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## Resection of a rare giant chondromesenchymal hamartoma of the scalp with intracranial blood supply in an adult woman: illustrative case

### BACKGROUND

Nasal chondromesenchymal hamartomas (NCMHs) are benign, slow-growing lesions formed by mesenchymal and cartilaginous components. They occur predominantly in male infants at the nasopharynx and orbit. Rare cases have been reported in adults. Ectopic NCMHs occurring in other head regions without the typical nasopharyngeal or orbital involvement have not been previously described.

### OBSERVATIONS

The authors presented the case of a 40-year-old woman with a giant mass in the left frontoparietal region that started to enlarge progressively after the patient’s first pregnancy at the age of 21 years. The tumor caused intense headaches, nausea, vomiting, asthenia, and syncope. On admission, the neurological examination revealed no abnormalities. Brain magnetic resonance imaging showed a solid homogeneous tumor without intraaxial involvement extending inferiorly to the left zygomatic arch, with a significant mass effect on the adjacent bones but no infiltration. Remarkably, digital subtraction angiography demonstrated that the tumor received blood supply from superficial as well as intracranial branches of the left vertebral artery. After tumor resection, histopathological analysis revealed characteristics indistinguishable from an NCMH.

### LESSONS

The authors described a rare NCMH of the scalp with intracranial blood supply in an adult patient. A case with similar characteristics had not been reported before.

Free access

## Teaching through the screen: a toolbox for creating a virtual neurosurgical subinternship program

### OBJECTIVE

The coronavirus disease 2019 (COVID-19) pandemic disrupted the landscape of traditional neurosurgical subinternships, ramifications of which persist to this day. The outright cancellation of in-person subinternships in 2020 presented not only a challenge to both applicants and programs, but also an opportunity to establish an effective and efficient platform for virtual neurosurgical training. To address this need, the authors designed and trialed a novel virtual neurosurgical subinternship (Virtual Sub-I).

### METHODS

The weeklong, case-based Virtual Sub-I program combined flipped-classroom and active learning approaches. Students worked in small groups to discuss neurosurgical cases. Faculty and residents offered personalized mentorship sessions to participants. Surveys were used to assess students’ experience with the authors’ subinternship program, consistent with level 1 of the Kirkpatrick model.

### RESULTS

A total of 132 students applied from both international and American medical schools. The final cohort comprised 27 students, of whom 8 (30%) were female and 19 (70%) were male. Students characterized the subinternship as “interactive,” “educational,” and “engaging.” One hundred percent of survey respondents were “very likely” to recommend the Virtual Sub-I to their peers. Faculty involved in the Virtual Sub-I stated that the program allowed them to determine the fit of participating medical students for their neurosurgery residency program, and that information gathered from the Virtual Sub-I had the potential to influence their ranking decisions.

### CONCLUSIONS

The Virtual Sub-I recapitulates the educational and interpersonal benefits of the traditional subinternship experience and can serve as a prototype for future virtual surgical education endeavors. Furthermore, the Virtual Sub-I presents a more equitable platform for introducing medical students across the undergraduate medical education spectrum to neurosurgical education and mentorship.

Restricted access

## Concordance of functional MRI memory task and resting-state functional MRI connectivity used in surgical planning for pediatric temporal lobe epilepsy

### OBJECTIVE

Assessing memory is often critical in surgical evaluation, although difficult to assess in young children and in patients with variable task abilities. While obtaining interpretable data from task-based functional MRI (fMRI) measures is common in compliant and awake patients, it is not known whether functional connectivity MRI (fcMRI) data show equivalent results. If this were the case, it would have substantial clinical and research generalizability. To evaluate this possibility, the authors evaluated the concordance between fMRI and fcMRI data collected in a presurgical epilepsy cohort.

### METHODS

Task-based fMRI data for autobiographical memory tasks and resting-state fcMRI data were collected in patients with epilepsy evaluated at Seattle Children’s Hospital between 2010 and 2017. To assess memory-related activation and laterality, signal change in task-based measures was computed as a percentage of the average blood oxygen level–dependent signal over the defined regions of interest. An fcMRI data analysis was performed using 1000 Functional Connectomes Project scripts based on Analysis of Functional NeuroImages and FSL (Functional Magnetic Resonance Imaging of the Brain Software Library) software packages. Lateralization indices (LIs) were estimated for activation and connectivity measures. The concordance between these two measures was evaluated using correlation and regression analysis.

