Rhoton’s Cranial Anatomy and Surgical Approaches

1063 Pages·2007·138.01 MB·English

by  Albert L. Rhoton Jr MD

Author
Albert L. Rhoton Jr. M.D.
Editor's Letter
MIRABILE VISU
This volume stands as a tribute to the remarkable vision, diligence, and intelligence of Albert L. Rhoton, Jr. It is
the concrete legacy of his character and persona. It serves as an example for all of us who would call ourselves
neurosurgeons and represents the epitome of the term “contribution to the field” - a notion and goal that is the
elusive “Holy Grail” for many of us.
In the progress of refinement of our surgical discipline over the centuries, the comprehension of anatomy, its
quintessential building block, has been central to any surgical endeavor. All of our surgical ancestors, from Galen
to Yaşargil, have been aware of this truism. The challenge of the microneurosurgical era requires precise
comprehension of the microsurgical anatomic substrate. In an effort spanning more than 40 years, Dr. Rhoton
has developed and refined the field's comprehension of this critical foundation of our surgical enterprise. The
work clearly stands alone as a remarkable contribution and accomplishment by an individual in this or any era.
As a unique addition to the content of this volume, Dr. Rhoton's genius for instrument design and the practical
craft of microneurosurgery is conveyed in generous detail.
NEUROSURGERY is proud to present the essential amalgam of the principal elements of this enterprise for our
colleagues around the world, and we are particularly grateful to Dr. Rhoton for affording us the singular privilege
of publishing this composite classic work. We are likewise indebted to Carl Zeiss Surgical and Medtronic Midas
Rex for their generous and insightful support of this important project.
Michael L.J. Apuzzo
Los Angeles, California
FIGURE. No caption avaiable.
FIGURE. Portrait of Thornas Willis by Vertue, 1742, printed by Knapton. It is a copy of the earlier Loggan
engraving done in 1666 when Willis was 45 years old.
FOREWORD
The BRAIN AND CRANIAL BASE: MICROSURGICAL ANATOMY AND
SURGICAL APPROACHES
Neurosurgeons throughout the world salute Neurosurgery and Editor-in-Chief Michael L.J. Apuzzo for their
magnificent academic and scientific contributions to our specialty. Neurosurgery has elevated the care of
neurosurgical patients everywhere. I am deeply appreciative to Dr. Apuzzo and the Editorial Board for giving me
the opportunity to work with them on this book, which was formed by the union of the Millennium and 25th
Anniversary issues of Neurosurgery (3, 4). I also salute Carl Zeiss, Inc., and Medtronic Midas Rex on the
occasion of the publication of this book and thank them for the grants that made it possible. The increased safety
and accuracy and the improved results obtained with the Zeiss microscope are some of my greatest professional
blessings and a great contributor to the quality of life of my patients. Medtronic Midas Rex, through the increased
ease and delicacy of bone removal made possible with the use of their drills, has also made a contribution to the
care of neurosurgical patients worldwide and has allowed neurosurgeons to focus on operating accurately and
precisely in the delicate neural tissue that is the basis of our specialty. Both Midas Rex and Zeiss have continued
to invest in modifying and upgrading their instruments by integrating them with modern technological advances to
aid us in our work and provide new benefits for our patients. Both Zeiss and Midas Rex have assisted with
educational endeavors, such as this book, that have improved neurosurgical care on every continent and have
made the academic aspects of my career much more rewarding. I am grateful for their support of the publication
of our studies on microsurgical anatomy and for partnering with neurosurgeons throughout the world to improve
neurosurgical care. As stated in the Millennium and 25th Anniversary Issues of Neurosurgery, this work on
microsurgical anatomy has grown out of my personal desire to improve the care of my patients (3, 4). It
represents a 40-plus years’ attempt to gain an understanding of the anatomy and intricacies of the brain with the
goal of improving the safety, gentleness, and accuracy of my operations on my patients.
Before proceeding with some additional thoughts about the role of microsurgical anatomy in neurosurgery, I
would like to share some thoughts about neurosurgery, some of which were included in my addresses as
president of the AANS and CNS (1, 2). Neurosurgeons share a great professional gift; our lives have yielded an
opportunity to help mankind in a unique and exciting way. In my early years, I never imagined that my life would
hold as gratifying, exciting, and delicate a challenge as that of being a physician or a neurosurgeon.
