Papillary glioneuronal tumor presenting with low-pressure hydrocephalus from intraventricular spread: Case Report.

Papillary glioneuronal tumors are a rare and typically benign entity with pathological and radiographic complexity. Presentation can mimic other neoplasms, making diagnosis more challenging. The literature to date describes the clinical understanding, diagnostic, therapeutic, and prognostic characteristics of this limited number of patients. In this article, we report an unusual case of a glioneuronal tumor with multifocal presentation, normal pressure hydrocephalus-like symptoms, and large peritumoral parenchymal cysts, which guided the surgical approach. This unusual presentation has not previously been reported and adds valuable information to the clinical recognition and management literature.

Live-Streaming Surgery for Medical Student Education - Educational Solutions in Neurosurgery During the COVID-19 Pandemic.

OBJECTIVE: The COVID-19 pandemic significantly altered medical student education. The ability for students to be a part of the operating room team was highly restricted. Technology can be used to ensure ongoing surgical education during this time of limited in-person educational opportunities. DESIGN: We have developed an innovative solution of securely live-streaming surgery with real-time communication between the surgeon and students to allow for ongoing education during the pandemic. RESULTS: We successfully live-streamed multiple different types of neurosurgical operations utilizing multiple video sources. This method uses inexpensive, universal equipment that can be implemented at any institution to enable virtual education of medical students and other learners. CONCLUSIONS: This technology has facilitated education during this challenging time. This technological set-up for live-streaming surgery has the potential of improving medical and graduate medical education in the future.

Vascularity of meningiomas.

Information on the vascular supply to meningiomas is critical to the neurosurgeon. Most meningiomas are supplied by the external carotid artery, though many get pial contribution as well. Angiogenesis is critical for these neoplasms to grow. Vascular endothelial growth factor (VEGF) has been a popular target of research to decrease angiogenesis. Peritumoral brain edema (PTBE) is occasionally seen in meningiomas, which makes surgical resection more challenging. The exact cause of PTBE remains unclear, but a number of factors have been postulated to contribute. Assessment of the vascularity of meningiomas is best carried out with angiography, but noninvasive techniques are improving, diminishing the need for more invasive imaging. Embolization of tumors can be performed to minimize perioperative blood loss and potentially lower surgical morbidity. However, it has not been shown to improve outcomes, and procedural risks exist. Higher grade tumors commonly have higher vascularity. Higher vascular meningiomas are more likely to recur and have higher levels of VEGF. The vascularity of meningiomas remains a topic of interest and is the focus of many research projects.

Surgical Management of Spinal Arachnoid Cysts in Adults.

BACKGROUND: Spinal arachnoid cysts (SACs) are uncommon lesions in the spinal canal. They are usually asymptomatic, but can occasionally cause mass effect leading to neurologic symptoms. They can be congenital or secondary to a variety of causes. They can produce a variety of neurologic symptoms including pain, weakness, sensory changes, incontinence, and more. Surgical intervention may be necessary when SACs cause symptomatic mass effect. METHODS: Thirteen consecutive patients who underwent surgical intervention for an SAC were retrospectively reviewed. The data included presenting symptoms, imaging findings, neurologic status, and follow-up. RESULTS: Of the 13 patients, the majority of cases were located in the thoracic spine (54%) and all but one case were located dorsally or dorsolaterally. Furthermore, 38% were located extradurally and 54% were located intradurally. Pain (80%) was the most common presenting symptom. Most patients had improvement or complete resolution of their symptoms after intervention. Extradural SACs and their capsules were completely resected, whereas intradural SACs underwent fenestration. No complications occurred in this series. CONCLUSIONS: SACs are usually asymptomatic, but rarely cause mass effect and neurologic deficits requiring surgical intervention. Surgical intervention is tailored to the position of the cysts' dorsal or ventral locations. Pain and weakness are the most likely symptoms to improve, whereas sensory symptoms are least likely to improve.

Virtual, 3-Dimensional Temporal Bone Model and Its Educational Value for Neurosurgical Trainees.

OBJECTIVE: Learning complex neuroanatomy is an arduous yet important task for every neurosurgical trainee. As technology has advanced, various modalities have been created to aid our understanding of anatomy. This study sought to assess the educational value of a virtual, 3-dimensional (3D) temporal bone model. METHODS: The 3D temporal bone model was created with assistance of computer graphic designers and published online. Its educational value as a teaching was tool was assessed by querying 73 neurosurgery residents at 4 institutions and was compared with that of a standard, 2-dimensional (2D) temporal bone resource. Data were collected via a survey, and significance among responses was analyzed via a univariate chi-square test. RESULTS: The survey response rate was 37%. Greater than 90% of residents preferred to study with the 3D model compared with the 2D resource and felt that the 3D model allowed them understand the anatomy more realistically (P = 0.001). Moreover, >90% of residents believed that reviewing the 3D model before an actual surgery could lead to improved operative efficiency and safety (P = 0.001). CONCLUSIONS: This study demonstrates the utility of a novel, 3D temporal bone model as a teaching tool for neurosurgery residents. The model contains accurate anatomic structures and allows user interaction via a virtual, immersive environment.

