Comprehensive Overview of Modern Surgical Approaches to Intrinsic Brain Tumors

By Alfredo Quinones-Hinojosa

Comprehensive Overview of Modern Surgical Approaches to Intrinsic Brain Tumors addresses limitations in the scientific literature by focusing primarily on surgical approaches to various intrinsic neoplasms using diagrams and step-by-step instructions. It provides the advantages and disadvantages of these approaches, controversies, and technical considerations and discusses topics such as anatomy, pathology and animal models, imaging, open brain tumor approaches and minimally invasive approaches. Additionally, it discusses controversial treatments and the pros and cons of each. This book is a valuable source for medical students, neurosurgeons and any healthcare provider who has an interest in brain tumors and techniques to treat them.

• Provides a comprehensive review of different approaches, explaining them step-by- step
• Includes diagrams that show surgical approaches
• Presents the advantages and disadvantages of each approach to aid in decision-making

• Language: English
• Publisher: Academic Press
• Release date: Feb 28, 2019
• ISBN: 9780128117842

Book preview

Comprehensive Overview of Modern Surgical Approaches to Intrinsic Brain Tumors

Editors

Kaisorn Chaichana

Alfredo Quiñones-Hinojosa

Table of Contents

Cover image

Title page

Copyright

Contributors

Preface

Introduction

Part I. Anatomy

Chapter 1. Gyral and Sulcal Microsurgical Anatomy

Introduction

The Cerebral Hemispheres

The Cerebral Lobes

Frontal Lobe

Central Lobe

Parietal Lobe

Occipital Lobe

Temporal Lobe

Insular Lobe

Limbic Lobe

Discussion

Chapter 2. Supratentorial White Matter Tracts

Introduction

White Matter Tract Types

Major Projection Fibers

Major Commissural Fibers

Anterior Commissure

Major Association Fibers

Frontal Aslant Tract

Uncinate Fasciculus

Discussion

Chapter 3. Neurovascular Anatomy in Relation to Intracranial Neoplasms

Introduction

Vascular Anatomy

Neurovascular Anomalies and Malformations

Tumor Vascularity

Conclusion

Chapter 4. Brain Stem Anatomy and Surgical Approaches

Introduction

External Structure of the Brain Stem

White Matter Fiber Anatomy of the Brain Stem

The Floor of the Fourth Ventricle

Pathways to Approach the Brain Stem

Conclusions

Chapter 5. Ventricular Anatomy

Lateral Ventricles

Corpus Callosum

Thalamus

Caudate Nucleus

Fornix

Choroidal Fissure

Septum Pellucidum

Hippocampus

Amygdala

Internal Capsule

Discussion

Conclusions

Part II. Pathology and Animal Models

Chapter 6. Pathology of Primary Brain Tumors—Gliomas

Introduction

Abbreviations

Chapter 7. Pathology of Intraventricular Tumors

Introduction

Epidemiology/Clinical Presentation

Intraventricular Pathology of the Lateral Ventricles

Intraventricular Pathology of the Third Ventricle

Intraventricular Pathology of the Fourth Ventricle

Conclusions

Chapter 8. Metastatic Brain Tumors

Introduction

Presentation, Pathology, and Imaging Findings

Common Metastatic Brain Tumors

Treatment of Metastatic Brain Tumors

Stereotactic Radiosurgery and Whole Brain Radiation

Surgical Resection

Summary of Treatment Modalities

Conclusion

Chapter 9. Animal Models of Brain Tumor Surgery

Introduction: Glioblastoma

Animals Used for Cancer Treatment and Surgery Models

Chemically Induced, Genetically Engineered, and Xenograft Mice Models

Evaluation of Tumor Formation and Progression

Conclusion

Chapter 10. Tumor Genetics and Their Outcomes on Surgery and Survival

Introduction

Glioblastoma (Grade IV Astrocytoma)

Midline Gliomas

Conclusion

Part III. Imaging

Chapter 11. Preoperative Imaging (MRI, Functional MRI, CT)

Introduction

Structural Magnetic Resonance Imaging and Computed Tomography

Magnetic Resonance Perfusion Imaging

MR Perfusion Techniques

Dynamic Susceptibility Contrast MRI

Dynamic Contrast Enhanced MRI

Arterial Spin Labeling

Clinical Use of Perfusion Imaging

Blood Oxygen Level–Dependent Functional MRI

Diffusion Tensor Imaging

Chapter 12. Innovations in Intraoperative Image Guidance for Intrinsic Brain Tumors

Introduction

Frame-Based Stereotactic Navigation

Frameless Stereotaxy

Functional Navigation

Intraoperative MRI

Case Illustration of Multimodal Navigation

Intraoperative Fluorescence-Guided Imaging (5-ALA and Fluorescein)

Intraoperative Ultrasound

Functional Mapping—Awake and Asleep

Emerging Techniques

Novel Technologies: From Pixels to Cells

Defining End Points of Resection

Conclusions

Chapter 13. Postoperative Imaging of Intrinsic Brain Tumors

Introduction

Immediate Postoperative Imaging

Early Findings (First 2Weeks)

Postoperative Complications

Late Complications (14–30days)

Posttreatment Follow-up and Surveillance

Radiation and Chemotherapy

Distinguishing Posttreatment Changes From Tumor Progression or Recurrence: Advanced MR and Multimodality Imaging

Conclusion

Part IV. Controversies

Chapter 14. Extent of Resection for High- and Low-Grade Gliomas

Introduction

Understanding Extent of Resection

Extent of Resection of High-Grade Gliomas

Strategies to Maximize Extent of Resection

Limitations of Extent of Resection Studies

Summary

Chapter 15. Awake Versus Non-awake Surgery for Brain Surgery

Introduction

Awake Craniotomy

Conclusions

Chapter 16. The Role of Surgical Resection Versus Stereotactic Radiosurgery in the Management of Brain Metastases

Introduction

Stereotactic Radiosurgery

Surgical Resection

Clinical Trials Comparing Surgical Resection and Stereotactic Radiosurgery

Considerations for Surgical Resection versus SRS for Brain Metastases

Conclusion

Chapter 17. En Bloc Versus Piecemeal Resection of Metastatic Brain Tumors

Introduction

Advancements in the Treatment of Malignancies

Management of Brain Metastases

Benefits of Surgery

Conclusions

Part V. Open Brain Tumor Approaches

Chapter 18. Awake Craniotomies for Motor Cortex Lesions

Introduction

Surgical Resection of Intrinsic Neoplasms

Neuroanatomy Considerations for Motor Cortex Tumors

Patient Selection and Presurgical Planning

Surgical Technique

Conclusion

Chapter 19. Awake Craniotomies for Neoplasms Involving Language Networks

Introduction

Evaluation of Cognitive Functions in Patients With Brain Neoplasm

Awake Craniotomy Is the Gold Standard in Surgery Within Eloquent Structures

A Reexamination of the Functional Anatomy of Language Networks: New Insights Gained From ISM

Resection of Neoplasms in Language Networks: Toward a Connectomal Surgical Neuro-Oncology

Outcome After Awake Craniotomy With Intraoperative Mapping

Conclusions

Chapter 20. Intraoperative MRI for High and Low Grade Gliomas

Introduction

Conclusion

Chapter 21. Transsylvian Approach to Intrinsic Brain Tumors: Insular Tumors

Introduction

Anatomy of the Sylvian Fissure and Surrounding Structures

Transsylvian Approach to Insular Tumors

Transsylvian Approach to Mesial Temporal Lesions

Conclusion

Chapter 22. Transsulcal Versus Transgyral Approaches for Subcortical Tumors

Introduction

Concept of the Approaches

Case Examples

Key Aspects of the Approach

Advantages and Disadvantages

Troubleshooting/Alternatives/Bailout Options

Conclusions

Chapter 23. Advances in Surgical Approaches to Supratentorial Deep-Seated Lesions