Neurosurgeons' work is performed in response to the idea that human life is sacred, that it makes sense to
spend years of one's life in study to prepare to help others. Our training brings into harmony a knowledgeable
mind, a skilled set of hands, and a well-trained eye, all of which are guided by a caring human being. The skills
that we use have been described as the most delicate, the most fateful, and, to the layperson, the most
awesome of any profession. The Gallup Poll has reported that neurosurgeons are among the most prestigious
and highly skilled members of American society. We share the opportunity to serve people in a unique way,
dealing surgically with the most delicate of tissues.
Our ranking among the most highly skilled members of society tends to lead us to forget that our work and
success are made possible by the benevolent order built into the universe around us. That people heal and
survive after surgery provides us with our work and serves as a constant reminder of this benevolent, protective
order. We are surrounded by biological and physical forces that could overcome us, outstripping our finest
medical and scientific achievements. The momentous process of injured tissues’ knitting together is as essential
to the work of the surgeon as the air people breathe is to their survival. That humanity survives and that
neurosurgeons can play a role in the process of healing are examples of the compassion and love that surround
us. A patient who writes a thank-you note or praises my efforts leads me to inwardly reflect that one of our
greatest gifts is that we were created to help each other. I am grateful for the opportunity to be a participant in
the miracle we call neurosurgery.
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Another gift we share is a historical one based on the standards set by early physicians. Hippocrates taught that
medicine is a difficult art that is inseparable from the highest morality and love of humanity. The noble values and
loyal obedience of generations of physicians since Hippocrates have raised the calling to the highest of all
professions. Many of us were attracted to neurosurgery by both the meticulousness of surgical craftsmanship
and the intellectual challenge posed by modern clinical neurology and neurophysiology. All of us have submitted
ourselves to the discipline of rigorous training, possibly the most demanding in modern society, and are capable
of giving a great deal of ourselves.
Our work has grown out of the belief in absolute standards of value and worth in humanity. These values are
reflected in the increasing importance of one man, one woman, or one child in American society and throughout
the world. An example of the evolving importance of the individual is found in examining great human creations
such as the Egyptian pyramids and the Great Wall of China. Through the decades and
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the centuries, humankind has evolved to the point where some of the pyramids of modern society are our
modern medical centers. In them, society's most highly trained teams, using humankind's most advanced
technology at great cost, are allowed to work for days trying to improve the lives of individual patients without
regard to whether they are rich or poor. Issues related to the dignity and worth of a single man, woman, and child
are clearer to us now than they were a century or two ago and provide the driving force behind our work. These
values and standards, which are inseparable from the highest morality and love of humanity, are built into us just
as the process of healing is built into our nature.
J. Lawrence Pool, who led the neurosurgical program at Columbia University, wrote, “As I look back on the
pattern of my life I see how fortunate it was that I had chosen a career in neurosurgery, which I passionately
loved despite its long hours and many grueling experiences.” He concluded with a statement about his belief that
the best surgeons have a strong sense of compassion. It is important that we grow in compassion just as we
grow in competence. Competence is the possession of a required skill or knowledge. Compassion, on the other
hand, does not require a skill or knowledge; it requires an innate feeling, commonly called love, toward someone
else. Both competence and compassion need to be developed simultaneously, just as the giant oak develops its
root system along with its leaves and branches. Competence without compassion is worthless. Compassion
without competence is meaningless. It is a great challenge to guide patients competently and compassionately
through neurosurgery. Death and darkness crowd near to our patients as we help them search for the correct
path. Neurosurgical illness threatens not only their physical but also their financial security, because it is so
expensive and the potential for disability is so great. No experience draws more frequently than the performance
of neurosurgical procedures on the passage in Psalm 23, “though I walk through the valley of the shadow of
death ….” Neurosurgeons’ competence should be reflected in our training, knowledge, and skill; our compassion
should be reflected in our kindness, sincerity, and concern. The Saints and Buddhas taught that compassion and
wisdom, which lead to competence, are one. Our patients are looking for help from someone who is
knowledgeable, patient, and wise and who can provide clarity, wisdom, and enlightenment so that they can face
life after surgery on the brain. That is the essence of integrating competence and compassion. Neurosurgeons
have the responsibility to develop the dialogue in understandable terms to help the patient, the patient's family,
and society understand the meaning of the patient's illness. One of my personal precepts is, “The best ally in the
treatment of neurosurgical illness is a well-informed patient.” Success requires more than advancing and
applying medical knowledge. It also requires increased compassion so that we can respond sympathetically and
with the best of our knowledge to all of our patients' questions and provide them with timely information that will
help them understand their illness and plan their lives. There comes a time in our work when we can make as
much of a difference in each other's lives by sitting for 30 minutes, for 1 hour, or longer to answer questions as
we can by hours in surgery. There is no substitute for an honest, concerned, and sympathetic attitude. Success
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may not mean that every patient survives or is cured, because some problems are insolvable and some illnesses
are incurable. Instead, success should mean giving every patient the feeling that he or she is cared about, no
matter how desperate their situation, that their pain is felt, that their anger is understood, and that we care and
will do our best. The greatest satisfaction in life comes from offering what you have to give. Devotion and giving
to others gives purpose and meaning to life.
