The Neurosurgical Atlas: advancing neurosurgical education in the digital age.

OBJECTIVE: The advent of the internet and the popularity of e-learning resources has promoted a shift in medical and surgical education today. The Neurosurgical Atlas has sought to capitalize on this shift by providing easily accessible video and online education to its users on an international scale. The rising popularity of social media has provided new avenues for expanding that global reach, and the Atlas has sought to do just that. In this study, the authors analyzed user demographics and web traffic patterns to quantify the international reach of the Atlas and examined the potential impact of social media platforms on the expansion of that reach. METHODS: Twitter, Facebook, and Instagram metrics were extracted using each respective service's analytics tool from the date of their creation through October 2019. Google Analytics was used to extract website traffic data from September 2018 to September 2019 and app data from January 2019 to October 2019. The metrics extracted included the number of platform users/followers, user demographic information, percentage of new versus returning visitors, and a number of platform-specific values. RESULTS: Since the authors' previous publication in 2017, annual website viewership has more than doubled to greater than 500,000 viewing sessions in the past year alone; international users accounted for more than 60% of the visits. The Atlas Twitter account, established in August 2012, has more than 12,000 followers, primarily hailing from the United States, the United Kingdom, Canada, and Saudi Arabia. The Atlas Facebook account, established in 2013, has just over 13,000 followers, primarily from India, Egypt, and Mexico. The Atlas Instagram account (established most recently, in December 2018) has more than 16,000 followers and the highest percentage (31%) of younger users (aged 18-24 years). The Atlas app was officially launched in May 2019, largely via promotion on the Atlas social media platforms, and has since recorded more than 60,000 viewing sessions, 80% of which were from users outside the United States. CONCLUSIONS: The Neurosurgical Atlas has attempted to leverage the many e-learning resources at its disposal to assist in spreading neurosurgical best practice on an international scale in a novel and comprehensive way. By incorporating multiple social media platforms into its repertoire, the Atlas is able to ensure awareness of and access to these resources regardless of the user's location or platform of preference. In so doing, the Atlas represents a novel way of advancing access to neurosurgical educational resources in the digital age.

Safety and Efficacy of Laser Interstitial Thermal Therapy as Upfront Therapy in Primary Glioblastoma and IDH-Mutant Astrocytoma: A Meta-Analysis.

Although primary studies have reported the safety and efficacy of LITT as a primary treatment in glioma, they are limited by sample sizes and institutional variation in stereotactic parameters such as temperature and laser power. The current literature has yet to provide pooled statistics on outcomes solely for primary brain tumors according to the 2021 WHO Classification of Tumors of the Central Nervous System (WHO CNS5). In the present study, we identify recent articles on primary CNS neoplasms treated with LITT without prior intervention, focusing on relationships with molecular profile, PFS, and OS. This meta-analysis includes the extraction of data from primary sources across four databases using the Covidence systematic review manager. The pooled data suggest LITT may be a safe primary management option with tumor ablation rates of 94.8% and 84.6% in IDH-wildtype glioblastoma multiforme (GBM) and IDH-mutant astrocytoma, respectively. For IDH-wildtype GBM, the pooled PFS and OS were 5.0 and 9.0 months, respectively. Similar to rates reported in the prior literature, the neurologic and non-neurologic complication rates for IDH-wildtype GBM were 10.3% and 4.8%, respectively. The neurologic and non-neurologic complication rates were somewhat higher in the IDH-mutant astrocytoma cohort at 33% and 8.3%, likely due to a smaller cohort size.

The human craniospinal venous system and its influence on postural intracranial pressure: a review.

