- Email: [email protected]
Epilepsy: models, mechanisms and concepts
302
book reviews / Electroencephalography
and clinical Neurophysiology,
94 (1995) 298-303
tive by presenting both its advantages and limitations. The tables and the EEG samples are carefully selected making this chapter a useful guide. Serum prolactin determinations are becoming a commonly used test and thus the chapter “Serum prolactin in the diagnosis of epilepsy” by Dr. Fisher is timely and does a great job presenting the controversies surrounding this test with an emphasis on its limited specificity. I also enjoyed the chapter on “Cerebrovascular imitators of epilepsy” by Dr. Krumholz which offers a good overview on the subject with excellent tables. A chapter on “Migraine and epilepsy” is overall good though the pathophysiology section might have benefited from an expanded presentation on the emerging role of serotonin. The chapter on “Delirium and epilepsy” also has some weaknesses in that, I believe, it would have benefited from a more in-depth discussion of the similarity and differences between non-convulsive status and delirium. I found this chapter to be repetitive within itself and with other chapters in the book. The chapter on “Psychogenic seizures” might have benefited from a better comparison with frontal lobe epilepsy, instead of just mentioning it towards the end of the chapter. The closing chapter is beautifully organized, defines the concepts, clearly emphasizing and summarizing the main points in the tables. The book ends with the same clarity and simplicity as it started with. By now it should be clear to the reader of this review that I enjoyed this book and recommend it to the epileptologist, the general neurologist, and the primary care practitioner as a valuable addition to one’s library.
simply reflects the dearth of research which addresses the relationship between electrical/magnetic and metabolic measures of brain activation. Nevertheless, electrical measures of brain activation have been used for many years and have produced some provocative results. Recent developments in magnetoencephalography, EEG/MEG frequency analysis, and EEG/MEG source localization have extended the possibilities for non-invasive imaging of functional brain activation. Furthermore, invasive EEG recordings using subdural and depth electrodes have allowed electrical measures of cortical activation at spatial resolutions and signal-to-noise ratios comparable to PET and functional MRI. Most importantly, however, electrical and magnetic measures of brain activation have clearly superior temporal resolution than metabolic measures and may be more direct since neural computation most likely relies upon complex electrochemical signalling among populations of neurons. The mechanisms by which neuronal signalling is coupled with changes in neuronal metabolism, and in turn with changes in regional cerebral blood flow, are the subject of the first 5 chapters of Roland’s book, and in this regard the book provides a valuable review of current knowledge in this area. However, it is clear that there are still significant gaps in our understanding, particularly regarding the time relationships between neuronal signalling and cerebral blood flow changes. It is perhaps for this very reason that clinical researchers using electrical measures of brain activation such as cortical and scalp EEG and evoked potentials, may find this book to be particularly useful for putting current and future developments in metabolic neuroimaging (e.g. functional MRI) in their proper perspective.
Silvana Riggio Department of Neurology, Mayo Clinic Jacksonville, Jacksonuille, FL (USA)
Nathan E. Crone Department of Neurology, The Johns Hopkins University School of Medicine and Hospital, Baltimore, MD (USA)
Brain activation. - P.E. Roland (Wiley-Liss, New York, 1993,600 p., Price: US $84.95) “Brain Activation,” a single author book by Per E. Roland, is a well organized and complete account of the basic mechanisms, methods and findings of tracer methods for measuring the metabolic manifestations of brain activation in humans. It is written from the perspective of Roland’s impressive body of work, spanning more than 20 years. As such this book is a valuable resource for understanding the development of metabolic neuroimaging techniques (i.e., Xenon blood flow, SPECI’, and PET) over the past two decades. In addition, this book allows Roland to present his “Cortical field and neuronal population activation theory,” which attempts to formulate a comprehensive story of how brain structure and function are related and which, right or wrong, may be the most thoughtprovoking and original part of the book. Any single-author research text which is written in today’s climate of rapid technological and scientific developments is likely to omit information which is relevant to its potential readers, and this book is no exception. For example, functional MRI techniques for identifying regional cerebral blood flow changes during brain activation have come into their own in the past few years and are now generating a number of valuable findings. Indeed, because of the low cost and wide distribution of MRI scanners, this method may easily overshadow PET and may allow metabolic measures of brain activation to eventually have more widespread clinical use. However, this book mentions functional MRI only briefly in a 3 page section describing non-tracer techniques for the measurement of brain activation. This small section is also where information about EEG and evoked potentials can be found. In this book there is no treatment of EEG, MEG or evoked potentials beyond the very basic mechanisms of neuronal signal transduction, i.e., action potentials, EPSPs, IPSPs, LTP, and their relationship to neuronal energy consumption. This is not surprising given the perspective of the author and, for that matter, the perspective of many other investigators using metabolic measures of brain activation. Perhaps this omission