Introduction

Preoperative and Intraoperative Adjuncts

Minimally Invasive Subcortical Surgery

MR-Guided Laser Interstitial Thermal Therapy

Conclusion

Chapter 24. Approaches to Third Ventricular Tumors

Introduction

Microsurgical Anatomy of the Third Ventricle

The Approaches to the Third Ventricle

Part VI. Keyhole/Minimally Invasive Approaches

Chapter 25. Keyhole Approaches for Deep-Seated Lesions

Introduction

The Keyhole Concept

How to Plan a Keyhole Approach to Deep-Seated Intrinsic Lesions

Five Deep-Seated Intrinsic Brain Tumors

Conclusion

Chapter 26. Tubular Retractors for Deep-Seated Brain Lesions: Modern Concepts in Minimally Invasive Brain Surgery

Introduction

Concept of the Approach

Case Examples

Key Aspects of the Approach

Advantages and Disadvantages

Trouble Shooting/Alternatives/Bail Out Options

Conclusions

Chapter 27. Tubular Retractors for Intraventricular Tumors

Introduction

Intraventricular Anatomy and Pathology

Surgical Technique

Approach

Visualization

Conclusion

Chapter 28. Port Approaches to Intrinsic Brain Tumors

Introduction

Port Technique

Case Illustration: Microscope-Assisted Port Surgery

Surgical Outcomes with Microscope-Assisted Port Surgery

Literature Review and Current Evidence

Selection of Patients for Port Surgery

Conclusion

Complication Avoidance and Clinical Pearls

Index

Copyright

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Contributors

Karl R. Abi-Aad

Precision Neuro-therapeutics Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Neurosurgery Simulation and Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Shruti Agarwal,     Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Oluwaseun O. Akinduro,     Department of Neurologic Surgery, Mayo Clinic, Jacksonville, FL, United States

Ossamy Akiyama,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Wajd N. Al-Holou,     Department of Neurosurgery, The University of Texas M.D. Anderson Cancer Center, Houston, TX, United States

Barrett J. Anderies

Department of Neurological Surgery, Neurovascular and Skullbase Program, Mayo Clinic, Phoenix, AZ, United States

Precision Neuro-therapeutics Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Neurosurgery Simulation and Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Román P. Arévalo,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Bernard R. Bendok

Department of Neurological Surgery, Neurovascular and Skullbase Program, Mayo Clinic, Phoenix, AZ, United States

Department of Otolaryngology, Mayo Clinic, Phoenix, AZ, United States

Precision Neuro-therapeutics Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Neurosurgery Simulation and Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Mitchel S. Berger,     Department of Neurological Surgery, University of California San Francisco, California, United States

Chetan Bettegowda,     Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Alexandre Bossi Todeschini,     Department of Neurological Surgery, Wexner Medical Center, The Ohio State University College of Medicine, Columbus, OH, United States

Antonio Cesar de Melo Mussi,     Staff Neurosurgeon - Hospital Governador Celso Ramos, Florianopolis, Brazil

Kaisorn L. Chaichana,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

William Clifton,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Evandro de Oliveira,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Hugues Duffau

Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France

Team Plasticity of Central Nervous System, Stem Cells and Glial Tumors, National Institute for Health and Medical Research (INSERM), U1051 Laboratory, Institute for Neurosciences of Montpellier, Montpellier University Medical Center, France

Jeff Ehresman,     Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States

J. Bradley Elder,     Department of Neurological Surgery, Wexner Medical Center, The Ohio State University College of Medicine, Columbus, OH, United States

Chikezie I. Eseonu,     Department of Neurological Surgery, Department of Radiology, Mayo Clinic Florida, Jacksonville, FL, United States

Linton Evans,     Department of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, United States

David Fernandes,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Juan Carlos Fernandez Miranda,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Sara Ganaha,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Tomas Garzon-Muvdi,     Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Sanjeet S. Grewal,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Hugo Guerrero-Cazares,     Department of Neurosurgery, Mayo Clinic Florida, Jacksonville, FL, United States

Sachin K. Gujar,     Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Vivek Gupta,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Neil Haranhalli,     Department of Neurologic Surgery, Mayo Clinic, Jacksonville, FL, United States

Tasneem F. Hasan,     Department of Neurologic Surgery, Mayo Clinic, Jacksonville, FL, United States

Bryson Hauck,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Shawn L. Hervey-Jumper,     Department of Neurosurgery, University of Michigan, Ann Arbor, MI, United States

Reid Hoshide,     Centre for Minimally Invasive Neurosurgery, Randwick, NSW, Australia

Rajiv R. Iyer,     Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore MD, United States

George I. Jallo

Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore MD, United States

Institute for Brain Protection Sciences, Johns Hopkins All Children's Hospital, St Petersburg, FL, United States

Sukhdeep Singh Jawar,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Stephanie Jeanneret

Department of Neurosurgery, Mayo Clinic Florida, Jacksonville, FL, United States

Department of Psychology, The University of Texas at Austin, Austin, TX, United States

Mark E. Jentoft,     Deparment of Pathology, Mayo Clinic, Jacksonville, FL, United States

Chandan Krishna

Department of Neurological Surgery, Neurovascular and Skullbase Program, Mayo Clinic, Phoenix, AZ, United States

Precision Neuro-therapeutics Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Neurosurgery Simulation and Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Frederick F. Lang,     Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, United States

Montserrat Lara-Velazquez

Department of Neurosurgery, Mayo Clinic Florida, Jacksonville, FL, United States

Universidad Nacional Autónoma de México (UNAM), Facultad de Medicina, Plan de Estudios Combinados en Medicina (PECEM), Ciudad de México, Mexico

Michael Lim,     Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD, United States

Juan Manuel Revuelta Barbero,     Department of Neurological Surgery, Wexner Medical Center, The Ohio State University College of Medicine, Columbus, OH, United States

Russell Maxwell,     Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD, United States

Mateus Reghin Neto,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Maximiliano A. Nuñez,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Eva F. Pamias-Portalatin,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Jay J. Pillai,     Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Evandro Pinto da Luz de Oliveira

Adjunct Professor of Neurological Surgery at Mayo Clinic, United States

Director - Institute of Neurological Sciences, São Paulo, Brazil

Hospital BP - A Beneficência Portuguesa de São Paulo, Brazil

Gustavo Pradilla,     Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, United States

Daniel M. Prevedello,     Department of Neurological Surgery, Wexner Medical Center, The Ohio State University College of Medicine, Columbus, OH, United States

Vicent Quilis-Quesada

Department of Neurosurgery, Hospital Clinic Universitari de València, València, Spain

Associate Professor of Neuroanatomy, Department of Human Anatomy and Embryology, Faculty of Medicine, University of Valencia, València, Spain

Alfredo Quinones-Hinojosa,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Andres Ramos-Fresnedo,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Rodolofo Recalde,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Karim ReFaey,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Ronald Reimer,     Department of Neurological Surgery, Department of Radiology, Mayo Clinic Florida, Jacksonville, FL, United States

Jordina Rincon-Torroella,     Department of Neurological Surgery, Department of Radiology, Mayo Clinic Florida, Jacksonville, FL, United States

Pablo A. Rubino,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Haris I. Sair,     Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Eduardo Salas,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

George Samandouras,     Victor Horsley Department of Neurosurgery, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom

Mithun G. Sattur

Department of Neurological Surgery, Neurovascular and Skullbase Program, Mayo Clinic, Phoenix, AZ, United States