Another circumstance leading to the esteem that neurosurgeons enjoy is the magnificent tissue with which we
work. The brain is the crown jewel of creation and evolution. It is a source of mystery and wonder. Of all of the
natural phenomena to which science can draw attention, none exceeds the fascination of the workings of the
human brain. The brain holds our greatest unexplored biological frontiers. It is the only organ that is hidden and
completely enclosed within a fortress of bone. The brain, although it does not move, is the most metabolically
active of all organs, receiving 20% of cardiac output while representing only 3% of total body weight. It is the
most frequent site of crippling, incurable disease. It is exquisitely sensitive to touch, anoxia, and derangements of
its internal environment. Its status determines whether the humanity within us lives or dies. It yields all we know
of the world. It controls both the patient and the surgeon.
Brain accounts for the mind, and through the mind, we are lifted from our immediate circumstances and are given
an awareness of ourselves, our universe, our environment, and even the brain itself. Here, in two handsful of
living tissue, we find an ordered complexity sufficient to preserve the record of a lifetime of the richest human
experience and create computers that can store amounts of data that can be comprehended only by the mind.
Perhaps the most significant achievement of this tissue is the ability, on the one hand, to conceive of a universe
more than a billion light-years across and, on the other, to conceptualize a microcosmic world out of the reach of
the senses and to model words completely separate from the reality that we can see, hear, smell, touch, and
taste. Mind and brain are the source of happiness, knowledge, and wisdom. The brain is not the seat of the soul,
but it is through the brain and mind that we become aware of our own souls.
In my early years, never in my wildest flights of imagination did I consider that life would yield such rewarding and
challenging work as that of being a physician, and I was unaware that neurosurgery even existed. My early life
was without exposure to physicians, hospitals, or other modern conveniences (Fig. 1). My birth was aided by a
midwife in exchange for a bag of corn. As I entered college, the goal of being a physician seemed so
unattainable that I had not considered that possibility. I first pursued chemistry, but the missing human element
led me to major in social work. Social work also failed to satisfy me because it lacked the opportunity to touch
and help others by working with my hands. That I might become a physician did not enter my mind until a
psychology instructor invited me to see a brain operation
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performed in his laboratory. To my amazement, a tiny lesion improved the small animal's behavior, but without
affecting its motor skills. That day, I sensed some of the amazement that must have been experienced in the
1870s when Broca presented his early observations regarding the cerebral localization of speech in his patient,
Tan, and when Fritsch and Hitzig described their experiments on the cerebral motor cortex. Before their time,
interest in the brain and its function centered on philosophical discussions of the brain as the seat of the mind
and the soul and not as a site possessing the localizing features suitable for the application of a physician's or
surgeon's skills. On that day in the psychology laboratory, I learned that surgery based on these concepts was
possible, and I knew that I had found my calling. I know that many neurosurgeons have had a similar meaningful
experience.
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FIGURE 1. Author's early home (A) and elementary school (B).
