Evaluating osteoporosis and bone quality in the aging spine: modern considerations for surgical management in the geriatric population

Surgical management paradigms of spinal pathologies in the aging population carry inherent substantial risks, with surgical complications being more prevalent among patients with osteoporosis compared to those with normal bone mineral density. In this narrative review, we aim to highlight important clinical understanding and considerations in perioperative evaluation and management of patients elected to undergo spinal surgery. Osteoporosis is a well-defined risk factor for mechanical complications following spinal surgery, and as such, perioperative optimization of bone health in the setting of surgery for geriatric patients remains a critical research area alongside intraoperative surgical augmentation techniques. Surgical techniques to circumvent challenges with instrumentation of poor bone mineral density have included augmentation of pedicle screw fixation, including segmental bicortical screw fixation techniques, cement augmentation with fenestrated screws, or use of expandable pedicle screws to improve bone-implant interface. Judicious selection of treatment modalities and subsequent perioperative optimization is paramount to minimize surgical complications. Contemporary guidelines and evolving paradigms in perioperative evaluation, optimization, and management of the aging spine include the advent of quantitatively evaluating computed tomography (CT) via assessment of the magnitude of Hounsfield units. Prescribing pharmacotherapeutic agents and monitoring bone health requires a multidisciplinary team approach, including endocrinologists and geriatricians to coordinate high-quality care for advanced-age patients who require surgical management of their spinal disorders.

Optimizing radiotherapy strategies for skull base chordoma: a comprehensive meta-analysis and systematic review of treatment modalities and outcomes

OBJECTIVE

In the treatment of skull base chordoma (SBC) surgery is considered the mainstay approach, and gross-total resection has an established relationship with progression-free survival (PFS) and overall survival (OS). However, the tumor's location often interferes with attempts at complete resection. In this case, surgery for maximal resection followed by high-dose radiotherapy has been demonstrated to be the standard treatment. In this context, various modalities are available, yet no consensus exists on the most effective. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of different radiotherapy modalities for SBC.

METHODS

Following PRISMA guidelines, the authors systematically searched for the treatment of SBC with radiation modalities in the PubMed, Cochrane, Web of Science, and EMBASE databases. Outcomes assessed for each modality were as follows: OS, PFS, local control (LC), and complications. The random-effects model was adopted. A single-proportion analysis with 95% CI was used to measure the effects in single-arm analysis. For the comparative analysis, the OR with 95% CI was used to compare outcome treatment effects. Heterogeneity was assessed using I2 statistics, and statistical significance was defined as p < 0.05.

RESULTS

A total of 32 studies comprising 3663 patients, with 2322 patients who were treated with radiotherapeutic modalities, were included. Regarding 5-year OS findings in each modality study, the findings were as follows: in photon fractionated radiotherapy, an estimated rate of 77% (69%-84%, 568 patients); in conventional fractionated radiotherapy, 76% (65%-87%, 517 cases); in proton-based + carbon ion-based radiotherapy, 85% (82%-88%, 622 cases); and in a comparative analysis of proton-based and carbon ion-based therapy, there was an OR of 1.2 (95% CI 0.59-2.43, 306 cases). Regarding the 5-year PFS estimate, the rates were as follows: 35% (26%-45%, 95 cases) for photon fractionated therapy; 35% (25%-45%, 85 cases) for stereotactic radiotherapy; 77% (50%-100%, 180 cases) for proton-based and carbon ion-based radiotherapy; and 74% (45%-100%, 102 cases) for proton-based radiotherapy. Regarding LC in periods of 3 and 5 years after proton- and carbon ion-based therapy, the overall estimated rates were 84% (78%-90%, 326 cases) and 75% (65%-85%, 448 cases), respectively. For proton-based radiotherapy and carbon ion-based therapy, the 5-year LC rates were 76% (67%-86%, 259 cases) and 75% (59%-91%, 189 cases), respectively.

CONCLUSIONS

The analysis highlights the finding that particle-based modalities like proton beam radiotherapy and carbon ion radiotherapy are the most effective radiation therapies available for the treatment of SBC. Furthermore, it reinforces the idea that surgery followed by radiotherapy constitutes the standard treatment.

Quantifying intra-tumoral genetic heterogeneity of glioblastoma toward precision medicine using MRI and a data-inclusive machine learning algorithm

BACKGROUND AND OBJECTIVE

Glioblastoma (GBM) is one of the most aggressive and lethal human cancers. Intra-tumoral genetic heterogeneity poses a significant challenge for treatment. Biopsy is invasive, which motivates the development of non-invasive, MRI-based machine learning (ML) models to quantify intra-tumoral genetic heterogeneity for each patient. This capability holds great promise for enabling better therapeutic selection to improve patient outcome.

METHODS

We proposed a novel Weakly Supervised Ordinal Support Vector Machine (WSO-SVM) to predict regional genetic alteration status within each GBM tumor using MRI. WSO-SVM was applied to a unique dataset of 318 image-localized biopsies with spatially matched multiparametric MRI from 74 GBM patients. The model was trained to predict the regional genetic alteration of three GBM driver genes (EGFR, PDGFRA and PTEN) based on features extracted from the corresponding region of five MRI contrast images. For comparison, a variety of existing ML algorithms were also applied. Classification accuracy of each gene were compared between the different algorithms. The SHapley Additive exPlanations (SHAP) method was further applied to compute contribution scores of different contrast images. Finally, the trained WSO-SVM was used to generate prediction maps within the tumoral area of each patient to help visualize the intra-tumoral genetic heterogeneity.

RESULTS

WSO-SVM achieved 0.80 accuracy, 0.79 sensitivity, and 0.81 specificity for classifying EGFR; 0.71 accuracy, 0.70 sensitivity, and 0.72 specificity for classifying PDGFRA; 0.80 accuracy, 0.78 sensitivity, and 0.83 specificity for classifying PTEN; these results significantly outperformed the existing ML algorithms. Using SHAP, we found that the relative contributions of the five contrast images differ between genes, which are consistent with findings in the literature. The prediction maps revealed extensive intra-tumoral region-to-region heterogeneity within each individual tumor in terms of the alteration status of the three genes.

CONCLUSIONS

This study demonstrated the feasibility of using MRI and WSO-SVM to enable non-invasive prediction of intra-tumoral regional genetic alteration for each GBM patient, which can inform future adaptive therapies for individualized oncology.

Timing and Morbidity of Intracranial Meningioma Resection Complications

BACKGROUND

Intracranial meningioma resection is associated with multiple acute postoperative complications, including cerebrovascular accidents, surgical site infections, and pneumonia. There is a paucity of research on the postoperative timeframe of these complications. Therefore, our objective is to characterize intracranial meningioma resection complications' time courses.

