Search

Colloid cysts are nonneoplastic epithelial lesions arising from the roof of the third ventricle near the foramen of Monro. They comprise approximately 0.5% to 2% of all brain lesions. 1-3 Surgical resection is the definitive treatment when indicated. The microsurgical approach is generally considered the "gold standard," but the endoscopic approach has been gaining popularity. 4-6 The choice is usually based on a surgeon's preference and key image findings such as the presence of hydrocephalus. The advantage of an endoscopic approach is shorter operative time, faster recovery, and a more anterolateral approach to avoid manipulation on the fornix. The major drawback of the endoscopic approach was previously reported as a higher recurrence rate due to incomplete removal of the cyst capsule. However, it has been shown that the rate of capsule excision may be similar to that of microsurgery, ranging from 80 to 100%. 7-14 The authors demonstrate an endoscopic resection of a recurrent colloid cyst with bimanual technique through parallel channels in a ventriculoscope. Video 1 highlights the critical steps involved in preserving both vascular and neural structures during the procedure., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Optimal management of patients with extracranial blunt cerebrovascular injury (BCVI) remains controversial, with both anticoagulation and antiplatelet therapy being recommended. The purpose of this study was to evaluate the efficacy and safety of using acetylsalicylic acid (ASA) in the management of BCVI., Methods: Patients with BCVI were identified from the registry of a Level 1 trauma center between 2010 and 2017. Digital imaging and electronic medical records were reviewed for patient information including demographic characteristics, injury type, therapy, outcomes, and follow-up., Results: Over the study period, 13,578 patients were admitted following blunt trauma, with 94 (0.7%) having confirmed BCVI (mean age, 42 years; 72% male). Mean Injury Severity Score and Glasgow Coma Score were 27 and 10, respectively. BCVI was identified in 130 vessels with Biffl grade I (38%) and grade II injury (29%) being most common. Twelve (13%) patients experienced an ischemic event, but only 3 events occurred after diagnosis. ASA was primary treatment for 56 (60%) patients. Thirty patients (32%) received no treatment; 21 patients died within 24 hours of primary injury. Only 4 patients had ASA contraindications. Four patients (7%) had ASA-related complications; there were 2 cases of intracranial hemorrhage progression and 2 cases of gastrointestinal bleeding. Follow-up vascular imaging at a mean of 36 days demonstrated stable or improved levels of BCVI in 94% of patients., Conclusions: An ASA-based management strategy for BCVI was efficacious and relatively safe in this study. This approach may be the preferred treatment for BCVI, but confirmation is needed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: An increasing body of literature describing use of high-fidelity surgical training models is challenging long-held dogma that cadavers provide the best medium for postgraduate surgical skills training. The purpose of this study was to describe a surgical skills course comprising entirely synthetic training models developed by resident and attending neurosurgeons and to evaluate their perceptions of the overall usefulness of this course and its usefulness compared with cadaveric courses., Methods: Ten high-fidelity neurosurgical training models were developed. A neurosurgical skills course for residents was structured to include 7 spinal and 3 cranial learning stations, each with its own model and assigned attending expert. Resident and attending neurosurgeons were asked to complete surveys on their overall impressions of the course and models and on workload comparisons between models and real cases. Student t tests were used for statistical comparisons., Results: Survey responses were collected from 9 of 16 participating residents (56.3%) and 3 of 10 attending neurosurgeons (30.0%). Both groups believed that the course was very helpful overall to resident education. Respondents furthermore believed that the course was more helpful overall than cadaveric courses. Task load index testing showed no significant workload difference between models and real cases (P ≥ 0.17), except in temporal demand (P < 0.001)., Conclusions: Resident and attending neurosurgeons subjectively believe that high-fidelity synthetic models were superior to cadavers as a surgical skills teaching platform. This study raises the question of whether cadavers should remain the gold standard for surgical skills courses. Expanded use of these teaching models and further study are warranted., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To analyze the effects of a surgical protocol for infections, nonhealing wound prophylaxis, and analgesia among patients who underwent posterior spinal fusion at a single tertiary-care neurosurgical center., Methods: This prospective study was conducted in the neurosurgery department of a tertiary-care neurosurgical center and compared a control group of patients who had posterior spinal fusion within 3 months before implementation of a surgical protocol with a study group of patients enrolled within 1 year after protocol implementation. The protocol included a surgical safety checklist, control of modifiable risks associated with surgical site infection, administration of intrawound vancomycin and local analgesia, and standard closure. Postoperative pain, demand for analgesics, and postoperative surgical site infections were assessed among patients before and after the introduction of the protocol., Results: The control group (n = 35; 30 women; median age, 40 years [interquartile range, 31-54 years]) experienced a higher-than-predicted rate of minor surgical infections and nonhealing wounds (12 patients; 34%). In the study group (n = 113; 74 women; median age, 45 years [interquartile range, 37-54 years]), 11 patients (10%) had minor surgical infections and nonhealing wounds. Introduction of the protocol was associated with a 24% absolute risk reduction for minor surgical site infection and a significant decrease in pain on postoperative days 1 and 2 (P < 0.01 for both). Interpersonal communication improved among specialists involved in patient management., Conclusions: The protocol was effective in reducing postoperative pain and the rate of surgical site infection among patients with posterior spinal surgeries., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: Patients with hydrocephalus secondary to third ventricular colloid cysts can require bilateral external ventricular drain (EVD) placement while awaiting surgery. However, some patients could develop auto-fenestration of the septum pellucidum (AFSP) and only require 1 EVD. We evaluated our experience with bedside iohexol ventriculography and staged EVD placement for patients with obstructive hydrocephalus., Methods: We retrospectively identified 34 patients who had been treated for third ventricular colloid cysts (2013-2016). The preoperative and postoperative data, including age, sex, colloid cyst size, preoperative hydrocephalus, preoperative EVD placement, preoperative iohexol ventriculography, operative approach, intraoperative findings, and postoperative ventriculoperitoneal shunt requirements, were reviewed., Results: Hydrocephalus was found in 23 patients (68%) on initial presentation. Nine patients (26%) had EVDs placed before surgery. Six patients (18%) underwent iohexol ventriculography after insertion of a right-sided EVD. Five patients (15%) demonstrated no evidence of ventricular communication. Four patients (67%) required left-sided EVD placement. One patient (17%) had robust communication between the lateral ventricles after intraventricular iohexol injection, which was managed with a single EVD. AFSP was observed during surgical resection of this patient's colloid cyst. One other patient who did not undergo preoperative EVD placement was noted to have AFSP intraoperatively, resulting in 2 of 34 patients (6%) with AFSP in our series., Conclusions: A subset of patients with obstruction at the foramina of Monro can develop AFSP. Iohexol ventriculography after unilateral EVD placement allows clinicians to assess for the presence of AFSP and identify patients who can be treated with a single EVD before surgery., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: The contralateral interhemispheric transprecuneus approach (CITP) and the supracerebellar transtentorial transcollateral sulcus approach (STTC) are 2 novel approaches to access the atrium of the lateral ventricle. We quantitatively compared the 2 approaches., Methods: Both approaches were performed in 6 sides of