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Objective: Deep learning enables precise hand tracking without the need for physical sensors, allowing for unsupervised quantitative evaluation of surgical motion and tasks. We quantitatively assessed the hand motions of experienced cerebrovascular neurosurgeons during simulated microvascular anastomosis using deep learning. We explored the extent to which surgical motion data differed among experts., Methods: A deep learning detection system tracked 21 landmarks corresponding to digit joints and the wrist on each hand of 5 expert cerebrovascular neurosurgeons. Tracking data for each surgeon were analyzed over long and short time intervals to examine gross movements and micromovements, respectively. Quantitative algorithms assessed the economy and flow of motion by calculating mean movement distances from the baseline median landmark coordinates and median times between sutures, respectively., Results: Tracking data correlated with specific surgical actions observed in microanastomosis video analysis. Economy of motion during suturing was calculated as 19, 26, 29, 27, and 28 pixels for surgeons 1, 2, 3, 4, and 5, respectively. Flow of motion during microanastomosis was 31.96, 29.40, 28.90, 7.37, and 47.21 seconds for surgeons 1, 2, 3, 4, and 5, respectively., Conclusions: Hand tracking data showed similarities among experts, with low movements from baseline, minimal excess motion, and rhythmic suturing patterns. The data revealed unique patterns related to each expert's habits and techniques. The results showed that surgical motion can be correlated with hand motion and assessed using mathematical algorithms. We also demonstrated the feasibility and potential of deep learning-based motion detection to enhance surgical training., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The contributions of Laurent Princeteau (1858-1932) to anatomy and to the establishment of neurosurgery have largely gone unrecognized, perhaps because he was educated and practiced in a French city other than Paris at a time when Paris was one of the chief centers of medicine in Europe. After completing a thesis describing an iliac artery anomaly and obtaining the distinguished agrégé teaching degree, Princeteau began his surgical career at the University of Bordeaux. Within 10 years, he became chef de clinique and one of the busiest surgeons in Saint-André Hospital, as well as head of the anatomy institute and professor of anatomy at the dental school. In 1891, he achieved the rank of surgeon. In the field of general anatomy, he was recognized for novel cadaveric preparations and vascular perfusion techniques. In the neurosciences, he made important contributions to the anatomy of the trigeminal nerve and trigeminal neuralgia. In 1898, Princeteau supervised a thesis that addressed contemporary surgical approaches to the trigeminal complex. In the course of this effort, he identified a bony prominence near the petrous apex (the retrogasserian tubercle) that helped to locate the gasserian ganglion. The surgical significance of the retrogasserian tubercle was quickly acknowledged in the European neurosurgical community and was noted in French textbooks of anatomy. Thierry de Martel, a founding member of the French neurosurgical School, named the tubercle after Princeteau. To the rest of the world, however, it remained almost unknown., (Copyright © 2024. Published by Elsevier Inc.)

Because of the complexity of the brain and its structures, anatomical knowledge is fundamental in neurosurgery. Anatomical dissection, body preservation, and vascular injection remain essential for training, teaching, and refining surgical techniques. This article explores the historical development of these practices and provides the contextual background of modern neurosurgical cadaveric brain models. Body preservation has ancient beginnings, evident in the Chinchorro mummifications and Egyptian embalming. However, brain preservation techniques for education were scarce until the beginning of the Renaissance in Europe. At the University of Bologna in the 13th century, occasional dissections were performed only in winter because of the lack of preservation techniques. Pope Sixtus IV's 1482 papal bull (official decree) formalized and expanded the use of dissection in medical education, leading to an explosion in anatomical studies. This surge brought advances in body preservation, such as soaking bodies in vinegar and distilled liquors. In subsequent centuries, Andreas Vesalius and Charles Bell advanced brain anatomical techniques and knowledge, combining novel illustrations and instruction. To better understand brain vasculature, Richard Lower developed vascular injection techniques using india ink and spirits of wine, leading to the 1664 description of the circle of Willis by Thomas Willis. In 1868, August Hofmann synthesized formaldehyde, markedly improving tissue preservation. Later, William Kruse introduced latex in 1939, and Sidney Sobin introduced silicone in 1965 for vascular studies. These advancements laid the foundation for modern neurosurgical cadaveric studies, many remaining relevant today., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Multicompartmental lesions of the anterior craniovertebral junction require aggressive management. However, the lesions can be difficult to reach, and the surgical procedure is difficult to understand. The aim of this study was to create a procedural, stepwise microsurgical educational resource for junior trainees to learn the surgical anatomy of the extreme lateral transodontoid approach (ELTOA)., Methods: Ten formalin-fixed, latex-injected cadaveric heads were dissected under an operative microscope. Dissections were performed under the supervision of a skull base fellowship-trained neurosurgeon who has advanced skull base experience. Key steps of the procedure were documented with a professional camera and a high-definition video system. A relevant clinical case example was reviewed to highlight the principles of the selected approach and its application. The clinical case example also describes a rare complication: a pseudoaneurysm of the vertebral artery., Results: Key steps of the ELTOA include patient positioning, skin incision, superficial and deep muscle dissection, vertebral artery dissection and transposition, craniotomy, clivus drilling, odontoidectomy, and final extradural and intradural exposure., Conclusions: The ELTOA is a challenging approach, but it allows for significant access to the anterior craniovertebral junction, which increases the likelihood of gross total lesion resection. Given the complexity of the approach, substantial training in the dissection laboratory is required to develop the necessary anatomic knowledge and to minimize approach-related morbidity., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Purpose: Multiple hippocampal transection (MHT) is a surgical technique that offers adequate seizure control with minimal perioperative morbidity. However, there is little evidence available to guide neurosurgeons in selecting this technique for use in appropriate patients. This systematic review analyzes patient-level data associated with MHT for intractable epilepsy, focusing on postoperative seizure control and memory outcomes., Methods: The systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant articles were identified from 3 databases (PubMed, Medline, Embase) up to August 1, 2021. Inclusion criteria were that the majority of patients had received a diagnosis of intractable epilepsy, the article was written in English, MHT was the primary procedure, and patient-level metadata were included., Results: Fifty-nine unique patients who underwent MHT were identified across 11 studies. Ten (17%) of 59 patients underwent MHT alone. Forty-three (75%) of 57 patients who had a follow-up 12 months or longer were seizure free at last follow-up. With respect to postoperative verbal memory retention, 9 of 38 (24%) patient test scores did not change, 14 (37%) decreased, and 16 (42%) increased. With respect to postoperative nonverbal memory retention, 12 of 38 (34%) patient test scores did not change, 13 (34%) decreased, and 13 (33%) increased., Conclusion: There are few reported patients analyzed after MHT. Although the neurocognitive benefits of MHT are unproven, this relatively novel technique has shown promise in the management of seizures in patients with intractable epilepsy. However, structured trials assessing MHT in isolation are warranted., (Copyright © 2022. Published by Elsevier Ltd.)