METHODS

The National Surgical Quality Improvement Project registry was queried for intracranial meningioma resection cases using CPT codes 61512 and 61519 from years 2016 to 2021. Baseline patient characteristics and 30-day complication frequency were calculated. The mean, median, and interquartile range of postoperative days to occurrence for 17 complications were calculated. Percent incidence predischarge was recorded. Time-to-occurrence curves were created. Rates of 30-day mortality and increased length-of-stay were compared between patients with and without each complication using a χ2 test. A covariance matrix showing associations between 11 complications using the Pearson method was made. Significance was set at P < 0.05.

RESULTS

Ten thousand eight hundred ninety cases were analyzed. The most frequent complications' median and interquartile range of postoperative days to occurrence and percentage occurring predischarge were bleeding requiring transfusion (0.0, 0.0-0.0, 99.9%), cerebrovascular accident/stroke with neurological deficit (2.0, 1.0-6.0, 83.8%), unplanned intubation (4.0, 1.0-8.0, 75.1%), on a ventilator for >48 hours (3.0; 2.0-5.5; 88.1%), deep vein thrombosis/thrombophlebitis (12.5, 5.2-19.7, 41.3%), urinary tract infection (13.0, 7.0-20.0, 44.2%), pneumonia (8.0, 4.0-16.0, 60.5%), and pulmonary embolism (14.0, 6.0-20.0, 29.1%). Most complications were associated with increased mortality and length-of-stay.

CONCLUSIONS

Postoperative meningioma resection complications have varying morbidity and timeframes. Surgeons should be aware of complication timing to better manage postoperative care.

Image-localized biopsy mapping of brain tumor heterogeneity: A single-center study protocol

Brain cancers pose a novel set of difficulties due to the limited accessibility of human brain tumor tissue. For this reason, clinical decision-making relies heavily on MR imaging interpretation, yet the mapping between MRI features and underlying biology remains ambiguous. Standard (clinical) tissue sampling fails to capture the full heterogeneity of the disease. Biopsies are required to obtain a pathological diagnosis and are predominantly taken from the tumor core, which often has different traits to the surrounding invasive tumor that typically leads to recurrent disease. One approach to solving this issue is to characterize the spatial heterogeneity of molecular, genetic, and cellular features of glioma through the intraoperative collection of multiple image-localized biopsy samples paired with multi-parametric MRIs. We have adopted this approach and are currently actively enrolling patients for our 'Image-Based Mapping of Brain Tumors' study. Patients are eligible for this research study (IRB #16-002424) if they are 18 years or older and undergoing surgical intervention for a brain lesion. Once identified, candidate patients receive dynamic susceptibility contrast (DSC) perfusion MRI and diffusion tensor imaging (DTI), in addition to standard sequences (T1, T1Gd, T2, T2-FLAIR) at their presurgical scan. During surgery, sample anatomical locations are tracked using neuronavigation. The collected specimens from this research study are used to capture the intra-tumoral heterogeneity across brain tumors including quantification of genetic aberrations through whole-exome and RNA sequencing as well as other tissue analysis techniques. To date, these data (made available through a public portal) have been used to generate, test, and validate predictive regional maps of the spatial distribution of tumor cell density and/or treatment-related key genetic marker status to identify biopsy and/or treatment targets based on insight from the entire tumor makeup. This type of methodology, when delivered within clinically feasible time frames, has the potential to further inform medical decision-making by improving surgical intervention, radiation, and targeted drug therapy for patients with glioma.

Predictive Model Evaluating Risk of Hemorrhage in Intracranial Aneurysms: Analysis from Prospectively Collected HEAT Trial Database

OBJECTIVE

We analyzed the data of patients enrolled in the Hydrogel Endovascular Aneurysm Treatment (HEAT) trial to develop and validate a model to predict the risk of aneurysmal hemorrhage.

METHODS

Analysis included data from 600 patients enrolled for the HEAT trial and included single saccular aneurysms of 3-14 mm size. Baseline characteristics were compared between patients with ruptured and unruptured aneurysms. Regression analysis was performed in the training set to identify significant risk factors and was validated in the validation dataset. The complete dataset was used to formulate a scoring model in which positive and negative predictors were assigned 1 and -1 points, respectively.

RESULTS

Data from 593 patients were analyzed in which 169 (28.5%) patients had ruptured aneurysms. The training (n = 297) and validation dataset (n = 296) had a comparable proportion of ruptured aneurysms (29.3% and 27.7%). Dome-to-neck ratio >2.5 (odds ratio [OR] 3.66), irregular shape (OR 3.79), daughter sac (OR 5.89), and anterior and posterior communicating artery locations (OR 3.32 and 3.56, respectively) had a higher rupture rate. Use of aspirin was associated with lower risk of hemorrhage (OR 0.16). The area under the curve from the receiver operating curve analysis was 0.88, 0.87, and 0.87 in the training, validation, and combined data set, respectively. The scoring model created a score of -1 to 2, yielding an of aneurysmal hemorrhage probability from 1.5% (score -1) to 70% (score 2).

CONCLUSIONS

This prospective study identifies dome-to-neck ratio >2.5, irregular shape, presence of daughter sac, absence of aspirin use, and aneurysm location at anterior communicating and posterior communicating artery as factors associated with increased risk of hemorrhagic presentation in small- to medium-sized intracranial aneurysms. Our model provides an estimate of rupture risk based on the presence or absence of these factors.

Integrated molecular and multiparametric MRI mapping of high-grade glioma identifies regional biologic signatures

Sampling restrictions have hindered the comprehensive study of invasive non-enhancing (NE) high-grade glioma (HGG) cell populations driving tumor progression. Here, we present an integrated multi-omic analysis of spatially matched molecular and multi-parametric magnetic resonance imaging (MRI) profiling across 313 multi-regional tumor biopsies, including 111 from the NE, across 68 HGG patients. Whole exome and RNA sequencing uncover unique genomic alterations to unresectable invasive NE tumor, including subclonal events, which inform genomic models predictive of geographic evolution. Infiltrative NE tumor is alternatively enriched with tumor cells exhibiting neuronal or glycolytic/plurimetabolic cellular states, two principal transcriptomic pathway-based glioma subtypes, which respectively demonstrate abundant private mutations or enrichment in immune cell signatures. These NE phenotypes are non-invasively identified through normalized K2 imaging signatures, which discern cell size heterogeneity on dynamic susceptibility contrast (DSC)-MRI. NE tumor populations predicted to display increased cellular proliferation by mean diffusivity (MD) MRI metrics are uniquely associated with EGFR amplification and CDKN2A homozygous deletion. The biophysical mapping of infiltrative HGG potentially enables the clinical recognition of tumor subpopulations with aggressive molecular signatures driving tumor progression, thereby informing precision medicine targeting.

