Microneurosurgical Anatomy Research Articles

Microneurosurgical anatomy of the basal cisterns: A brief review for cisternostomy.

Cisternostomy is a surgical technique thought of and developed as an option for severe brain trauma treatment. It demands a particular knowledge and skill to microsurgically approach basal cisterns and effectively manipulate their contents. To perform this procedure safely, the anatomy and pathophysiology must be clearly understood. Detailed microscopic dissection and anatomical review were done, after a detailed reading of facts and recent publications about cisternostomy. Cisternal pathways and landmark planning are described and augmented using a new method to show de arachnoid borders. Finally, a brief discussion is written as a synopsis. Cisternostomy requires thorough microscopic knowledge and microsurgical skills. This paper intends to provide information to understand better the anatomy related, thus, easing the learning curve. The technique used to show arachnoid borders, complementing cadaveric and surgical images, was useful for this purpose. To perform this procedure safely, it is mandatory to handle microscopic details of cistern anatomy. Reaching a core cistern is necessary to assure effectiveness. This procedure needs, as well, surgical step-by-step landmark planning and performing. Cisternostomy could be a life-saving procedure and a new powerful tool for severe brain trauma treatment. Evidence is being collected to support its indications.

Posterior Transpetrosal Approaches to the Posterior Cranial Fossa: radiological preoperative assessment and microneurosurgical anatomy

Posterior Transpetrosal Approaches to the Posterior Cranial Fossa: radiological preoperative assessment and microneurosurgical anatomy

Microneurosurgical Anatomy of the Posterior fossa and Craniocervical Junction

The posterior fossa is a site where blood vessels and nerves are very dense, so surgery can be very difficult. Therefore, serious sequelae may occur due to complications. Surgeons should be familiar with the complex anatomy of the posterior fossa. This paper outlines the anatomy of the bone, brain, and nerves involved in the surgical approach from the lateral posterior to the cerebellar pontine angle and foramen magnum.

Evolution of microneurosurgical anatomy with special reference to the history of anatomy, surgical anatomy, and microsurgery: historical overview.

This article reviews the evolution of microneurosurgical anatomy (MNA) with special reference to the development of anatomy, surgical anatomy, and microsurgery. Anatomy can be said to have started in the ancient Greek era with the work of Hippocrates, Galen, and others as part of the pursuit of natural science. In the sixteenth century, Vesalius made a great contribution in reviving Galenian knowledge while adding new knowledge of human anatomy. Also in the sixteenth century, Ambroise Paré can be said to have started modern surgery. As surgery developed, more detailed anatomical knowledge became necessary for treating complicated diseases. Many noted surgeons at the time were also anatomists eager to spread anatomical knowledge in order to enhance surgical practice. Thus, surgery and anatomy developed together, with advances in each benefiting the other. The concept of surgical anatomy evolved in the eighteenth century and became especially popular in the nineteenth century. In the twentieth century, microsurgery was introduced in various surgical fields, starting with Carl O. Nylen in otology. It flourished and became popularized in the second half of the century, especially in the field of neurosurgery, following Jacobson and Suarez's success in microvascular anastomosis in animals and subsequent clinical application as developed by M.G. Yasargil and others. Knowledge of surgical anatomy as seen under the operating microscope became important for surgeons to perform microneurosurgical procedures accurately and safely, which led to the fuller development of MNA as conducted by many neurosurgeons, among whom A.L. Rhoton, Jr. might be mentioned as representative.

Use of Neuroanatomic Knowledge and Neuronavigation System for a Safe Anterior Petrosectomy

Introduction: The petroclival region is among the most challenging anatomical areas to deal with in skull base surgery. Drilling of the anterior part of the petrous bone during the anterior transpetrosal approach involves the risk of injury of the cochlea, superior semicircular canal, internal carotid artery, and internal auditory canal. A thorough understanding of the microneurosurgical anatomy of this region is mandatory to execute the transpetrosal approaches, decreasing the risk of complications. The aim of this study is to describe the anatomical structures of the petroclival region, highlighting the importance of neuronavigation for safe performance of the anterior transpetrosal approach. Methods: Three adult cadaveric human heads were formalin-fixed and injected with colored silicone. They underwent an axial 1 mm slab CT scan, which was used for neuronavigation during the surgical approaches. The anterior petrosectomy was performed with the aid of neuronavigation during the drilling of the petrous bone. The surgical management of a patient harboring a petroclival meningioma, operated on using an anterior transpetrosal approach, was reported as an illustrative case. Results: The anterior petrosectomy was completed accurately with wide exposure of the surgical target without injuring the cochlea and other structures in all three cadaveric specimens. In the surgical case, no approach-related complications occurred, and a gross total resection of the tumor was achieved. Conclusions: Deep knowledge of the location and relationships of the vital elements located within the temporal bone, along with the use of neuronavigation, are the key aspects to perform the anterior transpetrosal approach safely, reducing the risk of complications.

