Genomic alterations associated with postoperative nodular leptomeningeal disease after resection of brain metastases

OBJECTIVE

The relationship between brain metastasis resection and risk of nodular leptomeningeal disease (nLMD) is unclear. This study examined genomic alterations found in brain metastases with the aim of identifying alterations associated with postoperative nLMD in the context of clinical and treatment factors.

METHODS

A retrospective, single-center study was conducted on patients who underwent resection of brain metastases between 2014 and 2022 and had clinical and genomic data available. Postoperative nLMD was the primary endpoint of interest. Targeted next-generation sequencing of > 500 oncogenes was performed in brain metastases. Cox proportional hazards analyses were performed to identify clinical features and genomic alterations associated with nLMD.

RESULTS

The cohort comprised 101 patients with tumors originating from multiple cancer types. There were 15 patients with nLMD (14.9% of the cohort) with a median time from surgery to nLMD diagnosis of 8.2 months. Two supervised machine learning algorithms consistently identified CDKN2A/B codeletion and ERBB2 amplification as the top predictors associated with postoperative nLMD across all cancer types. In a multivariate Cox proportional hazards analysis including clinical factors and genomic alterations observed in the cohort, tumor volume (× 10 cm3; HR 1.2, 95% CI 1.01-1.5; p = 0.04), CDKN2A/B codeletion (HR 5.3, 95% CI 1.7-16.9; p = 0.004), and ERBB2 amplification (HR 3.9, 95% CI 1.1-14.4; p = 0.04) were associated with a decreased time to postoperative nLMD.

CONCLUSIONS

In addition to increased resected tumor volume, ERBB2 amplification and CDKN2A/B deletion were independently associated with an increased risk of postoperative nLMD across multiple cancer types. Additional work is needed to determine if targeted therapy decreases this risk in the postoperative setting.

Epidemiology, Genetics, and DNA Methylation Grouping of Hyperostotic Meningiomas

BACKGROUND AND OBJECTIVES

Meningiomas are the most common primary intracranial tumors and are among the only tumors that can form lamellar, hyperostotic bone in the tumor microenvironment. Little is known about the epidemiology or molecular features of hyperostotic meningiomas.

METHODS

Using a retrospective database of 342 meningiomas treated with surgery at a single institution, we correlated clinical, tumor-related, targeted next-generation DNA sequencing (n = 39 total, 16 meningioma-induced hyperostosis [MIH]), and surgical variables with the presence of MIH using generalized linear models. Meningioma DNA methylation grouping was analyzed on a separate population of patients from the same institution with preoperative imaging studies sufficient for identification of MIH (n = 200).

RESULTS

MIH was significantly correlated with anterior fossa (44.3% of MIH vs 17.5% of non-MIH were in the anterior fossa P < .001, c2) or skull base location (62.5% vs 38.3%, P < .001, c2) and lower MIB-1 labeling index. Gross total resection was accomplished in 27.3% of tumors with MIH and 45.5% of nonhyperostotic meningiomas (P < .05, t test). There was no association between MIH and histological World Health Organization grade (P = .32, c2). MIH was significantly more frequent in meningiomas from the Merlin-intact DNA methylation group (P < .05). Somatic missense mutations in the WD-repeat-containing domain of the TRAF7 gene were the most common genetic alteration associated with MIH (n = 12 of 15, 80%, P < .01, c2).

CONCLUSION

In this article, we show that MIH has a predilection for the anterior skull base and affected tumors are less amenable to gross total resection. We find no association between MIH and histological World Health Organization grade, but show that MIH is more common in the Merlin-intact DNA methylation group and is significantly associated with TRAF7 somatic missense mutations. These data provide a framework for future investigation of biological mechanisms underlying MIH.

Acquired Chiari Type I Malformation Associated with Type IV Dural Arteriovenous Fistula: Case Report

BACKGROUND

 Chiari malformations, usually congenital, can rarely be associated with arteriovenous (AV) fistulas. We present the first case involving a type IV dural AV fistula with a Chiari type I malformation.

METHODS

 Retrospective chart review was performed to obtain pertinent details regarding history and examination, pathologic findings, and treatment course.

RESULTS

 A 63-year-old woman with a 2-year history of migraines presented with 5 months of occipital, right-sided headaches and neck pain exacerbated by Valsalva maneuvers. Computed tomography (CT) and magnetic resonance imaging (MRI) of the head showed a possible right occipital AV malformation, bilateral cerebellar subdural hygromas, and tonsillar crowding at the foramen magnum indicating an acquired Chiari type I malformation. Angiography demonstrated a Cognardtype IV right posterior occipital dural AV fistula supplied by bilateral middle meningeal and posterior meningeal arteries.

CONCLUSION

 After treatment of the dural AV fistula, hygroma evacuation, and decompression of the acquired Chiari malformation, the patient's Valsalva-induced headaches abated.

A new perspective on an old method: gated SPECT imaging for left ventricular contractile function assessment

The ejection fraction (LVEF) is a commonly used marker of left ventricular function. However, because it is strongly influenced by loading conditions, it can be inaccurate in representing cardiac contractility. We therefore evaluated a gated SPECT based tool to simultaneously assess preload, afterload, and contractility. Using gated SPECT-determined ventricular volumes and arterial tension measurements, we calculated ventricular and arterial elastance (Ev and Ea), as well as end-diastolic volumes, which are surrogates for contractility, afterload, and preload, respectively. We applied this protocol to 1462 consecutive patients and assessed the ventricular function in patients with and without myocardial infarction. The median LVEF was 68% (IQR 62-74%). Patients with infarction exhibited decreased contractility (ventricular elastance of 3 mmHg/ml vs. 6 mmHg/ml), compensated by an increase of preload (end-diastolic volume of 100 ml vs. 78 ml) and a decrease in afterload (arterial elastance of 1.8 mmHg/ml vs. 2.2 ml/mmHg). These interactions yielded a preserved ejection fraction in both groups. Gated SPECT-measured volumes were consistent with values reported in the literature. In addition, the combination of nuclear imaging and arterial tension measurement accounted for not only the ejection fraction but also the loading context, providing a more accurate representation of cardiac contractility.

Gender Diversity in Hand Surgery Leadership

BACKGROUND

Diversity in leadership drives innovation; however, women are underrepresented in leadership positions across academic medicine. The aim of this study was to assess the current gender representation in hand surgery leadership positions.

METHODS

This was a cross-sectional analysis of leaders in hand surgery. Leaders were defined as President, Board and Committee members of the American Society for Surgery of the Hand and the American Association for Hand Surgery, as well as hand surgery fellowship program directors and physician lead editors of peer-reviewed hand journals. The representation of women in leadership was compared to the percentage of female hand fellows over the same period. Years in practice, academic rank, additional degrees, h-index, m-index, National Institutes of Health (NIH) funding, publications, and citations were compared between male and female leaders.

RESULTS

Twenty-nine of 213 leadership positions (13.6%) are held by women which is fewer than would be expected based on hand surgery fellowship composition. Female leaders were earlier in practice than their male counterparts (13.5 ± 5.7 versus 20.8 ± 11.1 years, P < .01). Women were more likely to hold position of assistant professor and less likely to be full professors (P < .05). There was no gender difference in NIH funding, h-index, m-index, publications, or citations. The greatest gender disparity was at the level of National Society President, which is a title held by only 2 women and 119 men.

CONCLUSIONS

Gender disparities in hand surgery exist and are accentuated at the leadership level. Further work is needed to decrease leadership promotion disparities between men and women.

Superior Hypophyseal Artery Intraoperative Indocyanine Green Angiogram as a Predictor of Postoperative Visual Function After Endoscopic Endonasal Surgery

BACKGROUND AND OBJECTIVES

To date, there are no tools to intraoperatively predict postoperative visual function after endoscopic endonasal surgery (EES) for suprasellar lesions. The objective of this study was to retrospectively evaluate the utility of indocyanine green (ICG) angiography as an intraoperative tool to measure optic chiasm perfusion and determine its relationship with postoperative visual function.

