Full-endoscopic technique mitigates obesity-related perioperative morbidity of minimally invasive lumbar decompression.

PURPOSE: Obesity is associated with increased surgical complexity and postoperative complications in spine surgery. Minimally invasive procedures have been shown to lessen some of the increased risk in obese patients. This study investigated whether utilization of a working channel endoscope can further mitigate obesity-associated challenges in spinal surgery. METHODS: A retrospective review of a single-surgeon database was conducted for all adult patients undergoing full-endoscopic unilateral laminotomies for bilateral decompression between November 2015 and March 2021. Data collected included body mass index, in operating room preparation time, procedure time, length of hospital stay, use of analgesics, complications, and quality of life measured by Oswestry Disability Index. RESULTS: Our cohort included 174 patients. Of these, 74 (42.5%) were obese. The average age was 63.6 years. In-operating room preparation time was 70.0 ± 1.7 min for obese patients and 64.4 ± 1.5 min for non-obese patients (p = 0.02). There was no difference in operative time, durotomy rates or other perioperative complications between obese and non-obese patients. Hospital length of stay trended toward longer in the obese group, but did not reach significance. A greater percentage of obese patients were still using both narcotic and non-narcotic pain medications 2 weeks after surgery. There was no significant difference in functional outcomes between groups. CONCLUSION: Full-endoscopic unilateral laminotomies for bilateral decompression are safe and effective in both non-obese and obese patients. The use of an endoscope can partially mitigate obesity-related morbidity in lumbar decompression. However, obesity is significantly related to increased postoperative analgesic use.

Bone metastasis from glioblastoma: a systematic review.

INTRODUCTION: Glioblastoma (GBM) is a devastating disease with poor overall survival. Despite the common occurrence of GBM among primary brain tumors, metastatic disease is rare. Our goal was to perform a systematic literature review on GBM with osseous metastases and understand the rate of metastasis to the vertebral column as compared to the remainder of the skeleton, and how this histology would fit into our current paradigm of treatment for bone metastases. METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant literature search was performed using the PubMed database from 1952 to 2021. Search terms included "GBM", "glioblastoma", "high-grade glioma", "bone metastasis", and "bone metastases". RESULTS: Of 659 studies initially identified, 67 articles were included in the current review. From these 67 articles, a total of 92 distinct patient case presentations of metastatic glioblastoma to bone were identified. Of these cases, 58 (63%) involved the vertebral column while the remainder involved lesions within the skull, sternum, rib cage, and appendicular skeleton. CONCLUSION: Metastatic dissemination of GBM to bone occurs. While the true incidence is unknown, workup for metastatic disease, especially involving the spinal column, is warranted in symptomatic patients. Lastly, management of patients with GBM vertebral column metastases can follow the International Spine Oncology Consortium two-step multidisciplinary algorithm for the management of spinal metastases.

The feasibility of computer-assisted 3D navigation in multiple-level lateral lumbar interbody fusion in combination with posterior instrumentation for adult spinal deformity.

OBJECTIVE: The lateral lumbar interbody fusion (LLIF) technique is used to treat many common spinal degenerative pathologies including kyphoscoliosis. The use of spinal navigation for LLIF has not been broadly adopted, especially in adult spinal deformity. The purpose of this study was to evaluate the feasibility as well as the intraoperative and navigation-related complications of computer-assisted 3D navigation (CaN) during multiple-level LLIF for spinal deformity. METHODS: Retrospective analysis of clinical and operative characteristics was performed for all patients > 18 years of age who underwent multiple-level CaN LLIF combined with posterior instrumentation for adult spinal deformity at the University of Michigan between 2014 and 2020. Intraoperative CaN-related complications, LLIF approach-related postoperative complications, and medical postoperative complications were assessed. RESULTS: Fifty-nine patients were identified. The mean age was 66.3 years (range 42-83 years) and body mass index was 27.6 kg/m2 (range 18-43 kg/m2). The average coronal Cobb angle was 26.8° (range 3.6°-67.0°) and sagittal vertical axis was 6.3 cm (range -2.3 to 14.7 cm). The average number of LLIF and posterior instrumentation levels were 2.97 cages (range 2-5 cages) and 5.78 levels (range 3-14 levels), respectively. A total of 6 intraoperative complications related to the LLIF stage occurred in 5 patients. Three of these were CaN-related and occurred in 2 patients (3.4%), including 1 misplaced lateral interbody cage (0.6% of 175 total lateral cages placed) requiring intraoperative revision. No patient required a return to the operating room for a misplaced interbody cage. A total of 12 intraoperative complications related to the posterior stage occurred in 11 patients, with 5 being CaN-related and occurring in 4 patients (6.8%). Univariate and multivariate analyses revealed no statistically significant risk factors for intraoperative and CaN-related complications. Transient hip weakness and numbness were found to be in 20.3% and 22.0% of patients, respectively. At the 1-month follow-up, weakness was observed in 3.4% and numbness in 11.9% of patients. CONCLUSIONS: Use of CaN in multiple-level LLIF in the treatment of adult spinal deformity appears to be a safe and effective technique. The incidence of approach-related complications with CaN was 3.4% and cage placement accuracy was high.

