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Intracranial pressure II
445 it clear, however, that he feels that preoccupation with the study of individual neurons stands in the way of eventually explaining the basis of behaviour. ! feel that this view is carried to a destructive extreme in this book, with the result that the foundation of basic information which is laid is not strong enough to allow the reader to make a confident analysis of the behaviour of networks of nerve cells. This is most clearly seen in the chapters which deal with the basic physiology of individual nerve cells and synapses. I think that in trying to de-emphasize the more physical aspects of the description of such phenomena as the resting potential and the cable properties of neurons, the author has ended up with a qualitative description which not only lacks rigour, but fails to communicate some of the essential aspects of this subject. For example, after failing to provide the reader with a firm intuitive grasp of the cable properties of ceils, the author is in no position to show how the very characteristic shapes of nerve cells influence their integrative behavior, and he does not try. In some ways, I feel that what the author calls an "interpretive" introduction to neurophysiology is really a "selective" one. For example, much space is devoted to treatment of the anatomy and physiology of sensory cells in vertebrates (though there is not so much as a mention of the muscle spindle). Yet the treatment of synaptic transmission is at best cursory, giving almost no hint of the new findings concerning the nature of transmitter release and its control, or of the post-synaptic action of transmitters. When such basic elements of an understanding of neural integration are slighted, it seems odd indeed to spend almost 1 0 ~ of the book on a chapter devoted to compound action potentials. The later sections of the book deal with integration in neural networks; both in a general chapter, and in one dealing specifically with integration in a "model preparation", the sea hare, Aplysia. The former is weakened by the amount of time spent on phenomena of questionable biological significance such as oscillation of the compound action potential and the dorsal root reflex. At the same time, the reader is tantalised by reference to phenomena such as neural feature specificity in the visual system, without being given any further indication of what they are, or how they might arise from the basic properties of nerve cells treated earlier in the book. The section on Aplysia I found more interesting since it deals with substantial details of a well studied and interesting nervous system. In the final chapter, the author presents a "Summary of General Principles" - - 50 of them t Hardly the stuff of a memorable "take home message+'. This tabulation reflects a tendency exhibited throughout the book to attempt to classify various aspects of the material dealt with in ways that to me seem very artificial. In the chapter on anatomy, for example, a distinction is made between "transmission" neurons and "integrative" ones. But by including vertebrate motor neurons in the first class, and the fish Mauthner cell in the second (both have long, large diameter mye[inated axons for transmission, and prominent regions where extensive integration of inputs takes place), the author himself shows how arbitrary such classifications can be. At a time when there are numerous useful introductory texts in neurophysiology available, I find little to recommend this one. C. R. Slater
lntracranial Pressure H ( P r o c e e d i n g s o f t h e 2 n d I n t e r n a t i o n a l S y m p o s i u m o n l n t r a cranial Pressure, Lund, B r o c k ( E d s . ) , xxii +
17-19 June,
1974), b y N . L u n d b e r g , U . P o n t 6 n a n d M .
527 p a g e s , 184 i l l u s t r a t i o n s , 42 t a b l e s , S p r i n g e r - V e r l a g , B e r l i n ,
H e i d e l b e r g , N e w Y o r k , 1975, D M 72.00, U S $ 31.00. A cursory glance through Intracranial Pressure II is likely to discourage the casual browser - - the presentation is dreary, and the text, covering nearly 100 titles, seems too ambitious in concept. The offset form of printing accounts for the former, but as it was apparently chosen to reduce the price of the book, is justifiable. The effort put in by the organisers of the 2nd International Symposium on Intracranial Pressure makes the number of papers far easier to digest than first impressions would suggest. The scientific proceedings were carefully directed to give each of the 12 sessions a predetermined limited scope, and the whole conference, and therefore this book, a logical format which some other international conventions could profitably emulate. Much of this "editing" was done by the chairman and co-chairman before each session.
