Operative Techniques in Epilepsy

316 Pages·2015·18.119 MB·English

by  John P. Girvin (auth.)

Operative
Techniques in
Epilepsy
John P. Girvin
123
Operative Techniques in Epilepsy

John P. Girvin
Operative Techniques
in Epilepsy
John P. Girvin
Department of Clinical
Neurological Sciences
Western University
London , ON
Canada
ISBN 978-3-319-10920-6 ISBN 978-3-319-10921-3 (eBook)
DOI 10.1007/978-3-319-10921-3
Springer Cham Heidelberg New York Dordrecht London
Library of Congress Control Number: 2014957641
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Prefa ce
The impetus leading to the authorship of this book was derived from the many
young resident and fellow neurosurgical trainees who lamented the fact that there
were limited comprehensive resources that covered purely t echnical aspects of neu-
rosurgery, especially those of epilepsy surgery. This is not to say that there are not
good articles and books in the literature dealing with epilepsy surgery, but rather
that there is a paucity of literature primarily devoted to considerations of functional
cortical localization and the surgery of the majority of the epilepsies. The usual
complaint that I hear from the trainees is that most articles dealing with epilepsy
surgery are in large part confi ned primarily to the results of the surgery, rather than
any signifi cant details of the techniques and surgical anatomy employed in the sur-
gery. This monograph is entirely limited to what I believe are the most important
operative aspects of neurosurgery in general, but particularly those associated with
so-called epilepsy surgery and, again, more particularly resective surgery.
S ome of the comments and discussions will be too elementary for many readers.
I make no apologies for this, as the primary objective of the monograph is to be of
use to all young surgeons, from fi rst-year residents (PGY1) to more experienced
and sophisticated epilepsy surgery fellows and recently graduated consultants. The
amount of writing lent to the use of appropriate coagulation, electrocortical map-
ping, and the technique of subpial dissection refl ects the importance I attach to these
principles in the surgery of the central nervous system.
I have not included an exhaustive bibliography, but I have included many origi-
nal articles that are less likely to have appeared in the lists of current everyday litera-
tures of residents’ programs. Some of these older articles are just as important and
in some cases perhaps more important as resource references than many of the more
recent references. However, the last decade has witnessed a remarkable increase in
the numbers of medical journal articles that can be retrieved easily from the Internet
and particularly from universities’ medical libraries. Many of them have made it
easy to retrieve the majority of articles from the twentieth-century literature and
now even many of those of the nineteenth century. Thus, now the reader should be
able to fi nd from them a broad, comprehensive insight into the literature pertaining
to whatever category of interest she/he might wish to pursue.
At the end of some of the chapters dealing with the common cortical sites of
epilepsy surgery, I have made reference to the “Safe Limits of Resection.” The
observations in these sections have been derived from the combination of the uses
v
vi Preface
of local anesthesia and intraoperative cortical stimulation, which have been the pri-
mary historical tools for defi ning the functional localization of the human cerebral
cortex. The operations of nearly all my patients were conducted under these circum-
stances, and thus individual chapters have been devoted to local anesthesia and elec-
trocortical stimulation in this book. Indeed the use of local anesthesia is not
anywhere near as important now with the sophistication of imaging and instrumen-
tation as many decades ago, but there is no doubt that its use is mandatory in many
neurosurgical operations, and my personal view is that every neurosurgeon should
feel comfortable using it. The provision of these safe limits of resection is simply
noted, as I believe they are helpful guides in the conduct of many resections of the
cortex in the immediate vicinity of what I will refer to as eloquent cortex. These are,
in essence, reviews of functional cortical localization for which I have drawn heav-
ily on the comments of the Montreal School of Epilepsy Surgery, especially those
of Drs. Penfi eld and Rasmussen, in addition to my own.
Springer’s publishing mandate requires bibliographic references to be at the end
of each chapter, and thus is the case with this monograph. Springer has also allowed
me to still place the whole bibliography at the end of the book, which I requested,
so that it may help the reader to easily locate where each bibliographic reference has
been cited in the book. Within the Bibliography, each reference, per se, has a num-
ber in bold, within square brackets ([ …] ), which identifi es the chapter, section, and
subsection (by their numbers) in which that particular reference has been cited.
T he Index is similar to that of many other books in that there is a cross-r eference
to where some of the various subjects of the Index can be found in the text of the
book. The places where the indices are cited are identifi ed, as in the preceding para-
graph, by a combination of the chapter, section, and subsection numbers; boldface
for the numbers suggests a greater signifi cance of the cross-reference and even more
by an associated asterisk (*).
I have already indicated that this monograph is not confi ned to clinical results,
and thus it is not helpful with regard to statistically signifi cant outcome assess-
ments. Having said that, infrequent clinical examples are used wherever I felt the
text description requires them.
There are many that I would like to acknowledge who have contributed through
the years to the content of this manuscript. However, my fear of leaving some out
who deserve to be so acknowledged leads me to follow the path of not becoming
involved in trying to accurately determine when and where names, which I can
remember, should be recorded. However, putting this aside, I do believe that my
major acknowledgment would be attributed to the patients upon whom I have oper-
ated. I feel a responsibility to thank them for how much they have contributed to our
neurosurgical understanding of the functional localization within the human cere-
bral neocortex. This has been and continues to be achieved from their tolerance and
acceptance of being operated upon awake – often with a dreaded feeling of the
unknown, of what such an operation might bring, and often with a sense of volun-
teerism in their willingness to accept extension of the times required to conduct
electrocortical stimulation purely for academic purposes. As surgeons, we are for-
ever indebted to all of them. Witnessing the acceptance and the behavior of patients
Preface vii
undergoing these types of operation, particularly the young teenagers and adoles-
cents, is always an inspiration and cannot help but make one feel that this is the
“stuff” that makes one proud to be a member of the human race!
I thank the young residents and fellows who continually question our methods
and who have led to a number of improvements in surgical techniques, either
directly by their independent suggestions or indirectly through discussions associ-
ated with the surgical aspects that are described in the following chapters. I would
be remiss in not thanking my neurosurgical colleagues from all of whom I have
learned and who became part of the staff of the UWO (University of Western
Ontario; now, as of three years ago, known as “Western University”) Department of
Clinical Neurological Sciences and its Epilepsy Surgical Program; these included
Drs. Howard Reichman, Andrew Parrent, Ram Sahjpaul, and David Steven.
I particularly would like to acknowledge and thank very much Ms. Caren
Erlichman and Mr. Tom Adam for their so freely provided unending expenditure of
time on my behalf, as without their help I would have very unlikely been able to
obtain the necessary Permissions for publication of this book. And, fi nally, I thank
my wife, Bettye, for the many hours without conversation to which she has been
committed during the preparation of this monograph.
Finally, it is my responsibility to indicate that within the monograph any errors
in interpretation, failure to provide the reader with a text easy to understand, failure
to have acknowledged pertinent articles, or errors in presenting the accuracy of
reports to which I have referred are entirely attributable to me, for which I apologize
in advance.
London, ON, Canada John P. Girvin

