTR was more common in the EES group (85.7% vs 53.3%, p = 0.03). Recurrence rate (40% vs 14.2%, p = 0.13) and need for adjuvant radiation (20.0% vs 10.7%, p = 0.71) were higher in the open surgical group, although not statistically significant. Pseudoaneurysm development was only observed in the open surgical group. Volumetric imaging analysis showed a trend toward larger preoperative tumor volumes in the open surgical group, so a matched cohort analysis was performed with the largest tumors from the EES group. This revealed no difference in residual tumor volume (p = 0.28), but the volume of postoperative ischemia was still significantly larger in the open group (p = 0.004). Postoperative weight gain was more common in the open surgical group, a statistically significant finding in the complete patient group that trended toward significance in the matched cohort groups. Body mass index at follow-up correlated with volume of ischemic injury in regression analysis of the complete patient cohort (p = 0.05).CONCLUSIONSEES was associated with similar, if not better, extent of resection and significantly less ischemic injury than open surgery. Pseudoaneurysms were only seen in the open surgical group. Weight gain was also less prevalent in the EES cohort and appears be correlated with extent of ischemic injury at time of surgery.

Rotational vertebrobasilar insufficiency, or bow hunter's syndrome, is a rare cause of posterior circulation ischemia, which, following rotation of the head, results in episodic vertigo, dizziness, nystagmus, or syncope. While typically caused by dynamic occlusion of the vertebral artery in its V2 and V3 segments, the authors here describe a patient with dynamic occlusion of the vertebral artery secondary to a persistent first intersegmental artery, a rare variant course of the vertebral artery. In this case the vertebral artery coursed under rather than over the posterior arch of the C-1. This patient was also found to have incomplete development of the posterior arch of C-1, as is often seen with this variant. The patient underwent dynamic digital subtraction angiography, which demonstrated occlusion at the variant vertebral artery with head turning. He was then taken for decompression of the vertebral artery through removal of the incomplete arch of C-1 that was causing the dynamic compression. After surgery the patient had a complete resolution of symptoms. In this report, the authors present the details of this case, describe the anatomical variants involved, and provide a discussion regarding the need for atlantoaxial fusion in these patients.

Simulated practice may improve resident performance in endoscopic endonasal surgery. Using the NeuroTouch haptic simulation platform, we evaluated resident performance and assessed the effect of simulation training on performance in the operating room. First- (N=3) and second- (N=3) year residents were assessed using six measures of proficiency. Using a visual analog scale, the senior author scored subjects. After the first session, subjects with lower scores were provided with simulation training. A second simulation served as a task-learning control. Residents were evaluated in the operating room over six months by the senior author-who was blinded to the trained/untrained identities-using the same parameters. A nonparametric bootstrap testing method was used for the analysis (Matlab v. 2014a). Simulation training was associated with an increase in performance scores in the operating room averaged over all measures (p=0.0045). This is the first study to evaluate the training utility of an endoscopic endonasal surgical task using a virtual reality haptic simulator. The data suggest that haptic simulation training in endoscopic neurosurgery may contribute to improvements in operative performance. Limitations include a small number of subjects and adjudication bias-although the trained/untrained identity of subjects was blinded. Further study using the proposed methods may better describe the relationship between simulated training and operative performance in endoscopic Neurosurgery.