Spectrally Tunable Neural Network-Assisted Segmentation of Microneurosurgical Anatomy.

BackgroundDistinct tissue types are differentiated based on the surgeon’s knowledge and subjective visible information, typically assisted with white-light intraoperative imaging systems. Narrow-band imaging (NBI) assists in tissue identification and enables automated classifiers, but many anatomical details moderate computational predictions and cause bias. In particular, tissues’ light-source-dependent optical characteristics, anatomical location, and potentially hazardous microstructural changes such as peeling have been overlooked in previous literature.MethodsNarrow-band images of five (n = 5) facial nerves (FNs) and internal carotid arteries (ICAs) were captured from freshly frozen temporal bones. The FNs were split into intracranial and intratemporal samples, and ICAs’ adventitia was peeled from the distal end. Three-dimensional (3D) spectral data were captured by a custom-built liquid crystal tunable filter (LCTF) spectral imaging (SI) system. We investigated the normal variance between the samples and utilized descriptive and machine learning analysis on the image stack hypercubes.ResultsReflectance between intact and peeled arteries in lower-wavelength domains between 400 and 576 nm was significantly different (p < 0.05). Proximal FN could be differentiated from distal FN in a higher range, 490–720 nm (p < 0.001). ICA with intact tunica differed from proximal FN nearly thorough the VIS range, 412–592 nm (p < 0.001) and 664–720 nm (p < 0.05) as did its distal counterpart, 422–720 nm (p < 0.001). The availed U-Net algorithm classified 90.93% of the pixels correctly in comparison to tissue margins delineated by a specialist.ConclusionSelective NBI represents a promising method for assisting tissue identification and computational segmentation of surgical microanatomy. Further multidisciplinary research is required for its clinical applications and intraoperative integration.

The Evolutionary Development of the Brain As It Pertains to Neurosurgery

BackgroundNeuroanatomists have long been fascinated by the complex topographic organization of the cerebrum. We examined historical and modern phylogenetic theories pertaining to microneurosurgical anatomy and intrinsic brain tumor development.MethodsLiterature and history related to the study of anatomy, evolution, and tumor predilection of the limbic and paralimbic regions were reviewed. We used vertebrate histological cross-sections, photographs from Albert Rhoton Jr.’s dissections, and original drawings to demonstrate the utility of evolutionary temporal causality in understanding anatomy.ResultsPhylogenetic neuroanatomy progressed from the substantial works of Alcmaeon, Herophilus, Galen, Vesalius, von Baer, Darwin, Felsenstein, Klingler, MacLean, and many others. We identified two major modern evolutionary theories: “triune brain” and topological phylogenetics. While the concept of “triune brain” is speculative and highly debated, it remains the most popular in the current neurosurgical literature. Phylogenetics inspired by mathematical topology utilizes computational, statistical, and embryological data to analyze the temporal transformations leading to three-dimensional topographic anatomy. These transformations have shaped well-defined surgical planes, which can be exploited by the neurosurgeon to access deep cerebral targets. The microsurgical anatomy of the cerebrum and the limbic system is redescribed by incorporating the dimension of temporal causality. Yasargil’s anatomical classification of glial tumors can be revisited in light of modern phylogenetic cortical categorization.ConclusionHistorical and modern topological phylogenetic notions provide a deeper understanding of neurosurgical anatomy and approaches to the limbic and paralimbic regions. However, many questions remain unanswered and further research is needed to elucidate the anatomical pathology of intrinsic brain tumors.

The microneurosurgical anatomy legacy of Albert L. Rhoton Jr., MD: an analysis of transition and evolution over 50 years.

