Predicting pediatric optic pathway glioma progression using advanced magnetic resonance image analysis and machine learning.

BACKGROUND: Optic pathway gliomas (OPGs) are low-grade tumors of the white matter of the visual system with a highly variable clinical course. The aim of the study was to generate a magnetic resonance imaging (MRI)-based predictive model of OPG tumor progression using advanced image analysis and machine learning techniques. METHODS: We performed a retrospective case-control study of OPG patients managed between 2009 and 2015 at an academic children's hospital. Progression was defined as radiographic tumor growth or vision decline. To generate the model, optic nerves were manually highlighted and optic radiations (ORs) were segmented using diffusion tractography tools. For each patient, intensity distributions were obtained from within the segmented regions on all imaging sequences, including derivatives of diffusion tensor imaging (DTI). A machine learning algorithm determined the combination of features most predictive of progression. RESULTS: Nineteen OPG patients with progression were matched to 19 OPG patients without progression. The mean time between most recent follow-up and most recently analyzed MRI was 3.5 ± 1.7 years. Eighty-three MRI studies and 532 extracted features were included. The predictive model achieved an accuracy of 86%, sensitivity of 89%, and specificity of 81%. Fractional anisotropy of the ORs was among the most predictive features (area under the curve 0.83, P < 0.05). CONCLUSIONS: Our findings show that image analysis and machine learning can be applied to OPGs to generate a MRI-based predictive model with high accuracy. As OPGs grow along the visual pathway, the most predictive features relate to white matter changes as detected by DTI, especially within ORs.

Transcriptome signatures associated with meningioma progression.

Meningiomas are the most common primary brain tumor of adults. The majority are benign (WHO grade I), with a mostly indolent course; 20% of them (WHO grade II and III) are, however, considered aggressive and require a more complex management. WHO grade II and III tumors are heterogeneous and, in some cases, can develop from a prior lower grade meningioma, although most arise de novo. Mechanisms leading to progression or implicated in de novo grade II and III tumorigenesis are poorly understood. RNA-seq was used to profile the transcriptome of grade I, II, and III meningiomas and to identify genes that may be involved in progression. Bioinformatic analyses showed that grade I meningiomas that progress to a higher grade are molecularly different from those that do not. As such, we identify GREM2, a regulator of the BMP pathway, and the snoRNAs SNORA46 and SNORA48, as being significantly reduced in meningioma progression. Additionally, our study has identified several novel fusion transcripts that are differentially present in meningiomas, with grade I tumors that did not progress presenting more fusion transcripts than all other tumors. Interestingly, our study also points to a difference in the tumor immune microenvironment that correlates with histopathological grade.

Polymer scaffolds facilitate spinal cord injury repair.

During the past decades, improving patient neurological recovery following spinal cord injury (SCI) has remained a challenge. An effective treatment for SCI would not only reduce fractured elements and isolate developing local glial scars to promote axonal regeneration but also ameliorate secondary effects, including inflammation, apoptosis, and necrosis. Three-dimensional (3D) scaffolds provide a platform in which these mechanisms can be addressed in a controlled manner. Polymer scaffolds with favorable biocompatibility and appropriate mechanical properties have been engineered to minimize cicatrization, customize drug release, and ensure an unobstructed space to promote cell growth and differentiation. These properties make polymer scaffolds an important potential therapeutic platform. This review highlights the recent developments in polymer scaffolds for SCI engineering. STATEMENT OF SIGNIFICANCE: How to improve the efficacy of neurological recovery after spinal cord injury (SCI) is always a challenge. Tissue engineering provides a promising strategy for SCI repair, and scaffolds are one of the most important elements in addition to cells and inducing factors. The review highlights recent development and future prospects in polymer scaffolds for SCI therapy. The review will guide future studies by outlining the requirements and characteristics of polymer scaffold technologies employed against SCI. Additionally, the peculiar properties of polymer materials used in the therapeutic process of SCI also have guiding significance to other tissue engineering approaches.

On-Demand Prolongation of Peripheral Nerve Blockade through Bupivacaine-Loaded Hydrogels with Suitable Residence Periods.