METHODS

Videos of patients undergoing EES for resection of suprasellar lesions were reviewed, where 5 mg of ICG was diluted in 10 mL of saline and administered. Time between luminescence of the anterior cerebral artery and the superior hypophyseal artery branches supplying the optic chiasm was noted, and the percentage of optic chiasm vessels that luminesced was recorded. Postoperative examinations and imaging studies were used to assess visual function. Patients with and without new deficits were compared with examination of trends in ICG findings.

RESULTS

A total of 7 trials were reviewed on 6 patients, with no complications occurring from ICG administration. Mean time to chiasm peak luminescence was 3.8 seconds, and 81.8% of chiasm vessels luminesced. Patients with stable or improved vision after resection demonstrated over 90% chiasm luminescence in every case, and mean chiasm time in these postresection ICG administrations was 4.0 seconds. One patient experienced new postoperative visual deficits; on review of their ICG administration, 11.5% of chiasm vessels luminesced, and the chiasm itself failed to display robust luminescence after 30 seconds of direct observation.

CONCLUSION

This pilot study showed the capability of intraoperative ICG angiography to demonstrate perfusion of the optic chiasm during EES for resection of suprasellar lesions. While larger studies are required, preliminary results suggest chiasm times under 5 seconds and over 90% chiasm vessel illumination may reflect adequate chiasm perfusion, while those with delayed or absent chiasm luminescence may have compromised chiasm perfusion.

Association of CDKN2A alterations with increased postoperative seizure risk after resection of brain metastases

OBJECTIVE

Seizures are common and significantly disabling for patients with brain metastases (BMs). Although resection can provide seizure control, a subset of patients with BMs may continue to suffer seizures postoperatively. Genomic BM characteristics may influence which patients are at risk for postoperative seizures. This work explores correlations between genomic alterations and risk of postoperative seizures following BM resection.

METHODS

All patients underwent BM resection at a single institution, with available clinical and sequencing data on more than 500 oncogenes. Clinical seizures were documented pre- and postoperatively. A random forest machine learning classification was used to determine candidate genomic alterations associated with postoperative seizures, and clinical and top genomic variables were correlated with postoperative seizures by using Cox proportional hazards models.

RESULTS

There were 112 patients with BMs who underwent 114 surgeries and had at least 1 month of postoperative follow-up. Seizures occurred preoperatively in 26 (22.8%) patients and postoperatively in 25 (21.9%). The Engel classification achieved at 6 months for those with preoperative seizures was class I in 13 (50%); class II in 6 (23.1%); class III in 5 (19.2%), and class IV in 2 (7.7%). In those with postoperative seizures, only 8 (32.0%) had seizures preoperatively, and preoperative seizures were not a significant predictor of postoperative seizures (HR 1.84; 95% CI 0.79-4.37; p = 0.156). On random forest classification and multivariate Cox analysis controlling for factors including recurrence, extent of resection, and number of BMs, CDKN2A alterations were associated with postoperative seizures (HR 3.22; 95% CI 1.27-8.16; p = 0.014). Melanoma BMs were associated with higher risk of postoperative seizures compared with all other primary malignancies (HR 5.23; 95% CI 1.37-19.98; p = 0.016). Of 39 BMs with CDKN2A alteration, 35.9% (14/39) had postoperative seizures, compared to 14.7% (11/75) without CDKN2A alteration. The overall rate of postoperative seizures in melanoma BMs was 42.9% (15/35), compared with 12.7% (10/79) for all other primary malignancies.

CONCLUSIONS

CDKN2A alterations and melanoma primary malignancy are associated with increased postoperative seizure risk following resection of BMs. These results may help guide postoperative seizure prophylaxis in patients undergoing resection of BMs.

Identification of risk factors associated with leptomeningeal disease after resection of brain metastases

OBJECTIVE

Resection of brain metastases (BMs) may be associated with increased risk of leptomeningeal disease (LMD). This study examined rates and predictors of LMD, including imaging subtypes, in patients who underwent resection of a BM followed by postoperative radiation.

METHODS

A retrospective, single-center study was conducted examining overall LMD, classic LMD (cLMD), and nodular LMD (nLMD) risk. Logistic regression, Cox proportional hazards, and random forest analyses were performed to identify risk factors associated with LMD.

RESULTS

Of the 217 patients in the cohort, 47 (21.7%) developed postoperative LMD, with 19 cases (8.8%) of cLMD and 28 cases (12.9%) of nLMD. Six-, 12-, and 24-month LMD-free survival rates were 92.3%, 85.6%, and 71.4%, respectively. Patients with cLMD had worse survival outcomes from the date of LMD diagnosis compared with nLMD (median 2.4 vs 6.9 months, p = 0.02, log-rank test). Cox proportional hazards analysis identified cerebellar/insular/occipital location (hazard ratio [HR] 3.25, 95% confidence interval [CI] 1.73-6.11, p = 0.0003), absence of extracranial disease (HR 2.49, 95% CI 1.27-4.88, p = 0.008), and ventricle contact (HR 2.82, 95% CI 1.5-5.3, p = 0.001) to be associated with postoperative LMD. A predictive model using random forest analysis with an area under the receiver operating characteristic curve of 0.87 in a test cohort identified tumor location, systemic disease status, and tumor volume as the most important factors associated with LMD.

CONCLUSIONS

Tumor location, absence of extracranial disease at the time of surgery, ventricle contact, and increased tumor volume were associated with LMD. Further work is needed to determine whether escalating therapies in patients at risk of LMD prevents disease dissemination.

Genomic alterations associated with rapid progression of brain metastases

OBJECTIVE

The aim of this study was to investigate associations between genomic alterations in resected brain metastases and rapid local and distant CNS recurrence identified at the time of postoperative adjuvant radiosurgery.

METHODS

This was a retrospective study on patients who underwent resection of intracranial brain metastases. Next-generation sequencing of more than 500 coding genes was performed on brain metastasis specimens. Postoperative and preradiosurgery MR images were compared to identify rapid recurrence. Genomic data were associated with rapid local and distant CNS recurrence of brain metastases using nominal regression analyses.

RESULTS

The cohort contained 92 patients with 92 brain metastases. Thirteen (14.1%) patients had a rapid local recurrence, and 64 (69.6%) patients had rapid distant CNS progression by the time of postoperative adjuvant radiosurgery, which occurred in a median time of 25 days (range 3-85 days) from surgery. RB1 and CTNNB1 mutations were seen in 8.7% and 9.8% of the cohort, respectively, and were associated with a significantly higher risk of rapid local recurrence (RB1: OR 13.6, 95% CI 2.0-92.39, p = 0.008; and CTNNB1: OR 11.97, 95% CI 2.25-63.78, p = 0.004) on multivariate analysis. No genes were found to be associated with rapid distant CNS progression. However, the presence of extracranial disease was significantly associated with a higher risk of rapid distant recurrence on multivariate analysis (OR 4.06, 95% CI 1.08-15.34, p = 0.039).

CONCLUSIONS

Genomic alterations in RB1 or CTNNB1 were associated with a significantly higher risk of rapid recurrence at the resection site. Although no genomic alterations were associated with rapid distant recurrence, having active extracranial disease was a risk factor for new lesions by the time of adjuvant radiotherapy after resection.

Risk Factors for Significant Postoperative Hemorrhage After Pituitary Neuroendocrine Tumor Resection: A Case-Control Study of 1066 Surgeries

BACKGROUND

Postoperative hemorrhage is a rare but potentially serious complication after pituitary surgery. The risk factors for this complication are mostly unknown, and further knowledge would help guide postoperative management.

OBJECTIVE

To investigate the perioperative risks and clinical presentation of significant postoperative hemorrhage (SPH) after endonasal surgery for pituitary neuroendocrine tumors.

METHODS

A population of 1066 patients undergoing endonasal (microscopic and endoscopic) surgery for pituitary neuroendocrine tumor resection at a high-volume academic center was reviewed. SPH cases were defined as postoperative hematoma evident on imaging requiring return to the operating room for evacuation. Patient and tumor characteristics were analyzed with uni- and multivariable logistic regression, and postoperative courses were descriptively examined.