Development and validation of an artificial intelligence model to accurately predict spinopelvic parameters.

OBJECTIVE: Achieving appropriate spinopelvic alignment has been shown to be associated with improved clinical symptoms. However, measurement of spinopelvic radiographic parameters is time-intensive and interobserver reliability is a concern. Automated measurement tools have the promise of rapid and consistent measurements, but existing tools are still limited to some degree by manual user-entry requirements. This study presents a novel artificial intelligence (AI) tool called SpinePose that automatically predicts spinopelvic parameters with high accuracy without the need for manual entry. METHODS: SpinePose was trained and validated on 761 sagittal whole-spine radiographs to predict the sagittal vertical axis (SVA), pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), T1 pelvic angle (T1PA), and L1 pelvic angle (L1PA). A separate test set of 40 radiographs was labeled by four reviewers, including fellowship-trained spine surgeons and a fellowship-trained radiologist with neuroradiology subspecialty certification. Median errors relative to the most senior reviewer were calculated to determine model accuracy on test images. Intraclass correlation coefficients (ICCs) were used to assess interrater reliability. RESULTS: SpinePose exhibited the following median (interquartile range) parameter errors: SVA 2.2 mm (2.3 mm) (p = 0.93), PT 1.3° (1.2°) (p = 0.48), SS 1.7° (2.2°) (p = 0.64), PI 2.2° (2.1°) (p = 0.24), LL 2.6° (4.0°) (p = 0.89), T1PA 1.1° (0.9°) (p = 0.42), and L1PA 1.4° (1.6°) (p = 0.49). Model predictions also exhibited excellent reliability at all parameters (ICC 0.91-1.0). CONCLUSIONS: SpinePose accurately predicted spinopelvic parameters with excellent reliability comparable to that of fellowship-trained spine surgeons and neuroradiologists. Utilization of predictive AI tools in spinal imaging can substantially aid in patient selection and surgical planning.

The role of stereotactic radiosurgery for multiple brain metastases in stable systemic disease: a review of the literature.

BACKGROUND: Cancer patients with brain metastases display a median survival of only 1 to 2 months if left untreated. Although whole-brain radiation therapy (WBRT) has lengthened median patient survival, the long-term neurotoxic effects of WBRT have become a deterrent to its use in the context of stable systemic disease. Therefore, it is important to identify patients who might benefit from stereotactic radiosurgery (SRS) in order to delay or avoid WBRT. Here we present a review of the literature to elucidate the role of SRS in patients with multiple brain metastases. METHODS: MEDLINE search for English-language articles from 1998 to 2012 describing survival or neurocognitive functioning of patients with multiple brain metastases treated with SRS, WBRT, or a combination. RESULTS: SRS monotherapy yields an equivalent survival with low risk of long-term neurotoxicity, but higher rate of recurrence, compared to WBRT or combined radiotherapy. Patients with ≤4 brain metastases or KPS ≥ 80 are expected to survive significantly longer than the onset time of prominent WBRT-induced neurocognitive decline. CONCLUSIONS: SRS, administered alone or adjuvant to surgical resection of symptomatic metastases, is preferred for patients with ≤4 brain metastases or KPS ≥ 80 to delay or avoid WBRT. WBRT can then be employed in the event of recurrence. WBRT with or without resection is preferred for patients with ≥5 brain metastases and KPS < 80, due to these patients' shorter survival and increased recurrence risk. SRS boost treatments can then be used in the event of poor tumor response or progression.