Epilepsy: models, mechanisms and concepts. - PA Schwartzkroin (Ed.) (Cambridge University Press, New York, 1993, 544 p., Price: us $120.00) This is a volume of chapters by individual authors that attempts to integrate concepts in epilepsy, rather than straight presentation of data. The major task of the authors for this volume is development of a discussion about “key hypotheses” important to the field of modern epilepsy. The volume is divided conceptually into 3 areas: intrinsic neuronal properties relevant to epilepsy including ions and channels; local interactions among populations of neurons, and systems involved in epilepsy including those relating to development and spread of seizures. Knowledge about mechanisms of epilepsy is dependent upon models for study. This book develops in detail concepts about 3 models: the kindling model of epilepsy, genetic models of the epilepsies, and in vitro brain slices. Data from other models are interwoven throughout the remainder of the text. The kindling model has held special importance in studies of epilepsy, and thousands of articles have been written about kindling. McNamara and associates review the concepts of kindling, without becoming bogged down in methodological details. They take a balanced view as to whether or not kindling occurs in people, and develop a concept that the kindling model may be useful for studying the development of epilepsy as well as mechanisms of seizures. Jobe and colleagues review the genetic models of the epilepsies. Emphasis is on the genetically epilepsy prone rat, with which the authors have extensive experience. Much is known about neurotransmitter and functional anatomical deficits in genetic models of epilepsy, but we still lack knowledge of the specific gene, resulting proteins and the means by which the genetic defect produces the phenotypic seizures. The author of this volume has been a pioneer in development of brain slice models for the study of seizures. Expert colleagues, Wilson and Bragdon, review brain slice models in animals, and Avoll summarizes
book reviews / Electroencephalography
and clinical Neurophysiology,
studies of in vitro human epileptiform tissue. Interestingly, the usual order is reversed with human tissue coming first. Emphasis is on the low magnesium model which produc8es seizure-like events. The authors discuss a unique opportunity to explore the relations between the interictal and ictal spiking. The following chapter by Connors and Amitai examines neocortical slices. This chapter provides an integration of microanatomy and connectivity of cerebral cortex with physiology of epileptiform bursting. The role of neurotransmitter systems is relatively underemphasized in this volume. Wong and Miles ::eview GARA in some detail, but no special attention is given to the excitatory amino acid transmitter system, nor acetylcholine, peptides, or catecholamines. Potassium and calcium ions are involved intimately in interictal-ictal transitions and in excitability of epileptifonn tissue. A chapter reviews current research on the role of these two cations. About one-third of this volume is devoted to issues of developmental and plastic changes in the brain in relation to epilepsy. Lindval reviews his seminal work on transplantation of neural tissue and its potential for treatment of epilepsy. Swarm and associates specifically consider the special issues of seizure susceptibility during brain development. The late JoAnn Frank, to whom this book is dedicated, examines models of hippocampal sclerosis, the underlying pathology of complex partial epilepsy in many clinical cases. Seizures occur in these model systems before hippocampal sclerosis, and the latter cannot therefore be a simple cause of the former. Sutula reviews secondary changes in the form of sprouting that might carry the effects of cell loss from seizures forward
94 (1995) 298-303
303
into a chronic condition. Epilepsy is a systems property involving selective cell injuries and subsequent reorganization of tissue with changes and excitability. Gale considers the anatomic systems involved in different aspects of seizures and epilepsy. In severest form seizures result in status epilepticus. Lothman and colleagues review an electrical stimulation model of status epilepticus, and the important insights gained from this model. The book does not have a conclusion, but uses the rather unusual feature of “recent advances” summaries for each chapter, l-2 pages in length each. A reader in a hurry can get an overview of the entire book by reading this last section. The chapters are individually clear, well written and well edited. The level of the book is advanced and assumes that the reader has some familiarity with basic neurophysiology and epilepsy research. Emphasis is on physiological rather than pharmacological or anatomical approaches to epilepsy; however, wherever possible, the disciplines are integrated into a single approach. The production quality is very good, figures are appropriate and references comprise the latest work in the field. This is not a book for a beginning student, but would provide a more advanced reader an excellent overview of where research on basic mechanisms of the epilepsies now stands, and where it is heading. Robert S. Fisher Epilepsy Center, Barrow Neurological Institute, Phoenix, AZ (USA)