RESULTS

Ten patients were found to have SPH. On univariable analysis, these cases were significantly more likely to present with apoplexy ( P = .004), have larger tumors ( P < .001), and lower gross total resection rates ( P = .019). A multivariate regression analysis showed that tumor size (odds ratio 1.94, P = .008) and apoplexy at presentation (odds ratio 6.00, P = .018) were significantly associated with higher odds of SPH. The most common symptoms for patients with SPH were vision deficits and headache, and the median time for symptom onset was 1 day after surgery.

CONCLUSION

Larger tumor size and presentation with apoplexy were associated with clinically significant postoperative hemorrhage. Patients presenting with pituitary apoplexy are more likely to experience a significant postoperative hemorrhage and should be carefully monitored for headache and vision changes in the days after surgery.

Heterogeneous growth of the insula shapes the human brain

The human cerebrum consists of a precise and stereotyped arrangement of lobes, primary gyri, and connectivity that underlies human cognition [P. Rakic, Nat. Rev. Neurosci. 10, 724-735 (2009)]. The development of this arrangement is less clear. Current models explain individual primary gyrification but largely do not account for the global configuration of the cerebral lobes [T. Tallinen, J. Y. Chung, J. S. Biggins, L. Mahadevan, Proc. Natl. Acad. Sci. U.S.A. 111, 12667-12672 (2014) and D. C. Van Essen, Nature 385, 313-318 (1997)]. The insula, buried in the depths of the Sylvian fissure, is unique in terms of gyral anatomy and size. Here, we quantitatively show that the insula has unique morphology and location in the cerebrum and that these key differences emerge during fetal development. Finally, we identify quantitative differences in developmental migration patterns to the insula that may underlie these differences. We calculated morphologic data in the insula and other lobes in adults (N = 107) and in an in utero fetal brain atlas (N = 81 healthy fetuses). In utero, the insula grows an order of magnitude slower than the other lobes and demonstrates shallower sulci, less curvature, and less surface complexity both in adults and progressively throughout fetal development. Spherical projection analysis demonstrates that the lenticular nuclei obstruct 60 to 70% of radial pathways from the ventricular zone (VZ) to the insula, forcing a curved migration to the insula in contrast to a direct radial pathway. Using fetal diffusion tractography, we identify radial glial fascicles that originate from the VZ and curve around the lenticular nuclei to form the insula. These results confirm existing models of radial migration to the cortex and illustrate findings that suggest differential insular and cerebral development, laying the groundwork to understand cerebral malformations and insular function and pathologies.

CDKN2A/B co-deletion is associated with increased risk of local and distant intracranial recurrence after surgical resection of brain metastases

Background

While genetic alterations in brain metastases (BMs) have been previously explored, there are limited data examining their association with recurrence after surgical resection. This study aimed to identify genetic alterations within BMs associated with CNS recurrence after surgery across multiple cancer types.

Methods

A retrospective, single-center study was conducted with patients who underwent resection of a BM with available clinical and gene sequencing data available. Local and remote CNS recurrence were the primary study outcomes. Next-generation sequencing of the coding regions in over 500 oncogenes was performed in brain metastasis specimens. Cox proportional hazards analyses were performed to identify clinical features and genomic alterations associated with CNS recurrence.

Results

A total of 90 patients undergoing resection of 91 BMs composed the cohort. Genes most frequently mutated in the cohort included TP53 (64%), CDKN2A (37%), TERT (29%), CDKN2B (23%), NF1 (14%), KRAS (14%), and PTEN (13%), all of which occurred across multiple cancer types. CDKN2A/B co-deletion was seen in 21 (23.1%) brain metastases across multiple cancer types. In multivariate Cox proportional hazard analyses including patient, tumor, and treatment factors, CDKN2A/B co-deletion in the brain metastasis was associated with increased risk of local (HR 4.07, 95% CI 1.32-12.54, P = 0.014) and remote (HR 2.28, 95% CI 1.11-4.69, P = 0.025) CNS progression. Median survival and length of follow-up were not different based on CDKN2A/B mutation status.

Conclusions

CDKN2A/B co-deletion detected in BMs is associated with increased CNS recurrence after surgical resection. Additional work is needed to determine whether more aggressive treatment in patients with this mutation may improve outcomes.

Frequent aneuploidy in primary human T cells after CRISPR-Cas9 cleavage

Multiple clinical trials of allogeneic T cell therapy use site-specific nucleases to disrupt T cell receptor (TCR) and other genes^1-6. In this study, using single-cell RNA sequencing, we investigated genome editing outcomes in primary human T cells transfected with CRISPR-Cas9 and guide RNAs targeting genes for TCR chains and programmed cell death protein 1. Four days after transfection, we found a loss of chromosome 14, harboring the TCRα locus, in up to 9% of the cells and a chromosome 14 gain in up to 1.4% of the cells. Chromosome 7, harboring the TCRβ locus, was truncated in 9.9% of the cells. Aberrations were validated using fluorescence in situ hybridization and digital droplet PCR. Aneuploidy was associated with reduced proliferation, induced p53 activation and cell death. However, at 11 days after transfection, 0.9% of T cells still had a chromosome 14 loss. Aneuploidy and chromosomal truncations are, thus, frequent outcomes of CRISPR-Cas9 cleavage that should be monitored and minimized in clinical protocols.

SURG-05. SUPERVISED MACHINE LEARNING IDENTIFIES RISK FACTORS ASSOCIATED WITH LEPTOMENINGEAL DISEASE AFTER SURGICAL RESECTION OF BRAIN METASTASES

INTRODUCTION

Predictors of postoperative leptomeningeal disease (LMD) after resection of brain metastases (BMs) are not well defined.

OBJECTIVE

This study examined rates and predictors of LMD, including subtypes, in patients who underwent resection of a BM followed by postoperative radiation.Method: A retrospective, single-center study was conducted examining overall LMD, classical LMD (cLMD), and nodular LMD (nLMD) risk. Logistic regression and a Cox proportional hazards analyses were performed to identify risk factors associated with LMD. Random forest models were constructed to predict LMD and differentiate cLMD versus nLMD. Accuracy and the area under the receiver operating characteristic curve (AUROC) were calculated to evaluate the models.Result: Of the 217 patients in the cohort, 47 (21.7%) developed postoperative LMD with 19(8.8%) cLMD cases and 28(12.9%) nLMD cases . Six-, 12-, and 24-month LMD-free survival rates were 92.3%, 85.6%, and 71.4%, respectively. Patients with cLMD had worse survival outcomes from LMD diagnosis compared to nLMD (2.4 vs 6.9 mo, Log-rank p=0.02), and treatment of LMD was associated with improved survival for both cLMD and nLMD subtypes. Multivariate Cox hazard analysis identified cerebellar/insular/occipital location (HR 3.25, 95% CI 1.73-6.11, p=0.0003), absence of extracranial disease (HR 2.49, 95% CI 1.27-4.88, p=0.008), and ventricle contact (HR 2.82, 95% CI 1.5-5.3, p=0.001) to be associated with postoperative LMD. A predictive model using random forest analysis with an AUROC of 0.87 in a test cohort identified tumor location, systemic disease status, and tumor volume as the most important factors associated with LMD. Both regression analysis and random forest analysis identified postoperative systemic therapy exposure as the main factor differentiating cLMD from nLMD development.

CONCLUSION

Tumor location, absence of extracranial disease at the time of surgery, contact with a ventricle, and increased tumor volume are associated with LMD. Classical LMD is associated with worse prognosis compared to nLMD.

Targeted Next-Generation Sequencing Reveals Divergent Clonal Evolution in Components of Composite Pleomorphic Xanthoastrocytoma-Ganglioglioma

Composite pleomorphic xanthoastrocytoma-ganglioglioma (PXA-GG) is an extremely rare central nervous system neoplasm with 2 distinct but intermingled components. Whether this tumor represents a "collision tumor" of separate neoplasms or a monoclonal neoplasm with divergent evolution is poorly understood. Clinicopathologic studies and capture-based next generation sequencing were performed on extracted DNA from all available PXA-GG at 2 medical centers. Five PXA-GG were diagnosed in 1 male and 4 female patients ranging from 13 to 25 years in age. Four arose within the cerebral hemispheres; 1 presented in the cerebellar vermis. DNA was sufficient for analysis in 4 PXA components and 3 GG components. Four paired PXA and GG components harbored BRAF p.V600E hotspot mutations. The 4 sequenced PXA components demonstrated CDKN2A homozygous deletion by sequencing with loss of p16 (protein product of CDKN2A) expression by immunohistochemistry, which was intact in all assessed GG components. The PXA components also demonstrated more frequent copy number alterations relative to paired GG components. In one PXA-GG, shared chromosomal copy number alterations were identified in both components. Our findings support divergent evolution of the PXA and GG components from a common BRAF p.V600E-mutant precursor lesion, with additional acquisition of CDKN2A homozygous deletion in the PXA component as is typically seen in conventional PXA.