Precision Neuro-therapeutics Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Neurosurgery Simulation and Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Raymond Sawaya,     Department of Neurosurgery, The University of Texas M.D. Anderson Cancer Center, Houston, TX, United States

Paula Schiapparelli,     Department of Neurosurgery, Mayo Clinic Florida, Jacksonville, FL, United States

Ivan Segura-Duran,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

Changbin Shi,     Department of Neurosurgery, The First Affiliated Hospital of Harbin Medical University, Harbin, China

Nir Shimony,     Institute for Brain Protection Sciences, Johns Hopkins All Children's Hospital, St Petersburg, FL, United States

Valentina Tardivo,     Centre for Minimally Invasive Neurosurgery, Randwick, NSW, Australia

Rabih G. Tawk,     Department of Neurologic Surgery, Mayo Clinic, Jacksonville, FL, United States

Charles Teo,     Centre for Minimally Invasive Neurosurgery, Randwick, NSW, Australia

Fucheng Tian

Precision Neuro-therapeutics Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Neurosurgery Simulation and Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Department of Neurosurgery, The First Affiliated Hospital of Harbin Medical University, Harbin, China

Andrew E. Tyan,     Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Krishanthan Vigneswaran,     Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, United States

Seclen Voscoboinik,     Department of Neurosurgery, Hospital El Cruce, Buenos Aires, Argentina

Matthew E. Welz

Department of Neurological Surgery, Neurovascular and Skullbase Program, Mayo Clinic, Phoenix, AZ, United States

Precision Neuro-therapeutics Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Neurosurgery Simulation and Innovation Lab, Mayo Clinic, Phoenix, AZ, United States

Robert E. Wharen,     Department of Neurosurgery, Mayo Clinic College of Medicine, Jacksonville, FL, United States

David M. Wildrick,     Department of Neurosurgery, The University of Texas M.D. Anderson Cancer Center, Houston, TX, United States

Derek Wong,     Department of Pathology & Laboratory Medicine, Vancouver General Hospital, Vancouver, BC, Canada

Stephen Yip,     Department of Pathology & Laboratory Medicine, Vancouver General Hospital, Vancouver, BC, Canada

Pascal Zinn,     Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, United States

Preface

Intrinsic brain tumors can affect diverse areas of the brain. Accessing and resecting these lesions can be done using different surgical techniques. These ways include standard asleep craniotomy with a fundamental understanding of eloquent regions, awake brain mapping to identify and avoid these eloquent cortical and subcortical areas, and minimally invasive approaches using tubular retractors, endoscopic techniques, and laser interstitial therapy, among others. As knowledge of these eloquent regions are becoming more and more elucidated through imaging techniques such as functional magnetic resonance imaging (MRI) and tractography as well as cortical and subcortical mapping, it is becoming essential to understand ways to minimize injuries to these regions. The body of work from multiple authors, multiple institutions, and multiple countries in this book focuses on the different surgical approaches to various intrinsic neoplasms as explained by experts in the field and experts in the particular approaches.

In the first section of the book, we will focus on anatomy of the brain namely the cortex, subcortical white matter tracts, ventricles, brainstem, and vascular supplies. The second section will describe the pathology of tumors that can affect these different brain regions, as well as developing animal models to better study these diseases and tumor genetics. The third section will describe pre, intra, and postop imaging to help evaluate lesions, eloquent regions surrounding the pathology, and ways to identify potential complications associated with surgical approaches. The next section will focus on controversies in the management of different pathologies including low and high grade gliomas, as well as brain metastases. Lastly, we will describe in depth different surgical approaches for open and minimally invasive surgery from experts in the field including awake motor and language mapping, intraoperative MRI, trans-sulcal techniques, keyhole surgeries, and endoscopic and exoscopic guided surgeries.

This book is meant to serve as a comprehensive guide for neurosurgeons, fellows, residents, and other medical staff who participate in the care of patients with intrinsic brain lesions. This will provide anatomical descriptions of the brain, imaging techniques to identify brain tumors, pathology that affects these areas, and approaches to these lesions. We have had international experts on these various subjects contribute to this book in order to provide the most up-to-date information from leaders in the field. We hope you enjoy this book as much as we enjoyed putting it together.

Kaisorn L. Chaichana, MD

Alfredo Quiñones-Hinojosa, MD

Introduction

The incidence of brain tumors continues to rise. This is due to a combination of factors. This includes the widespread availability of imaging modalities, improvements in diagnostic modalities, longer survival times, and better medical and surgical management of these pathologies. As the number of people with brain tumors increases, there is a growing need to better understand the diagnoses, surgical approaches, and treatment paradigms for these lesions. This understanding is critical for delaying recurrence, prolonging survival, and optimizing patient’s quality of life.

The treatment of brain tumors is in constant evolution. This is because our understanding of tumor physiology, cellular processes, genetic and epigenetic modifications, neuroanatomy, and natural history is continually changing. We are developing a better understanding not only of the pathologies that can affect the brain but also of the functional processes of the brain where these lesions reside. As the knowledge and understanding of tumor pathophysiology and the brain parenchyma they infiltrate increases, there is a need for a literary source that encompasses the most up-to-date understanding of these disease processes. The neurosurgical literature is lacking in regard to a book that encompasses the different options and approaches one can use for intrinsic brain tumors. This book will attempt to address these limitations. The multidisciplinary work presented here will explain our current understanding of cerebral neuroanatomy including gyri and sulci, vascular, and ventricular anatomy; the present pathological grading system of primary and metastatic brain tumors; modern imaging modalities used to identify tumors and surrounding eloquent gray and white matter; existing controversies on their management; and the most contemporary open and minimally invasive approaches to treat these intrinsic lesions. By providing a comprehensive source of information that encompasses these facets, we hope the reader uses this knowledge to continue to push the fields of neurosurgery, oncology, pathology, radiology, and engineering forward with the goal of making these diseases curable with minimal to no morbidity.

Kaisorn L. Chaichana, MD

Alfredo Quiñones-Hinojosa, MD

Part I

Anatomy

Outline

Chapter 1. Gyral and Sulcal Microsurgical Anatomy

Chapter 2. Supratentorial White Matter Tracts

Chapter 3. Neurovascular Anatomy in Relation to Intracranial Neoplasms

Chapter 4. Brain Stem Anatomy and Surgical Approaches

Chapter 5. Ventricular Anatomy

Chapter 1

Gyral and Sulcal Microsurgical Anatomy

Vicent Quilis-Quesada ¹ , ²       ¹ Department of Neurosurgery, Hospital Clinic Universitari de València, València, Spain      ² Associate Professor of Neuroanatomy, Department of Human Anatomy and Embryology, Faculty of Medicine, University of Valencia, València, Spain

Abstract

The complex set of sulci and gyri on the surface of the brain form a map with which neurosurgeons should be familiar when it comes to planning and carrying out their procedures, more particularly in the case of intrinsic brain lesions. Based on the general organization of the lobes and gyral convolutions of the brain, as defined by sulci and fissures, the pre- and intraoperative identification of the anatomical features of each patient is of critical importance. Knowledge of brain morphology is also essential to identify its different functional areas, given that both are closely associated.

The correct interpretation of the excellent imaging techniques that are currently available is only possible through a solid grounding in anatomy and precise microsurgical principles. Only this way is it possible to achieve excellence in the indication, planning, and execution of the neurosurgical approach and microsurgical technique.