fixed and color-injected cadaver heads. We predefined the 6 targets in the atrium for measurement and standardization of the approaches. Using a navigation system, we quantitatively measured the working distance, cortical transgression, angle of attack, area of exposure, and surgical freedom., Results: The distances from the craniotomy edge to the posterior pole of the choroid plexus of the CITP (mean ± standard deviation, 67 ± 5.3 mm) and STTC (mean, 57 ± 4.0 mm) differed significantly (P < 0.01). Cortical transgression with the CITP (mean, 27 ± 2.8 mm) was significantly greater than that with the STTC (mean, 21 ± 6.7 mm; P = 0.03). The CITP showed a significantly wider rostrocaudal angle of attack than that with the STTC (P = 0.01). The STTC showed a significantly wider mediolateral angle (P < 0.01). No significant difference was found for surgical freedom of any target except for point E, for which the CITP was larger. The exposure area did not differ significantly between the 2 approaches (P = 0.07)., Conclusions: Both approaches were feasible for accessing the atrium. The STTC provided a shorter working distance and wider mediolateral angle, CITP provided a wider rostrocaudal angle of attack and better exposure and maneuverability to the anterior and superior atrium. In contrast, the STTC was more favorable for the inferior and posterior regions., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: The Barrow Innovation Center comprises an educational program in medical innovation that enables residents to identify problems in patient care and rapidly develop and implement solutions to these problems. Residents involved in this program noted an elevated risk of iatrogenic spinal cord injury during posterior cervical and thoracic procedures. The objective of this study was to describe this complication, and a novel solution was developed through a new innovation training program., Methods: A case report demonstrates the risk of iatrogenic spinal cord injury during posterior cervical decompression and fusion. Solutions to this problem were developed at the innovation center via an iterative process of prototype creation, cadaveric testing, and redesign. Patent law students who partnered with the center wrote and filed a provisional patent protecting the novel prototype designs., Results: The concept of a protective shield for the spinal cord was developed, and within only 6 weeks the devices were provisionally patented and used in the operating room. This device was named the Myeloshield. Initial clinical experience indicates that the Myeloshield can be used without impeding the flow of surgery and has the potential to prevent iatrogenic spinal cord injury; this experience is presented through 2 case reports demonstrating the use of Myeloshields in the operating room., Conclusions: This report demonstrates how programs like the Barrow Innovation Center can provide neurosurgery residents with a unique educational experience in medical device innovation and intellectual property development and can serve as an avenue of surgical quality improvement and problem solving., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: We describe and quantitatively assess minimally invasive keyhole retrosigmoid approaches targeted to the upper, middle, and lower cranial nerve (CN) complexes of the cerebellopontine angle (CPA)., Methods: Anatomic dissections were performed on 10 sides of 5 fixed, silicone-injected cadaver heads. Surgical views through various trajectories were assessed in endoscopic videos and 3-dimensional (3D) interactive virtual reality microscope views. Surgical freedom and angles of attack to the proximal and distal areas of CN complexes of the CPA were compared among upper and lower keyholes and conventional retrosigmoid craniotomy using neuronavigation., Results: Compared with keyholes, the conventional approach had superior surgical freedom to most areas except for the distal CN V, the root of CN VII, and the root of CN IX, where differences were not significant. The conventional retrosigmoid approach provided a larger horizontal angle of attack than either the upper or lower keyholes for all selected areas; however, the vertical angles of attack were not different. Splitting the petrosal fissure resulted in a significant increase in the vertical angle of attack to the root zones of CNs V and VII but not to the distal areas of these nerves or CN IX. Illustrative cases of endoscope-assisted keyhole retrosigmoid approaches for the treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia are presented., Conclusions: Targeted keyhole retrosigmoid approaches require detailed understanding of the 3D anatomy of the CPA to create appropriate locations of corridors, including skin incisions and keyholes. Endoscope assistance complements the standard microsurgical technique by maximizing the visualization and identification of the delicate neurovascular structures., (Copyright © 2018. Published by Elsevier Inc.)

Objective: Because the clinical course of spontaneous aneurysmal subarachnoid hemorrhage (aSAH) can be compromised by pulmonary complications, we sought to review posttreatment outcomes in aSAH patients with and without pulmonary complications., Methods: Patient demographic, clinical, and outcome data (March 2003-January 2007) were analyzed retrospectively. Patients underwent microsurgical or endovascular treatment for aSAH; pulmonary complications were reported. Outcomes were assessed using the Glasgow Outcome Scale (GOS) scores at the 1-year, 3-year, and 6-year follow-up visits., Results: The cohort comprised 471 patients (mean age, 53.7 ± 12.4 years; men, 332/471 [70%]). The mean Glasgow Coma Scale (GCS) score at presentation was 11.9 ± 3.0. Of 471 patients, 47% (n = 223) presented with a Hunt and Hess score of ≥3 and 76% (n = 357) with a Fisher grade of 3. Treatment was clipping for 69% (279/407) and coiling for 31% (128/407) of patients. Pulmonary complications occurred in 210 of 471 (45%) patients. Nearly one-half of patients were discharged to home (215/471, 46%), and more than one-half had a good outcome defined as a GOS score of 5 at their 1-year (226/403, 56%), 3-year (217/397, 55%), and 6-year (203/380, 53%) follow-up visits. Logistic regression showed age and GCS scores as outcome predictors at all time points, whereas pulmonary complications predicted poor outcome only at the 1-year follow-up visit., Conclusions: Pulmonary problems represent the most common nonneurologic medical complications after aSAH. Despite advances in critical care, pulmonary complications represented predictors of short-term poor outcome only at the 1-year follow-up visit, whereas the medical history of the patient became more relevant for prognosis in long-term follow-up., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: To compare transcallosal-transchoroidal and transcallosal-subchoroidal approaches to the ipsilateral and contralateral edges of the floor of the third ventricle using quantitative analyses., Methods: Five formalin-fixed cadaveric human heads (10 sides) were examined under the operating microscope. Quantitative measurements (area of surgical freedom and angle of attack) were obtained using 3-T magnetic resonance imaging and a StealthStation image guidance system. The limits of the surgical approaches were shown by touching a probe to 6 designated points on the floor of the third ventricle., Results: The transchoroidal approach provided greater surgical freedom than the subchoroidal approach to access ipsilateral and contralateral middle landmarks at the edges of the floor of the third ventricle in both longitudinal and horizontal planes (P ≤ 0.03). No significant difference between the 2 approaches was found in accessing the anterior and posterior landmarks of the third ventricle in each plane. The surgical freedom to the contralateral anterior, middle, and posterior landmarks was greater than to the ipsilateral landmarks in both the transchoroidal and subchoroidal approaches., Conclusions: The transcallosal-transchoroidal approach, compared with the transcallosal-subchoroidal approach, may provide better exposure and require less retraction for removal of ipsilateral or contralateral lesions located in the midbrain or hypothalamus and situated near the floor of the third ventricle. The contralateral transcallosal approach with either the transchoroidal or subchoroidal approach may provide good surgical freedom for removal of lesions located near the floor of the third ventricle, such as lesions in the midbrain., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: The neurosurgical literature rarely describes managing open head injuries caused by machetes, although this is a common head injury in developing countries. We present our experience managing