### RESULTS

In this epilepsy cohort studied, the authors observed concordance between fMRI activation and fcMRI connectivity, with an LI regression coefficient of 0.470 (R2 = 0.221, p = 0.00076).

### CONCLUSIONS

Previously published studies have demonstrated fMRI and fcMRI overlap between measures of vision, attention, and language. In the authors’ clinical sample, task-based measures of memory and analogous resting-state mapping were similarly linked in pattern and strength. These results support the use of fcMRI methods as a proxy for task-based memory performance in presurgical patients, perhaps including those who are more limited in their behavioral compliance. Future investigations to extend these results will be helpful to explore how the magnitudes of effect are associated with neuropsychological performance and postsurgical behavioral changes.

Restricted access

## Cost-effectiveness analysis of radiosurgical capsulotomy versus treatment as usual for treatment-resistant obsessive-compulsive disorder

### OBJECTIVE

Stereotactic radiosurgical capsulotomy (SRS-C) is an effective neurosurgical option for patients with treatment-resistant obsessive-compulsive disorder (TROCD). Unlike other procedures such as deep brain stimulation and radiofrequency ablation, the cost-effectiveness of SRS-C for TROCD has not been investigated. The authors herein report the first cost-effectiveness analysis of SRS-C for TROCD.

### METHODS

Using a decision analytic model, the authors compared the cost-effectiveness of SRS-C to treatment as usual (TAU) for TROCD. Treatment response and complication rates were derived from a review of relevant clinical trials. Published algorithms were used to convert Yale-Brown Obsessive Compulsive Scale scores into utility scores reflecting improvements in quality of life. Costs were approached from the healthcare sector perspective and were drawn from Medicare reimbursement rates and available healthcare economics data. A Monte Carlo simulation and probabilistic sensitivity analysis were performed to estimate the incremental cost-effectiveness ratio.

### RESULTS

One hundred fifty-eight TROCD patients across 9 studies who had undergone SRS-C and had at least 36 months of follow-up were included in the model. Compared to TAU, SRS-C was more cost-effective, with an estimated incremental cost-effectiveness ratio of $28,960 per quality-adjusted life year (QALY) gained. Within the 3-year time horizon, net QALYs gained were greater in the SRS-C group than the TAU group by 0.27 (95% CI 0.2698–0.2702, p < 0.0001). At willingness-to-pay thresholds of$50,000 and \$100,000 per QALY, the Monte Carlo simulation revealed that SRS-C was more cost-effective than TAU in 83% and 100% of iterations, respectively.

### CONCLUSIONS

Compared to TAU, SRS-C for TROCD is more cost-effective under a range of possible cost and effectiveness values.

Restricted access

## Creation and validation of a predictive model for lumbar synovial cyst recurrence following decompression without fusion

### OBJECTIVE

Lumbar synovial cysts (LSCs) represent a relatively rare clinical pathology that may result in radiculopathy or neurogenic claudication. Because of the potential for recurrence of these cysts, some authors advocate for segmental fusion, as opposed to decompression alone, as a way to eliminate the risk for recurrence. The objective of this study was to create a predictive score for synovial cyst recurrence following decompression without fusion.

### METHODS

A retrospective chart review was completed of all patients evaluated at a single center over 20 years who were found to have symptomatic LSCs requiring intervention. Only patients undergoing decompression without fusion were included in the analysis. Following this review, baseline characteristics were obtained as well as radiological information. A machine learning method (risk-calibrated supersparse linear integer model) was then used to create a risk stratification score to identify patients at high risk for symptomatic cyst recurrence requiring repeat surgical intervention. Following the creation of this model, a fivefold cross-validation was completed.

### RESULTS

In total, 89 patients were identified who had complete radiological information. Of these 89 patients, 11 developed cyst recurrence requiring reoperation. The Lumbar Synovial Cyst Score was then created with an area under the curve of 0.83 and calibration error of 11.0%. Factors predictive of recurrence were found to include facet inclination angle > 45°, canal stenosis > 50%, T2 joint space hyperintensity, and presence of grade I spondylolisthesis. The probability of cyst recurrence ranged from < 5% for a score of 2 or less to > 88% for a score of 7.

### CONCLUSIONS

The Lumbar Synovial Cyst Score model is a quick and accurate tool to assist in clinical decision-making in the treatment of LSCs.

Restricted access

## Endoscopic third ventriculostomy in previously shunt-treated patients

### OBJECTIVE

Endoscopic third ventriculostomy (ETV) is an option for treatment of hydrocephalus, including for patients who have a history of previous treatment with CSF shunt insertion. The purpose of this study was to report the success of postshunt ETV by using data from a multicenter prospective registry.