446 Even to a reader with no more than a passing interest in the subject of intracranial pressure (ICP) monitoring, the result of these efforts is valuable. In each session, the chairman's introduction summarises the current state of knowledge, while the co-chairman sums up the discussion. At least half the sessions covered subjects of general interest to those concerned with any aspect whatever of neurological function, normal or disordered, viz. CSF dynamics, pathogenesls of hydrocephalus, the effects of ICP and ischaemia on brain metabolism and morphology, inter-relations between 1CP and blood circulation within the cranial cavity, the respiratory and cardiovascular effects of increased ICP, and the importance of ICP monitoring in clinical practice. Neurosurgeons and anaesthetists would find additional interest in the sections on the effects of anaesthetic and other agents, as well as those of long-term controlled ventilation on ICP. With the virtual deluge of papers contained in this book. their quality is understandably uneven, and. in some instances, one gets a distinct feeling of d6jb. vu, while others are mere potboilers. The fact that out of 132 papers originally submitted, t02 were accepted by the organisers. shows the limited appeal that such a symposium has, based as it is on measurement of a single factor in a complex, dynamic and very vulnerable system like the brain. Most of the aulhors and the material they present could equally well have appeared under suitably modified headings in other conferences, such as cerebral blood flow to mention just one. But this is more a reflection on the trends in conference organisation than on the book itself. To one nurtured in the highest traditions of British clinical medicine, it is reassuring to find that many a classical hypothesis based on careful bedside observations has been substantiated by some of the experimental work, while the riddles have not always been resolved by even the most elegant and elaborate laboratory studies. A few misconceptions, however, have been clarified. Many a neurosurgeon still holds the view that the "pinched" lateral ventricles on ventriculography, are not only a sine q u a non for the diagnosis of benign intracranial hypertension, but also indicate brain oedema as the responsible factor. Johnston, however, shows in his clinical studies on a small group of 6 patients that the defect is one of CSF absorption. The diagnosis of benign intracranial hypertension covers a variety o f aetiological factors, and there are no clinical details in the paper to enable critical evaluation. But this does not apply to the experimental work on dogs given m the same paper. In those cases where the venous outflow was occluded, the demonstrated reduction in CSF absorption was not unexpected; more significant, in one's opinion, is that even in dogs m whom intracranial hypertension was produced by corticosteroid withdrawal after administration for 4 weeks, the mean absorption of CSF was reduced by nearly 50~. This paper is in the section on CSF hydrodynamics, but Johnston comes back with a caveat in the final section with another viewpoint on the same subject: the clinical recognition of benign intracraniat hypertension over a 4year period at the Glasgow Neurosurgical Unit was incorrect in up to 25 ~ of the cases when tested with continuous intracranial pressure monitoring and fluorescein retinography. Our confidence in clinical management of the condition is then given a further jolt by mentioning patients in whom steroid therapy had no significant effect on intracranial pressure after 1 week, while at 3 months, hressures were still abnormally high despite resolution of all signs and symptoms of intracranial pypertension. If there are still people, and these must be few, who do not question the semantic appropriateness of a diagnosis of "low pressure hydrocephalus", section C on the "Pathogenesis of Hydrocephalus" should help the term towards a long overdue interment. In fact that entity, elusive both in its pathogenesis and sometimes in therapeutic success, is obviously in search of a new name. "Normal pressure" hydrocephalus seems a poor contender, as the work presented shows that in fact in all such cases of hydrocephalus there are periods of high pressure and the normal pressure state is therefore also a misnomer. In the selection of those patients likely to benefit from shunting, in addition to the already known monitoring of ICP during sleep, a second pre-operative criterion has been presented: an increase in cerebral blood flow after reducing CSF pressure by lumbar puncture is an indication for operation. Unfortunately this technique is only available to those centres able to carry out blood flow measurements readily. Much of the interest about the effects of various anaesthetic agents on ICP has been concentrated on the induction and maintenance o f anaesthesia. However, Leech et al. make a Valuable point in demonstrating the significant elevations in ICP and systemic arterial pressure that occur as the anaesthetic is terminated, even when the intracranial contents were considered to be slack when the wound was closed. Fifteen years after Lundberg's monograph on intracranial pressure monitoring, this book . . . . . . . . . • . - _. . . . . . . . . . . . . , ~ ~ ,,t,x~l r,¢,hp otlnlt~al