cranial machete injuries in Nicaragua over a 5-year period., Methods: A retrospective chart review identified patients admitted to a neurosurgery service for cranial machete injury., Results: Among 51 patients studied, the majority (n = 42, 82%) presented with mild neurologic deficits (Glasgow Coma Scale score ≥14). Nondepressed skull fracture (25/37, 68%) was the most common injury identified on skull radiography, and pneumocephalus (15/29, 52%) was the most common injury identified with computed tomography. Overall, 38 patients (75%) underwent surgical intervention for 1 or more conditions, including laceration length ≥10 cm (n = 20), open intracranial wound (n = 8), pneumocephalus (n = 7), cerebral contusion (n = 6), intracranial hemorrhage (n = 5), and depressed fracture (n = 5). All patients received aggressive antibiotic therapy. Patients without intracranial injury received a 7-day course of intravenous ceftriaxone, followed by a 10-day course of oral ciprofloxacin. Patients with violation of the dura received a 7- to 14-day course of intravenous metronidazole, ceftriaxone, and vancomycin, followed by a 10-day course of oral ciprofloxacin. Postoperative complications included a visible skull defect (n = 6), infection (n = 3), and unspecified neurologic (n = 2) and mixed (n = 1) complications. At discharge, most patients had only minimal disabilities (47/51, 92%). In-hospital mortality rate was zero., Conclusions: An aggressive approach to managing open head injury caused by machete yields good outcomes, with the majority of patients experiencing minimal disability at hospital discharge and a low rate of infection., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: The Barrow Innovation Center consists of an educational program that promotes interdisciplinary collaboration among neurosurgery, legal, and engineering professionals to foster the development of new medical devices. This report describes a common issue faced during the placement of ventricular shunts for the treatment of hydrocephalus and the solution to this problem that was developed through the Barrow Innovation Center., Methods: Neurosurgery residents involved in the Barrow Innovation Center presented the problem of ferromagnetic retractors interfering with pinless image-guidance systems at a monthly meeting. Potential solutions were openly discussed by an interdisciplinary committee of neurosurgeons, patent lawyers, and biomedical engineers. The committee decided to pursue development of a novel self-retaining retractor made of nonferromagnetic material as a solution to the problem., Results: Each retractor design was tested in the cadaver laboratory for size and functionality. A final design was chosen and used in a surgical case requiring ventriculoperitoneal shunt placement. The new retractor successfully retracted the scalp without interfering with the electromagnetic image-guidance system., Conclusions: Through the interdisciplinary Barrow Innovation Center program, a newly designed, 3-dimensional-printed skin and soft-tissue retractor was created, along with an innovative universal shunt retainer. Through this integrated program dedicated to surgical innovation (i.e., the Barrow Innovation Center), the process of developing and implementing new technology at our institution has been streamlined, creating a culture of innovation within the neurosurgery training program., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: A frequently encountered problem during posterolateral fusion (PLF) is bone graft displacement from the posterolateral space during closure. Commercially available solutions to this problem are seldom used because of their exceptionally high cost. The purpose of this report is to describe 3 novel, low-cost techniques we developed for bone graft containment during PLF., Methods: Three low-cost bone graft containment techniques are described: rapid suture weave, makeshift bone bag, and cellulose rooftop. Early clinical experience with these techniques is reported for a 5-patient case series., Results: One or more of these bone graft containment techniques were used in 5 patients who underwent PLF. Rapid suture weave was the least expensive (<$5.00) but required the longest additional time to perform (20 minutes). Makeshift bone bag and cellulose rooftop cost approximately the same ($48.00 and $46.00, respectively); the makeshift bone bag took less additional time (3 minutes) but created a potential barrier between the bone graft and the host site, whereas the cellulose rooftop took slightly longer to perform (5 minutes) but permitted direct contact between the bone graft and host site., Conclusions: These 3 novel surgical techniques for bone graft containment in the posterolateral space add minimally to the cost and length of the procedure. Our early clinical experience suggests that these techniques are safe and effective. Additional clinical experience is warranted, and prospective data collection is ongoing., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: Glioma resection with fluorescein sodium (FNa) guidance has a potential drawback of nonspecific leakage of FNa from nontumor areas with a compromised blood-brain barrier. We investigated the diagnostic accuracy of in vivo confocal laser endomicroscopy (CLE) after FNa administration to differentiate normal brain, injured normal brain, and tumor tissue in an animal glioma model., Methods: GL261-Luc2 gliomas in C57BL/6 mice were used as a brain tumor model. CLE images of normal, injured normal, and tumor brain tissues were collected after intravenous FNa administration. Correlative sections stained with hematoxylin and eosin were taken at the same sites. A set of 40 CLE images was given to 1 neuropathologist and 3 neurosurgeons to assess diagnostic accuracy and rate image quality (1-10 scale). Additionally, we developed a deep convolution neural network (DCNN) model for automatic image classification., Results: The mean observer accuracy for correct diagnosis of glioma compared with either injured or uninjured brain using CLE images was 85%, and the DCNN model accuracy was 80%. For differentiation of tumor from nontumor tissue, the experts' mean accuracy, specificity, and sensitivity were 90%, 86%, and 96%, respectively, with high interobserver agreement overall (Cohen κ = 0.74). The percentage of correctly identified images was significantly higher for images with a quality rating >5 (104/116, 90%) than for images with a quality rating ≤5 (32/44, 73%) (P = 0.007)., Conclusions: With sufficient FNa present in tissues, CLE was an effective tool for intraoperative differentiation among normal, injured normal, and tumor brain tissue. Clinical studies are warranted to confirm these findings., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: Fluorescence-guided surgery with protoporphyrin IX (PpIX) as a photodiagnostic marker is gaining acceptance for resection of malignant gliomas. Current wide-field imaging technologies do not have sufficient sensitivity to detect low PpIX concentrations. We evaluated a scanning fiber endoscope (SFE) for detection of PpIX fluorescence in gliomas and compared it to an operating microscope (OPMI) equipped with a fluorescence module and to a benchtop confocal laser scanning microscope (CLSM)., Methods: 5-Aminolevulinic acid-induced PpIX fluorescence was assessed in GL261-Luc2 cells in vitro and in vivo after implantation in mouse brains, at an invading glioma growth stage, simulating residual tumor. Intraoperative fluorescence of high and low PpIX concentrations in normal brain and tumor regions with SFE, OPMI, CLSM, and histopathology were compared., Results: SFE imaging of PpIX correlated to CLSM at the cellular level. PpIX accumulated in normal brain cells but significantly less than in glioma cells. SFE was more sensitive to accumulated PpIX in fluorescent brain areas than OPMI (P < 0.01) and dramatically increased imaging time (>6×) before tumor-to-background contrast was diminished because of photobleaching., Conclusions: SFE provides new endoscopic capabilities to view PpIX-fluorescing tumor regions at cellular resolution. SFE may allow accurate imaging of 5-aminolevulinic acid labeling of gliomas and other tumor types when current detection techniques have failed to provide reliable visualization. SFE was significantly more sensitive than OPMI to low PpIX concentrations, which is relevant to identifying the leading edge or metastasizing cells of malignant glioma or to treating low-grade gliomas. This new application has the potential to benefit surgical outcomes., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: In our study, we comprehensively detail the technique of the low retrosigmoid approach to the lateral medullary area, including the inferior cerebellar peduncle, postolivary