### METHODS

Prospectively collected data in the Hydrocephalus Clinical Research Network (HCRN) Core Data Project (i.e., HCRN Registry) were reviewed. Children who underwent ETV between 2008 and 2019 and had a history of previous treatment with a CSF shunt were included. A Kaplan-Meier survival curve was created for the primary outcome: time from postshunt ETV to subsequent CSF shunt placement or revision. Univariable Cox proportional hazards models were created to evaluate for an association between clinical and demographic variables and subsequent shunt surgery. Postshunt ETV complications were also identified and categorized.

### RESULTS

A total of 203 children were included: 57% male and 43% female; 74% White, 23% Black, and 4% other race. The most common hydrocephalus etiologies were postintraventricular hemorrhage secondary to prematurity (56, 28%) and aqueductal stenosis (42, 21%). The ETV Success Score ranged from 10 to 80. The median patient age was 4.1 years. The overall success of postshunt ETV at 6 months was 41%. Only the surgeon’s report of a clear view of the basilar artery was associated with a lower likelihood of postshunt ETV failure (HR 0.43, 95% CI 0.23–0.82, p = 0.009). None of the following variables were associated with postshunt ETV success: age at the time of postshunt ETV, etiology of hydrocephalus, sex, race, ventricle size, number of previous shunt operations, ETV performed at time of shunt infection, and use of external ventricular drainage. Overall, complications were reported in 22% of patients, with CSF leak (8.6%) being the most common complication.

### CONCLUSIONS

Postshunt ETV was successful in treating hydrocephalus, without subsequent need for a CSF shunt, in 41% of patients, with a clear view of the basilar artery being the only variable significantly associated with success. Complications occurred in 22% of patients. ETV is an option for treatment of hydrocephalus in children who have previously undergone shunt placement, but with a lower than expected likelihood of success.

Restricted access

## Equity in neurosurgery: a worldwide survey of women neurosurgeons

### OBJECTIVE

The global neurosurgery workforce does not have a defined stance on gender equity. The authors sought to study and characterize the demographic features of the international women neurosurgery community and to better understand the perceptions and reflections of their neurosurgical careers. The objective was to define and characterize the workplace inequities faced by the global women neurosurgeon community.

### METHODS

A 58-item cross-sectional survey was distributed to the global women neurosurgery community. The survey was distributed via an online and mobile platform between October 2018 and December 2020. Responses were anonymized. The authors utilized chi-square analysis to differentiate variables (e.g., career satisfaction) between various groups (e.g., those based on academic position). The authors calculated 95% CIs to establish significance.

### RESULTS

Among 237 respondents, approximately 40% were between the ages of 26 and 35 years. Within their respective departments, 45% identified themselves as the only woman neurosurgeon in their practice. Forty-three percent stated that their department supported women neurosurgeons for leadership roles. Seventy-five percent of respondents were members of organized neurosurgery professional societies; of these, 38% had been involved in leadership roles. Almost 60% of respondents postponed their decision to get pregnant because of resident or work-related influences.

### CONCLUSIONS

This survey provides international feedback for characterizing and understanding the experiences of women neurosurgeons worldwide. Future research should aim to understand all neurosurgeons’ experiences throughout the pipeline and career life cycle of neurosurgery in order to improve the field of neurosurgery.

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## Evaluation of differences across age groups in the incidence, severity, and recovery of concussion in adolescent student-athletes from 2009 to 2019

### OBJECTIVE

Concussion incidence is known to be highest in children and adolescents; however, there is conflicting evidence about the effect of age on concussion risk and recovery within the adolescent age range. The heterogeneity of results may be partially due to the use of age groupings based on convenience, making comparisons across studies difficult. This study evaluated the independent effect of age on concussion incidence, severity, and recovery in student-athletes aged 12–18 years using cluster analysis to define groupings.

### METHODS

Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) scores of 11,403 baseline tests and 4922 postinjury tests were used to calculate the incidence rates for adolescent student-athletes grouped into 3 age bands (12–13, 14–15, and 16–18 years of age) on the basis of clustering analysis. The recently created Severity Index was used to compare concussion severity between groups. Follow-up tests for subjects who sustained a concussion were used to evaluate recovery time. The chi-square test and 1-way ANOVA were used to compare differences in demographic characteristics and concussion incidence, severity, and recovery. Multivariable logistic and linear regressions were used to evaluate the independent effects of age on concussion incidence and severity, respectively. Multivariable Cox hazard regression was used to evaluate differences in recovery time. Further analyses were conducted to directly compare findings across studies on the basis of the age groupings used in prior studies.