OBJECTIVE: The cerebral and spinal venous systems have similar functions but unique anatomical and physiological properties. CSF occupies space in the cranial and spinal vaults, is continuously produced, and has many roles, including maintaining a favorable environment for CNS structures. The influence of the cerebrospinal venous system on CSF dynamics has been theorized since the 1940s. Newer studies suggest venous outflow pattern alterations in response to changes in body position. However, the relationship of postural cerebrospinal venous outflow shifts with and their influence on CSF homeostasis is not well understood. METHODS: The authors searched the published literature related to the anatomy and function of vertebral venous plexus (VVP), CSF, and positional cerebral venous flow characteristics. A comprehensive collection of literature was compiled and reviewed, and the relationship between cerebrospinal and venous system changes and alterations in body positions, with an emphasis on the craniocervical system, is discussed. RESULTS: The VVP is a network of valveless veins extending from the sacrum to the cranium that are interconnected with the cranial dural sinuses. The internal VVP occupies space within the extradural spinal canal and functions to return spinal venous blood to the heart, but it has additional properties, including the capability of bidirectional venous flow, an intraspinal dilatory capacity, and a role in cerebral venous outflow. When one rises to the upright position, CSF shifts toward the spinal canal and force vectors change, leading to reduced intracranial CSF pressure; simultaneously, cerebral venous outflow shifts from the jugular vein to the VVP outflow pathway. The venous outflow shift mechanism and its purpose are poorly understood. The authors review the known physiology of the system, identify gaps in knowledge to direct future research, and propose an interpretation of these data, concluding that position-dependent CSF and cerebrospinal venous shifts are part of a complementary positional craniospinal pressure regulation system that must be kept in balance for optimal CNS function. CONCLUSIONS: Current knowledge of the cerebrospinal venous anatomy, dynamic flow characteristics in response to gravity, and the venous system's influence on CSF suggests that the VVP plays a role in influencing CSF pressure, and the authors hypothesize that it plays a role in supporting intracranial pressure in the upright body posture. Further research is needed to better characterize the functional relationship of the VVP to CSF dynamics as well as identify potentially related disease states.

Incidental Meningiomas: Potential Predictors of Growth and Current State of Management.

The rise in availability of neuroimaging has led to an increase in incidentally discovered meningiomas. These tumors are typically asymptomatic and tend to display slow growth. Treatment options include observation with serial monitoring, radiation, and surgery. Although optimal management is unclear, clinicians recommend a conservative approach, which preserves quality of life and limits unnecessary intervention. Several risk factors have been investigated for their potential utility in the development of prognostic models for risk assessment. Herein, the authors review the current literature on incidental meningiomas, focusing their discussion on potential predictive factors for tumor growth and appropriate management practices.

Targeted Public Health Training for Neurosurgeons: An Essential Task for the Prioritization of Neurosurgery in the Evolving Global Health Landscape.

The gap between the tremendous burden of neurological disease requiring surgical management and the limited capacity for neurosurgical care has fueled the growth of the global neurosurgical movement. It is estimated that an additional 23 300 neurosurgeons are needed to meet the burden posed by essential cases across the globe. Initiatives to increase neurosurgical capacity through systems strengthening and workforce development are key elements in correcting this deficit. Building on the growing interest in global health among neurosurgical trainees, we propose the integration of targeted public health education into neurosurgical training, in both high-income countries and low- and middle-income countries. This effort will ensure that graduates possess the fundamental skillsets and experience necessary to participate in and lead capacity-building efforts in the developing countries. This additional public health training can also help neurosurgical residents to achieve the core competencies outlined by accreditation boards, such as the Accreditation Committee on Graduate Medical Education in the United States. In this narrative review, we describe the global burden of neurosurgical disease, establish the need and role for the global neurosurgeon, and discuss pathways for implementing targeted global public health education in the field of neurosurgery.

The Role of Vancomycin Powder During Spinal Cord Stimulator Implantation: A Case Series and Review of the Literature.