The authors chronologically categorized the 160 original articles written by Dr. Rhoton and his fellows to show why they selected their themes and how they carried out their projects. The authors note that as neurosurgery progresses and new techniques and approaches are developed, accurate and safe treatment will depend upon continued clarification of microsurgical anatomy.

Microsurgical Anatomy of Medial Temporal Lobe in North-West Indian Population: Cadaveric Brain Dissection.

Aim:The medial temporal lobe (MTL) is a highly complex neuroanatomical structure of tremendous neurosurgical importance. It is a common site for epilepsy, vascular lesions, and tumors. Owing to the critical location behind the sphenoid wing, it is more prone for traumatic contusion often with surgical implications. Hence, its microneurosurgical anatomy needs to be evaluated in detail.Materials and Methods:Twelve formalin-fixed human cadaveric brains from North-west Indian population were dissected under neurosurgical microscope and various dimensions of the MTL and their distance from important neurovascular structures were measured.Results:The MTL consists of important neural structures such as parahippocampal gyrus, uncus, hippocampus, temporal horn, and choroidal fissure. The average distance of tentorium from the uncus was 1.96 mm. The temporal horn and the inferior choroidal point were located from the anterior temporal pole at 22.9 mm and 30.9 mm, respectively. Important vessels that are intimately related to the MTL were anterior choroidal artery (AchA), posterior communicating artery, the P1 segment of posterior cerebral artery, and the M1 segment of middle cerebral artery.Conclusion:Complex anatomic and cytostructural organization makes the MTL unique. In this study, along with the descriptive anatomy, morphometric measurements of various structures were performed. The uncus and its relation to other neurovascular structures is well described in literature, but its exact distance from them as determined in this study is particularly helpful in guiding the surgeons while approaching in this area. Knowledge of the distance of the temporal horn from various surfaces is important while opening the temporal horn to avoid unnecessary damage to nearby structures.

The history of Rhoton's Lab.

The work performed in Dr. Rhoton's Lab, represented by over 500 publications on microneurosurgical anatomy, greatly contributed to improving the level of neurosurgical treatment throughout the world. The authors reviewed the development and activities of the Lab over 40years. Dr. Albert L. Rhoton Jr., the founder of, and leader in, this field, displayed great creativity and ingenuity during his life. He devoted himself to perfecting his study methodology, employing high-definition photos and slides to enhance the quality of his published papers. He dedicated his life to the education of neurosurgeons. His "lab team," which included microneuroanatomy research fellows, medical illustrators, lab directors, and secretaries, worked together under his leadership to develop the methods and techniques of anatomical study to complete over 160 microneurosurgical anatomy projects. The medical illustrators adapted computer technologies and integrated art and science in the field of microneurosurgical anatomy. Dr. Rhoton's fellows established methods of injecting colors and pursued a series of projects to innovate surgical approaches and instruments over a 40-year period. They also continued to help Dr. Rhoton to conduct international educational activities after returning to their home countries. Rhoton's Lab became a world-renowned anatomical lab as well as a microsurgical training center and generated the knowledge necessary to perform accurate, gentle, and safe surgery for the sake of patients.

Japanese neurosurgeons and microsurgical anatomy: a historical review.

Research in microneurosurgical anatomy has contributed to great advances in neurosurgery in the last 40 years. Many Japanese neurosurgeons have traveled abroad to study microsurgical anatomy and played major roles in advancing and spreading the knowledge of anatomy, overcoming their disadvantage that the cadaver study has been strictly limited inside Japan. In Japan, they initiated an educational system for surgical anatomy that has contributed to the development and standardization of Japanese neurosurgery. For example, the Japanese Society for Microsurgical Anatomy started an annual educational meeting in the middle of 1980s and published its proceedings in Japanese every year for approximately 20 years. These are some of the achievements that bring worldwide credit to Japanese neurosurgeons. Not only should Japanese neurosurgeons improve their educational system but they should also contribute to the international education in this field, particularly in Asia.