Peripheral nerve blockade is an important perioperative intervention for pain management. However, this management always results in a limited analgesia effect due to the rapid elimination of local anesthetic drugs after a single injection, while continuous infusion leads to multiple side effects associated with catheter insertion. In this study, three thermosensitive hydrogels, i.e., Pluronic F127, and poly(l-alanine)-block-poly(ethylene glycol)-block-poly(l-alanine) (PAla-PEG-PAla), and poly(lactic-co-glycolic acid)-block-poly(ethylene glycol)-block-poly(lactic-co-glycolic acid) (PLGA-PEG-PLGA), with distinct properties were applied to encapsulate bupivacaine (BUP) for prolonged analgesia with one single injection. All three hydrogel platforms exhibited a homogeneous three-dimensional structure with thermosensitive properties and high BUP encapsulation efficiency. The BUP loaded in PAla-PEG-PAla showed a sustained drug release profile, which was advantageous over those from Pluronic F127 and PLGA-PEG-PLGA with either burst release or inadequate release. The hydrogel platforms exhibited prolonged nerve blockade duration compared with BUP·HCl in vivo. Furthermore, the in vivo residence period of PAla-PEG-PAla/BFB was shorter than that of PLGA-PEG-PLGA/BFB while longer than that of Pluronic F127/BFB. All the hydrogels induced reversible inflammatory response without neurotoxicity. Overall, in comparison with the other two hydrogel platforms, PAla-PEG-PAla exhibited controlled drug release, appropriate residence period, and long-acting analgesia effect. Moreover, it might be a potential method to meet the different demands of regional nerve blockade and guide clinical pain management.

Surgical Approaches for the Treatment of Multilevel Cervical Ossification of the Posterior Longitudinal Ligament: Results of a Decision Analysis.

BACKGROUND: Ossification of the posterior longitudinal ligament (OPLL) often leads to cervical myelopathy. Although multiple procedures have been shown to be effective in the treatment of OPLL, outcomes are less predictable than in degenerative cervical myelopathy, and surgery is associated with high rates of complications and reoperation, which affect quality of life. In this study, we performed a decision analysis using postoperative complication data and health-related quality of life (HRQoL) utility scores to assess the average expected health utility and 5-year quality-adjusted life years (QALYs) associated with the most common surgical approaches for multilevel cervical OPLL. METHODS: We searched Medline, EMBASE, and the Cochrane Library for relevant articles published between 1990 and October 2017. Meta-analytically pooled complication data and HRQoL utility scores associated with each complication were evaluated in a long-term model. RESULTS: The overall incidence of perioperative complications ranged from 6.2% for laminectomy alone to 11.0% for anterior decompression and fusion. Revision surgery for hardware/fusion failure or progression was highest for laminectomy alone (3.0%) and lowest for laminectomy and fusion (1.6%). Laminoplasty resulted in the highest 5-year QALYs gained, compared with laminectomy and anterior approaches (P < 0.001). There was no significant difference in QALY gained between laminectomy-fusion and laminoplasty. CONCLUSION: The results suggest that owing to the higher rates of complications associated with anterior cervical approaches, laminoplasty may result in improved long-term outcomes from an HRQoL standpoint. These findings may guide surgeons in cases where either procedure is a reasonable option.

Near-infrared fluorescent image-guided surgery for intracranial meningioma.