A comparison of treating physician versus independent core lab assessments of post-aneurysm treatment imaging outcomes: an analysis of prospectively collected data from a randomized trial

OBJECTIVE

Aneurysm occlusion has been used as surrogate marker of aneurysm treatment efficacy. Aneurysm occlusion scales are used to evaluate the outcome of endovascular aneurysm treatment and to monitor recurrence. These scales, however, require subjective interpretation of imaging data, which can reduce the utility and reliability of these scales and the validity of clinical studies regarding aneurysm occlusion rates. Use of a core lab with independent blinded reviewers has been implemented to enhance the validity of occlusion rate assessments in clinical trials. The degree of agreement between core labs and treating physicians has not been well studied with prospectively collected data.

METHODS

In this study, the authors analyzed data from the Hydrogel Endovascular Aneurysm Treatment (HEAT) trial to assess the interrater agreement between the treating physician and the blinded core lab. The HEAT trial included 600 patients across 46 sites with intracranial aneurysms treated with coiling. The treating site and the core lab independently reviewed immediate postoperative and follow-up imaging (3-12 and 18-24 months, respectively) using the Raymond-Roy occlusion classification (RROC) scale, Meyer scale, and recanalization survey. A post hoc analysis was performed to calculate interrater reliability using Cohen's kappa. Further analysis was performed to assess whether degree of agreement varied on the basis of various factors, including scale used, timing of imaging, size of the aneurysm, imaging modality, location of the aneurysm, dome-to-neck ratio, and rupture status.

RESULTS

Minimal interrater agreement was noted between the core lab reviewers and the treating physicians for assessing aneurysm occlusion using the RROC grading scale (k = 0.39, 95% CI 0.38-0.40) and Meyer scale (k = 0.23, 95% CI 0.14-0.38). The degree of agreement between groups was slightly better but still weak for assessing recanalization (k = 0.45, 95% CI 0.38-0.52). Factors that significantly improved degree of agreement were scales with fewer variables, greater time to follow-up, imaging modality (digital subtraction angiography), and wide-neck aneurysms.

CONCLUSIONS

Assessment of aneurysm treatment outcome with commonly used aneurysm occlusion scales suffers from risk of poor interrater agreement. This supports the use of independent core labs for validation of outcome data to minimize reporting bias. Use of outcome tools with fewer point categories is likely to provide better interrater reliability. Therefore, the outcome assessment tools are ideal for clinical outcome assessment provided that they are sensitive enough to detect a clinically significant change.

TMIC-58. PATTERNS OF CELLULAR SUBPOPULATION COHABITATION DEFINE GLIOBLASTOMA STATES

Characterizing intra- and inter-tumoral heterogeneity of glioblastoma has historically relied on discrete classifications of malignant cell populations leaving immune and other cell populations, known to exist admixed with the malignant tumor cells, relatively neglected. Manifold learning algorithms can manage deconvolving multiple cell populations and are often used to track cell state transitions in single cell transcriptomics. We applied a manifold learning approach to TCGA microarray data (Nf525) and bulk transcriptomics of 134 image localized biopsies across 30 patients with primary and 9 with recurrent glioblastoma to further elucidate how to organize biopsies across a spectrum of possible tissue states. The algorithm revealed a low-dimensional manifold graph for which each biopsy lives across 3 polarizing tissue states - one that is associated with diffusely invaded brain, one that is enriched in mesenchymal genes, and one that is enriched in classical proliferative tumor signatures. We deconvolved the bulk transcriptomics of the image-localized biopsies to reveal the relative abundance of 18 malignant, immune, and other cell subpopulations in each biopsy. Overlaying the cellular decomposition onto the manifold graph visualizing the tissue state distributions revealed that transitions between states correlate with changes in cellular cohabitation composition. The tumor cellular cohabitation ecologies have the lowest diversity, as inferred by ecological measures such as Shannon entropy and evenness, at the distal poles of the graph when compared to the transitional arms. Further, we found that the relationship between imaging appearance of contrast enhancement on T1-weighted MRI and the biopsy cellular composition varies with sex and primary vs recurrent biopsy status. The limited spectrum of possible tissue states revealed by the manifold learning is suggestive of a limited continuum along which tumor and non-tumoral cell populations can cohabitate. Such a limited low-dimensional biological space may constrain the dynamics of tumor biology in a predictable manner.

Optimizing Door-to-Groin Puncture Time: The Mayo Clinic Experience

OBJECTIVES

To provide a better understanding of methods that can be used to improve patient outcomes by reducing the door-to-groin puncture (DTP) time and present the results of a stroke quality improvement project (QIP) conducted by Mayo Clinic Arizona's stroke center.

METHODS

We conducted a systematic literature search of Ovid MEDLINE(R), Ovid EMBASE, Scopus, and Web of Science for studies that evaluated DTP time reduction strategies. Those determined eligible for the purpose of this analysis were assessed for quality. The strategies for DTP time reduction were categorized on the basis of modified Target: Stroke Phase III recommendations and analyzed using a meta-analysis. The Mayo Clinic QIP implemented a single-call activation system to reduce DTP times by decreasing the time from neurosurgery notification to case start.

RESULTS

Fourteen studies were selected for the analysis, consisting of 2277 patients with acute ischemic stroke secondary to large-vessel occlusions. After intervention, all the studies showed a reduction in the DTP time, with the pooled DTP improvement being the standardized mean difference (1.37; 95% confidence interval, 1.20-1.93; τ²=1.09; P<.001). The Mayo Clinic QIP similarly displayed a DTP time reduction, with the DTP time dropping from 125.1 to 82.5 minutes after strategy implementation.

CONCLUSION

Computed tomography flow modifications produced the largest and most consistent reduction in the DTP time. However, the reduction in the DTP time across all the studies suggests that any systematic protocol aimed at reducing the DTP time can produce a beneficial effect. The relative novelty of mechanical thrombectomy and the consequential lack of research call for future investigation into the efficacy of varying DTP time reduction strategies.

Real-Time MRI-Guided Stereotactic Aspiration of Spontaneous Intracerebral Hematoma: A Preclinical Feasibility Study

BACKGROUND

Minimally invasive surgical techniques have reinvigorated the role of surgical options for spontaneous intracranial hematomas; however, they are limited by the lack of real-time feedback on the extent of hematoma evacuation.

OBJECTIVE

To describe the development of a MRI-guided catheter-based aspiration system, the ClearPoint Pursuit Neuroaspiration Device (ClearPoint Neuro) and validation in phantom models.

METHODS

In this preclinical experimental trial, 8 phantom brains with skull models were created to simulate an intracranial hematoma with 2 clot sizes, 30 cc (small clot) and 60 cc (large clot). After registration, the aspiration catheter (Pursuit device) was aligned to the desired planned trajectory. The aspiration of the clot was performed under real-time MRI scan in 3 orthogonal views. The primary end point was reduction of the clot volume to less than 15 cc or 70% of the original clot volume.

RESULTS

Successful completion of clot evacuation was achieved in all models. The average postaspiration clot volume was 9.5 cc (8.7 cc for small clots and 10.2 cc for large clots). The average percentage reduction of clot volume was 76.3% (range 58.7%-85.2%). The average total procedure time (from frame registration to final postaspiration clot assessment) was 50 min. The average aspiration time was 6.9 min.