book reviews / Electroencephalography
and clinical Neurophysiology,
94 (1995) 298-303
tive by presenting both its advantages and limitations. The tables and the EEG samples are carefully selected making this chapter a useful guide. Serum prolactin determinations are becoming a commonly used test and thus the chapter “Serum prolactin in the diagnosis of epilepsy” by Dr. Fisher is timely and does a great job presenting the controversies surrounding this test with an emphasis on its limited specificity. I also enjoyed the chapter on “Cerebrovascular imitators of epilepsy” by Dr. Krumholz which offers a good overview on the subject with excellent tables. A chapter on “Migraine and epilepsy” is overall good though the pathophysiology section might have benefited from an expanded presentation on the emerging role of serotonin. The chapter on “Delirium and epilepsy” also has some weaknesses in that, I believe, it would have benefited from a more in-depth discussion of the similarity and differences between non-convulsive status and delirium. I found this chapter to be repetitive within itself and with other chapters in the book. The chapter on “Psychogenic seizures” might have benefited from a better comparison with frontal lobe epilepsy, instead of just mentioning it towards the end of the chapter. The closing chapter is beautifully organized, defines the concepts, clearly emphasizing and summarizing the main points in the tables. The book ends with the same clarity and simplicity as it started with. By now it should be clear to the reader of this review that I enjoyed this book and recommend it to the epileptologist, the general neurologist, and the primary care practitioner as a valuable addition to one’s library.
simply reflects the dearth of research which addresses the relationship between electrical/magnetic and metabolic measures of brain activation. Nevertheless, electrical measures of brain activation have been used for many years and have produced some provocative results. Recent developments in magnetoencephalography, EEG/MEG frequency analysis, and EEG/MEG source localization have extended the possibilities for non-invasive imaging of functional brain activation. Furthermore, invasive EEG recordings using subdural and depth electrodes have allowed electrical measures of cortical activation at spatial resolutions and signal-to-noise ratios comparable to PET and functional MRI. Most importantly, however, electrical and magnetic measures of brain activation have clearly superior temporal resolution than metabolic measures and may be more direct since neural computation most likely relies upon complex electrochemical signalling among populations of neurons. The mechanisms by which neuronal signalling is coupled with changes in neuronal metabolism, and in turn with changes in regional cerebral blood flow, are the subject of the first 5 chapters of Roland’s book, and in this regard the book provides a valuable review of current knowledge in this area. However, it is clear that there are still significant gaps in our understanding, particularly regarding the time relationships between neuronal signalling and cerebral blood flow changes. It is perhaps for this very reason that clinical researchers using electrical measures of brain activation such as cortical and scalp EEG and evoked potentials, may find this book to be particularly useful for putting current and future developments in metabolic neuroimaging (e.g. functional MRI) in their proper perspective.
Silvana Riggio Department of Neurology, Mayo Clinic Jacksonville, Jacksonuille, FL (USA)
Nathan E. Crone Department of Neurology, The Johns Hopkins University School of Medicine and Hospital, Baltimore, MD (USA)
Brain activation. - P.E. Roland (Wiley-Liss, New York, 1993,600 p., Price: US $84.95) “Brain Activation,” a single author book by Per E. Roland, is a well organized and complete account of the basic mechanisms, methods and findings of tracer methods for measuring the metabolic manifestations of brain activation in humans. It is written from the perspective of Roland’s impressive body of work, spanning more than 20 years. As such this book is a valuable resource for understanding the development of metabolic neuroimaging techniques (i.e., Xenon blood flow, SPECI’, and PET) over the past two decades. In addition, this book allows Roland to present his “Cortical field and neuronal population activation theory,” which attempts to formulate a comprehensive story of how brain structure and function are related and which, right or wrong, may be the most thoughtprovoking and original part of the book. Any single-author research text which is written in today’s climate of rapid technological and scientific developments is likely to omit information which is relevant to its potential readers, and this book is no exception. For example, functional MRI techniques for identifying regional cerebral blood flow changes during brain activation have come into their own in the past few years and are now generating a number of valuable findings. Indeed, because of the low cost and wide distribution of MRI scanners, this method may easily overshadow PET and may allow metabolic measures of brain activation to eventually have more widespread clinical use. However, this book mentions functional MRI only briefly in a 3 page section describing non-tracer techniques for the measurement of brain activation. This small section is also where information about EEG and evoked potentials can be found. In this book there is no treatment of EEG, MEG or evoked potentials beyond the very basic mechanisms of neuronal signal transduction, i.e., action potentials, EPSPs, IPSPs, LTP, and their relationship to neuronal energy consumption. This is not surprising given the perspective of the author and, for that matter, the perspective of many other investigators using metabolic measures of brain activation. Perhaps this omission