OBJECTIVE: We examined the role of intrawound vancomycin powder as prophylaxis against postoperative surgical site infection (SSI) after spinal cord stimulator (SCS) implantation. METHODS: We performed a retrospective analysis of 153 consecutive patients who had undergone permanent SCS implantation surgery via open laminectomy between 2014 and 2020. We queried the patients' medical records for patient age, sex, relevant medical history, and whether intrawound vancomycin had been administered. We compared the rates of SSI (primary outcome) and seroma (secondary outcome) within 3 months after surgery between the vancomycin and no-vancomycin groups. Finally, we conducted multivariable logistic regression analyses to identify independent predictors of postoperative SSI or seroma. RESULTS: Of the 153 patients, 59% were women, and the average age was 65.4 years. Overall, 3 patients (2%) had developed an SSI: 2 (methicillin-resistant Staphylococcus aureus, Klebsiella) in the vancomycin group and 1 (methicillin-sensitive Staphylococcus aureus) in the no-vancomycin group. This difference in SSI rate between the 2 groups was insignificant (P = 0.73). Three seromas, all in the no-vancomycin group, accounted for a statistically significant difference in seroma formation between the 2 groups (P = 0.04). Multivariate logistic regression failed to identify any perioperative characteristics as independent predictors of postoperative SSI or seroma. CONCLUSIONS: Our experience suggests open laminectomy for SCS implantation surgery can be performed with a low postoperative SSI rate, with or without the use of powdered vancomycin. We found no evidence suggesting that the use of powdered vancomycin is unsafe or related to postoperative seroma formation. We failed to draw any definitive conclusions regarding its efficacy, despite referencing the largest single case series of SCS implantation to date.

Motor Cortex Stimulation for Facial Pain.

Motor cortex stimulation (MCS) has been used in the treatment of intractable neuropathic facial pain for nearly 30 years. While efficacy rates have been noted as high as 88% in some studies, considerable variability in treatment response remains. Additionally, MCS is often cited as providing diminishing relief over time, and there are few long-term studies on efficacy. Complications are generally mild and include infection, hardware complication, seizure, and transient neurological deficit. Despite relatively minimal use, MCS remains a viable treatment option for the appropriately selected facial pain patients that have proved refractory to conservative management.

Novel Use of Stimulating Fence-Post Technique for Functional Mapping of Subcortical White Matter During Tumor Resection: A Technical Case Series.

BACKGROUND: Maximal safe resection remains a key principle in infiltrating glioma management. Stimulation mapping is a key adjunct for minimizing functional morbidity while "fence-post" procedures use catheters or dye to mark the tumor border at the start of the procedure prior to brain shift. OBJECTIVE: To report a novel technique using stereotactically placed electrodes to guide tumor resection near critical descending subcortical fibers. METHODS: Navigated electrodes were placed prior to tumor resection along the deep margin bordering presumed eloquent tracts. Stimulation was administered through these depth electrodes for subcortical motor and language mapping. RESULTS: Twelve patients were included in this preliminary technical report. Seven patients (7/12, 58%) were in asleep cases, while the other 5 cases (5/12, 42%) were performed awake. Mapping of motor fibers was performed in 8 cases, and language mapping was done in 1 case. In 3 cases, both motor and language mapping were performed using the same depth electrode spanning corticospinal tract and the arcuate fasciculus. CONCLUSION: Stereotactic depth electrode placement coupled with stimulation mapping of white matter tracts can be used concomitantly to demarcate the border between deep tumor margins and eloquent brain, thus helping to maximize extent of resection while minimizing functional morbidity.

Transtentorial Approach to Parahippocampal Lesions: A Technically Challenging Approach for Preserving Temporal Lobe Structures.

In this installment of the Neurosurgical Atlas Series for WORLD NEUROSURGERY, the authors examine the paramedian supracerebellar transtentorial (SCTT) approach as a means of accessing the basal posteromedial temporal lobe for both intradural and extradural lesions. While other approaches, such as the subtemporal, transtemporal, and transsylvian routes, are often used to reach this otherwise impervious region, all of them do so at the expense of supratentorial structural integrity. Despite the long and narrow working distance provided by the SCTT approach, the access it provides to critical, deep-seated regions with little to no associated morbidity makes it our preferred approach in these patients. In this work, we highlight the perioperative considerations for this procedure, discuss the technical nuances of all aspects of the operation, and provide discussion on the approach in the context of its evolution and alternatives.

PEEK interbody devices for multilevel anterior cervical discectomy and fusion: association with more than 6-fold higher rates of pseudarthrosis compared to structural allograft.