In medical school, I began to work in a neuroscience laboratory in my spare time. At the end of my residency, I
completed a fellowship in neuroanatomy. It was during this fellowship that I realized the potential for greater
knowledge of microneurosurgery and microneurosurgical anatomy to improve the care of my patients. I resolved
early in my career to incorporate this new technique into my practice, because it seemed to increase the safety
with which we could delve deep into and under the brain. One of my favorite personal goals has been to find
images of a single operation performed perfectly, because the inner discipline of striving toward perfection leads
to improvement. Such images are the essential building blocks for the improvement of operative techniques.
During my training and thereafter, I lay awake many nights, as I know all neurosurgeons have, worrying about a
patient who was facing a necessary, critical, high-risk operation the next day. With the use of this new technique,
I found that difficult operations that carried significant risk were performed with greater accuracy and less
postoperative morbidity. During my training, I did not see a facial nerve preserved during the surgical removal of
an acoustic neuroma. Today, that goal is accomplished in a high percentage of microsurgical procedures on
acoustic neuromas. In the past, in operating on patients with pituitary tumors, there was minimal discussion of
preserving the normal pituitary gland; today, however, the combination of new diagnostic and surgical techniques
has made tumor removal with the preservation of normal pituitary function a frequent achievement. The
application of microsurgery in neurosurgery has yielded a whole new level of neurosurgical performance and
competence, and the microsurgical anatomy is the road map for applying microsurgical techniques.
As I began to work with microsurgical techniques, I realized that there was a need to train many neurosurgeons
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in their use. When I moved to the University of Florida, I began trying to develop a center for teaching
neurosurgeons these techniques. Eventually, with the help of private contributions, my institution was able to
purchase the necessary microscopes and equipment for a laboratory in which seven surgeons could learn at one
time. The next task was to find seven individuals who were willing to come to the university for a course. Finally,
after much solicitation, seven surgeons joined us for a 1-week course. I was quite apprehensive about that
course, because I was not sure that we could keep seven surgeons busy learning microvascular skills for a
whole week. It was comforting to learn that Harvey Cushing, early in his career, had developed a similar
laboratory in which surgeons could practice and perfect their operative skills. I still remember and am grateful to
each member of the initial group of neurosurgeons who were willing to invest 1 week of their valuable time in our
first course, more than 25 years ago. During the first afternoon of that course, I walked into the laboratory and, to
my amazement, found seven surgeons working quietly and diligently. Nothing was said for long periods of time.
In the midst of this intense endeavor and amazing quietness, I realized that we had tapped into a great force: the
desire of neurosurgeons to improve themselves. Each individual neurosurgeon can acquire new skills so that a
new level of performance in the specialty is achieved. Over the years, more than 1000 neurosurgeons have
attended courses in our microneurosurgery laboratories. Microtechniques are now being applied throughout the
specialty, thus adding a new level of delicacy and gentleness to neurosurgery. The competence of the whole
specialty has been improved and with this experience has come the realization that neurosurgeons, as a group,
are constantly aspiring to and achieving higher levels of performance
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that are not based on advances in diagnostic equipment and medication but are dependent on inspired
individuals striving to improve their surgical skills to better serve their patients. Every year provides multiple
examples of modifications in neurosurgery, based on the study and knowledge of microsurgical anatomy, that
make operations more successful. It is amazing that, even after many years of study and practice, the insights
gained from recent patients as well as continuing studies of microsurgical anatomy have led to new and
improved operative approaches. It is rewarding to see that most neurosurgery training programs now provide a
laboratory for studying microsurgical anatomy and perfecting microsurgical techniques.
When we began our studies of anatomy more than 40 years ago, our dissections, even with microsurgical
techniques, were crude by current standards. Photographs needed to be retouched to bring out the facets of
anatomy important for achieving a satisfactory outcome at surgery. As we learned, over the years, to expose fine
neural structures, the display of microsurgical anatomy became more vividly accurate and beautiful than we had
imagined at the outset and has enhanced the accuracy and safety of our surgery. We hope that it will do the
same for our readers.
Microsurgical anatomy will continue to be the science most fundamental to neurosurgery in the future. It will
always occupy a major role in the training of neurosurgeons. The study and dissection of anatomic specimens
improves surgical skill. The study of microsurgical anatomy continues to be important in the improvement and
adaptation of old techniques to new situations. Its study will lead to numerous new and more accurate operative
approaches and the application of new neurosurgical technologies in the future. Microsurgical anatomy provides
the basis for understanding the constantly improving imaging studies and provides an understanding of the
safest and most effective surgical pathways for visualizing and treating neurosurgical pathology. Every year,
there are advances in neurological technology that yield new therapeutic possibilities that must be evaluated and
directed according to an enhanced understanding of anatomy.