The Application of FLOW 800 ICG Videoangiography Color Maps for Neurovascular Surgery and Intraoperative Decision Making.

BACKGROUND: Indocyanine green (ICG) videoangiography can assess cerebral blood flow, but results are primarily qualitative. FLOW 800 software measures fluorescence dynamics and creates a semiquantitative color delay map for assessment of relative sequence of blood flow within the vasculature. METHODS: We retrospectively reviewed 23 consecutive patients for whom FLOW 800 ICG videoangiography was used. They harbored aneurysms, arteriovenous malformations (AVMs), dural arteriovenous fistula (dAVF), or hemangioblastoma. Patients' characteristics, FLOW 800 data, and clinical findings were recorded. Color map data were readily available intraoperatively and guided surgery. RESULTS: The cohort included 10 patients with AVMs, 11 with aneurysms, 1 with dAVF, and 1 with hemangioblastoma. Approximately two thirds of patients underwent intraoperative angiography. FLOW 800 data provided semiquantitative data regarding localization, flow status in major feeding arteries, and dominance of the arterialized draining veins for AVMs, more than data from ICG videoangiography alone. For complex aneurysms, color maps confirmed relative adequate flow in parent and branching vessels. For the foramen magnum dAVF, the location of the dominant transdural connection was appreciated only via flow analysis. Flow analysis created the blood flow map of a large complex solid brainstem hemangioblastoma and guided devascularization. All FLOW 800 findings agreed with intraoperative and postoperative angiography. CONCLUSIONS: ICG videoangiography with FLOW 800 analysis can provide semiquantitative and relative flow magnitude data that are efficient and noninvasive. This process helps identify early arterialized veins and their flow status during AVM and dAVF surgery and can confirm adequate relative flow within branching vessels during aneurysm surgery when clip-induced stenosis is suspected.

Supracerebellar Infratentorial and Occipital Transtentorial Approaches to the Pulvinar: Ipsilateral Versus Contralateral Corridors.

BACKGROUND: Due to the critical neurovascular structures that surround the pulvinar, deciding the best surgical approach can be challenging, with multiple options available. OBJECTIVE: To analyze and compare the ipsilateral vs the contralateral version of the 2 main approaches to the cisternal pulvinar surface: paramedian supracerebellar infratentorial (PSCI) and interhemispheric occipital transtentorial (IOT). METHODS: The PSCI and IOT approaches were performed on 7 formalin-fixed adult cadaveric heads to evaluate qualitatively and quantitatively the microsurgical exposure of relevant anatomic structures. We quantitatively measured the corridor distance to our target with each approach. RESULTS: The ipsilateral PSCI approach provided an easier access and a better exposure of the anteromedial portion of the cisternal pulvinar surface. The contralateral approach provided a wider and more accessible exposure of the posterolateral portion of the cisternal pulvinar surface. When protrusion of the posterior parahippocampal gyrus above the free edge of the tentorium was present, the contralateral PSCI approach provided an unobstructed view to both areas. The IOT approach provided a better view of the anteromedial portion of the cisternal pulvinar surface, especially with a contralateral approach. CONCLUSION: Multiple approaches to the pulvinar have been described, modified, and improved. Based on this anatomic study we believe that although the corridor distance with a contralateral approach is longer, the surgical view and access can be better. We recommend the use of a PSCI contralateral approach especially when a significant protrusion of the posterior parahippocampal gyrus is present.

External cortical landmarks for localization of the hippocampus: Application for temporal lobectomy and amygdalohippocampectomy.

BACKGROUND: Accessing the hippocampus for amygdalohippocampectomy and minimally invasive procedures, such as depth electrode placement, require an accurate knowledge regarding the location of the hippocampus. METHODS: The authors removed 10 human cadaveric brains from the cranium and observed the relationships between the lateral temporal neocortex and the underlying hippocampus. They then measured the distance between the hippocampus and superficial landmarks. The authors also validated their study using magnetic resonance imaging (MRI) scans of 10 patients suffering from medial temporal lobe sclerosis where the distance from the hippocampal head to the anterior temporal tip was measured. RESULTS: In general, the length of the hippocampus was along the inferior temporal sulcus and inferior aspect of the middle temporal gyrus. Although the hippocampus tended to be more superiorly located in female specimens and on the left side, this did not reach statistical significance. The length of the hippocampus tended to be shorter in females, but this too failed to reach statistical significance. The mean distance from the anterior temporal tip to the hippocampal head was identical in the cadavers and MRIs of patients with medial temporal lobe sclerosis. CONCLUSIONS: Additional landmarks for localizing the underlying hippocampus may be helpful in temporal lobe surgery. Based on this study, there are relatively constant anatomical landmarks between the hippocampus and overlying temporal cortex. Such landmarks may be used in localizing the hippocampus during amygdalohippocampectomy and depth electrode implantation in verifying the accuracy of image-guided methods and as adjuvant methodologies when these latter technologies are not used or are unavailable.

Three-Dimensional Printed Model Used to Teach Skull Base Anatomy Through a Transsphenoidal Approach for Neurosurgery Residents.