Comparison of shunt outcomes for non-bacterial infectious hydrocephalus with common hydrocephalus etiologies: a retrospective case-control study

BACKGROUND

Shunting is an established treatment for hydrocephalus, yet reports on shunt outcomes for non-bacterial infectious (NBI) hydrocephalus are limited. Furthermore, comparison of mechanisms and rates of failure for shunted NBI hydrocephalus versus more typical etiologies remains undetermined.

METHODS

Patients who underwent shunting for hydrocephalus at two centers (1995-2020) were included. Indications for shunting were grouped as "typical" (congenital, post-hemorrhagic, normal pressure hydrocephalus, malignancy-related, trauma, and idiopathic) and NBI hydrocephalus (coccidioidomycosis, cryptococcus, and neurocysticercosis). Rates of shunt malfunction were compared.

RESULTS

There were 261 patients shunted for typical hydrocephalus (48.7% male; age 50.7±21.7) and 93 NBI hydrocephalus (72.0% male; age 41.8±13.2). For patients with typical hydrocephalus, 29.5% required ≥1 shunt revision, compared with 64.5% with NBI hydrocephalus (p<1E-5). Of those with malfunction, NBI shunts required more revision operations (median 3.0; max 21) compared with typical shunts (median 2.0; max 6; p<0.05). Censored median time to shunt failure for NBI hydrocephalus was 26.9 months and not reached for typical etiologies by 180 months. Multivariate analysis showed shunts for NBI hydrocephalus were significantly more likely to fail (HR 2.25; 95% CI 1.58-3.19). A distal pseudocyst was implicated in 30.0% and 2.6% of shunt failures for NBI and typical hydrocephalus, respectively (p<1E-5). Sixteen (26.7%) NBI shunt failures required revision to lower resistance systems compared to six (7.8%) typical failures (p<0.05).

CONCLUSIONS

Shunts placed for hydrocephalus secondary to non-bacterial infections are complicated by significantly higher rates of malfunction. These patients are prone to develop distal abdominal pseudocysts and often require revision to low-resistance systems.

Complications from Multimodal Monitoring Do not Affect Long-Term Outcomes in Severe Traumatic Brain Injury

BACKGROUND

Invasive neuromonitoring is a mainstay of modern management of severe traumatic brain injury (TBI). Complication rates of neuromonitor placement are widely reported, but their effects on long-term outcomes are less studied. We evaluated the association of neuromonitor complications on long-term outcomes in a prospective severe TBI cohort.

METHODS

We reviewed 599 patients with severe TBI from November 2002 through 2018 for neuromonitor-associated hemorrhage and infection. We compared outcome differences between patients with and without neuromonitoring-associated complications using the Glasgow Outcomes Scale (GOS) at 3, 6, 12, and 24 months post trauma. When analyzing neuromonitoring infections, we removed all patients who expired before discharge as early mortality was associated with reduced infection rates.

RESULTS

Neuromonitor-associated hemorrhage occurred in 62 out of 534 patients with post placement imaging (11.6%) and was increased in patinets who underwent a craniotomy (24% vs. 11%, P = 0.005). Clinical outcomes did not differ in patients with neuromonitor-associated hemorrhage. Neuromonitor-associated infection occurred in 30 of 389 patients (7.7%) who survived to discharge. Infection was associated with worse outcomes at 3 months (P = 0.03), where the proportion of patients with favorable outcomes (P = 0.02) was decreased despite similar mortality (P = 0.24). Patients with an infection recovered by 6 months, at which point there were no differences in total GOS or rates of favorable outcomes then or at later time points (P > 0.26). Neuromonitor-associated infection was associated with increased length of stay (P = 0.01) and depressed skull fractures (P = 0.03) but did not affect rates of shunting (P = 0.99).

CONCLUSIONS

Complications of neuromonitoring in severe TBI are associated with delayed recovery but not long-term outcomes.

Hemorrhagic vestibular schwannoma: a case example of vestibular apoplexy syndrome. Illustrative case

BACKGROUND

Acute intratumoral hemorrhage within a vestibular schwannoma, or vestibular apoplexy, is a rare condition. Unlike the typical insidious vestibulopathy typically caused by vestibular schwannoma growth, patients with vestibular apoplexy have an acute and severe presentation with nausea and emesis in addition to severe vertigo and hearing loss. Here, the authors present an illustrative case demonstrating this rare clinical condition and an operative video detailing the surgical management.

OBSERVATIONS

A 76-year-old man presented to the emergency department with acute-onset dizziness, left-ear fullness, double vision, gait ataxia, emesis, and facial numbness. Imaging revealed a 2.8-cm hemorrhagic left cerebellopontine angle lesion extending into the left internal auditory canal, consistent with hemorrhagic vestibular schwannoma. The patient subsequently underwent a retrosigmoid craniotomy for resection of the hemorrhagic mass, and by 1 month after surgery, all his presenting symptoms had resolved, allowing his return to daily activities.

LESSONS

Vestibular schwannomas typically present with decreased hearing and chronic vestibulopathy. Acute presentation should raise the suspicion for an apoplectic event, and surgical debulking may lead to improvement in most vestibular symptoms.

Contralateral sialadenitis after resection of a right cerebellar metastasis: illustrative case

BACKGROUND

Acute postoperative sialadenitis is a rare and potentially morbid complication of cranial neurosurgery. This rapidly progressive, unilateral neck swelling often presents within hours of extubation. Diagnosis is made by imaging and exclusion of other causes of etiologies, such as neck hematoma, sialolithiasis, and dependent soft tissue edema.

OBSERVATIONS

The authors presented a case of acute postoperative sialadenitis after suboccipital resection of a right cerebellar metastasis. Shortly after extubation, extensive left-sided neck swelling was apparent in the postanesthesia care unit. No central lines were placed during the procedure. Imaging revealed submandibular gland edema and fluid accumulation in the surrounding tissue. The patient was managed conservatively with steroids, antibiotics, and warm compresses, with complete resolution of symptoms 2 weeks after the procedure.

LESSONS

This case emphasizes the broad differential of acute neck swelling after cranial surgery. Physical examination of the neck and airway protection should guide initial treatment. If a patient is stable, bedside ultrasound and computed tomography can be helpful with the differential diagnosis. Here the authors proposed an algorithm for diagnosis and treatment of acute neck swelling after cranial surgery.

Hydrocephalus and Cerebrospinal Fluid Analysis Following Severe Traumatic Brain Injury: Evaluation of a Prospective Cohort

The development of hydrocephalus after severe traumatic brain injury (TBI) is an under-recognized healthcare phenomenon and can increase morbidity. The current study aims to characterize post-traumatic hydrocephalus (PTH) in a large cohort. Patients were prospectively enrolled age 16-80 years old with Glasgow Coma Scale (GCS) score ≤8. Demographics, GCS, Injury Severity Score (ISS), surgery, and cerebrospinal fluid (CSF) were analyzed. Outcomes were shunt failure and Glasgow Outcome Scale (GOS) at 6 and 12-months. Statistical significance was assessed at p < 0.05. In 402 patients, mean age was 38.0 ± 16.7 years and 315 (78.4%) were male. Forty (10.0%) patients developed PTH, with predominant injuries being subdural hemorrhage (36.4%) and diffuse axonal injury (36.4%). Decompressive hemicraniectomy (DHC) was associated with hydrocephalus (OR 3.62, 95% CI (1.62-8.07), p < 0.01). Eighteen (4.5%) patients had shunt failure and proximal obstruction was most common. Differences in baseline CSF cell count were associated with increased shunt failure. PTH was not associated with worse outcomes at 6 (p = 0.55) or 12 (p = 0.47) months. Hydrocephalus is a frequent sequela in 10.0% of patients, particularly after DHC. Shunt placement and revision procedures are common after severe TBI, within the first 4 months of injury and necessitates early recognition by the clinician.