Keywords

Anatomy; Fissure; Gyrus; Microsurgery; Sulcus

Introduction

Knowledge of the microsurgical anatomy of the brain is a basic pillar of neurosurgery. The series of sulci and gyri on the surface of the brain forms a map with which neurosurgeons should be familiar when it comes to planning and carrying out their procedures, more particularly in the case of intrinsic brain lesions. Based on the general organization of the lobes and gyral convolutions of the brain, as defined by sulci and fissures, the preoperative (by means of neuroimaging) and intraoperative identification of the anatomical features of each patient is of critical importance. Knowledge of the microsurgical anatomy of the surface enables us to correctly locate the lesions for which surgery is to be performed, make the appropriate decision regarding the surgical approach, and treat the lesions with Optimal functional results. Each brain function has been shown to have a close relationship with the areas of the cerebral cortex (gray matter) and subcortical elements (white matter), and therefore microanatomical knowledge is the basis for the precise and safe execution of neurosurgical techniques (Quiñones-Hinojosa et al., 2003, Ribas, 2010, Türe et al., 1999, Yasargil, 1994, 1996, 1999, Yasargil et al., 2005). New technologies provide high-definition imaging studies, highly accurate pre- and intraoperative functional tests, and exceptional possibilities for mapping and neuronavigation. However, they should not replace the neurosurgeon's exhaustive neuroanatomical knowledge. Familiarity with brain geography and a well-honed surgical technique are a surgeon's best tools in the daily battle against conditions affecting the brain.

The Cerebral Hemispheres

The brain is divided into two hemispheres (telencephalon, from the Ancient Greek for endbrain), separated by the longitudinal or interhemispheric fissure, connected by the corpus callosum, and further by the diencephalon (from the Ancient Greek for between the brain). The anatomically continuous superolateral, basal, and medial surfaces can be identified on each hemisphere, and these are delimited by their superior, lateral, and medial edges (Ludwig and Klinger, 1956, Ono et al., 1990, Rhoton, 2002). The complex system of sulci and gyri on the surface defines the external telencephalic morphology. Deep below the surface, axons of white matter, areas of gray matter, and the different elements of the ventricular system complete the intrinsic brain anatomy (Ludwig and Klinger, 1956, Ono et al., 1990, Rhoton, 2002). The arterial and venous networks of the vascular tree around the surface structures (like an exoskeleton) and around the inside of the brain anatomy (similar to an endoskeleton) provide a negative image of the overall anatomy of the intracranial volume.

The Cerebral Lobes

The first descriptions of the general organization of the brain sulci and gyri, and their subdivision into what are now known as cerebral lobes, date to the 19th century and the work of French anatomist Louis Pierre Gratiolet. The first divisions of the cerebral lobes were determined by those areas of the brain underlying the different bones of the cranial vault. In this way, Gratiolet was initially able to describe the frontal, parietal, occipital, and temporal lobes. Throughout the history of anatomical nomenclature, the definition of the cerebral lobes has seen the addition of morphological and functional aspects, until the current definition was achieved in Terminologia Anatomica (1998) in which there are six lobes: frontal, parietal, occipital, temporal, insular, and limbic (Rhoton, 2002, Ribas, 2010, Ribas et al., 2006, Yasargil, 1994, Yasargil et al., 2005) This chapter conceptually divides each hemisphere into seven lobes, with the addition of the so-called central lobe to the six described in the 1998 edition of Terminologia Anatomica, based on the microsurgical and functional principles developed by Prof. M. G. Yasargil (Yasargil, 1994, 1996, 1999).

Frontal Lobe

The frontal lobe is the largest and farthest forward of the seven lobes into which we have divided the brain in this work. Its posterior limit is what is known as the precentral sulcus, the anteriormost of the slightly oblique sulci that can be identified on the lateral surface of the brain. The lateral surface of the frontal lobe comprises three main longitudinal gyri: the superior frontal gyrus (adjacent to the sagittal suture or midline), the middle frontal gyrus (centered on the lateral surface of the lobe), and the inferior frontal gyrus (the most lateral of the frontal gyri, in contact with the anterior cranial fossa and the lateral fissure of the cerebrum, the sylvian fissure), also referred to as F1, F2, and F3, respectively, in a number of works (Yasargil, 1994, 1996). They are delimited by the two longitudinal sulci, the superior frontal sulcus, and the inferior frontal sulcus (Figs. 1.1 and 1.3). The anatomical particularities of these sulci and gyri enable each one to be precisely identified, both in neuroimaging and neurosurgery, and provide references of orientation, location, and surgical access, more particularly for the treatment of intrinsic brain disorders (Rhoton, 2002, Yasargil, 1994, 1996). Each of the frontal gyri bears a relation with elements of the cranial surface. Thus, the superior frontal sulcus is located at the midpoint between the midline and the superior temporal line. The inferior frontal sulcus lies below the front half of the superior temporal line. The inferior frontal gyrus (the frontal operculum) lies below the bone between the superior temporal line and the temporal squama. The anteriormost part of the sylvian fissure lies below the anteriormost part of the temporal squama (Rhoton, 2002, Ribas, 2010) (Fig. 1.2).

Figure 1.1 Gyral and sulcal basic configuration of the lateral surface of the brain. Red dashed line, superior frontal sulcus; yellow dashed line, inferior frontal sulcus; green dashed line, intraparietal sulcus; green line, intermediate sulcus of Jensen; blue dashed line, sylvian fissure; orange dashed line, superior temporal sulcus; pink dashed line, inferior temporal sulcus; red dotted line, precentral sulcus; black dotted line, central sulcus; green dotted line, postcentral sulcus; pink dotted line, inferior occipital sulcus; orange dotted line, superior occipital sulcus; ag, angular gyrus; ifg, inferior frontal gyrus; iog, inferior occipital gyrus; itg, inferior temporal gyrus; mfg, middle frontal gyrus; mog, middle occipital gyrus; mtg, middle temporal gyrus; pcg, precentral gyrus; pg, postcentral gyrus; po, pars orbitalis; pop, pars opercularis; pt, pars triangularis; sfg, superior frontal gyrus; sg, supramarginal gyrus; sog, superior occipital gyrus; spl, superior parietal lobule; stg, superior temporal gyrus.

Figure 1.2 Superolateral view of the right hemisphere. The cranial sutures and the superior temporal line were kept in place. 1, Sagittal suture; 2, bregma; 3, superior sagittal sinus; 4, superior parietal lobule; 5, postcentral gyrus; 6, central sulcus; 7, precentral gyrus; 8, superior frontal gyrus; 9, middle frontal gyrus; 10, the coronal suture; 11, superior frontal sulcus; 12, frontomarginal sulcus; 13, supramarginal gyrus; 14, euryon (parietal tuberosity); 15, superior temporal line; 16, stephanion; 17, angular gyrus; 18, superior temporal sulcus; 19, sylvian fissure (ascending termination of the posterior ramus); 20, pars opercularis; 21, pars orbitalis; 22, squamous suture; 23, sylvian fissure; 24, pterion; 25, greater sphenoid wing; 26, middle temporal gyrus; 27, inferior temporal gyrus; 28, inferior temporal sulcus.

Figure 1.3 Lateral view of the brain (left hemisphere). 1, Frontal pole; 2, superior frontal gyrus; 3, superior frontal sulcus; 4, precentral gyrus; 5, central sulcus; 6, postcentral gyrus; 7, postcentral sulcus; 8, supramarginal gyrus; 9, angular gyrus; 10, roof of the orbit; 11, middle frontal gyrus; 12, inferior frontal sulcus; 13, precentral sulcus; 14, ascending termination of the posterior ramus of the sylvian fissure; 15, pars orbitalis; 16, anterior horizontal ramus of the sylvian fissure; 17, pars triangularis; 18, anterior ascending ramus of the sylvian fissure; 19, pars opercularis; 20, anterior subcentral ramus of sylvian fissure; 21, subcentral gyrus; 22, posterior subcentral ramus of sylvian fissure; 23, lesser sphenoid wing; 24, sylvian fissure; 25, anterior sylvian point; 26, temporal pole; 27, superior temporal gyrus; 28, superior temporal sulcus; 29, middle temporal gyrus.