Procedures performed along the skull base require technical prowess and a thorough knowledge of cranial anatomy to navigate the operative field. Anatomical triangles created by unique anatomical structures serve as landmarks to guide the surgeon during meticulous skull base procedures. The corridors rapidly orient the surgeon to the operative field and permit greater confidence regarding skull base position during dissection. A literature review was performed with use of the PubMed database and reference list searches from full-text reviewed articles, which resulted in the identification of 31 distinct anatomical triangles of the skull base. The 31 anatomical triangles are categorized into a corresponding cranial fossa or the extracranial subsection. The triangles described in the manuscript include junctional, interoptic, precommunicating, opticocarotid, supracarotid, parasellar, clinoidal, oculomotor, carotid-oculomotor, supratrochlear, infratrochlear, anteromedial, quadrangular, anterolateral, posteromedial, posterolateral, lateral, superior petrosal, oculomotor-tentorial, inferomedial, inferolateral, glossopharyngo-cochlear, vagoaccessory, suprahypoglossal, hypoglossal-hypoglossal, infrahypoglossal, parapetrosal, suprameatal, retromeatal, suboccipital, and the inferior suboccipital. The goal of this review is to create a comprehensive resource for existing skull base triangles that includes borders, contents, surgical applications, and illustrations to enhance awareness and inform microsurgical dissection., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: Although several commercially available sutureless anastomotic techniques are available, they are not routinely used in neurosurgery. We performed an in vivo flow analysis of end-to-end anastomosis using a microvascular coupler device in rats. We report our first clinical use of the microvascular anastomotic coupler., Methods: Bilateral rat common carotid arteries (CCAs) were exposed, and a microvascular coupler was used to perform 8 anastomoses. A microflow probe provided quantitative measurement of blood-flow volume. Flow augmentation was assessed with end-to-side anastomoses connecting the distal CCA to the jugular vein (JV). A patient with chronic dominant hemisphere atherosclerotic ischemic disease and progressive symptoms refractory to medical management underwent end-to-end cerebral artery bypass using the microvascular coupler., Results: Mean preanastomosis flow in the rat CCA was 3.95 ± 0.45 mL/min; this flow was maintained at 3.99 ± 0.24 mL/min on final measurements 54-96 minutes postanastomosis. Total occlusion time for each rat CCA was 12-19 minutes. After end-to-side anastomosis, with proximal and distal JV patent, CCA flow increased 477% to 22.8 ± 3.70 mL/min (P = 0.04, proximal; P = 0.01, distal). After in vivo testing, we successfully used the coupler clinically in a superficial temporal artery-to-middle cerebral artery bypass for dominant hemisphere flow augmentation., Conclusions: In vivo quantitative flow analysis demonstrated no flow difference between an unaltered artery and artery with end-to-end anastomosis using a microvascular coupler in rats. A 1-mm coupled anastomosis achieved a 4-fold flow increase with low-resistance venous outflow in rats, simulating increased arterial demand. The coupler was successfully used for extracranial-to-intracranial bypass in a patient., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: Transcranial anterior petrosectomy (AP) is a classic approach; however, it is associated with adverse consequences. The endoscopic endonasal approach (EEA) has been developed as an alternative. We describe surgical techniques for AP and EEA and compare the anatomic exposures of each., Methods: Ten cadaveric heads (20 sides) were dissected. Specimens were divided into 4 groups: 1) AP, 2) EEA for medial petrosectomy (MP), 3) EEA for inferior petrosectomy (IP), and 4) EEA for inferomedial petrosectomy (IMP). Outcomes were areas of exposure, angles of attack to neurovascular structures, and bone resection volumes., Results: AP had a greater area of exposure than did MP and IP (P = 0.30, P < 0.01) and had a higher angle of attack to the distal part of the facial nerve-vestibulocochlear nerve (cranial nerve [CN] VII/VIII) complex than did IP and IMP (P < 0.01). MP had a lower angle of attack than IMP to the midpons (P = 0.04) and to the anterior inferior cerebellar artery (P < 0.01). Compared with IMP, IP had a lower angle of attack to the proximal part of the CN VII/VIII complex (P < 0.01) and the flocculus (P < 0.01). The bone resection volume in AP was significantly less than that in MP, IP, and IMP (P < 0.01)., Conclusions: AP and all EEA techniques had specific advantages for each specific area. We suggest AP for the ventrolateral pons and the anterior superior internal auditory canal, MP for the midline clivus, IP for the ventrolateral brainstem, and IMP to enhance the lateral corridor of the abducens nerve., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Various well-known people associated with the history of the presidency of the United States have experienced neurologic disease or injury, especially trauma to the head or spine. Nancy Reagan, however, as the wife of President Ronald Reagan and First Lady, would leave a significant and lasting mark on the progress of neurosurgical science and education. Recognized for endeavors against drug abuse, Alzheimer disease, and polio, her interest in neurosurgical research is less well known. Nancy's father Loyal Davis was a remarkable neurosurgeon and educator of extraordinary influence. When Barrow Neurological Institute (BNI) founder John Green experienced complications after an illness, Davis served as BNI director during 1966 - 1967. After Davis's death in 1982, Robert Spetzler, who had been a student of Davis at Northwestern University Medical School and was then BNI director, convinced Green, despite his misgivings, to support a neurosurgical laboratory recognizing Davis. In 1988, Nancy Reagan, then First Lady, dedicated the Loyal and Edith Davis Neurosurgical Research Laboratory. At the dedication, she remarked on her years growing up in the home of a pioneering neurosurgeon and remarked that "my father believed deeply in the importance of research to develop new methods for treating patients." Green and Spetzler's unified efforts honored the extraordinary career of Davis in a manner he would have appreciated, were supported by a First Lady with deep involvement in politics and philanthropy dedicated to promoting advances in medicine, and are part of neurosurgery's unique heritage., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Transorbital neuroendoscopic surgery (TONES) offers a new level of minimally invasive, minimally disfiguring skull base surgery with maximal surgical visualization., Methods: This review systematically assesses the body of published anatomic (cadaveric) and clinical evidence for the approach. PubMed, Cochrane Library, Ovid MEDLINE, and Embase were systematically searched for articles in which the TONES surgical technique was used in an anatomic, clinical, or combined study. The