Utility of Nasal Access Guides in Endoscopic Endonasal Skull Base Surgery: Assessment of Use during Cadaveric Dissection and Workflow Analysis in Surgery

Background  A nasal access guide (NAG) for endoscopic endonasal approaches (EEAs) to the skull-base has been developed and approved for clinical use but its utility has not been formally investigated. Objective  The study aims to assess the effect of a NAG on endoscopic visualization during cadaveric dissection and to perform a workflow analysis with process-based performance measures in the operating room and their effect on clinical outcomes. Methods  Skull-base course participants were observed during hands-on cadaveric dissection with and without NAG. Instances of endoscope withdrawal for lens cleaning and inadequate visualization due to lens soiling were tabulated. Participants completed a Likert-scale survey examining the NAG utility and provided an overall grading. Surgical workflow and process-based performance on patients undergoing EEA to the skull-base was analyzed. Passage of powered and dissecting instruments, removal of endoscopes for cleaning, and dislodgment or migration of the device were reviewed. Postoperative assessments included mucosal trauma and synechiae formation. Results  Instances of endoscope soiling and manual cleaning were significantly reduced by 40% and 61% with the NAG during cadaveric dissection. The overall grading of the device was 2.75/3. Surgical workflow was observed in 35 patients. Average number of passes of endoscopes, instruments, and powered tools during a 10-minute observation period were 3,17, and 5 during the surgical approach, and 3, 18, and 1 during tumor dissection. Dislodgement of the device occurred in 25.7% and migration of the device in 2.8% of cases. Postoperative synechiae, exposed cartilage or septal perforation was not observed in follow up. Conclusion  NAG can significantly reduce inadequate visualization during EEA to the skull-base and has the potential to reduce instances of nasal trauma. Participants assessed its overall utility as being "excellent."

Blood supply to the corticospinal tract: A pictorial review with application to cranial surgery and stroke

The corticospinal tract (CST) is the main neural pathway responsible for conducting voluntary motor function in the central nervous system. The CST condenses into fiber bundles as it descends from the frontoparietal cortex, traveling down to terminate at the anterior horn of the spinal cord. The CST is at risk of injury from vascular insult from strokes and during neurosurgical procedures. The aim of this article is to identify and describe the vasculature associated with the CST from the cortex to the medulla. Dissection of cadaveric specimens was carried out in a manner, which exposed and preserved the fiber tracts of the CST, as well as the arterial systems that supply them. At the level of the motor cortex, the CST is supplied by terminal branches of the anterior cerebral artery and middle cerebral artery. The white matter tracts of the corona radiata and internal capsule are supplied by small perforators including the lenticulostriate arteries and branches of the anterior choroidal artery. In the brainstem, the CST is supplied by anterior perforating branches from the basilar and vertebral arteries. The caudal portions of the CST in the medulla are supplied by the anterior spinal artery, which branches from the vertebral arteries. The non-anastomotic nature of the vessel systems of the CST highlights the importance of their preservation during neurosurgical procedures. Anatomical knowledge of the CST is paramount to clinical diagnosis and treatment of heterogeneity of neurodegenerative, neuroinflammatory, cerebrovascular, and skull base tumors.

A Crowdsourced Consensus on Supratotal Resection Versus Gross Total Resection for Anatomically Distinct Primary Glioblastoma

BACKGROUND

Gross total resection (GTR) of contrast-enhancing tumor is associated with increased survival in primary glioblastoma. Recently, there has been increasing interest in performing supratotal resections (SpTRs) for glioblastoma.

OBJECTIVE

To address the published results, which have varied in part due to lack of consensus on the definition and appropriate use of SpTR.

METHODS

A crowdsourcing approach was used to survey 21 neurosurgical oncologists representing 14 health systems nationwide. Participants were presented with 11 definitions of SpTR and asked to rate the appropriateness of each definition. Participants reviewed T1-weighed postcontrast and fluid-attenuated inversion-recovery magnetic resonance imaging for 22 anatomically distinct glioblastomas. Participants were asked to assess the tumor location's eloquence, the perceived equipoise of enrolling patients in a randomized trial comparing gross total to SpTR, and their personal treatment plans.

RESULTS

Most neurosurgeons surveyed (n = 18, 85.7%) agree that GTR plus resection of some noncontrast enhancement is an appropriate definition for SpTR. Overall, moderate inter-rater agreement existed regarding eloquence, equipoise, and personal treatment plans. The 4 neurosurgeons who had performed >10 SpTRs for glioblastomas in the past year were more likely to recommend it as their treatment plan (P < .005). Cases were divided into 3 anatomically distinct groups based upon perceived eloquence. Anterior temporal and right frontal glioblastomas were considered the best randomization candidates.

CONCLUSION

We established a consensus definition for SpTR of glioblastoma and identified anatomically distinct locations deemed most amenable to SpTR. These results may be used to plan prospective trials investigating the potential clinical utility of SpTR for glioblastoma.

Impact of Frailty on Outcomes Following Spine Surgery: A Prospective Cohort Analysis of 668 Patients

BACKGROUND

With an aging population, elderly patients with multiple comorbidities are more frequently undergoing spine surgery and may be at increased risk for complications. Objective measurement of frailty may predict the incidence of postoperative adverse events.

OBJECTIVE

To investigate the associations between preoperative frailty and postoperative spine surgery outcomes including mortality, length of stay, readmission, surgical site infection, and venous thromboembolic disease.

METHODS

As part of a system-wide quality improvement initiative, frailty assessment was added to the routine assessment of patients considering spine surgery beginning in July 2016. Frailty was assessed with the Risk Analysis Index (RAI), and patients were categorized as nonfrail (RAI 0-29) or prefrail/frail (RAI ≥ 30). Comparisons between nonfrail and prefrail/frail patients were analyzed using Fisher's exact test for categorical data or by Wilcoxon rank sum tests for continuous data.

RESULTS

From August 2016 through September 2018, 668 patients (age of 59.5 ± 13.3 yr) had a preoperative RAI score recorded and underwent scheduled spine surgery. Prefrail and frail patients suffered comparatively higher rates of mortality at 90 d (1.9% vs 0.2%, P < .05) and 1 yr (5.1% vs 1.2%, P < .01) from the procedure date. They also had longer in-hospital length of stay (LOS) (3.9 d ± 3.6 vs 3.1 d ± 2.8, P < .001) and higher rates of 60 d (14.6% vs 8.2%, P < .05) and 90 d (15.8% vs 9.8%, P < .05) readmissions.

CONCLUSION

Preoperative frailty, as measured by the RAI, was associated with an increased risk of readmission and 90-d and 1-yr mortality following spine surgery. The RAI can be used to stratify spine patients and inform preoperative surgical decision making.

Brain folding shapes the branching pattern of the middle cerebral artery

The folds of the brain offer a particular challenge for the subarachnoid vascular grid. The primitive blood vessels that occupy this space, when the brain is flat, have to adapt to an everchanging geometry while constructing an efficient network. Surprisingly, the result is a non-redundant arterial system easily challenged by acute occlusions. Here, we generalize the optimal network building principles of a flat surface growing into a folded configuration and generate an ideal middle cerebral artery (MCA) configuration that can be directly compared with the normal brain anatomy. We then describe how the Sylvian fissure (the fold in which the MCA is buried) is formed during development and use our findings to account for the differences between the ideal and the actual shaping pattern of the MCA. Our results reveal that folding dynamics condition the development of arterial anastomosis yielding a network without loops and poor response to acute occlusions.