The combination of the knowledge of microsurgical anatomy and the use of the operating microscope has
improved the technical performance of many standard neurosurgical procedures (e.g., brain, spine, and cranial
base tumor removal; aneurysm obliteration; neurorrhaphy; and even lumbar and cervical discectomy) and has
opened new dimensions that were previously unattainable. The knowledge of microsurgical anatomy has
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improved operative results by permitting neural and vascular structures to be approached and delineated with
greater accuracy, deep areas to be reached by safer routes with less brain retraction and smaller cortical
incisions, bleeding to be controlled with less damage to adjacent neural and vascular structures, and nerves and
perforating arteries to be preserved with greater frequency. The use of the microscope, when combined with the
knowledge of microsurgical anatomy, has resulted in smaller wounds, less postoperative neural and vascular
damage, better hemostasis, more accurate nerve and vascular repairs, and surgical treatment for some
previously inoperable lesions. The microscopic study of anatomy has introduced a whole new era in surgical
education by permitting the recording of minute anatomic detail not visible to the eye for later study and
discussion.
Surgery with the operating microscope has led the neurosurgeon to the current limits of human dexterity, but in
the future, robotically assisted microsurgery will open new frontiers of delicate surgery that will require additional
microanatomic detail for optimization. The evolution of other technologies, such as endovascular surgery, will
continue to require an accurate knowledge of microsurgical anatomy. In the endovascular treatment of
aneurysms, an understanding of the variations in the anatomy of the parent vessel and the perforating arteries is
as important as it is to microsurgical treatment. Microsurgical anatomy provided the basis for our entry into
cranial base surgery and gave us a road map for reaching every site in the cranial base through carefully placed
windows. The joint development of microsurgery in combination with image guidance has made it possible to
work in long, narrow exposures to reach multiple deep sites within the brain. The study of microsurgical anatomy
has led to the development of new approaches, such as the transchoroidal approaches to the third ventricle, the
endonasal approach to pituitary tumor, and the telovelar approach to the fourth ventricle. In the future, there will
be new, better, and safer procedures that will continue to evolve from the continued study of microsurgical
anatomy. It is hoped that the body of knowledge embodied in this volume will continue to be relevant to
neurosurgical practice at the beginning of the next century and millennium.
Neurosurgery's 25th Anniversary issue (4) on the supratentorial area with 1000 color illustrations and the
Millennium issue (3) on the posterior fossa with nearly 800 illustrations represent a distillation of more than 40
years of work and study in which 65 residents and fellows have participated, resulting in several hundred
publications. For those wanting even greater detail than displayed in this volume, our prior works, published
largely in Neurosurgery and the Journal of Neurosurgery, can be consulted. In this volume, we have attempted
not only to display the brain and cranial base in the best views for understanding the anatomy but also to show
the anatomy as exposed in the surgical routes to the supratentorial and infratemporal areas and cranial base.
Areas examined include the cerebrum, the cerebellum, the lateral, third, and fourth ventricles, the cranial nerves,
the cranial base, the orbit, the cavernous sinus, the temporal bone, the cerebellopontine angle, the foramen
magnum, and numerous other structures. Our work is not complete in any area. Further study will yield new
information that will improve the operative approach and operative results in dealing with pathology in each of
the areas previously examined. There is no “finish line” for this effort. Future anatomic study will continue to yield
new insights throughout the future of our specialty. Insights gained from the other medical sciences and new
technologies, when combined with our increasing knowledge of microsurgical anatomy, will create new surgical
possibilities, therapies, and cures.
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It has been gratifying to view the role of our fellows and trainees in spreading this knowledge to other countries
around the world and to see the benefits of neurosurgeons applying this knowledge to improve their patients’
operations. Especially gratifying have been the relationships with Dr. Toshio Matsushima of Fukuoka, Japan,
and Dr. Evandro de Oliveira of São Paulo, Brazil, whose studies of microsurgical anatomy have elevated the
care of neurosurgical patients around the world. The following are the residents and fellows who have worked in
the laboratory:
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