447 scientist or a toy of the technological gadgeteer". The welcome but at times over-enthusiastic participation of the physicists has introduced refinements in technique which have perhaps dissuaded many clinicians from even considering the practical advantages of the measurement. As Jennett comments in his introduction to the final session, "this is still a field with many more spectators than players". Yet agents to reduce brain bulk are extensively used in cerebral infarction, intracranial haemorrhage and head injury; their speed of action or the duration of their efficacy have been shown to be unpredictable. To use them without any means of assessing their response is, in many respects, as irrational as prescribing antibiotics in severe infection, without attempting to identify the relevant organism or its sensitivity to antibiotics. Despite a few glaring defects this book deserves far wider readership than its title is likely to attract. R. M. Kalbag
Control Mechanisms of Drinking
(Proceedings of a Symposium
organized for the
U n i o n d e s S o c i 6 t 6 s S u i s s e s d e B i o l o g i e E x p 6 r i m e n t a l e , 2 0 - 2 1 O c t o b e r , L u g a n o , 1973), b y G . P e t e r s , J. T. F i t z s i m o n s a n d L. P e t e r s - H a e f e l i ( E d s . ) , xiii ÷ illustrations,
Springer-Verlag,
Berlin,
Heidelberg,
New
York,
209 p a g e s , 136
1975, D M
64.00,
U S $ 27.60. This volume has been prepared by editing the Proceedings of a Symposium on Thirst organised for the Union des Soci6t6s Suisses de Biologie Exp6rimentale. The papers which are included provide invaluable progress reports on the control of the intake of non-nutritive fluids. The sections conveniently cover the major areas of interest and controversy in water homeostasis. The sections on catecholaminergic mechanisms and peripheral aspects, and on central mechanisms in renin angiotensin induced drinking are of particular value and are particularly useful, providing reviews of the literature and some important new data. These new reports indicate the probable role of the renin-angiotensin system in the control of drinking in the intact animal. There is a useful section on oropharyngeal and gastric influences in drinking, which emphasises the importance of these influences (which has been much disputed in the past). The section on salt appetite usefully complements the other sections and is a timely reminder that the control of salt and water intake cannot be considered independently. It is unfortunate that one or two of the other sections are of less uniformly high quality and one or two of the contributions are frankly anecdotal. This slim, expensive volume is essential for all who study water (or salt) economy experimentally. It is difficult to believe, however, that it will reach a large general scientific audience. D. C. Evered
lntracranial Pressure H ( P r o c e e d i n g s o f t h e 2 n d I n t e r n a t i o n a l S y m p o s i u m o n l n t r a cranial Pressure, Lund, B r o c k ( E d s . ) , xxii +
17-19 June,
1974), b y N . L u n d b e r g , U . P o n t 6 n a n d M .
527 p a g e s , 184 i l l u s t r a t i o n s , 42 t a b l e s , S p r i n g e r - V e r l a g , B e r l i n ,
H e i d e l b e r g , N e w Y o r k , 1975, D M 72.00, U S $ 31.00. A cursory glance through Intracranial Pressure II is likely to discourage the casual browser - - the presentation is dreary, and the text, covering nearly 100 titles, seems too ambitious in concept. The offset form of printing accounts for the former, but as it was apparently chosen to reduce the price of the book, is justifiable. The effort put in by the organisers of the 2nd International Symposium on Intracranial Pressure makes the number of papers far easier to digest than first impressions would suggest. The scientific proceedings were carefully directed to give each of the 12 sessions a predetermined limited scope, and the whole conference, and therefore this book, a logical format which some other international conventions could profitably emulate. Much of this "editing" was done by the chairman and co-chairman before each session.