Contents
1 History of Epilepsy Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Pre-twentieth Century. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Twentieth Century. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Techniques in Epilepsy Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 The Use of Bipolar Coagulation. . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 The Physical Principles of Bipolar Coagulation. . . . . . . . . 7
2.1.2 The Separation of the Blades of the Bipolar
Coagulating Forceps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.3 Saline Irrigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.4 Suction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.1.5 Cottonoid Patties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1.6 The Strength of Coagulating Current . . . . . . . . . . . . . . . . . 17
2.1.7 The Ideal Components of Optimal Coagulation. . . . . . . . . 18
2.2 Subpial Dissection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2.2 Anatomy of the Cerebral Cortex and Leptomeninges . . . . 20
2.2.3 The Technique of Subpial Dissection. . . . . . . . . . . . . . . . . 21
2.2.4 Retraction with Normal-Sized Retractors. . . . . . . . . . . . . . 30
2.3 Anatomical Measurements of Functional Areas of the Cortex. . . . 31
2.4 The Mandatory Bimanual Instrumental Use!. . . . . . . . . . . . . . . . . 35
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3 Surgery Under Local Anesthesia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.1 Philosophy of the “Traditional” Use of Local Anesthesia . . . . . . . 37
3.2 Preparation of the Patient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3 The Preoperative Use of Local Anesthesia. . . . . . . . . . . . . . . . . . . 42
3.3.1 The Local Anesthetic Agent . . . . . . . . . . . . . . . . . . . . . . . . 42
3.3.2 The Initial (Preoperative) Regional
Anesthetic Blockade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.3.3 The Local Anesthetic Blockade of Individual
Scalp Nerves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.3.4 The Anesthetic Blockade of the Scalp Incision . . . . . . . . . 48
3.3.5 The Quantity of Local Anesthetic Used . . . . . . . . . . . . . . . 49
ix