OBJECTIVE: Common interbody graft options for anterior cervical discectomy and fusion (ACDF) include allograft and polyetheretherketone (PEEK). PEEK has gained popularity due to its radiolucent properties and a modulus of elasticity similar to that of bone. PEEK devices also result in higher billing costs than allograft, which may drive selection. A previous study found a 5-fold higher rate of pseudarthrosis with the use of PEEK devices compared with structural allograft in single-level ACDF. Here the authors report on the occurrence of pseudarthrosis with PEEK devices versus structural allograft in patients who underwent multilevel ACDF. METHODS: The authors retrospectively reviewed 81 consecutive patients who underwent a multilevel ACDF and had radiographic follow-up for at least 1 year. Data were collected on age, sex, BMI, tobacco use, pseudarthrosis, and rate of reoperation for pseudarthrosis. Logistic regression was used for data analysis. RESULTS: Of 81 patients, 35 had PEEK implants and 46 had structural allograft. There were no significant differences between age, sex, smoking status, or BMI in the 2 groups. There were 26/35 (74%) patients with PEEK implants who demonstrated radiographic evidence of pseudarthrosis, compared with 5/46 (11%) patients with structural allograft (p < 0.001, OR 22.2). Five patients (14%) with PEEK implants required reoperation for pseudarthrosis, compared with 0 patients with allograft (p = 0.013). CONCLUSIONS: This study reinforces previous findings on 1-level ACDF outcomes and suggests that the use of PEEK in multilevel ACDF results in statistically significantly higher rates of radiographic pseudarthrosis and need for revision surgery than allograft. Surgeons should consider these findings when determining graft options, and reimbursement policies should reflect these discrepancies.

Spasm Freedom Following Microvascular Decompression for Hemifacial Spasm: Systematic Review and Meta-Analysis.

BACKGROUND: Hemifacial spasm (HFS) is a debilitating disorder characterized by intermittent involuntary movement of muscles innervated by the facial nerve. HFS is caused by neurovascular compression along the facial nerve root exit zone and can be treated by microvascular decompression (MVD). The goal was to determine rates and predictors of spasm freedom after MVD for HFS. METHODS: A literature search using the key terms "microvascular decompression" and "hemifacial spasm" was performed. The primary outcome variable was spasm freedom at last follow-up. Analysis was completed to evaluate for variables associated with spasm-free outcome. RESULTS: A total of 39 studies including 6249 patients were analyzed. Overall spasm freedom rate was 90.5% (5652/6249) at a follow-up of 1.25 ± 0.04 years. There was no significant relationship between spasm freedom versus persistent spasm and age at surgery, timing of follow-up, gender, disease duration, side of disease, or vessel type. Spasm freedom was more likely after an initial surgery versus a redo MVD (odds ratio 4.16, 95% confidence interval 1.99-8.68; P < 0.01). CONCLUSIONS: MVD works well for HFS with cure rates >90% at 1-year follow-up in 6249 patients from 39 studies. A significant predictor of long-term spasm freedom at 1 year was an initial MVD as compared to repeat MVD. The majority of published manuscripts on MVD for HFS are heterogeneous single-institutional retrospective studies. As such, a large-scale meta-analysis reporting outcome rates and evaluating significant predictors of spasm freedom provides utility in the absence of randomized controlled studies.

Distal Ventriculoatrial Shunt Revision in Adult Myelomeningocele Patient Performed via Endovascular Transvenous Approach.

BACKGROUND: Myelomeningocele patients with shunt-dependent hydrocephalus often require multiple shunt revisions, eventually exhausting first-line distal diversion sites. Ventriculoatrial (VA) shunts are used less commonly than ventriculoperitoneal shunts, but knowledge of their use and complications is important to the neurosurgeon's armamentarium. VA shunts differ from ventriculoperitoneal and ventriculopleural shunts in that the ideal distal catheter target is an anatomically small area in comparison with the peritoneal and pleural cavities. CASE DESCRIPTION: Here we present a case of an adult myelomeningocele patient who experienced migration of a distal VA shunt catheter. A minimally invasive revision technique that does not require recannulation of the vessels or open manipulation of the shunt is presented. CONCLUSIONS: This is the fourth reported instance of successful distal revision of a migrated VA shunt catheter via transfemoral endovascular snaring. Knowledge of the opportunities afforded by this technique and collaboration with thoracic surgery colleagues is of benefit to all neurosurgeons.