Epilepsy: models, mechanisms and concepts. - PA Schwartzkroin (Ed.) (Cambridge University Press, New York, 1993, 544 p., Price: us $120.00) This is a volume of chapters by individual authors that attempts to integrate concepts in epilepsy, rather than straight presentation of data. The major task of the authors for this volume is development of a discussion about “key hypotheses” important to the field of modern epilepsy. The volume is divided conceptually into 3 areas: intrinsic neuronal properties relevant to epilepsy including ions and channels; local interactions among populations of neurons, and systems involved in epilepsy including those relating to development and spread of seizures. Knowledge about mechanisms of epilepsy is dependent upon models for study. This book develops in detail concepts about 3 models: the kindling model of epilepsy, genetic models of the epilepsies, and in vitro brain slices. Data from other models are interwoven throughout the remainder of the text. The kindling model has held special importance in studies of epilepsy, and thousands of articles have been written about kindling. McNamara and associates review the concepts of kindling, without becoming bogged down in methodological details. They take a balanced view as to whether or not kindling occurs in people, and develop a concept that the kindling model may be useful for studying the development of epilepsy as well as mechanisms of seizures. Jobe and colleagues review the genetic models of the epilepsies. Emphasis is on the genetically epilepsy prone rat, with which the authors have extensive experience. Much is known about neurotransmitter and functional anatomical deficits in genetic models of epilepsy, but we still lack knowledge of the specific gene, resulting proteins and the means by which the genetic defect produces the phenotypic seizures. The author of this volume has been a pioneer in development of brain slice models for the study of seizures. Expert colleagues, Wilson and Bragdon, review brain slice models in animals, and Avoll summarizes
book reviews / Electroencephalography
and clinical Neurophysiology,
studies of in vitro human epileptiform tissue. Interestingly, the usual order is reversed with human tissue coming first. Emphasis is on the low magnesium model which produc8es seizure-like events. The authors discuss a unique opportunity to explore the relations between the interictal and ictal spiking. The following chapter by Connors and Amitai examines neocortical slices. This chapter provides an integration of microanatomy and connectivity of cerebral cortex with physiology of epileptiform bursting. The role of neurotransmitter systems is relatively underemphasized in this volume. Wong and Miles ::eview GARA in some detail, but no special attention is given to the excitatory amino acid transmitter system, nor acetylcholine, peptides, or catecholamines. Potassium and calcium ions are involved intimately in interictal-ictal transitions and in excitability of epileptifonn tissue. A chapter reviews current research on the role of these two cations. About one-third of this volume is devoted to issues of developmental and plastic changes in the brain in relation to epilepsy. Lindval reviews his seminal work on transplantation of neural tissue and its potential for treatment of epilepsy. Swarm and associates specifically consider the special issues of seizure susceptibility during brain development. The late JoAnn Frank, to whom this book is dedicated, examines models of hippocampal sclerosis, the underlying pathology of complex partial epilepsy in many clinical cases. Seizures occur in these model systems before hippocampal sclerosis, and the latter cannot therefore be a simple cause of the former. Sutula reviews secondary changes in the form of sprouting that might carry the effects of cell loss from seizures forward
94 (1995) 298-303
303
into a chronic condition. Epilepsy is a systems property involving selective cell injuries and subsequent reorganization of tissue with changes and excitability. Gale considers the anatomic systems involved in different aspects of seizures and epilepsy. In severest form seizures result in status epilepticus. Lothman and colleagues review an electrical stimulation model of status epilepticus, and the important insights gained from this model. The book does not have a conclusion, but uses the rather unusual feature of “recent advances” summaries for each chapter, l-2 pages in length each. A reader in a hurry can get an overview of the entire book by reading this last section. The chapters are individually clear, well written and well edited. The level of the book is advanced and assumes that the reader has some familiarity with basic neurophysiology and epilepsy research. Emphasis is on physiological rather than pharmacological or anatomical approaches to epilepsy; however, wherever possible, the disciplines are integrated into a single approach. The production quality is very good, figures are appropriate and references comprise the latest work in the field. This is not a book for a beginning student, but would provide a more advanced reader an excellent overview of where research on basic mechanisms of the epilepsies now stands, and where it is heading. Robert S. Fisher Epilepsy Center, Barrow Neurological Institute, Phoenix, AZ (USA)