OBJECTIVE Meningiomas are the most common primary tumor of the central nervous system. Complete resection can be curative, but intraoperative identification of dural tails and tumor remnants poses a clinical challenge. Given data from preclinical studies and previous clinical trials, the authors propose a novel method of localizing tumor tissue and identifying residual disease at the margins via preoperative systemic injection of a near-infrared (NIR) fluorescent contrast dye. This technique, what the authors call "second-window indocyanine green" (ICG), relies on the visualization of ICG approximately 24 hours after intravenous injection. METHODS Eighteen patients were prospectively identified and received 5 mg/kg of second-window ICG the day prior to surgery. An NIR camera was used to localize the tumor prior to resection and to inspect the margins following standard resection. The signal to background ratio (SBR) of the tumor to the normal brain parenchyma was measured in triplicate. Gross tumor and margin specimens were qualitatively reported with respect to fluorescence. Neuropathological diagnosis served as the reference gold standard to calculate the sensitivity and specificity of the imaging technique. RESULTS Eighteen patients harbored 15 WHO Grade I and 3 WHO Grade II meningiomas. Near-infrared visualization during surgery ranged from 18 to 28 hours (mean 23 hours) following second-window ICG infusion. Fourteen of the 18 tumors demonstrated a markedly elevated SBR of 5.6 ± 1.7 as compared with adjacent brain parenchyma. Four of the 18 patients showed an inverse pattern of NIR signal, that is, stronger in the adjacent normal brain than in the tumor (SBR 0.31 ± 0.1). The best predictor of inversion was time from injection, as the patients who were imaged earlier were more likely to demonstrate an appropriate SBR. The second-window ICG technique demonstrated a sensitivity of 96.4%, specificity of 38.9%, positive predictive value of 71.1%, and a negative predictive value of 87.5% for tumor. CONCLUSIONS Systemic injection of NIR second-window ICG the day before surgery can be used to visualize meningiomas intraoperatively. Intraoperative NIR imaging provides higher sensitivity in identifying meningiomas than the unassisted eye. In this study, 14 of the 18 patients with meningioma demonstrated a strong SBR compared with adjacent brain. In the future, reducing the time interval from dye injection to intraoperative imaging may improve fluorescence at the margins, though this approach requires further investigation. Clinical trial registration no.: NCT02280954 ( clincialtrials.gov ).

Photoacoustic-Guided Surgery with Indocyanine Green-Coated Superparamagnetic Iron Oxide Nanoparticle Clusters.

A common cause of local tumor recurrence in brain tumor surgery results from incomplete surgical resection. Adjunctive technologies meant to facilitate gross total resection have had limited efficacy to date. Contrast agents used to delineate tumors preoperatively cannot be easily or accurately used in the real-time operative setting. Although multimodal imaging contrast agents are developed to help the surgeon discern tumor from normal tissue in the operating room, these contrast agents are not readily translatable. This study has developed a novel contrast agent comprised solely of two Food and Drug Administration approved components, indocyanine green (ICG) and superparamagnetic iron oxide (SPIO) nanoparticles-with no additional amphiphiles or carrier materials, to enable preoperative detection by magnetic resonance (MR) imaging and intraoperative photoacoustic (PA) imaging. The encapsulation efficiency of both ICG and SPIO within the formulated clusters is ≈100%, and the total ICG payload is 20-30% of the total weight (ICG + SPIO). The ICG-SPIO clusters are stable in physiologic conditions; can be taken up within tumors by enhanced permeability and retention; and are detectable by MR. In a preclinical surgical resection model in mice, following injection of ICG-SPIO clusters, animals undergoing PA-guided surgery demonstrate increased progression-free survival compared to animals undergoing microscopic surgery.

Metastatic Alveolar Soft Part Sarcoma of the Spinal Cord: A Case Report and Review of Literature.

BACKGROUND: Alveolar soft part sarcoma (ASPS) is a rare, malignant soft-tissue neoplasm typically seen in young adults that possesses an unusual tendency to metastasize. Metastases to the intramedullary compartment of the spinal cord, however, are exceptionally rare and have not been described in the literature. CASE DESCRIPTION: We report the case of a 23-year-old woman with disseminated ASPS to the lung and brain who presented with progressive lower-extremity weakness and loss of sensation after radiation and chemotherapy. Magnetic resonance imaging revealed a 1.3-cm avidly enhancing lesion within the central thoracic spinal cord at T3. A T2-T4 laminectomy was undertaken and resulted in a gross total resection. Histopathologically, the mass was composed of organoid nests containing epithelioid cells with eosinophilic, granular cytoplasm separated by sinusoidal spaces. Immunohistochemistry demonstrated convincing positive TFE3 staining. Postoperative imaging confirmed the complete resection of the mass, and her examination was notable for intact sensation and impaired motor function that gradually improved. CONCLUSIONS: A review of the literature found that the reported case represents the first instance of primary or metastatic ASPS in the spinal cord. Metastatic ASPS should thus be included in the differential diagnosis in patients with known disease and neurologic impairment or back pain. Imaging of the spine should then be considered.