CONCLUSION

This preclinical trial confirms the feasibility and efficacy of MRI-guided aspiration under real-time image guidance in simulation models for intracranial hematoma. Clinical use of the system in patients would further validate its efficacy and safety.

Microvascular Decompression Technique for Trigeminal Neuralgia Using a Vascular Clip

Microvascular decompression (MVD) surgery is a well-established, effective treatment option for trigeminal neuralgia¹ and hemifacial spasm.² In 1967, Janetta et al³ introduced the concept of MVD surgery and pioneered the Janetta technique in which Teflon felt implants are placed between the trigeminal nerve and offending vessel. Though many cases are successfully managed with Teflon interposition, alternative techniques have been developed with the objective to alleviate vascular compression symptoms indefinitely, including transposition using biological glue,⁴ vascular clips,^5,6 and a variety of "sling" techniques.⁷ In Video 1, we demonstrate a fenestrated clip transposition technique in the treatment of trigeminal neuralgia. We present the case of a 72-year-old female who presented with classic trigeminal neuralgia pain along the V2 and V3 distributions. Magnetic resonance imaging revealed evident compression of the trigeminal nerve by the superior cerebellar artery (SCA). A retrosigmoid craniotomy was performed, and the vascular loop of the SCA was visualized compressing the root entry zone with significant indentation of the trigeminal nerve. Wide arachnoid dissection along the SCA was carried out in order to mobilize the SCA away from the nerve. A small slit was created in the undersurface of the tentorium, and then the SCA loop was transposed to the tentorium using a fenestrated aneurysm clip. The postoperative course was uneventful, and the patient had complete resolution of her facial pain at 6-month follow-up. This method is likely an effective and durable method of decompression for trigeminal neuralgia.

Initiation of a Robotic Program in Spinal Surgery: Experience at a Three-Site Medical Center

OBJECTIVE

To highlight the early experience of implementing a robotic spine surgery program at a three-site medical center, evaluating the impact of increasing experience on the operative time and number of procedures performed.

PATIENTS AND METHODS

A retrospective chart review of patients undergoing robotic screw placement between September 4, 2018, and October 16, 2019, was conducted. Baseline characteristics as well as intraoperative and post-operative outcomes were obtained.

RESULTS

For a total of 77 patients, the mean age (SD) was 55.7 years (11.5) and 49.4% (n=38) were female. A total of 402 screws were placed (384 pedicle screws, 18 cortical screws) using robotic guidance with a median of two operative levels (interquartile range [IQR], 1 to 2). Median (IQR) estimated blood loss was 100 mL (50 to 200 mL) and the median (IQR) operative time was 224 minutes (193 to 307 minutes). With accrual of surgical experience, operative time declined significantly (R=-0.39; P<.001) whereas the number of procedures performed per week increased (R=0.30; P=.05) throughout the study period. Median (IQR) length of hospital stay following surgery was 2 days (IQR, 2 to 3 days). There were two screws requiring revision intraoperatively. No postoperative revisions were required, and no complications were encountered related to screw placement.

CONCLUSION

Early experience at our institution using a spinal robot has demonstrated no requirement for postoperative screw revisions and no complications related to screw malposition. The increased operative times were reduced as the frequency of procedures increased. Moreover, procedural times diminished over a short period with a weekly increasing number of procedures.

Uncertainty quantification in the radiogenomics modeling of EGFR amplification in glioblastoma

Radiogenomics uses machine-learning (ML) to directly connect the morphologic and physiological appearance of tumors on clinical imaging with underlying genomic features. Despite extensive growth in the area of radiogenomics across many cancers, and its potential role in advancing clinical decision making, no published studies have directly addressed uncertainty in these model predictions. We developed a radiogenomics ML model to quantify uncertainty using transductive Gaussian Processes (GP) and a unique dataset of 95 image-localized biopsies with spatially matched MRI from 25 untreated Glioblastoma (GBM) patients. The model generated predictions for regional EGFR amplification status (a common and important target in GBM) to resolve the intratumoral genetic heterogeneity across each individual tumor-a key factor for future personalized therapeutic paradigms. The model used probability distributions for each sample prediction to quantify uncertainty, and used transductive learning to reduce the overall uncertainty. We compared predictive accuracy and uncertainty of the transductive learning GP model against a standard GP model using leave-one-patient-out cross validation. Additionally, we used a separate dataset containing 24 image-localized biopsies from 7 high-grade glioma patients to validate the model. Predictive uncertainty informed the likelihood of achieving an accurate sample prediction. When stratifying predictions based on uncertainty, we observed substantially higher performance in the group cohort (75% accuracy, n = 95) and amongst sample predictions with the lowest uncertainty (83% accuracy, n = 72) compared to predictions with higher uncertainty (48% accuracy, n = 23), due largely to data interpolation (rather than extrapolation). On the separate validation set, our model achieved 78% accuracy amongst the sample predictions with lowest uncertainty. We present a novel approach to quantify radiogenomics uncertainty to enhance model performance and clinical interpretability. This should help integrate more reliable radiogenomics models for improved medical decision-making.

Quality of Life of Patients with Unruptured Intracranial Aneurysms Before and After Endovascular Coiling: A HEAT Trial Secondary Study and Systematic Review of the Literature

BACKGROUND

The study of quality of life (QOL) in patients with asymptomatic diseases receiving interventional treatment provides an essential metric for the assessment of procedural benefits in the surgical patient population. In this study, we analyzed QOL data collected from patients with unruptured intracranial aneurysms (UIAs) before and after endovascular coiling in the HEAT Trial, alongside a systematic review on QOL in unruptured brain aneurysms.

METHODS

HEAT was a randomized controlled trial comparing recurrence rates in aneurysms treated with either bare platinum coils or hydrogel coils. Patients enrolled in this trial completed a short form-36 (SF-36) QOL questionnaire before treatment and at the 3- to 12- and 18- to 24-month follow-ups. The change in QOL before and after treatment was assessed. Regression analysis evaluated the effect of select baseline characteristics on QOL change.

RESULTS

A total of 270 patients were eligible for analysis. There was an increase in the role physical (P = 0.043), vitality (P = 0.022), and emotional well-being (P < 0.001) QOL components at the 18- to 24-month follow-up compared with baseline scores. Regression analysis showed that age younger than 60 and absence of serious adverse events were associated with improved social functioning and vitality. The literature review showed a mixed effect of intervention on QOL in patients with UIAs.

CONCLUSIONS

Our analysis has revealed that patients with 3- to 14-mm UIAs had improvements in some physical and emotional components of QOL at 18-24 months following aneurysm coiling in the HEAT study. The literature remains indeterminate on this issue. Further studies are needed to better understand the effects of the diagnosis of UIAs and their treatment on QOL.