The superior frontal sulcus separates the superior frontal gyrus from the middle frontal gyrus. This sulcus is easily identified both through magnetic resonance imaging and in surgery, as it runs longitudinally parallel to the midline until its intersection with the anteriormost of the oblique sulci of the lateral surface of the brain, the precentral sulcus (Figs. 1.13 and 1.14). Medial to the superior frontal sulcus is the superior frontal gyrus (the posterior portion of the superior frontal gyrus, close to the precentral gyrus, corresponds to the supplementary motor area). The precentral gyrus shows an Ω-shaped curve around the posteriormost end of the superior frontal sulcus, corresponding to the primary motor cortex controlling the contralateral hand. The intersection between the superior frontal sulcus and the precentral sulcus is an easy-to-identify anatomical landmark that allows the frontal lobe to be distinguished from the central lobe and functionally relevant areas (supplementary motor cortex and primary motor cortex) to be located (Fig. 1.14). The superior frontal gyrus is frequently divided longitudinally by a smaller sulcus known as the medial frontal sulcus.

Figure 1.4 Anterior view of the brain. A coronal cut has been performed in the right hemisphere at the level of the foramen of Monro. 1, Superior frontal gyrus; 2, superior frontal sulcus; 3, middle frontal gyrus; 4, cingulate gyrus; 5, corpus callosum; 6, external capsule; 7, caudate nucleus; 8, putamen; 9, lateral ventricle; 10, apex of the insula; 11, frontal operculum; 12, anterior perforated substance; 13, frontal pole; 14, frontomarginal sulcus; 15, frontal sinus; 16, roof of the orbit; 17, planum polare; 18, uncus; 19, middle cerebral artery; 20, optic nerve; 21, anterior cerebral arteries; 22, sylvian fissure; 23, superior temporal gyrus; 24, inferior frontal gyrus. The black arrows show how the sulci of the lateral and basal surface of the brain are oriented toward the ventricular cavities. Blue dotted line, cingulate sulcus; red dotted line, callosal sulcus.

The middle frontal gyrus is the largest of the three frontal gyri on the lateral surface of the frontal lobe. It can be divided longitudinally by what is known as the intermediate frontal sulcus. A large number of connections between the middle frontal gyrus and the inferior frontal gyrus are the cause of frequent interruptions to the continuity of the inferior frontal sulcus. Likewise, it can connect with the precentral gyrus by interrupting the continuity of the precentral sulcus (Figs. 1.3 and 1.4) (Rhoton, 2002, Ribas, 2010, Ribas et al., 2006, Yasargil, 1994).

Figure 1.5 Superolateral view of the brain (left hemisphere). 1, Superior frontal sulcus; 2, superior frontal gyrus; 3, precentral sulcus; 4, precentral gyrus (motor); 5, central sulcus; 6, postcentral gyrus; 7, postcentral sulcus; 8, superior parietal lobule; 9, intraparietal sulcus; 9′, postcentral-intraparietal sulci confluence; 10, occipital lobe; 11, middle frontal gyrus; 12, falx cerebri; 13, supramarginal gyrus; 14, gyrus of Jensen; 15, angular gyrus; 16, inferior frontal gyrus; 17, frontal pole.

Figure 1.6 Posterior view of the brain. The cranial sutures and the superior temporal line were kept in place. 1, Sagittal suture; 2, lambda; 3, superior parietal lobule; 4, intraparietal sulcus; 5, inferior parietal lobule; 6, superior temporal line; 7, lambdoid suture; 8, superior sagittal sinus; 9, inion (external occipital protuberance); 10, cuneus; 11, calcarine fissure; 12, lingual gyrus; 13, inferior occipital gyrus; 14, middle occipital gyrus; 15, superior occipital gyrus; 16, superior occipital sulcus; 17, inferior occipital sulcus; 18, superior nucal line; black∗, opistocranium; white∗, asterion.

Figure 1.7 Superior view of both temporal lobes. An axial cut through the third ventricle has been performed to expose both superior surfaces of the temporal lobes. The mediobasal temporal region has been dissected on the right temporal lobe to expose the intraventricular and extraventricular anatomical structures. 1, Anterior clinoid process; 2, optic nerve; 3, planum sphenoidale; 4, optic chiasm; 5, lamina terminalis; 6, optic tract; 7, carotid artery; 8, ophthalmic artery; 9, posterior communicating artery, 10, third nerve; 11, anterior choroidal artery; 12, middle cerebral artery; 13, temporal pole; 14, planum polare; 15, Heschl's gyrus; 16, middle transverse temporal gyrus; 17, semilunar gyrus; 18, temporal stem; 19, thalamus; 20, hypothalamus; 21, tuber cinereum; 22, mammillary bodies; 23, floor of the third ventricle; 24, mesencephalon; 25, apex of uncus; 26, amygdala; 27, uncal recess; 28, posterior segment of uncus; 29, head of hippocampus; 30, collateral eminence; 31, collateral trigone; 32, choroid plexus; 33, parahippocampal gyrus; 34, posterior cerebral artery; 35, anterior choroidal artery; 36, choroid glomus; 37, splenium of the corpus callosum.

The morphology of the inferior frontal gyrus is defined by the different arms (rami) of the sylvian fissure. Specifically, the anterior horizontal ramus and the anterior ascending ramus delimit, from anterior to posterior, the pars orbitalis, pars triangularis, and pars opercularis. These three anatomical elements, known as the frontal operculum, can be identified in both imaging studies and surgery, and are essential anatomical landmarks for locating the precentral and postcentral gyri (Figs. 1.3 and 1.13). From anterior to posterior, the pars orbitalis is located above the orbital roof in the anterior cranial fossa. The anterior horizontal and the anterior ascending rami of the sylvian fissure define the pars triangularis, which curves back to form a large subarachnoid cistern in the anterior portion of the sylvian fissure, the so-called anterior sylvian point (Fig. 1.3). This cisternal point forms an exceptional surgical landmark with which to plan the microsurgical dissection of the sylvian fissure, both for approaches to the basal cisterns and for the full opening of the sylvian fissure to expose the distal segments of the middle cerebral artery and the surface of the insular lobe. The anterior sylvian point lies slightly posterior, below what is known as the pterion of the skull (region of confluence of the sphenoid, frontal, parietal, and temporal bones) (Fig. 1.2). Immediately posterior to the anterior ascending ramus is the pars opercularis, which is characteristically U-shaped and in continuity with the precentral gyrus in its inferiormost part. The U that typifies the pars opercularis surrounds the inferior end of the precentral sulcus and constitutes another anatomical landmark for locating and identifying the different features of the lateral surface of the brain (Figs. 1.3 and 1.13). Finally, the pars opercularis, the posteriormost part of the frontal operculum, is bound by the central lobe through what is known as the anterior subcentral sulcus, occasionally located deep inside the sylvian fissure and therefore not visible from the surface. The Broca area (responsible for the production for the spoken language) of the dominant hemisphere is located in the pars triangularis and pars opercularis of the inferior frontal gyrus (Ono et al., 1990, Rhoton, 2002, Ribas, 2010, Ribas et al., 2006, Yasargil, 1994).