Realidade virtual e estereoscopia no ensino da neuroanatomia e neurocirurgia

Resumo Objetivo: Por motivos diversos, o ensino da neuroanatomia durante a graduação médica e na residência de neurocirurgia é deficitário. Apresentamos a realidade virtual e a estereoscopia como eventuais métodos complementares de ensino à neuroanatomia e neurocirurgia. Método: Diversa gama de conteúdo digital interativo e estereoscópico foi produzida utilizando esterogramas de dissecações anatômicas. Resultados: A realidade virtual tenta melhor elaborar o ensino da neuroanatomia e neurocirurgia. Embora o trabalho verse sobre neuroanatomia e neurocirurgia, esses recursos podem ser empregados em qualquer área médica. Conteúdo anatômico de excelência foi adquirido e armazenado de modo que pôde ser manipulado por programa de realidade virtual e estereoscopia. Conclusão: A realidade virtual e a estereoscopia são ferramentas úteis no ensino e na aprendizagem da neuroanatomia e da neurocirurgia.

Design and construction of a three-dimensional lateral ventricle model based on MRI data

Objective To construct a three-dimensional(3D) anatomic model of the lateral ventricles for teaching microneurosurgical anatomy and clinical surgery planning. Methods The 3D model was constructed with a series of 176 MRIT2 head sections of a healthy male volunteer(36 years old) using software Matlab,Geomagic,Maya,etc.The 176 sections were subjected to management with software Matlab for image preprocessing and contour extracting;the acquired contours were subjected to software geomagic for 3D model constructing,3D-model and image connecting and other processings. Results The 3D model of the lateral ventricles and related structures were successfully constructed using more than 240,000 remodeled polygons,and the contour of the model consisted well with the images.The model had a even better visual effect after combining the 3D-model and image.The model could be viewed from any angle and could be rotated by 360 degrees in any plane using any structure as the focal point of rotation.Moreover,the model could be reduced or enlarged using the zoom function. Conclusion The constructed 3D model can be observed and studied repeatedly at any time,with no stress from surgery.The model may be used for interactive surgical exercises,paving a way for subsequent clinical practice.

Setting up a microneurosurgical skull base lab: technical and operational considerations

Microneurosurgical cadaveric dissections have become popular due to their usefulness in obtaining a working knowledge of the microneurosurgical anatomy in a controlled environment. This same controlled environment is also conducive to experiment with new surgical approaches. These factors have increased the number of microneurosurgical anatomic laboratories. Despite the increase in microneurosurgical laboratories, there is very little literature regarding the logistics of starting and maintaining a new neurosurgical laboratory. The aim of this paper is to provide a general road map and basic guidelines in starting and running a microneurosurgical dissection laboratory. The information in this paper is based on a review of the literature and on the experience we gained in organizing and managing the Dardinger Microneurosurgical Skull Base Laboratory at The Ohio State University.

第24回微小脳神経外科解剖セミナー会長として(手術アプローチの選択とピットフォールII-第24回微小脳神経外科解剖セミナーより-)

第24回微小脳神経外科解剖セミナー会長として(<特集>手術アプローチの選択とピットフォールII-第24回微小脳神経外科解剖セミナーより-)

Classification of neurovascular compression in typical hemifacial spasm: three-dimensional visualization of the facial and the vestibulocochlear nerves

In this paper, the authors introduce a method of noninvasive anatomical analysis of the facial nerve-vestibulocochlear nerve complex and the depiction of the variable vascular relationships by using 3D volume visualization. With this technique, a detailed spatial representation of the facial and vestibulocochlear nerves was obtained. Patients with hemifacial spasm (HFS) resulting from neurovascular compression (NVC) were examined. A total of 25 patients (13 males and 12 females) with HFS underwent 3D visualization using magnetic resonance (MR) imaging with 3D constructive interference in a steady state (CISS). Each data set was segmented and visualized with respect to the individual neurovascular relationships by direct volume rendering. Segmentation and visualization of the facial and vestibulocochlear nerves were performed with reference to their root exit zone (REZ), as well as proximal and distal segments including corresponding blood vessels. The 3D visualizations were interactively compared with the intraoperative situation during microvascular decompression (MVD) to verify the results with the observed microneurosurgical anatomy. Of the 25 patients, 20 underwent MVD (80%). Microvascular details were recorded on the affected and unaffected sides. On the affected sides, the anterior inferior cerebellar artery (AICA) was the most common causative vessel. The posterior inferior cerebellar artery, vertebral artery, internal auditory artery, and veins at the REZ of the facial nerve (the seventh cranial nerve) were also found to cause vascular contacts to the REZ of the facial nerve. In addition to this, the authors identified three distinct types of NVC within the REZ of the facial nerve at the affected sides. The authors analyzed the varying courses of the vessels on the unaffected sides. There were no bilateral clinical symptoms of HFS and no bilateral vascular compression of the REZ of the facial nerve. The authors discovered that the AICA is the most common vessel that interferes with the proximal and distal portions of the facial nerve without any contact between vessels and the REZ of the facial nerve on the unaffected sides. Three-dimensional visualization by direct volume rendering of 3D CISS MR imaging data offers the opportunity of noninvasive exploration and anatomical categorization of the facial nerve-vestibulocochlear nerve complex. Furthermore, it proves to be advantageous in establishing the diagnosis and guiding neurosurgical procedures by representing original MR imaging patient data in a 3D fashion. This modality provides an excellent overview of the entire neurovascular relationship of the cerebellopontine angle in each case.