Utilization of 3D imaging reconstructions and assessment of symptom-free survival after microvascular decompression of the facial nerve in hemifacial spasm.

OBJECTIVE: Hemifacial spasm (HFS), largely caused by neurovascular compression (NVC) of the facial nerve, is a rare condition characterized by paroxysmal, unilateral, involuntary contraction of facial muscles. It has long been suggested that these symptoms are due to compression at the transition zone of the facial nerve. The aim of this study was to examine symptom-free survival and long-term quality of life (QOL) in HFS patients who underwent microvascular decompression (MVD). A secondary aim was to examine the benefit of utilizing fused MRI and MRA post hoc 3D reconstructions to better characterize compression location at the facial nerve root exit zone (fREZ). METHODS: The authors retrospectively analyzed patients with HFS who underwent MVD at a single institution, combined with a modified HFS-7 telephone questionnaire. Kaplan-Meier analysis was used to determine event-free survival, and the Wilcoxon signed-rank test was used to compare pre- and postoperative HFS-7 scores. RESULTS: Thirty-five patients underwent MVD for HFS between 2002 and 2018 with subsequent 3D reconstructions of preoperative images. The telephone questionnaire response rate was 71% (25/35). If patients could not be reached by telephone, then the last clinic follow-up date was recorded and any recurrence noted. Twenty-four patients (69%) were symptom free at longest follow-up. The mean length of follow-up was 2.4 years (1 month to 8 years). The mean symptom-free survival time was 44.9 ± 5.8 months, and the average symptom-control survival was 69.1 ± 4.9 months. Four patients (11%) experienced full recurrence. Median HFS-7 scores were reduced by 18 points after surgery (Z = -4.013, p < 0.0001). Three-dimensional reconstructed images demonstrated that NVC most commonly occurred at the attached segment (74%, 26/35) of the facial nerve within the fREZ and least commonly occurred at the traditionally implicated transition zone (6%, 2/35). CONCLUSIONS: MVD is a safe and effective treatment that significantly improves QOL measures for patients with HFS. The vast majority of patients (31/35, 89%) were symptom free or reported only mild symptoms at longest follow-up. Symptom recurrence, if it occurred, was within the first 2 years of surgery, which has important implications for patient expectations and informed consent. Three-dimensional image reconstruction analysis determined that culprit compression most commonly occurs proximally along the brainstem at the attached segment. The success of this procedure is dependent on recognizing this pattern and decompressing appropriately. Three-dimensional reconstructions were found to provide much clearer characterization of this area than traditional preoperative imaging. Therefore, the authors suggest that use of these reconstructions in the preoperative setting has the potential to help identify appropriate surgical candidates, guide operative planning, and thus improve outcome in patients with HFS.

Pain-free survival after vagoglossopharyngeal complex sectioning with or without microvascular decompression in glossopharyngeal neuralgia.

OBJECTIVE: Glossopharyngeal neuralgia (GN) is a rare pain condition in which patients experience paroxysmal, lancinating throat pain. Multiple surgical approaches have been used to treat this condition, including microvascular decompression (MVD), and sectioning of cranial nerve (CN) IX and the upper rootlets of CN X, or a combination of the two. The aim of this study was to examine the long-term quality of life and pain-free survival after MVD and sectioning of the CN X/IX complex. METHODS: A combined retrospective chart review and a quality-of-life telephone survey were performed to collect demographic and long-term outcome data. Quality of life was assessed by means of a questionnaire based on a combination of the Barrow Neurological Institute pain intensity scoring criteria and the Brief Pain Inventory-Facial. Kaplan-Meier analysis was performed to determine pain-free survival. RESULTS: Of 18 patients with GN, 17 underwent sectioning of the CN IX/X complex alone or sectioning and MVD depending on the presence of a compressing vessel. Eleven of 17 patients had compression of CN IX/X by the posterior inferior cerebellar artery, 1 had compression by a vertebral artery, and 5 had no compression. One patient (6%) experienced no immediate pain relief. Fifteen (88%) of 17 patients were pain free at the last follow-up (mean 9.33 years, range 5.16-13 years). One patient (6%) experienced throat pain relapse at 3 months. The median pain-free survival was 7.5 years ± 10.6 months. Nine of 18 patients were contacted by telephone. Of the 17 patients who underwent sectioning of the CN IX/X complex, 13 (77%) patients had short-term complaints: dysphagia (n = 4), hoarseness (n = 4), ipsilateral hearing loss (n = 4), ipsilateral taste loss (n = 2), and dizziness (n = 2) at 2 weeks. Nine patients had persistent side effects at latest follow-up. Eight of 9 telephone respondents reported that they would have the surgery over again. CONCLUSIONS: Sectioning of the CN IX/X complex with or without MVD of the glossopharyngeal nerve is a safe and effective surgical therapy for GN with initial pain freedom in 94% of patients and an excellent long-term pain relief (mean 7.5 years).