Performance of Standardized Relative CBV for Quantifying Regional Histologic Tumor Burden in Recurrent High-Grade Glioma: Comparison against Normalized Relative CBV Using Image-Localized Stereotactic Biopsies

BACKGROUND AND PURPOSE

Perfusion MR imaging measures of relative CBV can distinguish recurrent tumor from posttreatment radiation effects in high-grade gliomas. Currently, relative CBV measurement requires normalization based on user-defined reference tissues. A recently proposed method of relative CBV standardization eliminates the need for user input. This study compares the predictive performance of relative CBV standardization against relative CBV normalization for quantifying recurrent tumor burden in high-grade gliomas relative to posttreatment radiation effects.

MATERIALS AND METHODS

We recruited 38 previously treated patients with high-grade gliomas (World Health Organization grades III or IV) undergoing surgical re-resection for new contrast-enhancing lesions concerning for recurrent tumor versus posttreatment radiation effects. We recovered 112 image-localized biopsies and quantified the percentage of histologic tumor content versus posttreatment radiation effects for each sample. We measured spatially matched normalized and standardized relative CBV metrics (mean, median) and fractional tumor burden for each biopsy. We compared relative CBV performance to predict tumor content, including the Pearson correlation (r), against histologic tumor content (0%-100%) and the receiver operating characteristic area under the curve for predicting high-versus-low tumor content using binary histologic cutoffs (≥50%; ≥80% tumor).

RESULTS

Across relative CBV metrics, fractional tumor burden showed the highest correlations with tumor content (0%-100%) for normalized (r = 0.63, P < .001) and standardized (r = 0.66, P < .001) values. With binary cutoffs (ie, ≥50%; ≥80% tumor), predictive accuracies were similar for both standardized and normalized metrics and across relative CBV metrics. Median relative CBV achieved the highest area under the curve (normalized = 0.87, standardized = 0.86) for predicting ≥50% tumor, while fractional tumor burden achieved the highest area under the curve (normalized = 0.77, standardized = 0.80) for predicting ≥80% tumor.

CONCLUSIONS

Standardization of relative CBV achieves similar performance compared with normalized relative CBV and offers an important step toward workflow optimization and consensus methodology.

Vascular Transposition of the Superior Cerebellar Artery Using a Fenestrated Clip and Fibrin Glue in Trigeminal Neuralgia: 2-Dimensional Operative Video

This is the case of an 86-yr-old gentleman who presented with left facial pain exacerbated by eating, drinking, chewing, and shaving (distribution: V2, V3). The patient was diagnosed with trigeminal neuralgia and was refractory to medications. Imaging showed a superior cerebellar artery (SCA) loop adjacent to the trigeminal nerve root entry zone and a decision to perform a microvascular decompression of the fifth nerve was presented to the patient. After patient informed consent was obtained, a standard 3 cm × 3 cm retrosigmoid craniotomy was performed with the patient in a supine head turned position and in reverse Trendelenburg. The arachnoid bands tethering the SCA to the trigeminal nerve were sharply divided. A slit was then made in the tentorium and a 3 mm fenestrated clip was then used to secure the transposed SCA away from the trigeminal nerve. The SCA proximal to this was slightly patulous in its course so a small amount of a fibrin glue was also used to secure the more proximal SCA to the tentorium. The patient was symptom-free postoperatively and no longer required medical therapy. Additionally, imaging was consistent with adequate separation of the nerve from adjacent vessels.1-5

NIMG-52. UNCERTAINTY QUANTIFICATION IN RADIOMICS

INTRODUCTION

The quantification of intratumoral heterogeneity – through radiomics-based approaches - can help resolve the regionally distinct genetic drug targets that may co-exist within a single Glioblastoma (GBM) tumor. While this offers potential diagnostic value under the paradigm of individualized oncology, clinical decision-making must also consider the degree of uncertainty associated with each model. In this study, we evaluate the performance of a novel machine-learning (ML) algorithm, called Gaussian Process (GP) modeling, that can quantify the impact of multiple sources of uncertainty in ML model development and prediction accuracy, including variabilities in the copy number measurement, radiomics features, training sample characteristics, and training sample size.

METHOD

We collected 95 image-localized biopsies from 25 primary GBM patients. We coregistered stereotactic locations with preoperative multi-parametric MRI features (conventional MRI, DSC perfusion, Diffusion Tensor Imaging) to generate spatially matched pairs of MRI and copy number variants (CNV) for for each biopsy. We developed a Gaussian Process (GP) model to predict CNV for Epidermal Growth Factor Receptor (EGFR) based on MRI radiomic features in each patient. We used leave-one-patient-out cross validation to quantify prediction accuracy and model uncertainty. Spatial prediction and uncertainty (p-value) maps were overlaid to help visualize regional genetic variation of EGFR and uncertainty of the radiomic predictions. RESULT: The initial GP radiomics model for EGFR amplification (CNV > 3.5) produced a sensitivity of 0.8 and specificity of 0.8. Samples/regions associated with high uncertainty (p-value >0.05) correlated with either 1) extrapolation of radiomic features from the training set-defined feature space or 2) insufficient training samples in the feature space.

CONCLUSION

We present a ML-based model that quantifies spatial genetic heterogeneity in GBM, while also estimating model uncertainties that result from multi-source data variabilities. This approach lays the groundwork for prospective clinical integration of modeling-based diagnostic approaches in the paradigm of individualized medicine.

A Multicenter Pilot Study on the Clinical Utility of Computational Modeling for Flow-Diverter Treatment Planning

BACKGROUND AND PURPOSE

Selection of the correct flow-diverter size is critical for cerebral aneurysm treatment success, but it remains challenging due to the interplay of device size, anatomy, and deployment. Current convention does not address these challenges well. The goals of this pilot study were to determine whether computational modeling improves flow-diverter sizing over current convention and to validate simulated deployments.

MATERIALS AND METHODS

Seven experienced neurosurgeons and interventional neuroradiologists used computational modeling to prospectively plan 19 clinical interventions. In each patient case, physicians simulated 2-4 flow-diverter sizes that were under consideration based on preprocedural imaging. In addition, physicians identified a preferred device size using the current convention. A questionnaire on the impact of computational modeling on the procedure was completed immediately after treatment. Rotational angiography image data were acquired after treatment and compared with flow-diverter simulations to validate the output of the software platform.

RESULTS

According to questionnaire responses, physicians found the simulations useful for treatment planning, and they increased their confidence in device selection in 94.7% of cases. After viewing the simulations results, physicians selected a device size that was different from the original conventionally planned device size in 63.2% of cases. The average absolute difference between clinical and simulated flow-diverter lengths was 2.1 mm. In 57% of cases, average simulated flow-diverter diameters were within the measurement uncertainty of clinical flow-diverter diameters.