A comparison of ventricular volume and linear indices in predicting shunt dependence in aneurysmal subarachnoid hemorrhage.

Background: Guidelines for determining shunt dependence after aneurysmal subarachnoid hemorrhage (aSAH) remain unclear. We previously demonstrated change in ventricular volume (VV) between head CT scans taken pre- and post-EVD clamping was predictive of shunt dependence in aSAH. We sought to compare the predictive value of this measure to more commonly used linear indices. Methods: We retrospectively analyzed images of 68 patients treated for aSAH who required EVD placement and underwent one EVD weaning trial, 34 of whom underwent shunt placement. We utilized an in-house MATLAB program to analyze VV and supratentorial VV (sVV) in head CT scans obtained before and after EVD clamping. Evans' index (EI), frontal and occipital horn ratio (FOHR), Huckman's measurement, minimum lateral ventricular width (LV-Min.), and lateral ventricle body span (LV-Body) were measured using digital calipers in PACS. Receiver operating curves (ROC) were generated. Results: Area under the ROC curves (AUC) for the change in VV, sVV, EI, FOHR, Huckman's, LV-Min., and LV-Body with clamping were 0.84, 0.84, 0.65, 0.71.0.69, 0.67, and 0.66, respectively. AUC for post-clamp scan measurements were 0.75, 0.75, 0.74, 0.72, 0.72, 0.70, and 0.75, respectively. Conclusion: VV change with EVD clamping was more predictive of shunt dependence in aSAH than change in linear measurements with clamping and all post-clamp measurements. Measurement of ventricular size on serial imaging with volumetrics or linear indices utilizing multidimensional data points may therefore be a more robust metric than unidimensional linear indices in predicting shunt dependence in this cohort. Prospective studies are needed for validation.

Unifying theory of carotid plaque disruption based on structural phenotypes and forces expressed at the lumen/wall interface.

OBJECTIVES: To integrate morphological, haemodynamic and mechanical analysis of carotid atheroma driving plaque disruption. MATERIALS AND METHODS: First, we analysed the phenotypes of carotid endarterectomy specimens in a photographic dataset A, and matched them with the likelihood of preoperative stroke. Second, laser angioscopy was used to further define the phenotypes in intact specimens (dataset B) and benchmark with histology. Third, representative vascular geometries for each structural phenotype were analysed with Computational Fluid Dynamics (CFD), and the mechanical strength of the complicated atheroma to resist penetrating forces was quantified (n=14). RESULTS: In dataset A (n=345), ulceration (fibrous cap disruption) was observed in 82% of all plaques, intraplaque haemorrhage in 68% (93% subjacent to an ulcer) and false luminal formation in 48%. At least one of these 'rupture' phenotypes was found in 97% of symptomatic patients (n=69) compared with 61% in asymptomatic patients. In dataset B (n=30), laser angioscopy redemonstrated the structural phenotypes with near-perfect agreement with histology. In CFD, haemodynamic stress showed a large pulse magnitude, highest upstream to the point of maximal stenosis and on ulceration the inflow stream excavates the necrotic core cranially and then recirculates into the true lumen. Based on mechanical testing (n=14), the necrotic core is mechanically weak and penetrated by the blood on fibrous cap disruption. CONCLUSIONS: Fibrous cap ulceration, plaque haemorrhage and excavation are sequential phenotypes of plaque disruption resulting from the chiselling effect of haemodynamic forces over unmatched mechanical tissue strength. This chain of events may result in thromboembolic events independently of the degree of stenosis.