outcomes of interest included identification of the diseases, operative outcomes, and complication rates., Results: Twenty-three articles were selected for this systematic review: 10 were purely anatomic, 10 were clinical, and 3 had both clinical and cadaveric components. The articles reported 69 patients undergoing transorbital or combined transorbital and transnasal intervention. A total of 30 cases of cerebrospinal fluid leak were documented; of these, 28 (93%) had successful resolution, 2 (7%) had recurrence, and 5 (15%) experienced complications. A total of 31 tumors were biopsied (n = 1), resected (n = 22), or debulked (n = 8). Meningiomas were the most common lesion managed via TONES, with 5 of 7 patients with meningioma who reported preoperative neurologic deficits experiencing an improvement in extraocular movement impairment, visual acuity, proptosis, and ptosis. Transient postoperative clinical sequelae, including diplopia and ptosis, were increasingly associated with the superior lid crease incision and the sole transorbital approach., Conclusions: TONES is a significant development in transorbital skull base surgery. However, comprehensive, robust, comparative analyses and increasing use and generalizability of this technique in skull base surgery are awaited., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The incorporation of perspective into art and science revolutionized the study of the brain. Beginning in about 1504, Leonardo da Vinci began to model the ventricles of the brain in three dimensions. A few years later, Andreus Vesalius illustrated radically novel brain dissections. Thomas Willis' work, Cerebri Anatome (1664), illustrated by Christopher Wren, remarkably showed the brain undersurface. Later, in the early 1800s, Charles Bell's accurate images of neural structures changed surgery. In the 1960s, Albert L. Rhoton Jr. (1932-2016) began to earn his place among the preeminent neuroanatomists by focusing his lens on microanatomy to harness a knowledge of microneurosurgery, master microneurologic anatomy, and use it to improve the care of his patients. Although his biography and works are well known, no analysis has been conducted to identify the progression, impact, and trends in the totality of his publications, and no study has assessed his work in a historical context compared with the contributions of other celebrated anatomists. We analyzed 414 of 508 works authored by Rhoton; these studies were analyzed according to subjects discussed, including anatomic region, surgical approaches, subjects covered, anatomic methods used, forms of multimedia, and subspecialty. Rhoton taught detailed neuroanatomy from a surgical perspective using meticulous techniques that evolved as the technical demands of neurosurgery advanced, inspiring students and contemporaries. His work aligns him with renowned figures in neuroanatomy, arguably establishing him historically as the most influential anatomist of the neurosurgical era., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: Surgical techniques to achieve complete resection of mesial-basal temporal tumors should be pursued by neurosurgical oncologists. We describe the anatomical subpial amygdalohippocampectomy (SpAH) technique for tumor resection., Methods: The key anatomical landmarks and critical steps of the SpAH technique were outlined and emphasized with medical illustrations and intraoperative photographs. The senior author's 90-day surgical outcomes with this approach were reviewed., Results: Twenty-five patients (men, 17 [68%]; women, 8 [32%]; median [range] age, 59 [23-80] years) with temporal tumors involving the amygdalohippocampal region were included. SpAH was performed selectively in 8 [32%] patients, whereas 17 [68%] patients underwent SpAH in conjunction with an anterior temporal lobectomy due to tumor involvement of the anterolateral temporal cortex. The subpial resection of the amygdala protected the critical structures of the suprasellar cistern and sylvian fissure. Identifying the choroidal fissure as the superior-most aspect of hippocampal resection protected the optic tract and the thalamus. Subpial resection of the parahippocampal gyrus inferiorly protected the brainstem and critical structures of the ambient cistern. Tumors in the amygdalohippocampal region were anatomically and completely resected in all 25 patients. Of the 15 patients who presented with seizures, 13 (87%) were seizure-free at the 90-day postsurgical follow-up. Permanent neurologic deficits occurred in 3 patients (12%)., Conclusions: The SpAH technique permits complete resection of mesial-basal temporal tumors with an acceptable morbidity profile. An in-depth understanding of temporal lobe anatomy combined with a refined microsurgical technique allows for reproducible resection of tumor in the amygdalohippocampal region while protecting critical neurovascular structures., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Glioblastoma multiforme remains a therapeutic challenge. We offer a historical review of the outcomes of patients with glioblastoma from the earliest report of surgery for this lesion through the introduction of modern chemotherapeutics and aggressive approaches to tumor resection., Methods: We reviewed all major surgical series of patients with glioblastoma from the introduction of craniotomy for glioma (1884) to 2020., Results: The earliest reported craniotomy for glioblastoma resulted in the patient's death less than a month after surgery. Improved intracranial pressure management resulted in improved outcomes, reducing early postoperative mortality from 50% to 6% in Harvey Cushing's series. In the first major surgical series (1912), the mean survival was 10.1 months. This figure did not improve until the introduction of radiotherapy in the 1950s, which doubled survival relative to those who had surgery alone. The most recent significant advance, chemotherapy with the alkylating agent temozolomide, extended survival by 2.5 months compared with surgery and radiotherapy alone (14.6 and 12.1 months, respectively). This protocol remains the standard regimen for newly diagnosed glioblastoma. The innovative treatments being investigated have yet to show a survival benefit., Conclusions: With advancements in localization, imaging, anesthesia, surgical technique, control of cerebral edema, and adjuvant therapies, outcomes in glioblastoma improved incrementally from Cushing's time until the introduction of magnetic resonance imaging enabled better degrees of resection in the 1990s. Modest improvements came with the advent of biomarker-driven targeted chemotherapy in the first decade of the current century., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: Encephalocele is a common congenital malformation of the central nervous system; however, giant encephaloceles are rare. The use of folic acid supplementation and termination of pregnancies, which are prenatally diagnosed with encephaloceles and other congenital malformation of the central nervous system, has significantly reduced the occurrence of this type of congenital malformation, especially in developed countries., Methods: This