CONCLUSIONS

Physicians found computational modeling to be an impactful and useful tool for flow-diverter treatment planning. Validation results showed good agreement between simulated and clinical flow-diverter diameters and lengths.

Tulip Giant Aneurysm Amputation and "Shingle Clip Cut Clip" Technique for Microsurgical Reconstruction of a Giant Thrombosed Middle Cerebral Artery Aneurysm

In this video, we present the case of a 61-year-old female who was brought to the emergency department after she had partial complex seizures. Computed tomography and magnetic resonance imaging of the brain revealed a right temporal lobe mass, which was initially thought to be a tumor. The patient was therefore referred to us for further management. The round nature of the lesion raised suspicion for an aneurysm. Computed tomography angiography was performed, followed by a diagnostic conventional cerebral angiogram, and confirmed the presence of a giant thrombosed aneurysm. Giant aneurysms represent 3%-5% of all cerebral aneurysms.¹ They are more common in females with a ratio of 2:1 to 3:1.¹ They have a high risk of rupture up to 50% in the posterior circulation and 40% in the anterior circulation over 5 years according to the International Study of Unruptured Intracranial Aneurysms Investigators.^2,3 Their treatment can be complex and treacherous. Treatment options vary widely from parent artery sacrifice in select cases to clip reconstruction to an array of endovascular approaches such as flow diversion. In some cases a combination of both open and endovascular approaches might be necessary.^4-8 In our case, we opted for an open surgical clip reconstruction. A superior temporal artery-middle cerebral artery bypass was attempted to allow for trapping of the aneurysm without risking ischemic complication distal to it. Unfortunately, the patient's vessels were too atherosclerotic to maintain patency. A strategy was then devised, which consisted of cutting the dome of the aneurysm and clearing the distal two thirds of the clot ("tulip technique") and then completing thrombus resection under temporary occlusion. Once clot removal was completed, the aneurysm was clipped using the "shingle clip cut clip" technique (Video 1). The patient's postoperative course was uneventful, and the patient remained seizure free.

Assessment of the Interrater Reliability of the Congress of Neurological Surgeons Microanastomosis Assessment Scale

BACKGROUND

The potential for simulation-based learning in neurosurgical training has led the Congress of Neurosurgical Surgeons to develop a series of simulation modules. The Northwestern Objective Microanastomosis Assessment Tool (NOMAT) was created as the corresponding assessment tool for the Congress of Neurosurgical Surgeons Microanastomosis Module. The face and construct validity of the NOMAT have been previously established.

OBJECTIVE

To further validate the NOMAT by determining its interrater reliability (IRR) between raters of varying levels of microsurgical expertise.

METHODS

The NOMAT was used to assess residents' performance in a microanastomosis simulation module in 2 settings: Northwestern University and the Society of Neurological Surgeons 2014 Boot Camp at the University of Indiana. At Northwestern University, participants were scored by 2 experienced microsurgeons. At the University of Indiana, participants were scored by 2 postdoctoral fellows and an experienced microsurgeon. The IRR of NOMAT was estimated by computing the intraclass correlation coefficient using SPSS v22.0 (IBM, Armonk, New York).

RESULTS

A total of 75 residents were assessed. At Northwestern University, 21 residents each performed microanastomosis on 2 model vessels of different sizes, one 3 mm and one 1 mm. At the University of Indiana, 54 residents performed a single microanastomosis procedure on 3-mm vessels. The intraclass correlation coefficient of the total NOMAT scores was 0.88 at Northwestern University and 0.78 at the University of Indiana.

CONCLUSION

This study indicates high IRR for the NOMAT. These results suggest that the use of raters with varying levels of expertise does not compromise the precision or validity of the scale. This allows for a wider adoption of the scale and, hence, a greater potential educational impact.

Thrombectomy for a Patient with Concomitant Acute Cervical Internal Carotid and Middle Cerebral Artery Occlusion: Video Case

We present the case of a 62-yr-old female who presented with ground-level fall and new onset of left-sided weakness of 30 min duration. CT angiogram revealed right ICA pseudo-occlusion and thrombus filling the right proximal M1 segment of the right MCA. On detailed neurological exam patient was noted to have NIHSS of 25. Patient was started on IV TPA infusion and was taken to interventional angiography suite after an informed consent was obtained. Diagnostic angiography was performed which demonstrated critical stenosis of the right proximal internal carotid artery. Right carotid artery stenting and balloon angioplasty of the carotid stent with distal embolic protection device was performed. Post carotid stent angiogram once again confirmed proximal right M1 pseudo-occlusion in the right MCA distribution. The clot was removed using a stent retriever, thus achieving complete recanalization (TICI 3) of the right cerebral hemisphere. The patient returned to baseline neurological status and a 1 mo follow-up diagnostic angiogram revealed patent carotid stent. Following the case presentation, we present the nuances of acute ischemic stroke management of large vessel occlusion with an emphasis on technical nuances, recent published guidelines1 and the literature.2-8.

Diagnosis and Endovascular Embolization of a Sacral Spinal Arteriovenous Fistula with "Holo-Spinal" Venous Drainage

BACKGROUND

Spinal dural arteriovenous fistulas are the most common spinal vascular pathology, accounting for up to 70% of spinal vascular malformations. They most commonly present with insidious and progressive myelopathy and bowel, bladder, and sexual dysfunction. Although noninvasive imaging (e.g., magnetic resonance imaging, magnetic resonance angiography) may suggest the presence of a spinal arteriovenous fistula (AVF), the diagnosis requires confirmation with spinal angiography.

CASE DESCRIPTION

A 65-year-old woman presented with progressive myelopathy. Traditional spinal angiography of the paired radicular arteries failed to demonstrate any vascular malformation. However, injection of the right internal iliac artery demonstrated an AVF arising from the artery of Desproges-Gotteron with retrograde venous drainage to the upper thoracic region.

CONCLUSIONS

Selective transarterial catheterization and embolization with n-butyl cyanoacrylate resulted in complete occlusion of the AVF. Clinical improvement was also noted on postprocedural day 1. This case highlights the importance of internal iliac injections as a critical component of spinal angiography during an evaluation for vascular malformation.

Accurate Patient-Specific Machine Learning Models of Glioblastoma Invasion Using Transfer Learning

BACKGROUND AND PURPOSE

MR imaging-based modeling of tumor cell density can substantially improve targeted treatment of glioblastoma. Unfortunately, interpatient variability limits the predictive ability of many modeling approaches. We present a transfer learning method that generates individualized patient models, grounded in the wealth of population data, while also detecting and adjusting for interpatient variabilities based on each patient's own histologic data.