Ventricular Volume Change as a Predictor of Shunt-Dependent Hydrocephalus in Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage (aSAH) that often requires acute placement of an external ventricular drain (EVD). The current systems available for determining which patients will require long-term cerebrospinal fluid diversion remain subjective. We investigated the ventricular volume change (ΔVV) after EVD clamping as an objective predictor of shunt dependence in patients with aSAH. METHODS: We performed a retrospective medical record review and image analysis of patients treated for aSAH at a single academic institution who had required EVD placement for acute hydrocephalus and had undergone 1 EVD weaning trial. Head computed tomography (CT) scans obtained before and after EVD clamping were analyzed using a custom semiautomated MATLAB program (MathWorks, Natick, Massachusetts, USA), which segments each CT scan into 5 tissue types using k-means clustering. Differences in the pre- and postclamp ventricular volumes were calculated. RESULTS: A total of 34 patients with an indwelling shunt met the inclusion criteria and were sex- and age-matched to 34 controls without a shunt. The mean ΔVV was 19.8 mL in the shunt patients and 3.8 mL in the nonshunt patients (P < 0.0001). The area under the receiver operating characteristic curve was 0.84. The optimal ΔVV threshold was 11.4 mL, with a sensitivity of 76.5% and specificity of 88.2% for predicting shunt dependence. The mean ΔVV was significantly greater for the patients readmitted for shunt placement compared with the patients not requiring cerebrospinal fluid diversion (18.69 mL vs. 3.84 mL; P = 0.005). Finally, 70% of the patients with delayed shunt dependence had ΔVV greater than the identified threshold. CONCLUSIONS: The ΔVV volume between head CT scans taken before and after EVD clamping was predictive of early and delayed shunt dependence.

Navigated retrodiaphragmatic/retroperitoneal approach for the treatment of symptomatic kyphoscoliosis: an operative video.

Retropleural, retrodiaphragmatic, and retroperitoneal approaches are utilized to access difficult thoracolumbar junction (T10-L2) pathology. The authors present a 58-year-old man with chronic low-back pain who failed years of conservative therapy. Preoperative radiographs demonstrated significant levoconvex scoliosis with coronal and sagittal imbalance. He underwent a retrodiaphragmatic/retroperitoneal approach for T12-L1, L1-2, L2-3, and L3-4 interbody release and fusion in conjunction with second-stage facet osteotomies, L4-5 TLIF, and T10-iliac posterior instrumented fusion. This video focuses on the retrodiaphragmatic approach assisted by 3D navigation. The video can be found here: https://stream.cadmore.media/r10.3171/2022.3.FOCVID2215.

Rapid Automated Analysis of Skull Base Tumor Specimens Using Intraoperative Optical Imaging and Artificial Intelligence.

BACKGROUND: Accurate specimen analysis of skull base tumors is essential for providing personalized surgical treatment strategies. Intraoperative specimen interpretation can be challenging because of the wide range of skull base pathologies and lack of intraoperative pathology resources. OBJECTIVE: To develop an independent and parallel intraoperative workflow that can provide rapid and accurate skull base tumor specimen analysis using label-free optical imaging and artificial intelligence. METHODS: We used a fiber laser-based, label-free, nonconsumptive, high-resolution microscopy method (<60 seconds per 1 × 1 mm2), called stimulated Raman histology (SRH), to image a consecutive, multicenter cohort of patients with skull base tumor. SRH images were then used to train a convolutional neural network model using 3 representation learning strategies: cross-entropy, self-supervised contrastive learning, and supervised contrastive learning. Our trained convolutional neural network models were tested on a held-out, multicenter SRH data set. RESULTS: SRH was able to image the diagnostic features of both benign and malignant skull base tumors. Of the 3 representation learning strategies, supervised contrastive learning most effectively learned the distinctive and diagnostic SRH image features for each of the skull base tumor types. In our multicenter testing set, cross-entropy achieved an overall diagnostic accuracy of 91.5%, self-supervised contrastive learning 83.9%, and supervised contrastive learning 96.6%. Our trained model was able to segment tumor-normal margins and detect regions of microscopic tumor infiltration in meningioma SRH images. CONCLUSION: SRH with trained artificial intelligence models can provide rapid and accurate intraoperative analysis of skull base tumor specimens to inform surgical decision-making.

Present and Future Spinal Robotic and Enabling Technologies.