sulcus, pontomedullary sulcus, and inferior olivary nucleus, as well as the lateral recess of the fourth ventricle., Methods: Four formalin-fixed, silicone-injected, cadaveric human heads were examined under the operating microscope to demonstrate pertinent descriptive anatomy using the low retrosigmoid approach in a stepwise manner. Clinical parameters of a patient with a lateral medullary lesion were reviewed retrospectively to describe preoperative and postoperative examination and surgical details of the approach to the lateral medulla., Results: The clinical case report describes a low retrosigmoid craniotomy performed to access the exiting points of cranial nerves IX (glossopharyngeal) and X (vagus), foramen of Luschka, inferior cerebellar peduncle (lateral medullary zone), postolivary sulcus, and olivary nucleus. The lesion was exposed using the inferior cerebellar peduncle and removed using standard microsurgical technique., Conclusions: The lower retrosigmoid infratonsillar approach provides excellent exposure to medullary safe entry zones, including the transolivary, postolivary sulcus, pontomedullary sulcus, and lateral medullary (inferior cerebellar peduncle) zones, for removal of lesions in this area., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: Since the first resections of intradural extramedullary neoplasms, neurosurgeons have tended to preserve as much of the integrity of the spine as possible while ensuring a safe corridor to resect these lesions. A dimensional analysis of intradural lesions superimposed on a dimensional analysis of the thoracic canal would provide the anatomic basis for a minimal access approach. The authors report the results of such an analysis on a series of patients with intradural extramedullary lesions., Methods: A retrospective analysis was undertaken of 26 thoracic intradural extramedullary lesions managed with open or minimally invasive resection. The size of each lesion was measured in the rostrocaudal, lateral, and anteroposterior dimensions and then averaged and compared with reported dimensions of the thoracic spinal canal., Results: The mean (range) dimensions of the surgically resected thoracic lesions were 18.6 mm (10-25 mm) for rostrocaudal, 13.0 mm (7-18 mm) for lateral, and 13.6 mm (9-17 mm) for anteroposterior. No patient had any evidence of thoracic canal remodeling., Conclusions: Thoracic intradural extramedullary lesions become symptomatic as they approach the limits of the thoracic canal, resulting in an inherent dimensional limitation in the rostrocaudal, lateral, and anteroposterior dimensions. Displacement of the spinal cord by the lesion to one side further favors a minimally invasive unilateral approach. A paraspinal unilateral hemilaminectomy approach with a 35 × 20 mm exposure centered over the lesion offers a safe surgical corridor for resection while preserving the posterior tension band, facet complexes, and paraspinal musculature., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Endoscopic endonasal transsphenoidal and contralateral sublabial transmaxillary approaches are used for approaching parasellar lesions. The aim of this anatomical study was to compare endoscopic endonasal uninostril and binostril (contralateral) and contralateral sublabial transmaxillary approaches via a quantitative analysis of exposure limits and instrument working avenues., Methods: Six formalin-fixed silicone-injected adult cadaveric heads (12 sides) were studied. The surgical working area, depth of the surgical corridor, angle of attack, and surgical freedom were measured and compared for the 3 approaches., Results: The endoscopic binostril endonasal approach to the parasellar area provided greater surgical freedom in the opticocarotid recess (OCR) and superior orbital fissure (SOF) compared with that of the uninostril endonasal approach (OCR, P < 0.01; SOF, P = 0.01) and the contralateral sublabial transmaxillary approach (OCR, P = 0.01; SOF, P = 0.03). The horizontal and vertical angles of attack with the binostril endonasal approach also were greater than those of the uninostril approach (OCR, P ≤ 0.05; SOF, P ≤ 0.01) and the contralateral transmaxillary approach (OCR, P ≤ 0.01; SOF, P ≤ 0.01). However, the contralateral sublabial transmaxillary approach provided more lateral exposure than the uninostril or binostril endonasal approach to the parasellar area, and it enabled a shorter surgical trajectory to the contralateral parasellar area (P < 0.01)., Conclusions: An anatomical comparison of the 3 endoscopic approaches to the parasellar area showed that the binostril approach provides greater exposure and freedom for instrument manipulation. The contralateral transmaxillary route provided a more lateral view, increasing exposure on average by 48%, with shorter surgical depth; however, surgical freedom was inferior to that of the binostril approach., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: Proficient open surgical treatment of cerebral aneurysms requires extensive training and practice. This study tested the validity of a human placenta aneurysm model for surgical simulation training of aneurysm clipping., Methods: There were 30 participants divided into 3 groups (n = 10 per group) according to their neurosurgical experience: low experience, intermediate experience, and attending. Subjective measures were collected using the Aneurysm Clipping Participant Survey (n = 27). Objective measures were collected by observing the participants (n = 30) work through a series of aneurysm clipping tasks while 2 independent raters evaluated them using a newly developed standardized tool, the Objective Structured Assessment of Aneurysm Clipping Skills., Results: In terms of the subjective measures of face validity, most of the attending group (7/10; 70%) rated the models as "somewhat" to "very well" replicating real surgery. Content validity assessment of the model showed that it could improve the following skills: microdissection technique (27/27; 100%), use of clip appliers for aneurysm clipping (27/27; 100%), and surgical technique when applied to patients (25/27; 93%). The objective measure for construct validity demonstrated that mean Objective Structured Assessment of Aneurysm Clipping Skills scores between the 3 groups (low-experience group, 22.9 ± 5.4; intermediate-experience group, 32.8 ± 4.0; attending group, 43.3 ± 1.3) differed significantly (P < 0.001)., Conclusions: The human placenta aneurysm clipping model is a useful training tool for teaching residents, with evidence of internal consistency and face, content, and construct validities. The Objective Structured Assessment of Aneurysm Clipping Skills scale is a feasible tool to assess aneurysm clipping skills quantitatively., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: The V2 segment of the vertebral artery (VA) typically runs through the transverse foramen of C2-C6. V2 injury may occur during anterior approaches to the cervical spine and can cause significant morbidity. We describe landmarks and microsurgical V2 repair techniques through the standard anterolateral cervical diskectomy approach., Methods: Five silicone-injected cadaveric heads (necks-C7) were dissected bilaterally. An anterolateral approach with C3-4, C4-5, and C5-6 diskectomies and an ipsilateral VA injury were simulated. VA approach and repair were performed using microdissection techniques. Landmarks to the VA were identified, and distances from landmarks to the VA were measured in horizontal and vertical planes. Operative photographs of stepwise approach and repair techniques were processed for stereoscopic illustration. An illustrative case describes microsurgery to successfully repair an inadvertent VA injury during a C3-C6 diskectomy and fusion procedure., Results: The anatomic landmarks delineated were the intervertebral disk, uncinate apices, and anterior tubercles of C4-C6 transverse processes. After temporary hemostasis with packing, VA exposure and repair included dissection of the longus colli muscle, removal of the anterior root of the transverse processes above and below the injury level, intertransversarii muscle removal, vertebral plexus opening, VA handling, and microsuturing. In 30 dissected cadaver intertransverse intervals, 13 medial, 7 lateral, and 3 anterior branches of the V2 were encountered at C3-C6 levels., Conclusion: Familiarity with relevant vascular surgical anatomy allows neurosurgeons to be prepared in cases of VA injury and may facilitate repair when the VA is injured during anterior cervical spine surgery., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: The diagnosis and management of patients with idiopathic intracranial hypertension (IIH) frequently relies on lumbar puncture to ascertain intracranial pressure (ICP). However, ICP