MATERIALS AND METHODS

We recruited patients with primary glioblastoma undergoing image-guided biopsies and preoperative imaging, including contrast-enhanced MR imaging, dynamic susceptibility contrast MR imaging, and diffusion tensor imaging. We calculated relative cerebral blood volume from DSC-MR imaging and mean diffusivity and fractional anisotropy from DTI. Following image coregistration, we assessed tumor cell density for each biopsy and identified corresponding localized MR imaging measurements. We then explored a range of univariate and multivariate predictive models of tumor cell density based on MR imaging measurements in a generalized one-model-fits-all approach. We then implemented both univariate and multivariate individualized transfer learning predictive models, which harness the available population-level data but allow individual variability in their predictions. Finally, we compared Pearson correlation coefficients and mean absolute error between the individualized transfer learning and generalized one-model-fits-all models.

RESULTS

Tumor cell density significantly correlated with relative CBV (r = 0.33, P < .001), and T1-weighted postcontrast (r = 0.36, P < .001) on univariate analysis after correcting for multiple comparisons. With single-variable modeling (using relative CBV), transfer learning increased predictive performance (r = 0.53, mean absolute error = 15.19%) compared with one-model-fits-all (r = 0.27, mean absolute error = 17.79%). With multivariate modeling, transfer learning further improved performance (r = 0.88, mean absolute error = 5.66%) compared with one-model-fits-all (r = 0.39, mean absolute error = 16.55%).

CONCLUSIONS

Transfer learning significantly improves predictive modeling performance for quantifying tumor cell density in glioblastoma.

Extended Lateral Orbital Craniotomy: Anatomic Study and Initial Clinical Series of a Novel Minimally Invasive Pterional Approach

Background  Of the minimally invasive "keyhole" alternatives to the pterional region, the supraorbital eyebrow approach is the most widely adopted. Yet it can prove disadvantageous when a more direct lateral microsurgical trajectory of attack to the Sylvian fissure and anterior middle fossa are needed. Objective  The extended lateral orbital (XLO) approach was designed to be direct and minimally invasive, with the sphenoid ridge at the center of exposure. Methods  Five injected cadaver heads were used for anatomic study of the XLO approach. The anatomic course of the frontalis branch of facial nerve was studied in relation to the XLO incision. Following XLO incision, the bone exposure was measured. The intracranial microsurgical exposure was assessed subjectively. Application of the technique in representative clinical operative cases is provided. Results  The frontalis nerve was protected in the subgaleal fat pad, with an average minimum distance of 2.3 cm from the XLO incision. The mean calvarial area exposure was 4.95 cm ² and consistently centered on the sphenoid ridge. Excellent access to ipsilateral Sylvian's fissure, perisylvian regions, and supra-/parasellar structures was possible. The main limitations related to exposure of the posterior Sylvian fissure and the expected limitations of microsurgical instrument manipulation from a smaller craniotomy. Conclusions  The XLO approach is a minimally invasive keyhole approach to the pterional region that affords a unique lateral trajectory via a craniotomy centered on the sphenoid ridge. Excellent exposure to properly selected lesions is possible. The incision is at a safe distance from the frontalis branch and shows excellent cosmetic healing.

Use of 4D Computer Tomographic Angiography to Accurately Identify Distal Internal Carotid Artery Occlusions and Pseudo-Occlusions: Technical Note

BACKGROUND AND PURPOSE

Traditional methods of computed tomographic angiography (CTA) can be unreliable in detecting carotid artery pseudo-occlusions or in accurately locating the site of carotid artery occlusion. With these methods, lack of adequate distal runoff due to pseudo-occlusion or intracranial occlusion can result in the inaccurate diagnoses of complete occlusion or cervical carotid occlusion, respectively. The site of carotid occlusion has important therapeutic and interventional considerations. We present several cases in which 4D CTA was utilized to accurately and noninvasively diagnose carotid pseudo-occlusion and intracranial internal carotid artery (ICA) occlusion.

METHODS

We identified five patients who presented to our institute with ischemic stroke symptoms and evaluated images from traditional CTA protocols and 4D CTA protocols in each of these patients, comparing diagnoses rendered by each imaging technique.

RESULTS

In two patients, traditional CTA suggested the presence of complete ICA occlusion. However, 4D CTA demonstrated pseudo-occlusion. Similarly, in three patients, traditional CTA demonstrated cervical ICA occlusion, whereas the 4D CTA demonstrated intracranial ICA occlusion.

CONCLUSION

4D CTA may be a more effective noninvasive imaging technique than traditional CTA to detect intracranial carotid artery occlusions and carotid artery pseudo-occlusions. Accurate, rapid, and noninvasive diagnosis of carotid artery lesions may help tailor and expedite endovascular intervention.

Hemicraniectomy for Ischemic and Hemorrhagic Stroke: Facts and Controversies

Malignant large artery stroke is associated with high mortality of 70% to 80% with best medical management. Decompressive craniectomy (DC) is a highly effective tool in reducing mortality. Convincing evidence has accumulated from several randomized trials, in addition to multiple retrospective studies, that demonstrate not only survival benefit but also improved functional outcome with DC in appropriately selected patients. This article explores in detail the evidence for DC, nuances regarding patient selection, and applicability of DC for supratentorial intracerebral hemorrhage and posterior fossa ischemic and hemorrhagic stroke.

Spinal Schwannoma and Meningioma Mimicking a Single Mass at the Craniocervical Junction Subsequent to Remote Radiation Therapy for Acne Vulgaris

BACKGROUND

Schwannomas and meningiomas are relatively common tumors of the nervous system. They have been reported in the literature as existing concurrently as a single mass, but very rarely have they been shown to present at the craniocervical junction.

CASE DESCRIPTION

We present a rare and interesting case of a patient previously treated with radiation therapy for acne vulgaris and who presented to us with a concurrent schwannoma and meningioma of the craniocervical junction mimicking a single mass.

CONCLUSIONS

These tumors can be solitary or mixed masses, and are known to be associated with certain disease processes such as long-term sequelae of radiation therapy and neurofibromatosis type 2. The precise mechanism behind the formation of these tumors is unknown; however, molecular cues in the tumor microenvironment may play a role.

Patency of anterior circulation branch vessels after Pipeline embolization: longer-term results from 82 aneurysm cases

OBJECTIVE The Pipeline Embolization Device (PED) has become increasingly used for the treatment of intracranial aneurysms. Given its high metal surface area coverage, there is concern for the patency of branch vessels that become covered by the device. Limited data exist regarding the patency of branch vessels adjacent to aneurysms that are covered by PEDs. The authors assessed the rate of intracranial internal carotid artery, anterior circulation branch vessel patency following PED placement at their institution. METHODS The authors retrospectively reviewed the records of 82 patients who underwent PED treatment between 2009 and 2014 and in whom the PED was identified to cover branch vessels. Patency of the anterior cerebral, posterior communicating, anterior choroidal, and ophthalmic arteries was evaluated using digital subtraction angiography preoperatively and postoperatively after PED deployment and at longer-term follow-up. RESULTS Of the 127 arterial branches covered by PEDs, there were no immediate postoperative occlusions. At angiographic follow-up (mean 10 months, range 3-34.7 months), arterial side branches were occluded in 13 (15.8%) of 82 aneurysm cases and included 2 anterior cerebral arteries, 8 ophthalmic arteries, and 3 posterior communicating arteries. No cases of anterior choroidal artery occlusion were observed. Patients with branch occlusion did not experience any neurological symptoms. CONCLUSIONS In this large series, the longer-term rate of radiographic side branch arterial occlusion after coverage by a flow diverter was 15.8%. Terminal branch vessels, such as the anterior choroidal artery, remained patent in this series. The authors' series suggests that branch vessel occlusions are clinically silent and should not deter aneurysm treatment with flow diversion.