Enabling technologies include surgical planning software, computer-assisted navigation, intraoperative three-dimensional (3D) imaging, and robotic systems. Presently, these technologies are in various stages of refinement. Spinal robots in particular are currently limited to the positioning of an alignment guide for pedicle screw placement. Current generation spinal robots, therefore, play a more limited role in spinal surgery. In contrast to spinal robots, intraoperative imaging technology has been developed further, to a stage that allows accurate 3D spinal image acquisition that can be readily utilized for spinal navigation. The integration of these various technologies has the potential to maximize the safety, consistency, reliability, and efficacy of surgical procedures. To that end, the trend for manufacturers is to incorporate various enabling technologies into the spinal robotic systems. In the near-term, it is expected that integration of more advanced planning software and navigation will result in wider applicability and value. In the long-term, there are a variety of enabling technologies such as augmented reality that may be a component of spinal robots. This article reviews the features of currently available spinal robots and discusses the likely future advancements of robotic platforms in the near- and long-term.

Resection of a Lumbar Intradural Extramedullary Schwannoma: 2-Dimensional Operative Video.

Schwannomas are typically benign tumors that arise from the sheaths of nerves in the peripheral nervous system. In the spine, schwannomas usually arise from spinal nerve roots and are therefore extramedullary in nature. Surgical resection-achieving a gross total resection, is the main treatment modality and is typically curative for patients with sporadic tumors. In this video, we present the case of a 38-yr-old male with worsening left leg radiculopathy, found to have a lumbar schwannoma. Preoperative imaging demonstrated that the tumor was at the level of L4-L5. A laminectomy at this level was performed with gross total resection of the tumor. The key points of the video include use of intraoperative fluoroscopy to confirm surgical level and help plan surgical exposure, use of ultrasound for intradural tumor localization, and advocating for maximum safe resection using neurostimulation. The patient tolerated the surgery well without any complications. He was discharged home with no additional therapy needed. Appropriate patient consent was obtained.

Lumbar Laminoplasty for Resection of Myxopapillary Ependymoma of the Conus Medullaris: 2-Dimensional Operative Video.

Myxopapillary ependymomas are slow-growing tumors that are located almost exclusively in the region of the conus medullaris, cauda equina, and filum terminale of the spinal cord. Surgical intervention achieving a gross total resection is the main treatment modality. If, however, a gross total resection cannot be achieved, surgery is augmented with radiation therapy. In this video, we present the case of a 27-yr-old male with persistent back pain and radiculopathy who was found to have a myxopapillary ependymoma that was adherent to the conus. Preoperative imaging demonstrated that the tumor was displacing the conus and nerve roots ventrally. A laminoplasty at L1-L2 was performed with near-total resection because of the intimate involvement of neural tissue. The key features of the video include performing laminoplasty and rationale, and performing maximum safe tumor resection with a combination of bipolar cautery, suction, and ultrasonic aspiration augmented with frequent stimulation, gel foam pledgets intradurally, and achieving a watertight closure of the dura and fascia. The patient tolerated the surgery well without any complications. Given his gross residual disease along the conus and young age, he was at a high risk for continued tumor growth without adjuvant therapy, with a recurrence rate of roughly 33% to 45% in patients who underwent subtotal resection. With the addition of adjuvant radiation therapy, the recurrence rate is 20% to 29%.1,2 He was discharged to home with a plan for conventional fractionated external beam radiation. At the most recent follow-up, he reported decreased back pain and radiculopathy. Appropriate patient consent was obtained.

Volumetric quantification of aneurysmal subarachnoid hemorrhage independently predicts hydrocephalus and seizures.

OBJECTIVE: Hydrocephalus and seizures greatly impact outcomes of patients with aneurysmal subarachnoid hemorrhage (aSAH); however, reliable tools to predict these outcomes are lacking. The authors used a volumetric quantitative analysis tool to evaluate the association of total aSAH volume with the outcomes of shunt-dependent hydrocephalus and seizures. METHODS: Total hemorrhage volume following aneurysm rupture was retrospectively analyzed on presentation CT imaging using a custom semiautomated computer program developed in MATLAB that employs intensity-based k-means clustering to automatically separate blood voxels from other tissues. Volume data were added to a prospectively maintained aSAH database. The association of hemorrhage volume with shunted hydrocephalus and seizures was evaluated through logistic regression analysis and the diagnostic accuracy through analysis of the area under the receiver operating characteristic curve (AUC). RESULTS: The study population comprised 288 consecutive patients with aSAH. The mean total hemorrhage volume was 74.9 ml. Thirty-eight patients (13.2%) developed seizures. The mean hemorrhage volume in patients who developed seizures was significantly higher than that in patients with no seizures (mean difference 17.3 ml, p = 0.01). In multivariate analysis, larger hemorrhage volume on initial CT scan and hemorrhage volume > 50 ml (OR 2.81, p = 0.047, 95% CI 1.03-7.80) were predictive of seizures. Forty-eight patients (17%) developed shunt-dependent hydrocephalus. The mean hemorrhage volume in patients who developed shunt-dependent hydrocephalus was significantly higher than that in patients who did not (mean difference 17.2 ml, p = 0.006). Larger hemorrhage volume and hemorrhage volume > 50 ml (OR 2.45, p = 0.03, 95% CI 1.08-5.54) were predictive of shunt-dependent hydrocephalus. Hemorrhage volume had adequate discrimination for the development of seizures (AUC 0.635) and shunted hydrocephalus (AUC 0.629). CONCLUSIONS: Hemorrhage volume is an independent predictor of seizures and shunt-dependent hydrocephalus in patients with aSAH. Further evaluation of aSAH quantitative volumetric analysis may complement existing scales used in clinical practice and assist in patient prognostication and management.