Three-Dimensional Printed Modeling of Diffuse Low-Grade Gliomas and Associated White Matter Tract Anatomy.

BACKGROUND: Diffuse low-grade gliomas (DLGGs) represent several pathological entities that infiltrate and invade cortical and subcortical structures in the brain. OBJECTIVE: To describe methods for rapid prototyping of DLGGs and surgically relevant anatomy. METHODS: Using high-definition imaging data and rapid prototyping technologies, we were able to generate 3 patient DLGGs to scale and represent the associated white matter tracts in 3 dimensions using advanced diffusion tensor imaging techniques. RESULTS: This report represents a novel application of 3-dimensional (3-D) printing in neurosurgery and a means to model individualized tumors in 3-D space with respect to subcortical white matter tract anatomy. Faculty and resident evaluations of this technology were favorable at our institution. CONCLUSION: Developing an understanding of the anatomic relationships existing within individuals is fundamental to successful neurosurgical therapy. Imaging-based rapid prototyping may improve on our ability to plan for and treat complex neuro-oncologic pathology.

Operative Strategies to Minimize Complications Following Resection of Pituitary Macroadenomas.

Introduction We sought to identify factors associated with increased length of stay (LOS) and morbidity in patients undergoing resection of pituitary macroadenomas. Methods We reviewed records of 203 consecutive patients who underwent endoscopic endonasal resection of a pituitary macroadenoma (mean age = 55.7 [16-88]) years, volume = 11.3 (1.0-134.3) cm3. Complete resection was possible in 60/29.6% patients. Mean follow-up was 575 days. Multivariate logistic regression was performed using MATLAB. Results Mean LOS was 4.67 (1-66) days and was associated with CSF leak (p = 0.025), lumbar drain placement (p = 0.041; n = 8/3.9% intraoperative, n = 20/9.9% postoperative), and any infection (p = 0.066). Age, diabetes insipidus (n = 17/8.37%), and syndrome of inappropriate antidiuretic hormone secretion (n = 12/5.9%) were not associated with increased LOS (p > 0.2). Postoperative CSF leak in the hospital (n = 21/10.3%) was associated with intraoperative CSF leak (p = 0.002; n = 82/40.4%) and complete resection (p = 0.012). There was no significant association (p > 0.1) between postoperative CSF leak in the hospital following surgery and the use of a fat graft (n = 61/30.1%), nasoseptal flap (155/76.4%), or perioperative lumbar drain placement (n = 8/3.94%). Conclusion Complete resection is associated with increased risk of CSF leak and LOS. Operative strategies including placement of fat graft, nasoseptal flap, or intraoperative lumbar drain placement may have limited value in reducing the risk of postoperative CSF leak.

Correlations of atrial diameter and frontooccipital horn ratio with ventricle size in fetal ventriculomegaly.