Cavernous malformation of the optic chiasm: Neuro-endoscopic removal

Cavernous malformations (CMs) arising from the optic nerve and chiasm are extremely rare. In large autopsy series, CMs were estimated to range from 0.02 to 0.13% in the general population. However, with introduction of MRI, these lesions were found more often than previously thought, ranging from 0.2% to 0.4%. Only 29 cases have been reported according to our knowledge. Most patients present with drop in visual acuity and visual field. Although MRI findings of cavernous malformations have been reported, they may not be diagnostic enough. Among the 29 reported, 16 underwent total resection with good results. In some, resection was complicated by damage to the surrounding neural tissue. Surgical removal is the recommended treatment to restore or preserve vision and to eliminate the risk of future hemorrhage. However, the anatomical location and eloquence of nearby neural structures can make these lesions difficult to access and remove. CMs appear to occur in every age group (range 4 months to 84 years mean-34.6 years) ith an approximately equal male to female ratio. They typically present with chiasmal apoplexy, characterized by sudden visual loss, acute headaches, retro orbital pain, and nausea

Stent Retriever-Assisted Mechanical Thrombectomy for Acute Basilar Artery Occlusion: Single US Institution Experience

BACKGROUND

Acute basilar artery occlusion causes devastating strokes that carry high mortality and morbidity.

OBJECTIVE

To report the outcomes of mechanical thrombectomy in the posterior circulation with a focus on safety and efficacy of stent retrievers.

METHODS

We retrospectively reviewed our endovascular database for all patients treated with stent retrievers for posterior circulation stroke between June 2012 and June 2014. Twelve patients were identified. The following data were analyzed: thrombus location, previous stroke or transient ischemic attack, thrombus etiology, comorbidities, time from presentation to initiation of endovascular treatment, time from start of angiography to revascularization, and whether intravenous tissue plasminogen activator was administered pre-thrombectomy. Outcome was considered poor when modified Rankin Scale score was &gt;2.

RESULTS

Mean patient age was 63.42 years (median, 64.5; range, 28-83 years); 7 were women. Successful recanalization (Thrombolysis in Cerebral Infarction grade 2b or 3) was achieved in 11 of 12 patients (91.7%). Mean discharge modified Rankin Scale score was 2.3 (median, 2.0; standard deviation 1.96; range, 0-6), with a favorable discharge outcome in 9 of 12 (75%) patients. Two patients died as inpatients. Mean follow-up modified Rankin Scale score was 1.4 (median, 1.00; standard deviation 1.075; range, 0-4). Good outcome was achieved in 9 of 10 (90%) patients at last follow-up (mean follow-up duration, 132.42 days [median, 90.50; standard deviation 80.2; range, 8-378 days]).

CONCLUSION

Our single-institution study has shown that good clinical outcomes and successful recanalization with acceptable mortality can be achieved with current stent retrievers.

Impact of transfer status on hospitalization cost and discharge disposition for acute ischemic stroke across the US

OBJECT In this study, the authors used information provided in the Nationwide Inpatient Sample (NIS) to study the impact of transferring stroke patients from one facility to a center where they received some form of active stroke intervention (intravenous tissue plasminogen activator, thrombectomy, or a combination of both therapies). METHODS Patient demographic characteristics and hospital factors obtained from the 2008-2010 acute stroke NIS data were analyzed. Discharge disposition, hospitalization cost, and mortality were the dependent variables studied. Univariate analysis and multivariate binary logistic regression analysis were performed. Data analysis focused on the cohort of acute stroke patients who received some form of active intervention (55,913 of 1,311,511 patients in the NIS). RESULTS When overall outcome was considered, transferred patients had a significantly higher number of other-than-routine (OTR, i.e., other than discharge to home without home health care) discharge dispositions (p < 0.0001). In multivariate regression analysis including pertinent patient and hospital factors, transfer-in patients had significantly worse OTR discharge disposition (p < 0.0001, odds ratio [OR] 2.575, 95% CI 2.341-2.832). Mean hospitalization cost including an intervention was $70,325.11 for direct admissions and $97,546.92 for transferred patients. Transfer from another facility (p < 0.001, OR 1.677, 95% CI 1.548-1.817) was associated with higher hospitalization cost. CONCLUSIONS The study showed that hospital cost for acute stroke intervention is significantly higher for a transferred patient than for a direct admission. Moreover, the frequency of OTR discharge was significantly higher among transferred patients than direct admissions. Future strategies should focus on ways and means of transporting patients appropriately and directly to stroke centers.

The expanding realm of endovascular neurosurgery: flow diversion for cerebral aneurysm management

The worldwide prevalence of intracranial aneurysms is estimated to be between 5% and 10%, with some demographic variance. Subarachnoid hemorrhage secondary to ruptured intracranial aneurysm results in devastating neurological outcomes, leaving the majority of victims dead or disabled. Surgical clipping of intracranial aneurysms remained the definitive mode of treatment until Guglielmi detachable coils were introduced in the 1990s. This revolutionary innovation led to the recognition of neurointervention/neuroendovascular surgery as a bona fide option for intracranial aneurysms. Constant evolution of endovascular devices and techniques supported by several prospective randomized trials has catapulted the endovascular treatment of intracranial aneurysms to its current status as the preferred treatment modality for most ruptured and unruptured intracranial aneurysms. We are slowly transitioning from the era of coils to the era of flow diverters. Flow-diversion technology and techniques have revolutionized the treatment of wide-necked, giant, and fusiform aneurysms, where the results of microsurgery or conventional neuroendovascular strategies have traditionally been dismal. Although the Pipeline Embolization Device (ev3-Covidien, Irvine, CA) is the only flow-diversion device approved by the Food and Drug Administration for use in the United States, others are commercially available in Europe and South America, including the Silk (Balt Extrusion, Montmorency, France), Flow-Redirection Endoluminal Device (FRED; MicroVention, Tustin, CA), Surpass (Stryker, Kalamazoo, MI), and p64 (Phenox, Bochum, Germany). Improvements in technology and operator experience and the encouraging results of clinical trials have led to broader acceptance for the use of these devices in cerebral aneurysm management. Continued innovation and refinement of endovascular devices and techniques will inevitably improve technical success rates, reduce procedure-related complications, and broaden the endovascular therapeutic spectrum for varied aneurysm morphology.