was a retrospective review over a 5-year period from January 2006 to December 2010 at the Department of Neurosurgery, Regional Centre for Neurosurgery, Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria. The records of patients with giant encephalocele were retrieved from the case notes of patients who had excision and repair for encephalocele., Results: Seventy-three patients had excision and repair of encephalocele over the study period. However, the records of only 50 patients were retrieved. Fourteen (28%) of the 50 whose records were retrieved had giant encephalocele. There were 4 male and 10 female patients (1:2.5). Thirteen (92.9%) had the lesion located in the occipital region, whereas in 1 patient (7.1%) the lesion was at the vertex. Three (21%) of the cases had microcephaly, 1 (7.1%) had macrocephaly, and 1 (7.1%) developed postoperative hydrocephalus. The average size of defect was 2.43 cm, and the size of the lesion ranged from 12 × 6 cm to 40 × 50 cm. The average maternal age was 20.3 years (n = 6), and the paternal age was 29 years (n = 4). Four out of 7 (57%) mothers had febrile illness in early pregnancy. Seven out of 10 patients (70%) did not have antenatal care., Conclusions: This condition is more common in children conceived during the period when farm products are yet to be harvested, and whose mothers did not attend antenatal care visits. It is recommended that mothers should be educated on the necessity of preconception folic acid. Implementation of a national strategy on food fortification is also advised. We recommend surgery after the first month of life to reduce poor early postoperative outcomes. In developing countries and centers with suboptimal pediatric intensive care units, surgical intervention is preferred after the first month of life with good temperature control, adequate fluid replacement following rupture of the sac, blood transfusion availability, and, only if necessary, complex cranial reconstruction., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: Localization of the temporal horn of the lateral ventricle (TH) may be required during temporal lobe and ambient cistern surgery. Most available anatomic landmarks for TH localization are based on adjacent cortical landmarks that are inherently variable or subtle. This study aimed to localize the anterior tip of the TH relative to adjacent bony landmarks., Methods: The TH was exposed on 21 sides of 11 cadaveric heads via removal of the middle temporal gyrus. Two lines were defined: (1) a perpendicular line to the zygomatic arch projected from the anterior concavity of the posterior zygomatic root (line A), and (2) a parallel line passing through the anterosuperior corner of the external auditory canal (line B). Sagittal distances from lines A and B to a parallel line passing through the anterior recess of the TH (line H) were measured., Results: Mean (standard deviation) distances from lines A and B to line H were 13.3 (2.5) mm and 11.9 (2.2) mm, respectively. Line H was at 53% (8%) of the line A-line B interval measured from line A. The best way to search for the TH was to start approximately 15 mm posterior to line A and progress posteriorly such that a more posteriorly located TH tip would not be missed., Conclusions: The zygomatic-meatal landmark is a reliable tool to localize TH during various approaches. It is independent from the approach trajectory. This landmark may be used as an ancillary tool in conjunction with other cortical landmarks and image guidance., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Edward Archibald, Professor of Surgery at McGill University (1904-1945), Montreal, Canada, was the foremost thoracic surgeon of his generation. Although instrumental in establishing the American Board of Surgery and in standardizing surgical training, he was also influential as a neurosurgeon. Archibald, an early member invited by Harvey Cushing to join the Society of Neurological Surgeons, helped establish neurosurgery as a distinct, specialized discipline. We review Archibald's contributions to the development of neurosurgery in light of his encyclopedic 1908 monograph, "Surgical Affections and Wounds of the Head," which we compare and contrast to the contemporary treatise by Cushing in the same year. Through his writings and correspondence with Wilder Penfield and Cushing, we also describe his role in the creation of the Montreal Neurological Institute. Primary archival sources addressing the professional relationship between Archibald and Cushing and between Archibald and Penfield were consulted. Archibald's personal acquaintance with the principal neurosurgeons of the day, his insight into their personalities, their prominence in the field, and their career paths played a critical role in influencing Penfield to consider relocating to Montreal from Columbia University, despite tempting offers from Boston and Philadelphia. However, it was Archibald's support and mentorship for the creation of an academic center that finally convinced Penfield to move to McGill University. As one of the most influential surgeons of the early 20th century and a founding figure of modern neurosurgery, Archibald is an important part of neurosurgery's legacy., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Mastery of the microsurgical anastomosis is an indispensable component of neurosurgical training. However, in many resource-limited countries, the training, materials, and equipment to obtain these surgical and decision making skills are severely lacking. This study aimed to compare different suturing techniques for microvascular anastomosis and to complete a comparative assessment of the performance of a young neurosurgeon when using the various techniques., Methods: We compared 3 end-to-end suturing techniques for microvascular anastomosis: interrupted suturing, continuous suturing, and a 2-octyl-cyanoacrylate-based lid technique using an umbilical artery model. We assessed the subjective difficulty of the suturing technique, the time needed to perform the procedure, and the flow rate and leakage of the vessel after each technique. This study was designed to use materials that would be available in developing countries. Surgical apparatus used, such as operating microscopes, were first-generation technology, and testing procedures were designed for neurosurgical residents in developing countries., Results: The mean times to complete the anastomosis were 20.7 ± 7.7 minutes for the interrupted technique, 26.4 ± 7.7 minutes for the continuous technique, and 12.5 ± 2.5 minutes for the lid technique; these values were significantly different (P < 0.01). The differences among the 3 techniques in leakage and flow rates and subjective difficulty in performance were not significant., Conclusions: Suturing time was the only statistically significant difference among the 3 anastomotic techniques, with the lid technique apparently the quickest to perform. Such techniques can be designed to assess microsurgical abilities and help neurosurgery residents in developing countries improve their surgical skills and techniques., (Copyright © 2019 Elsevier Inc. All rights reserved.)