values derived this way may be spurious owing to patient body habitus and behavior. We recently incorporated direct continuous ICP monitoring into the work-up for IIH., Methods: Through billing records, we identified all patients during a 3-year period who had a diagnosis of IIH and who underwent ICP monitoring before shunt placement or revision. Patient demographics and clinical data were reviewed., Results: Of 30 patients who underwent ICP monitoring with an intraparenchymal wire, 17 had undergone lumbar puncture within the previous 6 months. Results from lumbar punctures showed an elevated opening pressure in all 17 patients, whereas only 2 patients (12%) were found to have consistently elevated ICP with direct ICP monitoring. Of 15 patients being evaluated for shunting, 4 (27%) were found to have elevated ICP. Of the 15 patients with existing shunts, 2 patients (13%) were found to have malfunctioning shunts after pressure monitoring, and 3 patients (20%) had shunts that were found to be unnecessary and were removed. No patient experienced any complication from invasive monitoring., Conclusions: Direct ICP monitoring is the gold standard for determining ICP and can be safely and effectively applied to the work-up and treatment of patients with IIH to reduce the occurrence of misdiagnosis and unnecessary surgery., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: The second part of this study reanalyzes Ponce and Lozano's (2010) list of classics to create a new list of "foundational" articles in neurosurgery. Ponce and Lozano (2010) previously published a list of 106 neurosurgery classics, as defined by Garfield and his 400 citation criterion., Methods: We used the Web of Science citation reports to create graphs for each study showing the total citations it received as a function of time. Each graph was subjectively analyzed independently and scored as "foundational" or "classic only," based on whether the trend of citations received per year was uptrending, neutral, or downtrending., Results: Of the 101 evaluated classics, 53 qualified as foundational. Over half of these studies were published in Journal of Neurosurgery (13), New England Journal of Medicine (12), or Lancet (5). Grading systems, randomized trials, and prospective studies were most likely to achieve foundational status. Only 30% of functional and 17% of endovascular classics qualified as foundational (compared with 100% of spine classics), suggesting that these fields are rapidly changing or less mature subspecialties still developing a foundational literature base., Conclusion: By assessing citation counts as a function of time, we are able to differentiate classic neurosurgical studies that are critical to modern-day practice from those that are primarily of historic interest. Given the exponential growth of literature in our field, analyses such as these will become increasingly important to both trainees and senior neurosurgeons who strive to educate themselves on the data that drive modern-day clinical decision making., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To define the maxillary artery (MaxA) anatomy and present a novel technique for exposing and preparing this vessel as a bypass donor., Methods: Cadaveric and radiologic studies were used to define the MaxA anatomy and show a novel method for harvesting and preparing it for extracranial to intracranial bypass., Results: The MaxA runs parallel to the frontal branch of the superficial temporal artery and is located on average 24.8 ± 3.8 mm inferior to the midpoint of the zygomatic arch. The pterygoid segment of the MaxA is most appropriate for bypass with a maximal diameter of 2.5 ± 0.4 mm. The pterygoid segment can be divided into a main trunk and terminal part based on anatomic features and use in the bypass procedure. The main trunk of the pterygoid segment can be reached extracranially, either by following the deep temporal arteries downward toward their origin from the MaxA or by following the sphenoid groove downward to the terminal part of the pterygoid segment, which can be followed proximally to expose the entire MaxA. In comparison, the prebifurcation diameter of the superficial temporal artery is 1.9 ± 0.5 mm. The average lengths of the mandibular and pterygoid MaxA segments are 6.3 ± 2.4 and 6.7 ± 3.3 mm, respectively., Conclusions: The MaxA can be exposed without zygomatic osteotomies or resection of the middle fossa floor. Anatomic landmarks for exposing the MaxA include the anterior and posterior deep temporal arteries and the pterygomaxillary fissure., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Moyamoya angiopathy most often manifests in patients in the second and third decades of life. Although uncommon, it can also manifest later in life. We present our results in patients >50 years old with moyamoya angiopathy who were treated with surgical revascularization via either direct bypass or indirect bypass (encephaloduroarteriosynangiosis)., Methods: A retrospective review was conducted to identify patients with moyamoya disease who were treated with surgical revascularization at our institution between 2002 and 2015. Outcomes and complications were analyzed., Results: We identified 33 patients with moyamoya angiopathy >50 years old (mean age 59.0 years ± 7.6) who were treated with surgical revascularization of 45 affected hemispheres. Of the affected hemispheres, 27 (60%) were treated with indirect bypasses and 18 (40%) were treated with direct bypasses. Neurologic complications occurred in 4 (12%) patients. The mean length of follow-up was 18.7 months ± 18.6; 4 patients were lost to follow-up. At last follow-up, 11 of 18 (61%) direct bypasses were patent. Treatment failed in 5 of 45 (11%) treated hemispheres (stroke in 2 and persistent transient ischemic attacks in 3). In terms of functional outcome at last follow-up, 16 of 29 (55%) patients were the same as before surgery, 10 (35%) were better, and 3 (10%) were worse (including 1 death)., Conclusions: Although uncommon, moyamoya angiopathy can manifest in older adults. Surgical revascularization is a reasonable treatment option with good functional outcomes and an acceptable complication rate., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Arginine vasopressin (AVP) is a common second-line or third-line vasopressor used in critically ill neurosurgical patients. Neurosurgical indications include hyperdynamic therapy for vasospasm, maintenance of cerebral perfusion pressure in patients with intracranial hypertension, and prevention of hypotension in patients with sepsis., Case Description: A series of 6 neurosurgical patients receiving AVP infusions developed severe but transient diabetes insipidus (tDI) after cessation of AVP. To our knowledge, no previous reports of this phenomenon in neurosurgical patients have been published. We reviewed the clinical histories, intensive care unit treatment, medication administration records, and laboratory values of these patients, and we found recurrent elevated serum sodium and urine output and decreased urine specific gravity after discontinuation of AVP. Resolution of tDI occurred upon resumption of AVP or administration of desmopressin. Elevated serum sodium levels were often severe, resulting in worsened clinical outcomes. When AVP was resumed, tDI typically recurred if AVP was again tapered and discontinued. Routine administration of desmopressin was useful in controlling sodium levels until the tDI resolved., Conclusions: Recognition of this phenomenon has caused us to change our clinical management of neurosurgical patients receiving AVP. We hypothesize that tDI is caused by downregulation of the V2 receptor mass in the renal distal convoluted tubule and collecting duct cells. When AVP is discontinued, patients develop nephrogenic tDI secondary to decreased V2 receptor binding, which explains why desmopressin is effective in correcting tDI. Future research includes a large prospective study to determine risk factors for tDI, its incidence, and its pathophysiology., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: The safety of carotid endarterectomy in patients with a response to antiplatelet agents (aspirin and clopidogrel) confirmed by point-of-care testing is unknown. Thus, we sought to determine whether using point-of-care assessment of platelet inhibition reveals risk factors for operative complications or predicts clinical outcomes., Methods: We reviewed records of carotid endarterectomy patients treated from March 2013 to July 2015 to extract demographics, lesion characteristics, laboratory data, procedural complications, and follow-up. Administration of aspirin, clopidogrel, or therapeutic anticoagulation within 5 days before surgery was recorded., Results: We analyzed 79 patients with 86 