BACKGROUND: Skull base anatomy through a transsphenoidal approach is challenging for the neurosurgical resident to conquer. OBJECTIVE: To demonstrate that stereolithography, or 3-dimensional (3-D) printing, is a useful educational tool for neurosurgery residents to learn skull base anatomy. METHODS: Before any formal teaching, residents were brought into the operating room where they were asked to identify key structures seen through an endoscopic transsphenoidal approach. Scoring was based on correctly naming the anatomical structures. After the initial testing, all residents participated in a didactic lecture reviewing this anatomy by using 2-dimensional pictures. Residents were then divided into 2 groups: A and B. Group B residents were additionally taught through neurosurgical simulation using a 3-D printed model and an endoscope. Following all formal teaching, residents were retested in the operating room. RESULTS: A maximum score of 8 points was possible if all structures were identified correctly. Group A had mean scores of 2.75 on initial testing compared with 5 after the lecture (P = .041 using 2-tailed t test). Group B had mean scores of 2.75 on initial testing compared with 7.5 after the lecture and 3-D model simulation (P = .002). When comparing mean scores after formal teaching in groups A and B, 5 vs 7.5 were obtained for lecture only vs lecture and 3-D model simulation, respectively (P = .031). CONCLUSION: Three-dimensional models used in neurosurgical simulation to teach skull base anatomy through a transsphenoidal approach showed objective and subjective improvement in testing scores in neurosurgery residents. This study confirms that 3-D models are a useful educational tool.

Intracranial pseudoaneurysm after intracranial pressure monitor placement.

Traumatic intracranial pseudoaneurysms are a rare but severe complication following arterial injury. Pseudoaneurysm formation can occur secondary to blunt or penetrating trauma or iatrogenic injury. We report a case of traumatic pseudoaneurysm secondary to placement of an intracranial pressure (ICP) monitor. A 27-year-old man was involved in a motorcycle accident resulting in multiple intracranial hemorrhages. The patient underwent craniectomy and placement of an ICP monitor. 17 days later he developed dilation of his left pupil, with imaging demonstrating a new hemorrhage in the vicinity of the previous ICP monitor. A cerebral angiogram confirmed a left-sided distal M4 pseudoaneurysm which was treated by n-butyl cyanoacrylate embolization. Intracranial pseudoaneurysm formation following neurosurgical procedures is uncommon. Delayed intracranial hemorrhage in a region of prior intracranial manipulation, even following a procedure as 'routine' as placement of an ICP monitor, should raise the suspicion for this rare but potentially lethal complication.

Intracranial pseudoaneurysm after intracranial pressure monitor placement.

Traumatic intracranial pseudoaneurysms are a rare but severe complication following arterial injury. Pseudoaneurysm formation can occur secondary to blunt or penetrating trauma or iatrogenic injury. We report a case of traumatic pseudoaneurysm secondary to placement of an intracranial pressure (ICP) monitor. A 27-year-old man was involved in a motorcycle accident resulting in multiple intracranial hemorrhages. The patient underwent craniectomy and placement of an ICP monitor. 17 days later he developed dilation of his left pupil, with imaging demonstrating a new hemorrhage in the vicinity of the previous ICP monitor. A cerebral angiogram confirmed a left-sided distal M4 pseudoaneurysm which was treated by n-butyl cyanoacrylate embolization. Intracranial pseudoaneurysm formation following neurosurgical procedures is uncommon. Delayed intracranial hemorrhage in a region of prior intracranial manipulation, even following a procedure as 'routine' as placement of an ICP monitor, should raise the suspicion for this rare but potentially lethal complication.

Large Vestibular Schwannomas Presenting during Pregnancy: Management Strategies.

Objective Large vestibular schwannomas rarely present in pregnant women. Diagnosis and management of these tumors during pregnancy present a therapeutic challenge. Methods A 20-year-old primigravida woman at 26 weeks' gestation was transferred to our facility with gait imbalance, left facial weakness, left ear hearing loss, and recent nausea and vomiting. Magnetic resonance imaging revealed a large left cerebellopontine angle mass with extension into the left internal auditory canal and compression of the fourth ventricle resulting in mild hydrocephalus. The patient was admitted with a plan for early delivery at 32 weeks followed by tumor resection. One week later, the patient's headache and neurologic symptoms worsened due to increased hydrocephalus; a ventriculoperitoneal shunt was placed. The next day, an emergent cesarean delivery was performed due to worsening respiratory status. Four days later, a tracheostomy and percutaneous endoscopic gastrostomy tube were placed due to dysphagia. Eight days after the delivery, the mass was resected with a left retrosigmoid approach without complications. Immunohistochemistry confirmed vestibular cellular schwannoma on cranial nerve VIII showing unusually high mitotic activity. Results The patient was discharged to inpatient rehabilitation on postoperative day 12 without new neurologic deficit. At 1 month, the patient was swallowing without aspiration. Her facial sensation had returned, her facial weakness remained stable, and her gait was significantly improved. Conclusion If the patient is neurologically stable, the best option is to delay resection until after delivery. If resection is necessary during pregnancy, the optimal time is during the second trimester.