For nearly 90 years, notions of the brain have been inextricably associated with a homunculus that has become embedded within medical education as the precise representation of rolandic cortical function. We sought to define the history, evolution, accuracy, and impact of this pictorial means of showing cortical representation. We mathematically defined the evolutionary accuracy of appropriate homunculi using image analysis techniques for all points defined by Penfield, Boldrey, Rasmussen, Jasper, and Erickson, calculating perpendicular distances and defining areas and distributions of rolandic and sylvian regions labeled for sensory and motor activity with comparison with all homunculi. Prerolandic sensory representation composed 13%-47% of total sensory area (mean, 29%); postrolandic motor representation composed 15%-65% of total motor area (mean, 31%). Discrepancy between cortical perpendicular length attributed to a particular function on 1937 diagrams was greater than that attributed on the 1950 homunculus (motor: mean, 74%; range, 63%-96%; sensory: mean, 66%; range, 17%-92%) (P < 0.05). The homunculus, if truly drawn according to cortical mapping evidence, could never have been recognized as near humanoid, yet it has attained epic educational and practical longevity., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: We performed a bibliometric analysis of studies reporting cases of brain and spinal arteriovenous malformations (AVMs)., Methods: We retrieved the 100 most cited reports in brain and spinal AVM research from Scopus and assessed the citation count, journal of publication and its impact factor, year of publication, first author and corresponding authors and their h-index, country, institution, department, and study category., Results: The median number of citations per article was 215. The Journal of Neurosurgery was the most prolific journal (39 reports and 12,069 citations), including 9 of the 10 most cited reports. Seventy reports (19,251 citations), including 8 of the 10 most cited, were from the United States. The Barrow Neurological Institute was the most cited institution (7 reports; 2792 citations), and the Mayo Clinic had the greatest number of reports (8 reports; 1994 citations). Most studies had been reported before 2000 (71 reports; 19,262 citations). The most discussed topics were treatment (40 studies; 9560 citations) and natural history and/or clinical features (37 studies; 9595 citations). Neurosurgery was the most prolific department (58 studies; 15,860 citations). Spetzler was the author with the highest number of articles (n = 7) and citations (n = 2792)., Conclusions: Brain and spinal AVM research was centralized in the United States, has been mainly reported in specific neurosurgical journals, and has been more often related to treatment and natural history and/or clinical features. It is possible that high impact AVM research has been decreasing recently. Because the best approach to these pathological entities remains controversial, research stimulation within this field should be encouraged., (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.)

Background: Rootlets of the lower cranial nerves create a web that limits microsurgical maneuverability in the cerebellomedullary cistern (CMC). The vagoaccessory triangle (VAT) and 2 triangles within it were defined to identify surgical routes to aneurysms of the posterior inferior cerebellar artery (PICA). Dividing the VAT into 2 triangles (suprahypoglossal [SHT] and infrahypoglossal [IHT]), although elegant, oversimplifies CMC anatomy. The triangle formed by the superior and inferior hypoglossal rootlets (hypoglossal-hypoglossal triangle [HHT]) needs consideration as well., Methods: Far-lateral craniotomy was performed on 10 cadaveric heads bilaterally. Areas of CMC triangles were calculated. Relationships between the PICA origin and the adjacent triangles were analyzed. Vertebral artery (VA) exposure and clipping lengths were recorded for each triangle., Results: The area of SHT was almost twice those of IHT and HHT. The average VA depth relative to VAT increased significantly when moving distally from proximal VA (P < 0.001), but VA exposure and clipping lengths were not significantly different between triangles. IHT, HHT, and SHT defined VA subsegments (V 4i , V 4h , and V 4s ), with PICA most commonly originating from V 4h . Based on our cadaveric measurements, the V 4 subsegments were identified with 76% accuracy in angiograms., Conclusions: Based on this study, VAT should be divided into 3 triangles, not 2. Splayed rootlets of cranial nerve XII and multiple outlet foramina create an important space different from the previously recognized SHT and IHT. These triangles provide corridors to vascular pathologies. V 4 subsegments may be approximated from imaging studies and may help with preoperative planning., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Double origin of the posterior inferior cerebellar artery is rare. It has important clinical implications especially in cases of aneurysms of the vertebral artery or the posterior inferior cerebellar artery. Several radiologic reports of this variant exist. However, no anatomic illustration of this rarity exists in the literature. This brief report provides the first anatomic illustration of this important variation of the vertebrobasilar system., Case Description: A cadaveric specimen was prepared for dissection. A far lateral craniotomy was performed on the right side. While exploring the right cerebellomedullary cistern, 2 separate origins of the posterior inferior cerebellar artery were found from the vertebral artery as the caudal and rostral trunks that joined to form the distal posterior inferior cerebellar artery trunk at the tonsillomedullary segment. Microscopic and endoscopic illustrations are provided., Conclusions: To the best of our knowledge, this is the first anatomic report on the double origin of the posterior inferior cerebellar artery. Cadaveric illustration of this variant helps with understanding its anatomic relationship with adjacent neurovascular structures of the cerebellomedullary cistern including the perforating arteries and the lower cranial nerves., (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: To describe and compare surgical exposure through microsurgical cadaveric dissection of the intercollicular region afforded by the median, paramedian, and extreme-lateral supracerebellar infratentorial (SCIT) approaches., Methods: Ten cadaveric heads were dissected using SCIT variant approaches. A neuronavigation system was used to determine tridimensional coordinates for the intercollicular zone in each route. The areas of surgical and angular exposure were evaluated and determined by software analysis for each specimen., Results: The median surgical exposure was similar for the different craniotomies: 282.9 ± 72.4 mm 2 for the median, 341.2 ± 71.2 mm 2 for the paramedian, and 312.0 ± 79.3 mm 2 for the extreme-lateral (P = 0.33). The vertical angular exposure to the center of the intercollicular safe entry zone was also similar between the approaches (P = 0.92). On the other hand, the horizontal angular exposure was significantly