OBJECTIVE Fetal ventriculomegaly (FV), or enlarged cerebral ventricles in utero, is defined in fetal studies as an atrial diameter (AD) greater than 10 mm. In postnatal studies, the frontooccipital horn ratio (FOHR) is commonly used as a proxy for ventricle size (VS); however, its role in FV has not been assessed. Using image analysis techniques to quantify VS on fetal MR images, authors of the present study examined correlations between linear measures (AD and FOHR) and VS in patients with FV. METHODS The authors performed a cross-sectional study using fetal MR images to measure AD in the axial plane at the level of the atria of the lateral ventricles and to calculate FOHR as the average of the frontal and occipital horn diameters divided by the biparietal distance. Computer software was used to separately segment and measure the area of the ventricle and the ventricle plus the subarachnoid space in 2 dimensions. Segmentation was performed on axial slices 3 above and 3 below the slice used to measure AD, and measurements for each slice were combined to yield a volume, or 3D VS. The VS was expressed as the absolute number of voxels (non-normalized) and as the number of voxels divided by intracranial size (normalized). A Pearson correlation coefficient was used to measure the strength of the relationships between the linear measures and the size of segmented regions in 2 and 3 dimensions and over various gestational ages (GAs). Differences between correlations were compared using Steiger's z-test. RESULTS Fifty FV patients who had undergone fetal MRI between 2008 and 2014 were included in the study. The mean GA was 26.3 ± 5.4 weeks. The mean AD was 18.1 ± 8.3 mm, and the mean FOHR was 0.49 ± 0.11. When using absolute VS, the correlation between AD and 3D VS (r = 0.844, p < 0.0001) was significantly higher than that between FOHR and 3D VS (r = 0.668, p < 0.0001; p = 0.0004, Steiger's z-test). However, when VS was normalized, correlations were not significantly different between AD and 3D VS (r = 0.830, p < 0.0001) or FOHR and 3D VS (r = 0.842, p < 0.0001; p = 0.8, Steiger's z-test). For GAs of 24 weeks or earlier, AD correlated more strongly with normalized 3D VS (r = 0.902, p < 0.0001) than with FOHR (r = 0.674, p < 0.0001; p < 0.0001, Steiger's z-test). After 24 weeks, there was no difference in correlations between linear measures (AD or FOHR) and 3D VS (r > 0.9). Correlations of linear measures with VS in 2 and 3 dimensions were similar, and inclusion of the subarachnoid space did not significantly alter results. CONCLUSIONS Findings in the study support the use of AD as a measure of VS in fetal studies as it correlates highly with both absolute and relative VS, especially at early GAs, and captures the preferential dilation of the occipital horns in patients with FV. Compared with AD, FOHR similarly correlates with normalized VS and, after a GA of 24 weeks, can be reported in fetal studies to provide continuity with postnatal monitoring.

Surgical Approaches for the Treatment of Thoracic Disk Herniation: Results of a Decision Analysis.

STUDY DESIGN: A decision analysis. OBJECTIVE: To perform a decision analysis utilizing postoperative complication data, in conjunction with health-related quality of life (HRQoL) utility scores, to rank order the average health utility associated with various surgical approaches used to treat symptomatic thoracic disk herniation (TDH). SUMMARY OF BACKGROUND DATA: Symptomatic TDH is an uncommon entity accounting for <1% of all symptomatic herniated disks. A variety of surgical approaches have been developed for its treatment, which may be classified into 4 major categories: open anterolateral transthoracic, minimally invasive anterolateral thoracoscopic, posterior, and lateral. These treatments have varying risk/benefit profiles, but there is still no set algorithm for choosing an approach in cases with multiple surgical options. METHODS: We searched Medline, EMBASE, and the Cochrane Library for relevant articles on surgical approaches for TDHs published between 1990 and August 2014. Pooled complication data and HRQoL utility scores associated with each complication were evaluated using standard meta-analytic techniques to determine which surgical approach resulted in the highest average HRQoL. RESULTS: Posterior surgical approaches resulted in the highest average HRQoL, followed by thoracoscopic, lateral, and finally open anterolateral transthoracic procedures. The higher average HRQoL associated with posterior approaches over all others was highly significant (P<0.001); conversely, the open anterolateral approach resulted in a lower average postoperative utility compared with all other approaches (P<0.001). CONCLUSIONS: The results of this decision analysis favor posterior over lateral approaches, and thoracoscopic over open anterolateral approaches for the treatment of symptomatic TDHs, which may guide surgeons in cases where multiple surgical options are feasible. Future studies, such as randomized clinical trials, are necessary to ascertain whether novel surgical strategies have risk/benefit profiles that ultimately supersede those of traditional approaches, and whether enough cases are encountered by the average surgeon to justify their adoption.

Long-term utility and complication profile of open craniotomy for biopsy in patients with idiopathic encephalitis.