lesions (mean age 70.9 ± 10.0 years). More patients with a P2Y12 reaction unit (PRU) <170 had neck hematomas (4/10, 40.0%) than those with a PRU ≥170 (2/9, 22.2%) (P = 0.63). Estimated blood loss ≥100 mL was more frequent among patients with PRU <170 (9/10, 90.0%) than among those with PRU ≥170 (5/9, 55.6%) (P = 0.09). Clopidogrel use, regardless of response, independently predicted neck hematoma in a logistic regression model, with increased odds of 8.5. Mean postoperative modified Rankin Scale scores did not differ statistically between clopidogrel users and nonusers at a mean follow-up of 108.5 ± 146.3 days (P = 0.27)., Conclusions: Clopidogrel use within 5 days of carotid endarterectomy independently predicted postoperative neck hematomas, most of which were managed conservatively. Patients with PRU <170 were more likely to have estimated blood loss ≥100 mL during surgery and surgery lasting ≥3 hours., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Ethmoidal dural arteriovenous fistulas (dAVFs) have a malignant natural history and an anatomy that make endovascular therapy challenging. Their uniqueness begs for stratified analyses, but this has largely been precluded by their rarity. We sought to summarize the anatomic, presentation, treatment approaches, and clinical outcomes of patients with these lesions., Methods: We reviewed our prospectively maintained institutional database to identify patients diagnosed with ethmoidal dAVFs from January 1, 2000, to December 31, 2015. We evaluated demographic, presentation, angiographic, treatment, and follow-up data., Results: In total, 27 patients with ethmoidal dAVFs underwent endovascular and/or surgical treatment. Mean patient age was 62 years old and there was a male sex predilection (67% men; 2:1 male-female ratio). All dAVFs exhibited direct cortical venous drainage; venous ectasia was present in 59% of cases. Of the dAVFs, 30% drained posteriorly into the basal vein of Rosenthal or the sylvian veins. Embolization with casting of the draining vein was successful in 2 of 9 cases (22%), including 1 successful transvenous case. There were no clinical or permanent complications from embolization; specifically, no patients experienced visual loss after treatment. Surgical treatment with successful dAVF obliteration was carried out in 24 of 24 patients (100%). One patient declined surgical treatment after attempted endovascular embolization. There were no permanent complications after surgical treatment and no cases of wound infection or cerebrospinal fluid leakage., Conclusions: Surgical disconnection remains the gold standard in the treatment of ethmoidal dAVFs. Embolization is a consideration for well-selected cases with favorable arterial or venous access anatomy., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Surgical revascularization for adults with moyamoya disease (MD) includes direct, indirect, or combination bypasses. It is unclear which provides the best outcomes. We sought to determine the best surgical management for adults with MD by comparing perioperative complications and long-term outcomes among 3 bypass types., Methods: Literature databases were searched for articles reporting revascularization bypass outcomes for adults with MD. A pooled analysis of all qualified studies and meta-analysis using only studies reporting direct comparisons of 2 bypass types were performed. Overall odds ratios (ORs) comparing 2 bypass types were computed and publication bias was assessed. Rates of perioperative and long-term hemorrhage and ischemia and favorable outcomes were compared., Results: Forty-seven studies were analyzed; 8 had level 1 or 2 evidence. Pooled analyses showed that perioperative hemorrhage rates were significantly (P = 0.02) lower with indirect compared with direct (OR, 0.03; 95% confidence interval [CI], 0.002-0.55) or combined (OR, 0.03; 95% CI, 0.002-0.53) bypasses. Meta-analysis showed that direct bypass was better at preventing long-term hemorrhage than was indirect bypass (OR, 0.26; 95% CI, 0.09-0.79; P = 0.02). Pooled analyses showed that direct is significantly better (P < 0.01) than indirect (OR, 0.51; 95% CI, 0.33-0.77) and combined (OR, 0.47; 95% CI, 0.31-0.72) bypasses in preventing long-term ischemia. Meta-analysis showed that direct was better than indirect bypass in producing long-term favorable outcomes (OR, 2.62; 95% CI, 1.19-5.79; P = 0.02), and the pooled analysis showed that combined bypass was better than indirect bypass in producing long-term favorable outcomes (OR, 1.26; 95% CI, 1.03-1.54; P = 0.02)., Conclusions: Overall, our analyses suggest that direct bypass with or without indirect augmentation provides the best outcomes for adults with MD., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: Some aneurysms without a definable neck and associated parent vessel pathology are particularly difficult to treat and may require clipping with circumferential wrapping. We report the largest available contemporary series examining the techniques of Gore-Tex clip-wrapping of ruptured and unruptured intracranial aneurysms and patient outcomes., Methods: The presentation, location, and shape of the aneurysm; wrapping technique; outcome at discharge and last follow-up; and any change in the aneurysm at last angiographic follow-up were reviewed retrospectively in 30 patients with Gore-Tex clip-wrapped aneurysms., Results: Gore-Tex clip-wrapping was used in 8 patients with ruptured aneurysms and 22 patients with unruptured aneurysms. Aneurysms included 23 fusiform, 3 blister, and 4 otherwise complex, multilobed, or giant aneurysms. Of the 30 aneurysms, 63% were in the anterior circulation. The overall mean patient age was 52.5 years (range, 17-80 years). Postoperatively, there were no deaths or worsening of neurologic status and no parent vessel stenoses or strokes. The mean Glasgow Outcome Scale score at last follow-up was 4.7. The mean follow-up time was 42.3 months (median, 37.0 months; range, 3-96 months). There were 105.8 patient follow-up years. Aneurysms recurred in 2 patients with Gore-Tex clip-wrapping. No patients developed rehemorrhage. Overall risk of recurrence was 1.9% annually., Conclusions: Gore-Tex has excellent material properties for circumferential wrapping of aneurysms and parent arteries. It is inert and does not cause a tissue reaction or granuloma formation. Gore-Tex clip-wrapping can be used safely for microsurgical management of ruptured and unruptured cerebral aneurysms with acceptable recurrence and rehemorrhage rates., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Neurosurgery simulator development is growing as practitioners recognize the need for improved instructional and rehearsal platforms to improve procedural skills and patient care. In addition, changes in practice patterns have decreased the volume of specific cases, such as aneurysm clippings, which reduces the opportunity for operating room experience., Objective: The authors developed a hands-on, dimensionally accurate model for aneurysm clipping using patient-derived anatomic data and three-dimensional (3D) printing. Design of the model focused on reproducibility as well as adaptability to new patient geometry., Methods: A modular, reproducible, and patient-derived medical simulacrum was developed for medical learners to practice aneurysmal clipping procedures. Various forms of 3D printing were used to develop a geometrically accurate cranium and vascular tree featuring 9 patient-derived aneurysms. 3D printing in conjunction with elastomeric casting was leveraged to achieve a patient-derived brain model with tactile properties not yet available from commercial 3D printing technology. An educational pilot study was performed to gauge simulation efficacy., Results: Through the novel manufacturing process, a patient-derived simulacrum was developed for neurovascular surgical simulation. A follow-up qualitative study suggests potential to enhance current educational programs; assessments support the efficacy of the simulacrum., Conclusions: The proposed aneurysm clipping simulator has the potential to improve learning experiences in surgical environment. 