wider for the median approach (P < 0.001)., Conclusions: All the SCIT approaches warrant a safe route to the quadrigeminal plate. Among the different variants, the median approach had the smallest median surgical area exposure but presented superior results to access the intercollicular safe entry zone., (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: Although pterional craniotomy and its variants are the most used approaches in neurosurgery, few studies have evaluated their precise indications. We evaluate the pterional (PT), pretemporal (PreT), and orbitozygomatic (OZ) approaches through quantitative measurements of area, linear, and angular exposures of the major intracranial vascular structures., Methods: Eight fresh, adult cadavers were operated with the PT, followed by the PreT, and ending with the OZ approach. The working area, angular exposure of vascular structures and linear exposure of the basilar artery were measured., Results: The OZ approach presented a wider area (1301.3 ± 215.9 mm 2 ) with an increase of 456.7 mm 2 compared with the PT and of 167.4 mm 2 to the PreT (P = 0.011). The extension from PT to PreT and OZ increases linear exposure of the basilar artery. When comparing the PreT and OZ, we found an increase in the horizontal and vertical angle to the bifurcation of the ipsilateral middle cerebral artery (P = 0.005 and P = 0.032, respectively), horizontal angle to the basilar artery tip (P = 0.02), and horizontal angle to the contralateral ICA bifurcation (P = 0.048)., Conclusions: The OZ approach offered notable surgical advantages compared with the traditional PT and PreT regarding to the area of exposure and linear exposure to basilar artery. Regarding angle of attack, the orbital rim and zygomatic arch removal provided quantitatively wider exposure and increased surgical freedom. A detailed anatomic study for each patient and surgeon experience must be considered for individualized surgical approach indication., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: Apparently similar intra-axial pontine lesions may demand distinct surgical approaches. Selecting the optimal approach reduces unnecessary manipulation of tracts and nuclei. This study aims to reveal a quantitative analysis of main surgical corridors dealing with intrinsic pontine pathology., Methods: Six approaches were performed repeatedly in 10 cadaveric heads: 1) retrosigmoid, 2) retrolabyrinthine, 3) subtemporal transtentorial, 4) anterior petrosectomy, 5) combined petrosal approach, and 6) suboccipital telovelar. Six safe entry zones were studied: peritrigeminal, supratrigeminal, lateral pontine, supracollicular, infracollicular, and median sulcus of fourth ventricle. A neuronavigation device was used to collect 3-dimensional coordinates from fixed points over the edge of craniotomies and brainstem surface; 4 variables were studied: 1) angles of attack; 2) areas of exposure; 3) lengths of exposure; and 4) trajectories., Results: The mean area of exposure generated by the retrosigmoid approach over the brainstem was 538.6 ± 161.0 mm 2 , whereas that yielded by the retrolabyrinthine was 475.0 ± 173.4 mm 2 . There were no significant differences between both when considering areas of exposure and angles. Adding a tentorial cut to the subtemporal approach exposed the superior part of the lateral surface of pons; the area of exposure increased a mean of 33% (P < 0.001)., Conclusions: In addition to producing similar areas and angles of attack, the retrolabyrinthine yields a more orthogonal trajectory to lateral pons than the retrosigmoid approach. Adding a tentorial cut and anterior petrosectomy significantly increased areas and lengths of exposure of a regular subtemporal approach. The combined approach significantly increased angles of attack to both the supratrigeminal and lateral pontine safe zones., (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.)

Background: The subtemporal and orbitozygomatic approaches are the most commonly used surgical approaches for the treatment of basilar artery apex (BAX) aneurysms. Relative advantages and disadvantages are generally reported based on surgeons' experience. This study was performed to provide a detailed comparison between the subtemporal and orbitozygomatic approaches based on cadaveric dissection analysis for the treatment of BAX aneurysms., Methods: Subtemporal and orbitozygomatic approaches were performed on 5 cadaveric heads (10 sides), and the following variables were assessed and compared between the 2 approaches: 1) number of exposed perforators on P 1 -posterior cerebral arteries (PCA); 2) lengths of exposure and clipping for bilateral PCA, superior cerebellar arteries (SCA), and basilar trunk; 3) surgical area of exposure; and 4) surgical freedom at the BAX., Results: Number of perforators exposed on P 1 -PCA was not different between the subtemporal and orbitozygomatic approaches. Exposure and clipping of ipsilateral SCA and PCA were superior using the subtemporal approach, and better for contralateral SCA and PCA using the orbitozygomatic approach, all reaching statistical significance. The orbitozygomatic approach provided greater exposure and clipping length for the proximal basilar trunk. Although the surgical area of exposure was similar between the 2 approaches, the overall surgical freedom was greater in the orbitozygomatic approach., Conclusions: The orbitozygomatic approach provides a greater number of surgical corridors to the BAX and is superior regarding multiple surgically relevant anatomic parameters. Importantly, control over the basilar trunk and over the contralateral SCA and PCA (blind spots) is superior with the orbitozygomatic approach., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: The end-to-side anastomosis is 1 of the most common anastomosis configurations used in cerebrovascular surgery. Although several living practice models have been proposed for this technique, few involve purely arterial vessels. The purpose of the present study was to compare 2 arterial models using common carotid arteries (CCAs) and common iliac arteries (CIAs) in rats., Methods: The CIAs and CCAs were exposed in 10 anesthetized rats, and their lengths and diameters were measured. Also, the mobilization extent of each vessel along its contralateral counterpart was measured after each artery had been transected at its proximal exposure point. We also studied the technical advantages and disadvantages of each model for practicing end-to-side anastomosis., Results: The average diameters of the CCA and CIA were 1.1 and 1.3 mm, respectively. The average extent of mobilization along the contralateral vessel was 13.9 mm and 10.3 mm for CCA and CIA, respectively. The CCA model had the advantages of greater arterial redundancy (allowing completion of both suture lines extraluminally) and a minimal risk of venous injury. The main disadvantage of the CCA model was the risk of cerebral ischemia. The CIA model was not limited by the ischemic time and provided the technical challenge of microsurgical dissection of the common iliac vein from the CIA, although it had limited CIA redundancy., Conclusions: Both CCA and CIA models could be efficiently used for practicing