Neurosurgeons are often asked to perform open biopsy for diagnosis of encephalitis after medical investigations are non-diagnostic. These patients may be critically ill with multiple comorbidities. Patients and their families often request data regarding the success rates and complication profile of biopsy, but minimal literature exists in this area. Retrospective chart review of all patients undergoing open brain biopsy (burr hole or craniotomy) for encephalitis refractory to medical diagnosis between January 2009 and December 2013 was undertaken. Pathology records and outpatient follow-up were reviewed to determine most recent clinical status of each patient. A total of 59 patients were included with mean follow up of 20months. The average age at biopsy was 55years. The most common unconfirmed diagnoses leading to biopsy were vasculitis (44%), neoplasm (27%), infection (12%), autoimmune (12%), amyloidosis (5%). Tissue pathology was diagnostic in 42% of all cases. Overall, biopsy confirmed the preoperative diagnosis in 46% of cases and refuted the preoperative leading diagnosis in 25% of cases. At last follow-up, the tissue pathology resulted in a medical treatment change in 25% of cases. There was a 14% major neurological complication rate (postoperative stroke, hemorrhage, or neurological deficit) and 9% cardiopulmonary complication rate (delayed extubation and re-intubation) attributable to surgical intervention. In this limited series, diagnostic utility of biopsy in patients with idiopathic encephalitis is less than 50% and the major complication rate is 23%. Patients and providers must be counseled accordingly and weigh the risks and benefits of open biopsy for encephalitis cautiously.

3D printing in neurosurgery: A systematic review.

BACKGROUND: The recent expansion of three-dimensional (3D) printing technology into the field of neurosurgery has prompted a widespread investigation of its utility. In this article, we review the current body of literature describing rapid prototyping techniques with applications to the practice of neurosurgery. METHODS: An extensive and systematic search of the Compendex, Scopus, and PubMed medical databases was conducted using keywords relating to 3D printing and neurosurgery. Results were manually screened for relevance to applications within the field. RESULTS: Of the search results, 36 articles were identified and included in this review. The articles spanned the various subspecialties of the field including cerebrovascular, neuro-oncologic, spinal, functional, and endoscopic neurosurgery. CONCLUSIONS: We conclude that 3D printing techniques are practical and anatomically accurate methods of producing patient-specific models for surgical planning, simulation and training, tissue-engineered implants, and secondary devices. Expansion of this technology may, therefore, contribute to advancing the neurosurgical field from several standpoints.

Intraoperative Near-Infrared Optical Imaging Can Localize Gadolinium-Enhancing Gliomas During Surgery.

BACKGROUND: Although real-time localization of gliomas has improved with intraoperative image guidance systems, these tools are limited by brain shift, surgical cavity deformation, and expense. OBJECTIVE: To propose a novel method to perform near-infrared (NIR) imaging during glioma resections based on preclinical and clinical investigations, in order to localize tumors and to potentially identify residual disease. METHODS: Fifteen patients were identified and administered a Food and Drug Administration-approved, NIR contrast agent (Second Window indocyanine green [ICG], 5 mg/kg) before surgical resection. An NIR camera was utilized to localize the tumor before resection and to visualize surgical margins following resection. Neuropathology and magnetic resonance imaging data were used to assess the accuracy and precision of NIR fluorescence in identifying tumor tissue. RESULTS: NIR visualization of 15 gliomas (10 glioblastoma multiforme, 1 anaplastic astrocytoma, 2 low-grade astrocytoma, 1 juvenile pilocytic astrocytoma, and 1 ganglioglioma) was performed 22.7 hours (mean) after intravenous injection of ICG. During surgery, 12 of 15 tumors were visualized with the NIR camera. The mean signal-to-background ratio was 9.5 ± 0.8 and fluorescence was noted through the dura to a maximum parenchymal depth of 13 mm. The best predictor of positive fluorescence was enhancement on T1-weighted imaging; this correlated with signal-to-background ratio (P = .03). Nonenhancing tumors did not demonstrate NIR fluorescence. Using pathology as the gold standard, the technique demonstrated a sensitivity of 98% and specificity of 45% to identify tumor in gadolinium-enhancing specimens (n = 71). CONCLUSION: With the use of Second Window ICG, gadolinium-enhancing tumors can be localized through brain parenchyma intraoperatively. Its utility for margin detection is promising but limited by lower specificity. ABBREVIATIONS: 5-ALA, 5-aminolevulinic acidEPR, enhanced permeability and retentionFDA, Food and Drug AdministrationGBM, glioblastomaICG, indocyanine greenNIR, near-infraredNPV, negative predictive valuePPV, positive predictive valueROC, receiver operating characteristicROI, region of interestSBR, signal-to-background ratioWHO, World Health Organization.