SURG-21. A CROWDSOURCED CONSENSUS ON SUPRATOTAL RESECTION VERSUS GROSS TOTAL RESECTION FOR ANATOMICALLY DISTINCT PRIMARY GLIOBLASTOMA

Gross total resection (GTR) of contrast-enhancing tumor is associated with significantly increased overall survival in primary glioblastoma (GBM). Even when achieved, recurrence is likely, in part due to malignant cells infiltrating outside enhanced regions. Subsequently, there has been increasing interest in performing supratotal resections (SpTRs) for GBM. Published results have varied in part due to a lack of consensus on the definition of SpTR in GBM and its appropriate use. A crowdsourcing approach was used to survey 21 academic neurosurgical oncologists representing 13 health systems nationwide. Participants’ demographics including fellowship training status, years of experience, and operative volume with various techniques was collected. Participants were presented with 11 definitions of SpTR from published, peer-reviewed studies and asked to rate the appropriateness of each definition. Subsequently, participants reviewed T1-weighed post-contrast and FLAIR MR imaging videos in the axial, coronal, and sagittal planes for 22 GBMs. Participants were asked to assess eloquence of the tumor’s location, perceived equipoise of enrolling patients in a randomized clinical trial comparing GTR to SpTR, and their own personal surgical treatment plans. Most neurosurgeons surveyed (n=18, 85.7%) agree or strongly agree that GTR plus resection of some non-contrast enhancement is an appropriate definition for SpTR. Overall, there was only moderate inter-rater agreement, measured using sample variance and the index of qualitative variation, regarding eloquence, equipoise, and personal treatment plans. Neurosurgeons who performed more than 10 SpTRs for GBMs in the past year were more likely than counterparts to recommend it as their personal treatment plan (p&lt; 0.005). Anterior temporal and right frontal GBMs were considered the best randomization candidates. We established a consensus definition for SpTR of GBM and identified anatomically distinct locations deemed most amenable to SpTR. These results will be used to plan prospective trials further investigating the potential clinical utility of SpTR for GBMs.

The impact of a nationwide hands-on workshop on the diagnostic rates and management of obstetrical anal sphincter Injuries in Israel

AIM

The aim was to evaluate the influence of a half day, hands-on, workshop on the detection and repair of obstetric anal sphincter injuries (OASIs).

METHOD

Starting in February 2011, hands-on workshops for the diagnosis and repair of OASIs were delivered by trained urogynaecologists in departments of tertiary medical centres in Israel. The structure of the hands-on workshop resembles the workshop organized at the International Urogynecological Association annual conferences. Participants included medical staff, midwives and surgical residents from each medical centre. We collected data regarding the rate of OASIs, 1 year before and 1 year following the workshop, in 11 medical centres. The study population was composed of parturients with the following inclusion criteria: singleton pregnancy, vertex presentation and vaginal delivery. Pre-viable preterm gestations (< 24 weeks), birth weight < 500 g, stillborn, and those with major congenital anomalies, multifoetal pregnancies, breech presentations and caesarean deliveries were excluded from the analysis.

RESULTS

In the reviewed centres, 70 663 (49.3%) women delivered prior to the workshop (pre-workshop group) and 72 616 (50.7%) women delivered following the workshop (post-workshop group). Third- or fourth-degree perineal tears occurred in 248 women (0.35%) before the workshop, and in 328 (0.45%) following the workshop, a significant increase of 28.7% (P = 0.002). The increase in diagnosis was significant also in women with third-degree tears alone, 226 women (0.32%) before the workshop and 298 (0.41%) following the workshop, an increase of 28.3% (P = 0.005).

CONCLUSION

The detection rate of OASIs has significantly increased following the hands-on workshop. The implementation of such programmes is crucial for increasing awareness and detection rates of OASI following vaginal deliveries.

Endoscopic Endonasal Approach for Craniopharyngiomas with Intraventricular Extension: Case Series, Long-Term Outcomes, and Review

BACKGROUND

Traditionally, craniopharyngiomas with intraventricular extension were approached transcranially; however, endoscopic approaches are now increasingly used. We sought to study the endoscopic endonasal approach (EEA) in the setting of complex craniopharyngiomas with intraventricular extension and to compare it with existing literature.

METHODS

Patients undergoing EEA for resection of craniopharyngioma with ventricular involvement from 2002 to 2015 were retrospectively reviewed. Outcomes were compared with previously published EEA and transcranial approach (TCA) studies for all craniopharyngioma locations.

RESULTS

Sixty-two patients were included. Average tumor and intraventricular volume were 13.93 cm³ and 2.61 cm³, respectively. Patients presented with visual impairment, endocrinopathy, and, headache. Gross total resection (GTR) was achieved in 47% of all cases and increased to 77% after 2012 Approximately 98% experienced improvement or stability of vision. Postoperative cerebrospinal fluid (CSF) leak and meningitis rates were 19% and 8.1%, respectively. However, nasoseptal flap (NSF) use reduced CSF leak rate to 10%. Six (9.6%) patients required shunting before resection and 25% were shunted postoperatively. Seven of 10 patients (70%) treated before NSF use required shunting, whereas only 7 of 46 (15%) required shunting with NSF reconstruction. Review demonstrated similar outcomes between the present cohort and EEA or TCA for all craniopharyngioma locations. TCA had a greater GTR, however, with large study variation. EEA showed improved visual outcomes but also increased CSF leaks.

CONCLUSIONS

EEA for craniopharyngiomas with intraventricular extension shows similar outcomes to TCA and EEA for all craniopharyngiomas, expanding this anatomic limit. Given ventricular involvement, CSF leak rates are expectedly high. GTR increased and CSF leak rates dramatically decreased with time, suggestive of the steep learning curve to complex resection.

Far Lateral Approach (Transcondylar, Transtubercular) for Bypass and Trapping of a Ruptured, Dissecting PICA Aneurysm

Aneurysms of the posterior circulation pose a unique challenge due to higher rupture rates, higher recurrence rates following endovascular treatment, and extended open cranial base approaches required to reach the ventrally located brainstem circulation. While endovascular therapy has made tremendous strides in successful treatment for most posterior circulation aneurysms, open microscopic approaches remain essential in specific circumstances. Here, we present a case of a patient who presented with acute, severe headache, and sixth nerve palsies, and who was found to have hydrocephalus and a dissecting aneurysm at the anterolateral medullary segment of the posterior inferior cerebellar artery (PICA). Interestingly, this patient had a history of alpha-1 antitrypsin deficiency that has been linked with spontaneous aortic and cervical arterial dissections. The fusiform geometry of the dissecting aneurysm was deemed suboptimal for endovascular treatment, so an open microsurgical approach for occipital artery to PICA bypass and aneurysm trapping was planned. Because this patient had cerebral edema in the setting of a ruptured aneurysm and hydrocephalus, a far lateral craniotomy combined with drilling of the occipital condyle and jugular tubercle was critical to enhance exposure of the first segment of the PICA and to minimize brain retraction. In this video, we highlight the key steps and nuances for harvest of the occipital artery, achieving control of the extracranial vertebral artery, performing the transcondylar and transtubercular far lateral approach, and bypass with trapping technique for these challenging posterior circulation aneurysms.

The link to the video can be found at: https://youtu.be/dqgblwX6t0Q .

Visual Evoked Potentials and Intraoperative Awakening in Ophthalmic Artery Sacrifice During Aneurysm Clipping: 2 Cases and Literature Review

BACKGROUND

Complete aneurysm obliteration is the goal of aneurysm treatment. In selected cases, a neck remnant may be left to preserve a critical branch. Literature on ophthalmic artery sacrifice in the treatment of cerebral aneurysms and subsequent risk of vision loss is limited.

CASE DESCRIPTION

Herein, we describe 2 cases where the ophthalmic artery originated from the aneurysm dome, resulting in a situation where we either incompletely obliterate the aneurysm or sacrifice the ophthalmic artery in order to completely clip the lesion, risking visual function.

CONCLUSIONS

We report for the first time the use of visual evoked potential monitoring and intraoperative awakening to test visual function following intentional ophthalmic artery sacrifice to demonstrate gross vision preservation.

Different Principles Govern Different Scales of Brain Folding

The signature folds of the human brain are formed through a complex and developmentally regulated process. In vitro and in silico models of this process demonstrate a random pattern of sulci and gyri, unlike the highly ordered and conserved structure seen in the human cortex. Here, we account for the large-scale pattern of cortical folding by combining advanced fetal magnetic resonance imaging with nonlinear diffeomorphic registration and volumetric analysis. Our analysis demonstrates that in utero brain growth follows a logistic curve, in the absence of an external volume constraint. The Sylvian fissure forms from interlobar folding, where separate lobes overgrow and close an existing subarachnoid space. In contrast, other large sulci, which are the ones represented in existing models, fold through an invagination of a flat surface, a mechanistically different process. Cortical folding is driven by multiple spatially and temporally different mechanisms; therefore regionally distinct biological process may be responsible for the global geometry of the adult brain.