the end-to-side anastomosis technique. Each model provides the trainee with a specific set of advantages and disadvantages that could help with the optimal selection of the practice model according to trainee's skill level., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Despite the latest developments in microsurgery, electrophysiological monitoring, and neuroimaging, the surgical management of intrinsic brainstem lesions remains challenging. Several safe entry points have been described to access the different surfaces of the brainstem. Knowledge of this entry zone anatomy is critical to performing a safe and less morbid approach. To access the anterior midbrain surface, a well-known entry point is the anterior mesencephalic (AM) zone. Our aim was to quantify surgical AM zone exposure through the orbitozygomatic (OZ) and subtemporal (ST) approaches. We also analyzed the angular exposure along the horizontal and vertical axis angles for the AM zone., Methods: Ten cadaveric heads were dissected using the OZ and ST approaches for anterior midbrain surface exposure. A neuronavigation system was used to determine the 3-dimensional coordinates. The area of surgical exposure, angular exposure, and anatomical limits of each craniotomy were evaluated and determined using software analysis and compared for intersection areas and AM safe zone exposure., Results: The median surgical exposure was 164.7 ± 43.6 mm 2 for OZ and 369.8 ± 70.1 mm 2 for ST (P = 0.001). The vertical angular exposure was 37.7° ± 9.92° for the OZ and 18.4° ± 2.8° for the ST opening (P < 0.001). The horizontal angular exposure to the AM zone was 37.9° ± 7.3° for the OZ and 47.0° ± 3.2° for the ST opening (P = 0.002)., Conclusions: Although the OZ craniotomy offers reduced surgical exposure, it provides a better trajectory to the AM zone compared with the ST approach., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: The greater auricular nerve (GAN) may be used as a nerve graft during neurosurgical procedures to repair damaged nerves. There is extensive literature on localization of the GAN at the posterior triangle of the neck, but objective information on localization of the GAN at the anterior triangle of the neck close to cranial neurosurgical fields is lacking. The aim of this study was to introduce simple and reliable landmarks to localize the GAN at the anterior triangle of the neck to facilitate its harvest during neurosurgical procedures., Methods: The GAN was exposed bilaterally in 11 cadaveric specimens at the point of crossing the anterior border of the sternocleidomastoid muscle (anterior greater auricular point [AGA]). Distances from the AGA point to the angle of the mandible and the tip of the mastoid process were measured. Additionally, the location of the crossing point between the GAN and an imaginary line passing through the mastoid tip and the angle of the mandible (M-A line) was found relative to these bony landmarks., Results: Mean (±SD) distances from the AGA point to the mastoid tip and the angle of the mandible were 29.1 ± 3.4 mm and 27.5 ± 4.5 mm, respectively. The GAN was always found to cross the M-A line in its middle third (mean 48.2% ± 6.9% from the mastoid tip)., Conclusions: The AGA point and the M-A line are reliable landmarks for locating the GAN at the anterior triangle of the neck and for helping neurosurgeons expose and harvest the GAN efficiently., (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.)

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.)

Background: Animal models are commonly used in training protocols for microsurgical vascular anastomosis. Rat common carotid arteries (CCAs) are frequently used for this purpose. Much attention has been paid to the technical details of various anastomosis configurations using these arteries. However, technical nuances of exposing rat CCAs have been understudied. The purpose of this study is to describe nuances of technique for safely and efficiently exposing rat CCAs in preparation for a vascular anastomosis., Methods: Bilateral CCAs were exposed and prepared for anastomosis in 10 anesthetized Sprague-Dawley rats through a midline cervical incision. The exposed length of the CCA was measured. Additionally, technical nuances of exposure and surgically relevant anatomic details were recorded., Results: The CCAs were exposed from the sternoclavicular joint to their bifurcation (average length, 19.1 ± 2.8 mm). Tenets important for a safe and efficient exposure of the CCAs included 1) generous subcutaneous dissection to expose the external jugular veins (EJVs), 2) avoiding injury to or compression of the EJVs, 3) superior mobilization of the salivary glands, 4) division of internal jugular veins, 5) opening the carotid sheath at its midlevel and from medial to lateral, and 6) avoiding injury to the vagus nerve or sympathetic trunk., Conclusions: Using the principles introduced in this study, trainees may safely and efficiently expose rat CCAs in preparation for a bypass., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Vascularized bone grafts (VBGs) are described as having superior osteogenicity, osteoconductivity, and osteoinductivity compared with other graft types and have been used in high-risk patients to augment arthrodesis. Pedicled VBGs are rotated on an intact vascular pedicle and therefore maintain all the benefits of VBGs but avoid many of the challenges and additional morbidity of free-tissue transfer. This study describes a novel surgical technique for rotating vascularized spinous process into the posterolateral space for augmenting arthrodesis in patients undergoing posterolateral fusion (PLF)., Methods: A technique is described for rotating the spinous process into the posterolateral space on an intact vascular pedicle of paraspinal muscle. Early clinical and radiographic outcomes are reported for 4 patients who have undergone this procedure., Results: Four patients were treated with a single or 2-level PLF combined with posterior, anterior, or lateral interbody fusion and vascularized spinous process graft. Three-month postoperative computed tomography scans demonstrated a dislodged graft in 1 patient and successful arthrodesis in 3 patients. Additional operative time taken for graft harvest and implantation ranged from 22 minutes for the first patient to 6 minutes for the fourth patient., Conclusions: Rotation of vascularized spinous process graft for augmentation of posterolateral arthrodesis in the lumbar spine is a potentially safe, effective surgical technique that results in successful arthrodesis in as little as 3 months but requires further study. This technique is expected to add little additional time or morbidity to the traditional lumbar PLF because it requires no separate incision or additional bone removal., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Anterior, direct lateral, and transforaminal lumbar interbody fusions (ALIF, DLIF, and TLIF) are usually combined with posterior fixation to treat degenerative spinal diseases. Outcomes of ALIF, TLIF, or DLIF combined with a new wedge-shaped interfacet cage plate have not been reported. We assessed early clinical outcomes of patients treated with interbody fusion