### RESULTS

Multivariable regression analyses demonstrated that the 14- to 15-year-old age group had a significantly higher concussion incidence than both the 12- to 13-year-old (14- to 15-year-old group vs 12- to 13-year-old group, OR 1.57, 95% CI 1.16–2.17, p = 0.005) and 16- to 18-year-old (16- to 18-year-old group vs 14- to 15-year-old group, OR 0.79, 95% CI 0.69–0.91, p = 0.0008) age groups. There was no difference in incidence between the 12- to 13-year-old and 16- to 18-year-old groups (16- to 18-year group vs 12- to 13-year group, OR 1.26, 95% CI 0.93–1.72, p = 0.15). There were also no differences in concussion severity or recovery between any groups.

### CONCLUSIONS

This study found that concussion incidence was higher during mid-adolescence than early and late adolescence, suggesting a U-shaped relationship between age and concussion risk over the course of adolescence. Age had no independent effect on concussion severity or recovery in the 12- to 13-, 14- to 15-, and 16- to 18-year-old groups. Further analysis of the various age groups revealed that results may vary significantly with minor changes to groupings, which may explain the divergent results in the current literature on this topic. Thus, caution should be taken when interpreting the results of this and all similar studies, especially when groupings are based on convenience.

Open access

## Evolution of the AO Spine Sacral and Pelvic Classification System: a systematic review

### OBJECTIVE

The purpose of this study was to describe the genesis of the AO Spine Sacral and Pelvic Classification System in the context of historical sacral and pelvic grading systems.

### METHODS

A systematic search of MEDLINE, EMBASE, Google Scholar, and Cochrane databases was performed consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify all existing sacral and pelvic fracture classification systems.

### RESULTS

A total of 49 articles were included in this review, comprising 23 pelvic classification systems and 17 sacral grading schemes. The AO Spine Sacral and Pelvic Classification System represents both the evolutionary product of these historical systems and a reinvention of classic concepts in 5 ways. First, the classification introduces fracture types in a graduated order of biomechanical stability while also taking into consideration the neurological status of patients. Second, the traditional belief that Denis central zone III fractures have the highest rate of neurological deficit is not supported because this subgroup often includes a broad spectrum of injuries ranging from a benign sagittally oriented undisplaced fracture to an unstable “U-type” fracture. Third, the 1990 Isler lumbosacral system is adopted in its original format to divide injuries based on their likelihood of affecting posterior pelvic or spinopelvic stability. Fourth, new discrete fracture subtypes are introduced and the importance of bilateral injuries is acknowledged. Last, this is the first integrated sacral and pelvic classification to date.

### CONCLUSIONS

The AO Spine Sacral and Pelvic Classification is a universally applicable system that redefines and reorders historical fracture morphologies into a rational hierarchy. This is the first classification to simultaneously address the biomechanical stability of the posterior pelvic complex and spinopelvic stability, while also taking into consideration neurological status. Further high-quality controlled trials are required prior to the inclusion of this novel classification within a validated scoring system to guide the management of sacral and pelvic injuries.

Restricted access

## A history of Colombian neurosurgery: events, persons, and outcomes that have shaped the specialty in the country

The history of Colombian neurosurgery is a collective legacy of neurosurgeon-scientists, scholars, teachers, innovators, and researchers. Anchored in the country’s foundational values of self-determination and adaptability, these pioneers emerged from the Spanish colonial medical tradition and forged surgical alliances abroad. From the time of Colombian independence until the end of World War I, exchanges with the French medical tradition produced an emphasis on anatomical and systematic approaches to the emerging field of neurosurgery. The onset of American neurosurgical expertise in the 1930s led to a new period of exchange, wherein technological innovations were added to the Colombian neurosurgical repertoire. This diversity of influences culminated in the 1950s with the establishment of Colombia’s first in-country neurosurgery residency program. A select group of avant-garde neurosurgeons from this period expanded the domestic opportunities for patients and practitioners alike. Today, the system counts 10 recognized neurosurgery residency programs and over 500 neurosurgeons within Colombia. Although the successes of specific individuals and innovations were considered, the primary purpose of this historical survey was to glean relevant lessons from the past that can inform present challenges, inspire new opportunities, and identify professional and societal goals for the future of neurosurgical practice and specialization.