Figure 1.8 Inferior view of the brain. The posterior segment of the uncus and the middle segment of the parahippocampal gyrus have been dissected to expose the extraventricular representation of the head and body of the hippocampus (left hemisphere). 1, Frontal pole; 2, olfactory bulb; 3, anterior orbital gyrus; 4, lateral orbital gyrus; 5, medial orbital gyrus; 6, gyrus rectus; 7, olfactory tract; 8, temporal pole; 9, rhinal incisura; 10, anterior segment of the parahippocampal gyrus; 11, apex of the uncus; 12, anterior segment of the uncus; 13, uncinate gyrus (extraventricular representation of the head of hippocampus); 14, amygdala; 15, rhinal sulcus; 16, inferior temporal gyrus; 17, occipitotemporal sulcus; 18, fusiform gyrus; 19, collateral sulcus; 20, parahippocampal gyrus (middle segment); 20′, parahippocampal gyrus (posterior segment); 21, pons; 22, dentate gyrus; 23, temporal horn of the lateral ventricle; 24, intralingual sulcus; 25, lingual gyrus; 26, occipital pole; 27, inferior occipital gyrus; Black line, H-shaped orbital sulcus.

Figure 1.9 Lateral view of the right hemisphere. White fiber dissection of the brain and removal of the frontoparietal operculum to expose the surface of the insula. 1, Postcentral sulcus; 2, precentral sulcus; 3, middle frontal gyrus; 4, superior longitudinal fasciculus; 5, planum temporale; 6, sylvian point; 7, posterior long insular gyrus; 7′, postcentral insular sulcus; 8, anterior long insular gyrus; 9, posterior short insular gyrus; 10, precentral insular sulcus; 11, middle short insular gyrus; 12, short insular sulcus; 13, anterior short insular gyrus; 14, accessory insular gyrus; 15, pars orbitalis; 16, anterior horizontal ramus of sylvian fissure; 17, middle transverse temporal gyrus; 18, Heschl's gyrus, 19, superior temporal gyrus; 20, superior temporal sulcus; 21, middle temporal gyrus; 22, inferior temporal sulcus; 23, inferior temporal gyrus; 24, temporal pole. Yellow dotted line, representation of the lateral ventricle to illustrate how the insula is situated in the C-shaped curve of it; red line, superior limiting sulcus of the insula; green line, anterior limiting sulcus of the insula; blue line, inferior limiting sulcus of the insula; black dotted line, central sulcus of the insula; gray line, central sulcus of the brain; (∗), insular apex.

Figure 1.10 Medial surface of the right hemisphere. 1, Superior frontal gyrus; 1′, medial frontal gyrus; 2, paracentral sulcus; 2′, anterior paracentral lobule; 3, posterior paracentral lobule; 4, marginal ramus of the cingulate sulcus; 5, precuneus; 6, parietooccipital sulcus; 7, cuneus; 8, calcarine fissure; 9, occipital pole; 10, frontal pole; 11, gyrus rectus; 12, paraterminal gyrus; 13, paraolfactory gyri; 14, velum interpositum; 15, genu of the corpus callosum; 16, rostrum of the corpus callosum; 17, body of the corpus callosum; 18, cingulate gyrus; 19, callosal sulcus; 20, cingulate sulcus; 21, fornix; 22, anterior commissure; 23, optic chiasm; 24, lamina terminalis; 25, third ventricle; 26, splenium of the corpus callosum; 27, pineal gland; 28, subparietal sulcus; 29, parahippocampocingulate gyrus; 30, parahippocampolingual gyrus; 31, external perpendicular fissure (lateral surface); 32, lingual gyrus; 33, temporal pole; 34, fusiform gyrus; 35, rhinal sulcus; 36, anterior segment of the parahippocampal gyrus; 37, middle segment of the parahippocampal gyrus; 38, collateral sulcus; 39, apex of the uncus; 40, rhinal incisura; 41, uncal notch.

Figure 1.11 Inferior view of the right hemisphere. 1, Frontal pole; 2, olfactory nerve; 3, gyrus rectus; 4, optic nerve; 5, optic tract; 6, mesencephalon; 7, ambient cistern; 8, quadrigeminal cistern; 9, splenium of the corpus callosum; 10, isthmus of the cingulate gyrus; 11, parahippocampocingulate gyrus; 12, parahippocampolingual gyrus; 13, anterior calcarine sulcus; 14, parietooccipital sulcus; 15, precuneus; 16, cuneus; 17, lingual gyrus; 18, calcarine sulcus; 19, orbital gyri; 20, temporal pole; 21, rhinal incisura; 22, anterior segment of the parahippocampal gyrus; 23, rhinal sulcus; 24, anterior segment of the uncus; 25, apex of the uncus; 26, posterior segment of the uncus; 27, uncal notch; 28, middle segment of the parahippocampal gyrus; 29, collateral sulcus; 30, posterior segment of the parahippocampal gyrus; 31, fusiform gyrus; 32, inferior temporal gyrus; 33, occipitotemporal sulcus; 34, inferior occipital gyrus.

At the anterior end of the frontal lobe (frontal pole), the frontomarginal sulcus, parallel to the supraciliary margin, separates the superolateral surface of the frontal lobe from the basal surface (Fig. 1. 4). The basal surface of the frontal lobe is located above the so-called anterior fossa of the skull base. It comprises a continuous and straight gyrus running parallel to the midline, known as the gyrus rectus, and the so-called orbital gyri. The gyrus rectus is a continuation of the superior frontal gyrus on the superolateral and medial surfaces of the frontal lobe. Lateral to the rectus gyrus is the olfactory sulcus, a deep longitudinal and paramedian sulcus in which the olfactory tract is found. The division of the olfactory tract into medial and lateral striae marks the posterior limit of the basal surface of the frontal lobe and the start of what is known as the anterior perforated substance. Most of the basal surface of the frontal lobe is made up of orbital gyri, which are lateral to the olfactory sulcus. The characteristically H-shaped orbital sulcus delimits the four orbital gyri (anterior, medial, posterior, and lateral), which are all connected to the frontal gyri of the superolateral surface (Figs. 1.8 and 1.11).

Figure 1.12 Medial view of the mediobasal temporal region of the right hemisphere. The dissector opens the uncal notch to expose the inferior surface of the posterior segment of the uncus. 1, Entorhinal area; 2, dissector opening the uncal notch; 3, anterior segment of the uncus; 4, apex of the uncus; 5, optic tract; 6, uncinate gyrus; 7, band of Giacomini; 8, intralimbic gyrus; 9, inferior choroidal point; 10, lateral geniculate body; 11, choroidal fissure; 12, fimbria; 13, dentate gyrus; 14, hippocampal sulcus; 15, fimbrodentate sulcus; 16, parahippocampal gyrus; 17, parahippocampocingulate gyrus; 18, parahippocampolingual gyrus; 19, splenium of the corpus callosum.

The medial surface of the frontal lobe comprises the interhemispherical face of the superior frontal gyrus. The superior frontal gyrus continues at its anterior end as the rectus gyrus of the basal surface of the frontal lobe. The paracentral sulcus marks the posterior limit of the frontal lobe and the anterior limit of the paracentral lobule. A part of the supplementary motor cortex is found in the posterior and medial portions of the superior frontal gyrus (Figs. 1.10 and 1.13) (Ono et al., 1990, Rhoton, 2002, Ribas, 2010, Ribas et al., 2006, Yasargil, 1994).