Rapid, label-free detection of diffuse glioma recurrence using intraoperative stimulated Raman histology and deep neural networks.

BACKGROUND: Detection of glioma recurrence remains a challenge in modern neuro-oncology. Noninvasive radiographic imaging is unable to definitively differentiate true recurrence versus pseudoprogression. Even in biopsied tissue, it can be challenging to differentiate recurrent tumor and treatment effect. We hypothesized that intraoperative stimulated Raman histology (SRH) and deep neural networks can be used to improve the intraoperative detection of glioma recurrence. METHODS: We used fiber laser-based SRH, a label-free, nonconsumptive, high-resolution microscopy method (<60 sec per 1 × 1 mm2) to image a cohort of patients (n = 35) with suspected recurrent gliomas who underwent biopsy or resection. The SRH images were then used to train a convolutional neural network (CNN) and develop an inference algorithm to detect viable recurrent glioma. Following network training, the performance of the CNN was tested for diagnostic accuracy in a retrospective cohort (n = 48). RESULTS: Using patch-level CNN predictions, the inference algorithm returns a single Bernoulli distribution for the probability of tumor recurrence for each surgical specimen or patient. The external SRH validation dataset consisted of 48 patients (recurrent, 30; pseudoprogression, 18), and we achieved a diagnostic accuracy of 95.8%. CONCLUSION: SRH with CNN-based diagnosis can be used to improve the intraoperative detection of glioma recurrence in near-real time. Our results provide insight into how optical imaging and computer vision can be combined to augment conventional diagnostic methods and improve the quality of specimen sampling at glioma recurrence.

Three-Dimensional Navigated Lateral Lumbar Interbody Fusion: 2-Dimensional Operative Video.

Spondylolisthesis is a common cause of lower back and leg pain in adults. The initial treatment for patients is typically nonoperative in nature. However, when patients fail conservative management and their back and/or leg pain is recalcitrant, surgical intervention is warranted. Spinal decompression, either directly or indirectly, as well as fusion is often considered at this point. There are numerous approaches to fuse the spine, including anterior, lateral, or posterior, each with their own advantages and disadvantages. This video illustrates a case of symptomatic spondylolisthesis occurring after laminectomy treated by lateral lumbar interbody fusion for indirect decompression and stabilization. The approach utilizes 3-dimensional navigation rather than traditional fluoroscopy, resulting in markedly decreased radiation exposure for the surgeon and staff while maintaining accuracy. Appropriate patient consent was obtained. This video demonstrates the technique for a lateral lumbar interbody fusion using navigation assistance, which is a minimally invasive technique for the treatment of spondylolisthesis.

Lumbar Lateral Recess Decompression: 2-Dimensional Operative Video.

Lateral recess stenosis is a common cause of lumbar radiculopathy in adults. A lumbar nerve root travels in the lateral recess prior to exiting the spinal canal via the neural foramen. In the lateral recess, the traversing nerve root is susceptible to compression by the degenerative hypertrophy of the medial facet in addition to hypertrophied ligamentum flavum and herniated intervertebral disc.1 These degenerative changes are also typically associated with neural foraminal stenosis. Surgical treatment in unilateral cases consists of hemilaminectomy, medial facetectomy, foraminotomy, and, if applicable, microdiscectomy. In this video, we present a case of a 64-yr-old male presenting with progressive left L5 radiculopathy refractory to conservative management, with magnetic resonance imaging (MRI) findings of left L4-5 foraminal and lateral recess stenosis. We demonstrate the operative steps to complete a left L4-5 hemilaminectomy, medial facetectomy, foraminotomy, and microdiscectomy. Appropriate patient consent was obtained.