3D printing and elastomeric casting can produce patient-derived models for a dynamic learning environment that add value to surgical training and preparation., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: The potential for radiation exposure during neurosurgical training has increased dramatically in the last decade. Incorporation of instrumented and minimally invasive spinal surgery and neuroendovascular procedures into the curriculum has led to increased potential for exposure to ionizing radiation. Contemporary neurosurgery residents' exposure to radiation has not been previously reported., Objective: To determine neurosurgery residents' exposure to radiation over the course of 7 years of training., Methods: Retrospective analysis of a prospectively maintained radiation database from July 2009 to July 2014 for all neurosurgery residents based on radiation dosimetry data. Standard radiation safety precautions were used (e.g., lead gowns or aprons), although compliance was not specifically monitored., Results: Thirty-eight neurosurgery residents were monitored from 2009 to 2014. Radiation exposure data were available for 34 residents for the final analysis. A total of 20,541 days of radiation monitoring data were available. The mean deep dose equivalent over this period was 0.67 ± 0.75 mrem per resident/day. The calculated maximum cumulative exposure during the course of residency training was 12.15 ± 13.50 mSv, approximately equivalent to 6 computed tomography head scans., Conclusions: To our knowledge, this study is the first to quantify radiation exposure for neurosurgery residents in the current era of training. From this work, efforts may be initiated to increase awareness and safety with regard to radiation exposure. Although the total dose is not high, a better understanding of the impact of radiation exposure on practitioners may help to drive institutional policies to reduce occupational exposure., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: The three-dimensional (3D) endoscope is a novel tool that provides stereoscopic vision and may allow for improved dexterity and safety during surgical resection of ventral skull base lesions. We describe here the cumulative experience available in the neurosurgical literature., Methods: A PubMed literature review was performed to identify and analyze all studies pertaining to 3D endoscopic endonasal skull base surgery., Results: We identified 26 articles: 14 clinical articles, 5 simulated environment studies, 5 human cadaveric studies, and 2 expert opinions. In all the clinical studies, 262 patients were treated for the following 257 pathologies listed in the articles: 190 suprasellar/parasellar lesions (73.9%), 41 ventral skull base lesions (16.0%), 19 sinonasal pathologies (7.4%), and 7 cerebrospinal fluid leak repairs (2.7%). Complication rates, operative time, length of hospital stay, and extent of tumor resection were equivalent between two-dimensional (2D) and 3D endoscopy. However, all studies reported that subjective depth perception and spatial orientation were markedly improved with 3D technology. In 3 studies (11.5%), it was concluded that there was no clinically significant surgical benefit in switching from 2D to 3D endoscopy. All cadaveric studies and expert opinions concluded that 3D endoscopy improved the identification of key anatomical structures and was superior to 2D endoscopy. Simulated environment studies demonstrated that 3D endoscopy improved speed and accuracy of endonasal tasks, more so in novice surgeons., Conclusions: Our findings suggest that 3D endoscopy provides improved surgical dexterity by affording the surgeon with depth perception when manipulating tissue and maneuvering the endoscope in the endonasal corridor., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: We used microscopy with endoscopic assistance to conduct an objective analysis of 4 surgical approaches commonly used in the surgery of the ambient cistern: infratentorial supracerebellar (SC), occipital interhemispheric (OI), subtemporal (ST), and transchoroideal (TC). In addition, we performed a parahippocampalis gyrus resection in the ST context., Methods: Each approach (SC, OI, ST, TC) was performed on 3 cadaveric heads (6 sides). After the microscopic anatomic dissection, the 30-degree endoscope was used to explore the exposure. The parahippocampalis gyrus was resected through an ST approach and the exposure was evaluated. The quantitative analysis was based on linear exposure of the vascular structures (linear exposure), such as the posterior choroidal artery (PChA), the P2 and P3 segments of the posterior cerebral artery (PCA) with their branches, the basal vein of Rosenthal, and the area of exposure of the ambient cistern region (area of exposure) limited by points on its superior, mesial, and anterior walls. In all cases, a P value of less than 0.05 was considered significant., Results: There was a significant difference (P < 0.05) in linear exposure of the PCA and medial PChA between microsurgery and endoscopic assistance using the ST approach. This approach also improved the medial, superior, and total exposure of the ambient cistern region., Conclusions: This study demonstrates that endoscope assistance improved exposure of the ambient cistern region when using the ST approach. Endoscopic assistance provided similar surgical exposure compared with ST associated with parahippocampalis resection., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Educational simulators provide a means for students and experts to learn and refine surgical skills. Educators can leverage the strengths of medical simulators to effectively teach complex and high-risk surgical procedures, such as placement of an external ventricular drain., Objective: Our objective was to develop a cost-effective, patient-derived medical simulacrum for cerebral lateral ventriculostomy., Methods: A cost-effective, patient-derived medical simulacrum was developed for placement of an external lateral ventriculostomy. Elastomeric and gel casting techniques were used to achieve realistic brain geometry and material properties. 3D printing technology was leveraged to develop accurate cranial properties and dimensions. An economical, gravity-driven pump was developed to provide normal and abnormal ventricular pressures. A small pilot study was performed to gauge simulation efficacy using a technology acceptance model., Results: An accurate geometric representation of the brain was developed with independent lateral cerebral ventricular chambers. A gravity-driven pump pressurized the ventricular cavities to physiologic values. A qualitative study illustrated that the simulation has potential as an educational tool to train medical professionals in the ventriculostomy procedure., Conclusion: The ventricular simulacrum can improve learning in a medical education environment. Rapid prototyping and multi-material casting techniques can produce patient-derived models for cost-effective and realistic surgical training scenarios., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: The endoscopic supracerebellar-infratentorial (SCIT) approach is a viable method to access pathology of the posterior incisura, but a narrow working space and frequent instrument conflict can potentially limit its surgical efficacy. Until now, no rigorous studies were available comparing surgical freedom and angle of attack for four previously well-described approaches to pineal region targets., Methods: Four formalin-fixed cadaver heads were dissected bilaterally (eight sides). A midline approach and three progressively lateral approaches to the pineal region were performed (paramedian, lateral, extreme lateral), and anatomical targets were identified. Utilizing frameless stereotaxy, we calculated surgical freedom using the vector cross-product method for all approaches for the exposed area and for three anatomical targets (pineal gland, ipsilateral superior colliculus, splenium). The mean and maximum possible angles of attack were calculated in the axial and sagittal planes., Results: Point target surgical freedom, exposed area surgical freedom, and angle of attack for each individual pineal region target can be maximized depending on the medial-to-lateral location of the craniotomy. For endoscopic-controlled approaches, the extreme lateral approach provides the largest surgical freedom when accessing the ipsilateral superior colliculus (P < 0.0001), the lateral approach provides the largest surgical freedom to the pineal gland (P < 0.0001), and the paramedian craniotomy provides the largest surgical freedom when accessing the splenium (P < 0.0001). The extreme lateral approach to the pineal gland provided the largest horizontal angle of attack (P < 0.0001), and the extreme lateral approach to the ipsilateral superior colliculus provided the largest vertical angle of attack (P < 0.001). The microscope provides marginally increased surgical freedom and a better angle of attack to specific anatomical targets in the paramedian and extreme lateral approach compared with those provided by the endoscope, but these differences are negligible during intraoperative application., Conclusions: Presurgical planning and a detailed understanding of the important neurovascular structures in the pineal region are paramount to safe and successful surgical execution. Our current cadaveric study indicates that the medial-to-lateral