Balancing Operative Efficiency and Surgical Education: A Functional Neurosurgery Model.

BACKGROUND: Attending surgeons have dual obligations to deliver high-quality health care and train residents. In modern healthcare, lean principles are increasingly applied to processes preceding and following surgery. However, surgeons have limited data regarding variability and waste during any given operation. OBJECTIVE: To measure variability and waste during the following key functional neurosurgery procedures: retrosigmoid craniectomy (microvascular decompression [MVD] and internal neurolysis) and deep brain stimulation (DBS). Additionally, we correlate variability with residents' self-reported readiness for the surgical steps. The aim is to guide surgeons as they balance operative safety and efficiency with training obligations. METHODS: For each operation (retrosigmoid craniectomy and DBS), a standard workflow, segmenting the operation into components, was defined. We observed a representative sample of operations, timing the components, with a focus on variability. To assess perceptions of safety and risk among surgeons of various training levels, a survey was administered. Survey results were correlated with operative variability, attempting to identify areas for increasing value without compromising trainee experience. RESULTS: A sampling of each operation (n = 36) was observed during the study period. For MVD, craniectomy had the highest mean duration and standard deviation, whereas the MVD itself had the lowest mean duration and standard deviation. For DBS, the segments with largest standard deviation in duration were registration and electrode placement. For many steps of both procedures, there was a statistically significant relationship between increasing level of training and increasing perception of safety. CONCLUSION: This proof-of-concept study introduces an educational and process-improvement tool that can be used to aid surgeons in increasing the efficiency of patient care.

Natural history of neuromodulation devices and therapies: a patient-centered survival analysis.

OBJECTIVE: Despite rapid development and expansion of neuromodulation technologies, knowledge about device and/or therapy durability remains limited. The aim of this study was to evaluate the long-term rate of hardware and therapeutic failure of implanted devices for several neuromodulation therapies. METHODS: The authors performed a retrospective analysis of patients' device and therapy survival data (Kaplan-Meier survival analysis) for deep brain stimulation (DBS), vagus nerve stimulation (VNS), and spinal cord stimulation (SCS) at a single institution (years 1994-2015). RESULTS: During the study period, 450 patients underwent DBS, 383 VNS, and 128 SCS. For DBS, the 5- and 10-year initial device survival was 87% and 73%, respectively, and therapy survival was 96% and 91%, respectively. For VNS, the 5- and 10-year initial device survival was 90% and 70%, respectively, and therapy survival was 99% and 97%, respectively. For SCS, the 5- and 10-year initial device survival was 50% and 34%, respectively, and therapy survival was 74% and 56%, respectively. The average initial device survival for DBS, VNS, and SCS was 14 years, 14 years, and 8 years while mean therapy survival was 18 years, 18 years, and 12.5 years, respectively. CONCLUSIONS: The authors report, for the first time, comparative device and therapy survival rates out to 15 years for large cohorts of DBS, VNS, and SCS patients. Their results demonstrate higher device and therapy survival rates for DBS and VNS than for SCS. Hardware failures were more common among SCS patients, which may have played a role in the discontinuation of therapy. Higher therapy survival than device survival across all modalities indicates continued therapeutic benefit beyond initial device failures, which is important to emphasize when counseling patients.