CONSTRUCTION OF A THREE-DIMENSIONAL INTERACTIVE MODEL OF THE SKULL BASE AND CRANIAL NERVES

The goal was to develop an interactive three-dimensional (3-D) computerized anatomic model of the skull base for teaching microneurosurgical anatomy and for operative planning. The 3-D model was constructed using commercially available software (Maya 6.0 Unlimited; Alias Systems Corp., Delaware, MD), a personal computer, four cranial specimens, and six dry bones. Photographs from at least two angles of the superior and lateral views were imported to the 3-D software. Many photographs were needed to produce the model in anatomically complex areas. Careful dissection was needed to expose important structures in the two views. Landmarks, including foramen, bone, and dura mater, were used as reference points. The 3-D model of the skull base and related structures was constructed using more than 300,000 remodeled polygons. The model can be viewed from any angle. It can be rotated 360 degrees in any plane using any structure as the focal point of rotation. The model can be reduced or enlarged using the zoom function. Variable transparencies could be assigned to any structures so that the structures at any level can be seen. Anatomic labels can be attached to the structures in the 3-D model for educational purposes. This computer-generated 3-D model can be observed and studied repeatedly without the time limitations and stresses imposed by surgery. This model may offer the potential to create interactive surgical exercises useful in evaluating multiple surgical routes to specific target areas in the skull base.

Three-Dimensional Computerized Anatomy

Introduction: The goal of this study was to develop a three-dimensional (3D) computerized anatomical model for microneurosurgical anatomy education.

Some collected principles of microneurosurgery: simple and fast, while preserving normal anatomy: A review

Microneurosurgical techniques introduced by Prof Yasargil in the 1960s have increased the neurosurgeon's ability to operate in small and often very narrow and deep gaps. Microneurosurgical techniques—ensuring an almost bloodless field and mostly obviating need for transfusion—should be atraumatic and noninvasive to the already lesioned central nervous system tissues and structures. Instruments in microneurosurgery range from very short to very long and from sturdy to delicate, depending on the working depth, characteristics of tissues, and the microneurosurgical anatomy. However, to keep it simple and fast, and to appreciate normal anatomy, it is preferable to use only a limited array of instruments. Besides the use of instruments and the operating microscope, everything else in the neurosurgical arena should be optimized and professional, such as the positioning of the patient and the conduct of neuroanesthesia. This review of the very basics is distilled from the Helsinki and Kuopio neurosurgery practices in Finland and from the senior author's (JH) experience of close to 10 000 operations, and this is to encourage young neurosurgeons of the world—most of them working with limited resources—to continue to improve their microneurosurgical skills to serve their patients best.

Suprasellar and Sellar Tumors in Childhood and Adolescence

Suprasellar and sellar region tumors in children constitute a diverse group of lesions. We advocate an aggressive surgical approach to these tumors for diagnostic and therapeutic purposes. With detailed knowledge of the microneurosurgical anatomy of this region, the neurosurgeon can choose from a number of operative approaches on the basis of tumor size and location. The benefits of radiation therapy for craniopharyngiomas and optic chiasmatic/hypothalamic tumors must be carefully weighted against the substantial long-term risks associated with irradiation of the developing brain in this region. During the next decade, the role of primary chemotherapy for germinoma and adjuvant chemotherapy for optic pathway gliomas will be determined. Also, the role of stereotactic radiation therapy, of great value to some children with recalcitrant tumors in the suprasellar region, may be better defined.