location of craniotomy can maximize access to pineal region targets. Furthermore, the endoscope is a viable alternative to the microscope for identifying pathology of the posterior incisura. These differences in surgical freedom and angle of attack to the pineal region may be useful to consider when planning minimal-access approaches., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Giant intracranial aneurysms are rare lesions that present uniquely complex therapeutic challenges. Computational fluid dynamics (CFD) has been used to simulate the hemodynamic environments of developing and ruptured cerebral aneurysms. In this study, we use CFD to examine retrospectively hemodynamic changes during the complicated clinical course of a giant carotid aneurysm., Objective: To take an innovative, CFD-based approach to retrospective analysis of the surgical management and clinical course of a giant carotid aneurysm., Methods: Pre- and posttreatment image data were first segmented to produce computational aneurysm models. Flow within the models was then simulated using CFD. Simulated flow and wall shear stress (WSS) profiles were analyzed and used to examine hemodynamic changes during the clinical course of the patient, after 2 independent treatments., Results: Greater WSS magnitudes and a more localized flow impingement region were observed at the distal portion of the aneurysm after both clinical interventions. These relative, acute changes in hemodynamic features at the distal aneurysm wall were greatest after the second intervention and may have preceded rupture of the aneurysm in that region., Conclusions: The application of CFD to the management of a giant intracranial aneurysm showed unexpected posttreatment changes in flow and WSS profiles. The simulation results offer a viable explanation for the observed clinical course. This study demonstrates potential for the use of CFD preoperatively for decision-making in the surgical and endovascular management of intracranial aneurysms., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: There has been a progressive decrease in the indications for cerebral revascularization during the past 30 years, particularly with the advance of endovascular techniques. Our objective was to define indications for and evaluate outcomes of patients treated with bypass surgery in the modern endovascular era., Methods: We retrospectively reviewed the charts of all patients who underwent direct cerebral revascularization procedures between January 2006 and March 2013., Results: In total, 121 patients underwent 131 direct microsurgical revascularization procedures. The indications for bypass surgery were moyamoya angiopathy (40 patients, 47 bypasses), complex aneurysms (54 patients, 56 bypasses), and occlusive vascular disease (27 patients, 28 bypasses). Revascularization resulted in improvement of symptoms in 77.5% of patients with moyamoya angiopathy (mean clinical follow-up 18.8 months) and 55.5% of patients with occlusive vascular disease (mean clinical follow-up 10.4 months). Among the aneurysm patients treated with revascularization, 81.5% had a favorable outcome (Glasgow Outcome Scale score 4-5) at long-term follow-up (mean clinical followup 18.5 months)., Conclusions: Although microvascular cerebral revascularization is no longer performed as commonly as in the past, it remains an essential part of the skill set required to treat select vascular pathologies. Complex aneurysms are the single largest indication for direct bypass procedures. Moyamoya disease is by far the largest indication if indirect bypass procedures are included in the analysis. In experienced hands, the morbidity and mortality of patients undergoing cerebral revascularization procedures are low and long-term outcomes generally excellent., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: Neurenteric cysts (NECs) are uncommonly encountered lesions of the central nervous system with heterogeneous imaging characteristics. The object of this study was to review the preoperative imaging findings represented among a cohort of surgically treated posterior fossa NECs. These findings are considered in the context of surgical technique, and inform an understanding of aberrant neuroembryological development associated with NECs., Methods: A single-institution, multisurgeon series of 7 consecutive patients (5 female and 2 male patients, mean age 36 years, range 19 to 57 years) treated surgically for histopathologically confirmed posterior fossa NECs was retrospectively reviewed. Lesion imaging and anatomic characteristics were noted on preoperative magnetic resonance imaging (MRI). Imaging comparisons were made against an additional cohort of 266 consecutive surgically treated posterior fossa masses to validate unique anatomic findings., Results: T1 and T2 MRI signal characteristics were variable when compared across lesions. All NECs were found to be anteriorly located within the posterior fossa, but always situated between the brainstem pial surface and the vertebrobasilar system, causing ventral displacement of vertebrobasilar vessels., Conclusions: Posterior fossa NECs display variable patterns of MRI signal and are commonly considered as part of a broad differential of cystic posterior fossa masses. We identified tumor insinuation between the ventral brainstem and vertebrobasilar system as a highly sensitive and specific radiographic sign for NECs. This finding was not observed among a large cohort of posterior fossa masses representative of other multiple pathologies., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: The nasolacrimal duct resides in the wall of the medial nasal cavity and influences minimal access endoscopic transmaxillary approaches to the lateral skull base. We describe an algorithm for surgical approach selection on the basis of the relationship of the target lesion to a line drawn from the anterior nasal SEptum through the Nasolacrimal Duct to the lesion (i.e., SEND line)., Methods: We use the SEND line to estimate the lateral extent in the endonasal middle meatal transmaxillary approach, where the surgeon has good surgical freedom without the use of angled instruments and endoscopes. Lesions with an epicenter lateral to the SEND line were addressed through a sublabial anterior antrostomy transmaxillary corridor. Tumors with a more medially located epicenter, such as those involving the lateral sphenoid sinus and pterygoid plates, were addressed through the endonasal middle meatal corridor. Extensive tumors involving both domains were addressed through a combination approach., Results: We describe three instructive cases in which the approach selection was determined in part by preoperative assessment of the location of the tumor relative to the SEND line., Conclusions: The endoscopic sublabial transmaxillary and endoscopic endonasal middle meatal transmaxillary approaches are complementary corridors to the anterior skull base that can be used independently or in combination. The location of the target lesion relative to the SEND line as determined on preoperative imaging can serve as a guide for surgical decision making., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: Endoscopic approaches are increasingly utilized to treat third ventricular colloid cysts but have been associated with lower rates of complete cyst wall resection. Our objective was to assess the results of colloid cyst resection via an anterolateral endoscopic approach with a dual-instrument technique, with an emphasis on completeness of cyst wall resection., Methods: A retrospective review of the senior author's experience with 22 colloid cysts treated with endoscopic resection since 2004 was performed. Initial cyst size, completeness of resection, postoperative radiographic residual, recurrence at follow-up, need for reoperation, and neurologic morbidity were assessed. All cysts were approached from an anterolateral trajectory with two instruments working in concert through a single endoscope., Results: Of 22 patients, near-total resection was obtained in 95%. In 3 cases, a very small, radiographically occult residual was left. Complete cyst wall resection was therefore obtained in 18 (82%). There were no cases of recurrence at follow-up in any patient. No patients required craniotomy or underwent re-resection. Fifteen of 16 (94%) patients with long-term clinical follow-up remained stable or improved., Conclusion: High rates of complete colloid cyst resection, with low morbidity, are possible with an anterolateral endoscopic approach with dual-instrument technique. These results support the findings of other endoscopists that show how technical modifications to traditional endoscopic approaches can produce favorable results., (Copyright © 2013 Elsevier Inc. All rights reserved.)