and facet fixation using a titanium wedge-shaped cage plate., Methods: This retrospective observational cohort study included patients (n = 80) who underwent 1-level interbody fusion and facet joint fixation via ALIF (n = 24) or DLIF (n = 26) with bilateral facet fixation or TLIF with ipsilateral pedicle screws and contralateral facet fixation (n = 30). Duration of surgery, estimated blood loss, pain (visual analog scale), Oswestry Disability Index (ODI) scores, and Macnab score were assessed up to 12 months after surgery., Results: All patients had a significant decrease in pain scores (P < 0.01) and an increase in ODI scores (P < 0.01), without significant differences between treatment groups. Most surgical outcomes were excellent or good (n = 75, 93.8%) with 5 patients (6.2%) having satisfactory outcomes. Within 2 months, all patients returned to their previous work (66, 82.5%) or lighter work (14, 17.5%). Two patients had fusion failure requiring reoperation., Conclusions: Facet fixation with the wedge-shaped cage plate was associated with minimal soft tissue damage and a low level of postoperative pain. ALIF, DLIF, and TLIF combined with this technique showed good early postoperative clinical and radiologic outcomes. Further studies are needed to assess long-term results and compare them with other fusion methods., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: To describe an endoscopic anterolateral surgical route to the lateral portion of Meckel's cave., Methods: A sublabial transmaxillary transpterygoid approach was performed in 6 cadaveric heads (12 sides). A craniectomy was drilled between the foramen rotundum (FR) and foramen ovale (FO) with defined borders. Extradural dissection was performed up to the V2-V3 junction of the trigeminal ganglion. The working space was analyzed using anatomic measurements., Results: The approach allowed for extradural dissection to the lateral aspect of Meckel's cave and provided excellent exposure of V2, V3, and the V2-V3 junction at the gasserian ganglion. The mean distance between the FR and FO along the pterygoid process of the sphenoid bone was 21.3 ± 2.8 mm (range, 18-24.4 mm). The mean distance of V2 and V3 segments from their foramina to the gasserian ganglion junction was 12.0 ± 2.3 mm (range, 9.2-14.6 mm) and 15.2 ± 2.7 mm (range, 12.3-18.5 mm), respectively (6 sides). A potential working area (mean area, 89 mm 2 ) is described. Its superior edge is from the FR to the V2-V3 junction at the gasserian ganglion, its inferior edge is from the FO to the V2-V3 junction at the gasserian ganglion, and its base is from the FO to the FR. The surgical anatomy of the infratemporal fossa, pterygopalatine fossa, and lateral Meckel's cave is highlighted., Conclusions: An endoscopic anterolateral sublabial transmaxillary transpterygoid approach between the FR and FO avoids crossing critical neurovascular structures within the cavernous sinus and pterygopalatine fossa and can provide a safe surgical corridor for laterally based lesions in Meckel's cave., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objectives: Frozen section histological analysis is currently the mainstay for intraprocedural tissue diagnosis during the resection of intracranial neoplasms and for evaluating tumor margins. However, frozen sections are time-consuming and often do not reveal the histological features needed for final diagnosis when compared with permanent sections. Confocal scanning microscopy (CSM) with certain stains may be a valuable technology that can add rapid and detailed histological assessment advantage for the neurosurgical operating room. This study describes potential advantages of CSM imaging of fresh human brain tumor tissues labeled with acriflavine (AF), acridine orange (AO), cresyl violet (CV), methylene blue (MB), and indocyanine green (ICG) within the neurosurgical operating room facility., Patients and Methods: Acute slices from orthotopic human intracranial neoplasms were incubated with AF/AO and CV solutions for 10 s and 1 min respectively. Staining was also attempted with MB and ICG. Samples were imaged using a bench-top CSM system. Histopathologic features of corresponding CSM and permanent hematoxylin and eosin images were reviewed for each case., Results: Of 106 cases, 30 were meningiomas, 19 gliomas, 13 pituitary adenomas, 9 metastases, 6 schwannomas, 4 ependymomas, and 25 other pathologies. CSM using rapid fluorophores (AF, AO, CV) revealed striking microvascular, cellular and subcellular structures that correlated with conventional histology. By rapidly staining and optically sectioning freshly resected tissue, images were generated for intraoperative consultations in less than one minute. With this technique, an entire resected tissue sample was imaged and digitally stored for tele-pathology and archiving., Conclusion: CSM of fresh human brain tumor tissue provides clinically meaningful and rapid histopathological assessment much faster than frozen section. With appropriate stains, including specific cellular structure or antibody staining, CSM could improve the timeliness of intraoperative decision-making, and the neurosurgical-pathology workflow during resection of human brain tumors, ultimately improving patient care., (Copyright © 2018 Elsevier B.V. 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.)

Background: Microneurosurgical techniques involve complex manual skills and hand-eye coordination that require substantial training. Many factors affect microneurosurgical skills. The goal of this study was to use a systematic evidence-based approach to analyze the quality of evidence for intrinsic and extrinsic factors that influence microneurosurgical performance and to make weighted practical recommendations., Methods: A literature search of factors that may affect microsurgical performance was conducted using PubMed and Embase. The criteria for inclusion were established in accordance with the PRISMA-P (Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols) statement., Results: Forty-eight studies were included in the analysis. Most of the studies used surgeons as participants. Most used endoscopic surgery simulators to assess skills, and only 12 studies focused on microsurgery. This review provides 18 practical recommendations based on a systematic literature analysis of the following 8 domains: 1) listening to music before and during microsurgery, 2) caffeine consumption, 3) β-blocker use, 4) physical exercise, 5) sleep deprivation, 6) alcohol consumption before performing surgery, 7) duration of the operation, and 8) the ergonomic position of the surgeon., Conclusions: Despite the clear value of determining the effects of various factors on surgical performance, the available body of literature is limited, and it is not possible to determine standards for each surgical field. These recommendations may be used by neurosurgical trainees and practicing neurosurgeons to improve microsurgical performance and acquisition of microsurgical skills. Randomized studies assessing the factors that influence microsurgical performance are required., (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.)

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.)