Figure 1.13 A. Preoperative sagittal T1-weighted magnetic resonance image of a low-grade astrocytoma in the posterior segment of the middle frontal gyrus. (A) 1, Pars orbitalis; 2, pars triangularis; 3, pars opercularis; 4, subcentral gyrus; 5, precentral gyrus; 6, central sulcus; 7, postcentral gyrus; 8, supramarginal gyrus; 9, superior temporal gyrus; 10, middle temporal gyrus; 11, sylvian fissure; (∗), anterior sylvian point. (B) Preoperative sagittal T1-weighted magnetic resonance image of a low-grade astrocytoma in the anteriormost portion of the supramarginal gyrus. 1, Pars orbitalis; 2, pars triangularis; 3, pars opercularis; 4, subcentral sulcus; 5, central sulcus; 6, postcentral gyrus; 7, postcentral sulcus; 8, supramarginal gyrus; 9, superior temporal gyrus; 10, middle temporal gyrus; 11, middle frontal gyrus; 12, precentral gyrus; (∗), anterior sylvian point. (C) Preoperative sagittal T1-weighted magnetic resonance image of a cavernoma located in the confluence of the parietooccipital sulcus and calcarine fissure (white arrow). 1, Superior frontal gyrus; 2, cingulate gyrus; 3, splenium of corpus callosum; 4, paracentral lobule; 5, marginal ramus of cingulate sulcus; 6, cingulate sulcus; 7, precuneus; 8, parietooccipital sulcus; 9, cuneus; 10, calcarine fissure; 11, lingual gyrus. (D) Preoperative coronal T2-weighted magnetic resonance image of a low-grade astrocytoma in the right cingulate gyrus. 1, Parahippocampal gyrus; 2, fusiform gyrus; 3, inferior temporal gyrus; 4, middle temporal gyrus; 5, superior temporal gyrus; 6, inferior frontal gyrus; 7, middle frontal gyrus; 8, superior frontal gyrus; 9, cingulate gyrus (tumor); 10, corpus callosum; 11, thalamus; 12, caudate nucleus. (E) Preoperative coronal T2-weighted magnetic resonance image of a low-grade astrocytoma in the left fusiform gyrus. 1, Atrium of the lateral ventricle; 2, cingulate gyrus; 3, superior parietal lobule; 4, corpus callosum; 5, posterior segment of the parahippocampal gyrus; 6, fusiform gyrus (tumor); 7, inferior temporal gyrus; white arrow, collateral sulcus; black arrow, collateral trigone. (F) Preoperative sagittal T2-weighted magnetic resonance image of a low-grade astrocytoma in the cingulate gyrus and precuneus. 1, Corpus callosum; 2, cingulate gyrus; 3, superior frontal gyrus; 4, precuneus; 5, parietooccipital sulcus; 6, cuneus; 7, calcarine fissure; 8, lingual gyrus; 9, isthmus of the cingulate gyrus; 10, splenium of corpus callosum. (G) Preoperative axial T2-weighted magnetic resonance image of an arteriovenous malformation in the left precentral sulcus. 1, Middle frontal gyrus; 2, superior frontal gyrus; 3, precentral and superior frontal sulci point of confluence; 4, precentral gyrus (Ω); 5, central sulcus; 6, postcentral gyrus; 7, marginal ramus of cingulate sulcus; 8, postcentral sulcus; 9, superior parietal lobule. (H) Preoperative sagittal T2-weighted magnetic resonance image of a low-grade oligoastrocytoma located in the precuneus. 1, Subcallosal area; 2, gyrus rectus; 3, genu of corpus callosum; 4, superior frontal gyrus; 5, cingulate gyrus; 6, paracentral lobule; 7, marginal ramus of cingulate sulcus; 8, precuneus; 9, cuneus; 10, lingual gyrus; 11, splenium of corpus callosum; 12, thalamus; (∗), parietooccipital and calcarine point of confluence. (I) Preoperative sagittal T2-weighted magnetic resonance image of a metastasis located in the depth of the intermediate sulcus of Jensen (notice the vasogenic edema enhancing the inferior parietal lobule). 1, Posterior ramus of sylvian fissure; 2, supramarginal gyrus; 3, superior temporal gyrus; 4, angular gyrus; black arrow, intermediate sulcus of Jensen.

Central Lobe

The concept of the central lobe, introduced by Prof. M. G. Yasargil, is justified because it can be considered in morphological and functional terms to be a distinct area separate from the other cerebral lobes (Yasargil, 1994, 1996).

The central lobe comprises the precentral (motor) and postcentral (sensitive) gyri, separated by the central sulcus (frequently continuous and barely serpiginous). Arranged obliquely to the midline and located between the frontal and parietal lobes, it is limited anteriorly by the precentral sulcus and posteriorly by the postcentral sulcus, both commonly discontinuous. Both cerebral gyri run from the sylvian fissure (where they interconnect through what is known as the subcentral gyrus) and reach the medial surface of the brain where they give rise to the paracentral lobule. The brain surface point at which the central sulcus intersects with the interhemispheric fissure, known as the superior rolandic point, is located approximately 5   cm posterior to the bregma (Figs. 1.1–1.3). At the level of the sylvian fissure, the subcentral gyrus is limited anteriorly by the frontal operculum through the anterior subcentral sulcus and posteriorly by the parietal operculum through the posterior subcentral sulcus. The posterior half of the subcentral gyrus projects over Heschl's gyrus (also known as the anterior transverse temporal gyrus) in transition between the planum polare and the planum temporale of the temporal lobe. On the medial surface, the paracentral lobule is limited anteriorly by the superior frontal gyrus by means of the paracentral sulcus and is separated posterobasally from the parietal lobe through the marginal ramus of the cingulate gyrus. The paracentral lobule controls the motor and sensory innervations of the contralateral lower extremity (Figs. 1.10 and 1.13).

There is a third connection between the precentral gyrus and the postcentral gyrus, known as the medial frontoparietal pli de passage of Broca, generally located at the level of the posterior end of the superior frontal sulcus. This connection, together with the confluence of the precentral and superior frontal sulci, creates a subarachnoid cistern, previously described, associated with a Ω-shaped deformity of the precentral gyrus, which is easily identified in imaging studies and in surgery. The Ω of the precentral gyrus corresponds to the primary motor cortex of the contralateral hand and is a very useful landmark for locating each of the sulci and gyri of the lateral surface of the brain, in particular those associated with the central lobe (Figs. 1.2, 1.5 and 1.13) (Ribas et al., 2006, Yasargil, 1994, 1996).

Figure 1.14 A 33-year-old left-handed male who had suffered several seizures, at presentation, had no neurological abnormalities. (A–C) Preoperative T2-weighted magnetic resonance images of a low-grade astrocytoma located in the posterior portion of the superior frontal gyrus (supplementary motor area). Three years after surgery, the patient remains asymptomatic. (A) 1, Superior frontal gyrus; 2, superior frontal sulcus; 3, precentral gyrus; 4, postcentral gyrus; 5, central sulcus; (∗), precentral and superior frontal sulci point of confluence; black arrow, marginal ramus of the cingulate gyrus. (B) 1, Corpus callosum; 2, cingulate gyrus; 3, superior frontal gyrus; 4, paracentral lobule; white arrow, marginal ramus of the cingulate gyrus. (C) 1, Inferior frontal gyrus; 2, middle frontal gyrus; 3, superior frontal gyrus; 4, cingulate gyrus; 5, corpus callosum. (D) Surgical planning (see-through view). 1, Precentral gyrus; 2, superior frontal gyrus; 3, sagittal suture; 4, tumor; 5, middle frontal gyrus; (∗), precentral and superior frontal sulci point of confluence. (E) Cranial surface; (∗), sagittal suture (midline). (F) Brain surface after dural opening. 1, Precentral gyrus; 2, superior frontal gyrus (tumor); 3, superior frontal gyrus (anterior to the tumor); (∗), precentral and superior frontal sulci point of confluence (enlarged subarachnoid space). (G) Surgical field after radical resection of the tumor. 1, Precentral gyrus; 2, superior frontal gyrus; 3, middle frontal gyrus. (H) Postoperative T2-weighted magnetic resonance image. Radical resection of the tumor. 1, Superior frontal gyrus; 2, precentral gyrus; 3, postcentral gyrus; 4, middle frontal gyrus; 5, brain cavity after tumor removal. I. Postoperative sagittal gadolinium-enhanced T1-weighted magnetic resonance image. 1, Superior frontal gyrus; 2, cingulate gyrus; 3, splenium of corpus callosum; 4, paracentral lobule; 5, precuneus; 6, cuneus; 7, lingual gyrus; 8, brain cavity after tumor removal.