Using a Mobile Application for Evaluation of Procedural Learning in Neurosurgery.

BACKGROUND: Feedback is a major component of any educational process. Competency assessment and feedback are essential tools for teaching surgical skills. Most current systems of assessment within neurosurgical residency programs use evaluations aggregated over a period of time, which lead to significant bias, rather than case-specific feedback. We describe the use of a mobile device application called SIMPL (System for Improving and Measuring Procedural Learning) to allow for immediate surgical competency assessment and improve the quality of feedback after every operative experience. METHODS: We retrospectively assessed our use of this program and neurosurgery residents' response to the program. Institutional review board approval was not required, and no patients were involved in the study. This application has already been implemented within general surgery programs with promising results. We document its implementation in a neurosurgery program and the output of the program for residents and program directors. RESULTS: This is the first documentation of such an application within a neurosurgical residency program. In a 6-month period at a single institution, around 300 evaluations were completed by residents and faculty, with a >80% response rate within both groups. Furthermore, these evaluations were companied by a 60% dictation rate from faculty, which contains verbal feedback that is available to residents for playback at any time. CONCLUSIONS: The telephone-based SIMPL application allows for assessment of surgical competency and remains quick and easy to use, giving it the potential to improve individual neurosurgical training experiences across the United States.

Normal cerebral ventricular volume growth in childhood.

OBJECTIVE: Normal percentile growth charts for head circumference, length, and weight are well-established tools for clinicians to detect abnormal growth patterns. Currently, no standard exists for evaluating normal size or growth of cerebral ventricular volume. The current standard practice relies on clinical experience for a subjective assessment of cerebral ventricular size to determine whether a patient is outside the normal volume range. An improved definition of normal ventricular volumes would facilitate a more data-driven diagnostic process. The authors sought to develop a growth curve of cerebral ventricular volumes using a large number of normal pediatric brain MR images. METHODS: The authors performed a retrospective analysis of patients aged 0 to 18 years, who were evaluated at their institution between 2009 and 2016 with brain MRI performed for headaches, convulsions, or head injury. Patients were excluded for diagnoses of hydrocephalus, congenital brain malformations, intracranial hemorrhage, meningitis, or intracranial mass lesions established at any time during a 3- to 10-year follow-up. The volume of the cerebral ventricles for each T2-weighted MRI sequence was calculated with a custom semiautomated segmentation program written in MATLAB. Normal percentile curves were calculated using the lambda-mu-sigma smoothing method. RESULTS: Ventricular volume was calculated for 687 normal brain MR images obtained in 617 different patients. A chart with standardized growth curves was developed from this set of normal ventricular volumes representing the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles. The charted data were binned by age at scan date by 3-month intervals for ages 0-1 year, 6-month intervals for ages 1-3 years, and 12-month intervals for ages 3-18 years. Additional percentile values were calculated for boys only and girls only. CONCLUSIONS: The authors developed centile estimation growth charts of normal 3D ventricular volumes measured on brain MRI for pediatric patients. These charts may serve as a quantitative clinical reference to help discern normal variance from pathologic ventriculomegaly.

Automated histologic diagnosis of CNS tumors with machine learning.

The discovery of a new mass involving the brain or spine typically prompts referral to a neurosurgeon to consider biopsy or surgical resection. Intraoperative decision-making depends significantly on the histologic diagnosis, which is often established when a small specimen is sent for immediate interpretation by a neuropathologist. Access to neuropathologists may be limited in resource-poor settings, which has prompted several groups to develop machine learning algorithms for automated interpretation. Most attempts have focused on fixed histopathology specimens, which do not apply in the intraoperative setting. The greatest potential for clinical impact probably lies in the automated diagnosis of intraoperative specimens. Successful future studies may use machine learning to automatically classify whole-slide intraoperative specimens among a wide array of potential diagnoses.