Management of Giant Cervical Teratoma with Intracranial Extension Diagnosed in Utero.

Cervical teratomas are rare germ cell tumors affecting the fetus that are associated with significant morbidity and mortality due to an increased risk of airway obstruction at delivery. These tumors can commonly produce polyhydramnios that results from the fetus' impaired ability to swallow amniotic fluid. Improved rates of prenatal diagnosis through comprehensive evaluations and imaging have dramatically impacted the perinatal management of infants with this condition. Here, we report a patient diagnosed with polyhydramnios whose fetus was discovered to have a giant cervical teratoma on imaging studies. The child underwent surgical resection after having the airway secured under the uteroplacental support as part of an ex utero intrapartum treatment procedure performed at 37 weeks. The following gross pathological and magnetic resonance images demonstrate this condition and its currently accepted treatment.

Resident simulation training in endoscopic endonasal surgery utilizing haptic feedback technology.

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

Three-Dimensional Printed Modeling of an Arteriovenous Malformation Including Blood Flow.

BACKGROUND: Arteriovenous malformations (AVMs) represent a complex pathologic entity in terms of their associated angioarchitecture and blood flow dynamics. METHODS: Using existing imaging data, we generated a patient's giant AVM to scale. RESULTS: A series of 3-dimensional (3D) models were generated and blood flow dynamics were represented. Faculty and resident surveys were positive regarding the technology. CONCLUSIONS: This report represents a novel application of 3D printing in neurosurgery and a means to model dynamic blood flow in 3 dimensions. The 3D printed models may improve on our ability to plan for and treat complex vascular pathologies.

Microsurgical treatment of sacral perineural (Tarlov) cysts: case series and review of the literature.

OBJECTIVE Tarlov cysts (TCs) occur most commonly on extradural components of the sacral and coccygeal nerve roots. These lesions are often found incidentally, with an estimated prevalence of 4%-9%. Given the low estimated rates of symptomatic TC and the fact that symptoms can overlap with other common causes of low-back pain, optimal management of this entity is a matter of ongoing debate. Here, the authors investigate the effects of surgical intervention on symptomatic TCs and aim to solidify the surgical criteria for this disease process. METHODS The authors performed a retrospective review of data from consecutive patients who were surgically treated for symptomatic TCs from September 2011 to March 2013. Clinical evaluations and results from surveying pain and overall health were used. Univariate statistical analyses were performed. RESULTS Twenty-three adults (4 males, 19 females) who had been symptomatic for a mean of 47.4 months were treated with laminectomy, microsurgical exposure and/or imbrication, and paraspinous muscle flap closure. Eighteen patients (78.3%) had undergone prior interventions without sustained improvement. Thirteen patients (56.5%) underwent lumbar drainage for an average of 8.7 days following surgery. The mean follow-up was 14.4 months. Univariate analyses demonstrated that an advanced age (p = 0.045), the number of noted perineural cysts on preoperative imaging (p = 0.02), and the duration of preoperative symptoms (p = 0.03) were associated with a poor postoperative outcome. Although 47.8% of the patients were able to return to normal activities, 93.8% of those surveyed reported that they would undergo the operation again if given the choice. CONCLUSIONS This is one of the largest published studies on patients with TCs treated microsurgically. The data suggest that patients with symptomatic TCs may benefit from open microsurgical treatment. Although outcomes seem related to patient age, duration of symptoms, and extent of disease demonstrated on imaging, further study is warranted and underway.