Parietal Lobe

The parietal lobe is characterized by curvilinear gyri of short length and by its delimitation by long sulci. It is largely divided into two parietal lobules (superior and inferior) by the longitudinal intraparietal sulcus, which is parallel to the midline and continues along the length of the occipital lobe in the form of the superior occipital sulcus. It is limited anteriorly by the postcentral gyrus by means of the postcentral sulcus, which generally connects with the intraparietal sulcus to give rise to a large subarachnoid cistern (Fig. 1.5) (Ribas et al., 2006). This space facilitates identification of the different elements of the parietal lobe in imaging tests and their dissection in transsulcal approaches. The posterior limit of the parietal lobe is arbitrarily defined by a line that joins the protrusion on the superolateral surface of the parietooccipital sulcus (medial surface of the hemisphere) with what is known as the preoccipital notch (a laterobasal indentation of the brain that separates the temporal lobe from the occipital lobe, typically located about 5   cm anterior to the occipital pole). The intraparietal sulcus lies approximately below the posterior half of the superior temporal line on the cranial surface. The superior parietal lobule is located medial to superior temporal line, whereas the inferior parietal lobule is located below the cranial surface between the superior temporal line and the temporal squama (Ono et al., 1990, Rhoton, 2002, Ribas, 2010, Ribas et al., 2006, Yasargil, 1994, Yasargil, 1996) (Figs. 1.2 and 1.6).

In turn, the inferior parietal lobule is divided into two main gyri: the supramarginal gyrus, around the distal end of the posterior ramus of the sylvian fissure, and the angular gyrus, around the posterior end of the superior temporal sulcus. Both gyri are separated by what is known as the intermediate sulcus of Jensen, a ramus of the intraparietal sulcus, superior temporal sulcus, or both. The supramarginal gyrus is connected anteriorly to the postcentral gyrus surrounding the inferior end of the postcentral sulcus. The continuity of the posteroinferior portion of the supramarginal gyrus as the superior temporal gyrus, where the Wernicke area (speech comprehension) is found in the dominant hemisphere, is of great relevance. Like the supramarginal gyrus, the angular gyrus is located around the posterior end of the superior temporal sulcus, continuing from the middle temporal gyrus. The superior part of the supramarginal gyrus lies underneath the so-called euryon (craniometric point corresponding to the parietal tuberosity) (Wen et al., 2009) (Figs. 1.1, 1.2, 1.5 and 1.13).

The superior parietal lobe is frequently connected at its anterior end with the postcentral gyrus, creating the discontinuity of the superior portion of the postcentral sulcus. It is limited laterally by the intraparietal sulcus, which continues in the form of the superior occipital sulcus. The superior parietal lobule also continues as the superior occipital gyrus, after passing what is known as the external perpendicular fissure (superior end of the parietooccipital sulcus on the superolateral surface of the brain). The external perpendicular fissure, identifiable in imaging tests, is a landmark that delimits the superior parietal lobule (anterior) from the superior occipital gyrus (posterior) on the superolateral surface. Likewise, the parietooccipital sulcus (on the medial surface of the hemisphere) allows the precuneus (anterior and part of the superior parietal lobule) to be separated from the cuneus (posterior and part of the occipital lobe) (Rhoton, 2002, Ribas, 2010, Ribas et al., 2006) (Figs 1.10 and 1.13).

The superior parietal lobule, supramarginal gyrus, and angular gyrus are also referred to as the P1, P2, and P3, respectively, by a number of authors (Yasargil, 1994, 1996).

On the medial surface of each hemisphere, the superior parietal lobule continues as the precuneus, limited anteriorly by the marginal ramus of the cingulate gyrus, posteriorly by the parietooccipital sulcus, and inferiorly by the subparietal sulcus. The precuneus connects inferiorly with elements of the limbic lobe, such as the isthmus of the cingulate gyrus and the parahippocampal gyrus (Fig. 1.10).

Occipital Lobe

While the occipital lobe is anatomically the most inconsistent of the cerebral lobes, it is organized according to the general pattern of three longitudinal gyri (superior, middle, and inferior occipital gyri, also known as O1, O2, and O3, respectively) separated by two main sulci (superior and inferior) that converge at the occipital pole. The superior occipital sulcus and the inferior occipital sulcus have a great many ramifications, which together with a large number of anastomotic bridges between the different gyri produce a variable and irregular superolateral surface (Ribas et al., 2006) (Fig. 1.1).

The medial surface of the occipital lobe is more defined than the lateral surface. The parietooccipital sulcus forms its anterior limit, while another continuous sulcus, the calcarine fissure, divides it into the cuneus (anterior) and lingual gyrus (posteroinferior). The superior end of the parietooccipital sulcus, projected onto the lateral surface as the external perpendicular fissure, lies underneath the so-called lambda (craniometric point of the skull midline surface). The calcarine fissure is divided into an anterior portion and a posterior portion by the point where the parietooccipital sulcus begins. The precuneus is located over the anterior portion; the cuneus is found over the posterior portion; and finally, what is known as the lingual gyrus is found beneath the entire calcarine fissure. The lingual gyrus, which continues anteriorly as the parahippocampal gyrus (part of the mediobasal temporal region and limbic lobe), forms the mediobasal surface of the occipital lobe. The anteriormost part of the calcarine fissure is projected downward at the level of the medial wall of the ventricular atrium of the brain, in the form of the calcar avis. The primary visual cortex is found in the posterior part of the calcarine fissure, on both the superior (cuneus) and inferior (lingual gyrus) surfaces (Rhoton, 2002) (Figs. 1.10 and 1.11).

The inferior surface continues as the basal posterior surface of the temporal lobe, from which it is separated by an imaginary line that joins the preoccipital notch with the starting point of the parietooccipital sulcus from the calcarine fissure. The lingual gyrus is limited laterobasally by the so-called collateral sulcus, lateral to which is the fusiform gyrus, which runs along the basal surface of both temporal and occipital lobes. Lateral to the fusiform gyrus, what is known as the occipitotemporal sulcus runs from the temporal pole to the occipital pole along the basal surface of the brain. The inferior temporal gyrus, continuing from the inferior occipital gyrus, forms a part of both the lateral surface and basal surface of the brain, and both are located lateral to the occipitotemporal sulcus (Ono et al., 1990, Rhoton, 2002, Ribas et al., 2006) (Figs. 1.8 and 1.11).

Temporal Lobe

The limits of the temporal lobe are relatively artificial (defined descriptively but without any clear anatomical definition), particularly with regard to its posterior and basal limits. Viewed laterally, it is separated from the frontal, central, and parietal lobes by the posterior ramus of the sylvian fissure. It is delineated posteriorly by the occipital lobe by means of the imaginary lateral parietotemporal line, which runs between the parietooccipital sulcus on the lateral surface of the brain (external perpendicular fissure) to the preoccipital notch. It is separated from the parietal lobe by the temporooccipital line, which runs from the posterior end of the posterior ramus of the sylvian fissure to the midpoint of the lateral parietotemporal line. It is separated from the occipital lobe on its basal surface by the basal parietotemporal line, which connects the preoccipital notch with the inferior limit of the parietooccipital fissure.

In anatomical terms, the temporal lobe continues into the occipital lobe without any clear delineation. The parahippocampal gyrus of the mediobasal temporal region (actually part of the limbic lobe) continues anatomically