Endoscopic endonasal approach for clipping of a PICA aneurysm

This video depicts the case of a 59-year-old woman that presented to the emergency department with the worst headache of her life. CT showed subarachnoid hemorrhage and digital subtraction angiogram demonstrated a right-side posterior inferior cerebellar artery (PICA) aneurysm. Given the medial and ventral position of the aneurysm, deep to the lower cranial nerves, which obviated distal control from an open approach, and the absence of an endovascular option able to reliably preserve the PICA, an endonasal approach was offered. A far medial approach was performed, and the aneurysm was successfully clipped. The patient developed a postoperative CSF leak with persistent posthemorrhagic hydrocephalus treated with reexploration and an eventual ventriculoperitoneal shunt. The patient was discharged without neurological deficits.

The video can be found here: https://youtu.be/_9hsM2CaMow.

Radiosurgery to the spinal dorsal root ganglion induces fibrosis and inhibits satellite glial cell activation while preserving axonal neurotransmission

OBJECTIVE

Stereotactic radiosurgery (SRS) has been used to treat trigeminal neuralgia by targeting the cisternal segment of the trigeminal nerve, which in turn triggers changes in the gasserian ganglion. In the lumbar spine, the dorsal root ganglion (DRG) is responsible for transmitting pain sensitivity and is involved in the pathogenesis of peripheral neuropathic pain. Therefore, radiosurgery to the DRG might improve chronic peripheral pain. This study evaluated the clinical and histological effects of high-dose radiosurgery to the DRG in a rodent model.

METHODS

Eight Sprague-Dawley rats received either 40- or 80-Gy SRS to the fifth and sixth lumbar DRGs using the Leksell Gamma Knife Icon. Animals were euthanized 3 months after treatment, and the lumbar spine was dissected and taken for analysis. Simple histology was used to assess collagen deposition and inflammatory response. GFAP, Neu-N, substance P, and internexin were used as a measure of peripheral glial activation, neurogenesis, pain-specific neurotransmission, and neurotransmission in general, respectively. The integrity of the spinothalamic tract was assessed by means of the von Frey test.

RESULTS

The animals did not exhibit any signs of motor or sensory deficits during the experimentation period. Edema, fibrosis, and vascular sclerotic changes were present on the treated, but not the control, side. SRS reduced the expression of GFAP without affecting the expression of Neu-N, substance P, or internexin. The von Frey sensory perception elicited equivalent results for the control side and both radiosurgical doses.

CONCLUSIONS

SRS did not alter sensory or motor function but reduced the activation of satellite glial cells, a pathway for DRG-mediated pain perpetuation. Radiosurgery provoked changes equivalent to the effects of focal radiation on the trigeminal ganglion after SRS for trigeminal neuralgia, suggesting that radiosurgery could be successful in relieving radiculopathic pain.

Post-traumatic hydrocephalus following decompressive hemicraniectomy: Incidence and risk factors in a prospective cohort of severe TBI patients

BACKGROUND

In severe traumatic brain injury (TBI) patients undergoing decompressive hemicraniectomy (DHC), the rate of post-traumatic hydrocephalus (PTH) is high at 12-36%. Early diagnosis and shunt placement can improve outcomes. Herein, we examined the incidence of and predictors of PTH after craniectomy.

METHODS

A retrospective analysis of prospectively collected database of severe TBI patients at a single U.S. Level 1 trauma center from May 2000 to July 2014 was performed. Demographics, Injury Severity Score (ISS), Glasgow Coma Scale (GCS), bleeding pattern and time-to-cranioplasty were analyzed. Glasgow Outcome Scale (GOS) scores at 6 and 12-months were studied. Statistical significance was assessed at p < 0.05.

RESULTS

A total of 402 patients were enrolled and 105 patients had DHC. Twenty-two (21.0%) of 105 required ventriculoperitoneal shunt (VPS), compared to 18 (6%) of 297 patients without DHC. There was increased odds ratio for shunting after DHC at 3.62 (95%CI:1.62-8.07; p < 0.01). Mean age at time of DHC was 43.8 ± 17.7 years old, and 81.9% were male. Subdural hematoma (SDH) was most common at 57.1%. Median time from admission to cranioplasty was 63 days. Patients who experienced PTH after DHC were younger (35.5 ± 17.7 versus 46.0 ± 17.7 years, p < 0.01) and had higher ISS scores (35 versus 26, p = 0.04) compared to patients without shunt after DHC.

CONCLUSIONS

After severe TBI requiring hemicraniectomy, shunt-dependent hydrocephalus was 21%. Younger patients and higher ISS score were associated with PTH. Shunt-dependent patients achieved similar 6- and 12-month outcomes as those without PTH. Early diagnosis and shunt placement can enhance long-term neurological recovery.

Republished: Intracranial vessel occlusion preceding the development of mycotic aneurysms in patients with endocarditis

Mycotic aneurysms (MA) are an uncommon complication of infectious endocarditis. Septic emboli are thought to be the precipitating event in their development, but the evidence for this is sparse. We present three cases in which septic embolic occlusion preceded MA development at the occlusion site, suggesting that documented angiographic emboli in patients with infectious endocarditis and bacteremia constitute a risk factor for MA formation. Two adult patients with a history of intravenous drug use and one child with congenital heart disease are described. They were all diagnosed with infectious endocarditis and developed neurological symptoms during their hospital course. Initial catheter-based cerebral angiograms demonstrated vascular occlusions, which were followed by the development of MA at the same sites within 1 month. Septic emboli, documented on cerebral angiogram, in patients with infectious endocarditis may precede the appearance of MA. Patients with angiographic occlusions in the setting of endocarditis warrant close follow-up.

A preoperative risk classifier that predicts tumor progression in patients with cranial base chondrosarcomas

OBJECTIVE

The authors conducted a study to identify clinical features of cranial base chondrosarcomas that will predict tumor progression after resection.

METHODS

The authors performed a retrospective study at a tertiary referral cranial base center. Patients who underwent resection of cranial base chondrosarcomas between January 2004 and December 2018 were followed longitudinally. The main outcome measure was progression-free survival (PFS).

RESULTS

A total of 41 patients were treated for histopathologically proven "conventional" cranial base chondrosarcomas during the study period, and the median PFS was 123 months for the cohort. Univariate analysis was performed on clinical, anatomical, and radiographic parameters collected for each patient. Features that were statistically significant were fed into a multivariate regression model, which revealed two independent predictors of PFS: patient age and encasement of 3-4 major arteries (> 25% of the vessel wall surrounded by tumor). Using these two variables of age and multiple arterial vessel encasement, the authors generated a risk stratification model using a simple point system to predict PFS in patients with cranial base chondrosarcomas. Based on these two factors known preoperatively, this model could stratify patients into high-risk (10% of patients), intermediate-risk (68% of patients), and low-risk (22% of patients) subgroups corresponding to dramatically distinct median PFS (1.8 years, 10.2 years, and no progression, respectively).

CONCLUSIONS

In patients with cranial base chondrosarcomas, age and artery encasement are variables known preoperatively that can powerfully predict tumor progression, define operative goals, and aid in selecting postoperative adjuvant therapy.

Vertebral artery mobilization for C1–2 reduction and fixation

Craniocervical instability due to chronic atlantoaxial dissociation presents the challenge of providing adequate decompression, reduction, and fixation to promote long-term stability while avoiding iatrogenic vertebral artery dissection or entrapment. The authors present one patient with chronic atlantoaxial dissociation and basilar invagination treated via Goel’s technique and with bilateral vertebral artery mobilization. There was substantial decompression and reduction postoperatively and the patient was discharged with a stable examination. Vertebral artery mobilization at the C1–2 junction can be safely performed via a standard midline suboccipital incision and dissection without vertebral artery injury.

The video can be found here: https://youtu.be/VS1Mt1dBLO4.

Intracranial vessel occlusion preceding the development of mycotic aneurysms in patients with endocarditis

Mycotic aneurysms (MA) are an uncommon complication of infectious endocarditis. Septic emboli are thought to be the precipitating event in their development, but the evidence for this is sparse. We present three cases in which septic embolic occlusion preceded MA development at the occlusion site, suggesting that documented angiographic emboli in patients with infectious endocarditis and bacteremia constitute a risk factor for MA formation. Two adult patients with a history of intravenous drug use and one child with congenital heart disease are described. They were all diagnosed with infectious endocarditis and developed neurological symptoms during their hospital course. Initial catheter-based cerebral angiograms demonstrated vascular occlusions, which were followed by the development of MA at the same sites within 1 month. Septic emboli, documented on cerebral angiogram, in patients with infectious endocarditis may precede the appearance of MA. Patients with angiographic occlusions in the setting of endocarditis warrant close follow-up.

Effect of oxidized cellulose on human respiratory mucosa and submucosa and its implications for endoscopic skull-base approaches

BACKGROUND

Regenerated oxidized cellulose (ROC) sheets have gained popularity as an adjunct to a vascularized nasoseptal flap for closure of dural defects after endoscopic endonasal skull-base approaches (EESBS). However, evidence supporting its impact on the healing process is uncertain. This study was performed to evaluate the impact of ROC on the nasal mucosa and assess its effects on tissue pH, structure, and cell viability.

METHODS

In 5 patients, a 1-cm² piece of ROC gauze was placed on the surface of the middle turbinate before it was resected as part of a standard EESBS. Mucosa treated with ROC was separated from untreated mucosa and a histologic examination of structural changes in the respiratory epithelium was performed. To assess the effect of ROC on pH, increasing amounts of ROC were added to culture medium. Nasal fibroblasts viability was assessed in the presence of ROC before and after the pH was neutralized.

RESULTS

Compared with unexposed controls, treated mucosa exhibited a higher incidence of cell necrosis and epithelial cell detachment. When added to Dulbecco's modified Eagle medium, ROC caused a dose-dependent decrease in pH of the medium. Only 1 ± 0.8% of cultured fibroblasts exposed to the ROC-induced acidic medium were alive, whereas 98.25 ± 0.5% of the cells were viable when the pH was neutralized (p < 0.001).

CONCLUSION

ROC applied in vivo to nasal mucosa induced epithelial necrosis likely by diminishing the medium pH, because pH neutralization prevents its effect. The ultimate effect of this material on the healing process is yet to be determined.

Endoscopic Endonasal Transodontoid Approach for Degenerative Pseudotumor of the Craniocervical Junction

Ventral masses of the craniocervical junction threaten the medulla and upper spinal cord leading to lower cranial nerve dysfunction and myelopathy. Traditional transoral and newer endonasal approaches can access ventral pathology in this region, though both remain challenging due to the competing goals of achieving sufficient decompression, yet mitigating risk to nearby critical neurovascular structures. Transoral approaches have traditionally been avoided for degenerative pseudotumor which generally slowly regresses following posterior fixation. Here, we present two cases of patients with significant retroodontoid degenerative pseudotumor and pannus causing dysphagia and myelopathy. The first patient was found with a large broad pannus requiring a wide decompression extending from lower clivus to inferior aspect of the C1 arch and odontoid process. The second patient had a more focal mass effect due to pannus and synovial cyst at the level of the inferior half of C1 and midodontoid. Both patients underwent an endoscopic endonasal transodontoid approach for immediate decompression followed by a posterior C1–C2 fusion. In these surgical videos, we highlight anatomic considerations in this critical area, demonstrate nuances of technique, and outline strategies to avoid complications and maximize exposure.

The link to the video can be found at: https://youtu.be/19I-GQYGIr4 .

Spatial convergence of distant cortical regions during folding explains why arteries do not cross the sylvian fissure

OBJECTIVE

Cortical folding places regions that are separated by a large distance along the cortical surface in close proximity. This process is not homogeneous; regions such as the insular opercula have a much higher cortical surface distance (CSD) to euclidean distance (ED) than others. Here the authors explore the hypothesis that in the folded brain the CSD, and not the ED, determines regions of common irrigation, because this measure corresponds more closely with the distance along the prefolded brain, where the subarachnoid arterial vascular network starts forming.

METHODS

The authors defined a convergence index that compared the ED to the CSD and applied it to the cortical surface reconstruction of an average brain. They then compared cortical convergence to the irrigation patterns of major sulci and fissures of the brain, by assessing whether these structures were crossed or not crossed by arterial vessels in 20 fixed hemispheres.

RESULTS

The regions of highest convergence (top 1%) were clustered around the sylvian fissure, which is the only brain depression with high convergence values along its edges. Arterial crossings were commonly observed in every major sulcus of the brain, with the exception of the sylvian fissure, constituting a highly significant difference (p < 10-4).

CONCLUSIONS

Arteries do not cross regions of high convergence. In the adult brain the CSD, rather than the ED, predicts the regional irrigation pattern. The distant origin of the frontal and temporal lobes creates a region of high cortical convergence, which explains why arteries do not cross the sylvian fissure.

A History of the Lobes of the Brain

The division of the cerebrum into 5 lobes is widely accepted in the scientific community. Despite this, a history of the lobes of the brain has not been discussed in the literature. Therefore, this article recounts this history with emphasis on the contributions of Thomas Willis (1664), Felix Vicq d'Azyr (1796), Johann-Christian Reil (1796), François Chaussier (1807), and Louis Pierre Gratiolet and François Leuret (1857) into one of the most widely accepted concepts in neuroanatomy.

Endoscopic endonasal approach for brainstem cavernous malformation

This 25-year-old woman presented after a second hemorrhage from a mesencephalic cavernous malformation. High-definition fiber tracking demonstrated lateral displacement of the corticospinal tracts, making a midline approach ideal. The lesion appeared to present to the third ventricle, but a transcallosal approach was abandoned due to the posterior third ventricular location and after FIESTA imaging revealed a superior and medial rim of normal parenchyma that would have to be transgressed to access the malformation. An endoscopic endonasal approach with interdural pituitary hemitransposition was performed. The interpeduncular cistern was accessed and the thalamoperforating arteries dissected to access the cavernous malformation that was completely removed in a piecemeal fashion. The patient’s preexisting internuclear ocular palsies and hemiparesis were slightly worsened after surgery as predicted by a drop in anterior tibialis motor evoked potentials. Postoperative MRI showed no infarct, and the hemiparesis was back to baseline at 1-month follow-up.

The video can be found here: https://youtu.be/e6203R9HHmk.

Seizure Risk following Open and Expanded Endoscopic Endonasal Approaches for Intradural Skull Base Tumors

Objectives  The incidence of seizures following a craniotomy for tumor removal varies between 15 and 20%. There has been increased use of endoscopic endonasal approaches (EEAs) for a variety of intracranial lesions due to its more direct approach to these pathologies. However, the incidence of postoperative seizures in this population is not well described. Methods  This is a single-center, retrospective review of consecutive patients undergoing EEA or open craniotomy for resection of a cranial base tumor between July 2007 and June 2014. Patients were included if they underwent an EEA for an intradural skull base lesion. Positive cases were defined by electroencephalograms and clinical findings. Patients who underwent a craniotomy to remove extra-axial skull base tumors were analyzed in the same fashion. Results  Of the 577 patients treated with an EEA for intradural tumors, 4 experienced a postoperative seizure (incidence 0.7%, 95% confidence interval [CI]: 0.002-0.02). Over the same period, 481 patients underwent a craniotomy for a skull base lesion of which 27 (5.3%, 95% CI: 0.03-0.08) experienced a seizure after surgery. The odds ratio for EEA was 0.13 (95% CI: 0.05-0.35). Both populations were different in terms of age, gender, tumor histology, and location. Conclusion  This study is the largest series looking at seizure incidence after EEA for intracranial lesions. Seizures are a rare occurrence following uncomplicated endonasal approaches. This must be tempered by selection bias, as there are inherent differences in which patients are treated with either approach that influence the likelihood of seizures.