446 Even to a reader with no more than a passing interest in the subject of intracranial pressure (ICP) monitoring, the result of these efforts is valuable. In each session, the chairman's introduction summarises the current state of knowledge, while the co-chairman sums up the discussion. At least half the sessions covered subjects of general interest to those concerned with any aspect whatever of neurological function, normal or disordered, viz. CSF dynamics, pathogenesls of hydrocephalus, the effects of ICP and ischaemia on brain metabolism and morphology, inter-relations between 1CP and blood circulation within the cranial cavity, the respiratory and cardiovascular effects of increased ICP, and the importance of ICP monitoring in clinical practice. Neurosurgeons and anaesthetists would find additional interest in the sections on the effects of anaesthetic and other agents, as well as those of long-term controlled ventilation on ICP. With the virtual deluge of papers contained in this book. their quality is understandably uneven, and. in some instances, one gets a distinct feeling of d6jb. vu, while others are mere potboilers. The fact that out of 132 papers originally submitted, t02 were accepted by the organisers. shows the limited appeal that such a symposium has, based as it is on measurement of a single factor in a complex, dynamic and very vulnerable system like the brain. Most of the aulhors and the material they present could equally well have appeared under suitably modified headings in other conferences, such as cerebral blood flow to mention just one. But this is more a reflection on the trends in conference organisation than on the book itself. To one nurtured in the highest traditions of British clinical medicine, it is reassuring to find that many a classical hypothesis based on careful bedside observations has been substantiated by some of the experimental work, while the riddles have not always been resolved by even the most elegant and elaborate laboratory studies. A few misconceptions, however, have been clarified. Many a neurosurgeon still holds the view that the "pinched" lateral ventricles on ventriculography, are not only a sine q u a non for the diagnosis of benign intracranial hypertension, but also indicate brain oedema as the responsible factor. Johnston, however, shows in his clinical studies on a small group of 6 patients that the defect is one of CSF absorption. The diagnosis of benign intracranial hypertension covers a variety o f aetiological factors, and there are no clinical details in the paper to enable critical evaluation. But this does not apply to the experimental work on dogs given m the same paper. In those cases where the venous outflow was occluded, the demonstrated reduction in CSF absorption was not unexpected; more significant, in one's opinion, is that even in dogs m whom intracranial hypertension was produced by corticosteroid withdrawal after administration for 4 weeks, the mean absorption of CSF was reduced by nearly 50~. This paper is in the section on CSF hydrodynamics, but Johnston comes back with a caveat in the final section with another viewpoint on the same subject: the clinical recognition of benign intracraniat hypertension over a 4year period at the Glasgow Neurosurgical Unit was incorrect in up to 25 ~ of the cases when tested with continuous intracranial pressure monitoring and fluorescein retinography. Our confidence in clinical management of the condition is then given a further jolt by mentioning patients in whom steroid therapy had no significant effect on intracranial pressure after 1 week, while at 3 months, hressures were still abnormally high despite resolution of all signs and symptoms of intracranial pypertension. If there are still people, and these must be few, who do not question the semantic appropriateness of a diagnosis of "low pressure hydrocephalus", section C on the "Pathogenesis of Hydrocephalus" should help the term towards a long overdue interment. In fact that entity, elusive both in its pathogenesis and sometimes in therapeutic success, is obviously in search of a new name. "Normal pressure" hydrocephalus seems a poor contender, as the work presented shows that in fact in all such cases of hydrocephalus there are periods of high pressure and the normal pressure state is therefore also a misnomer. In the selection of those patients likely to benefit from shunting, in addition to the already known monitoring of ICP during sleep, a second pre-operative criterion has been presented: an increase in cerebral blood flow after reducing CSF pressure by lumbar puncture is an indication for operation. Unfortunately this technique is only available to those centres able to carry out blood flow measurements readily. Much of the interest about the effects of various anaesthetic agents on ICP has been concentrated on the induction and maintenance o f anaesthesia. However, Leech et al. make a Valuable point in demonstrating the significant elevations in ICP and systemic arterial pressure that occur as the anaesthetic is terminated, even when the intracranial contents were considered to be slack when the wound was closed. Fifteen years after Lundberg's monograph on intracranial pressure monitoring, this book . . . . . . . . . • . - _. . . . . . . . . . . . . , ~ ~ ,,t,x~l r,¢,hp otlnlt~al
447 scientist or a toy of the technological gadgeteer". The welcome but at times over-enthusiastic participation of the physicists has introduced refinements in technique which have perhaps dissuaded many clinicians from even considering the practical advantages of the measurement. As Jennett comments in his introduction to the final session, "this is still a field with many more spectators than players". Yet agents to reduce brain bulk are extensively used in cerebral infarction, intracranial haemorrhage and head injury; their speed of action or the duration of their efficacy have been shown to be unpredictable. To use them without any means of assessing their response is, in many respects, as irrational as prescribing antibiotics in severe infection, without attempting to identify the relevant organism or its sensitivity to antibiotics. Despite a few glaring defects this book deserves far wider readership than its title is likely to attract. R. M. Kalbag
Control Mechanisms of Drinking
(Proceedings of a Symposium
organized for the
U n i o n d e s S o c i 6 t 6 s S u i s s e s d e B i o l o g i e E x p 6 r i m e n t a l e , 2 0 - 2 1 O c t o b e r , L u g a n o , 1973), b y G . P e t e r s , J. T. F i t z s i m o n s a n d L. P e t e r s - H a e f e l i ( E d s . ) , xiii ÷ illustrations,
Springer-Verlag,
Berlin,
Heidelberg,
New
York,
209 p a g e s , 136
1975, D M
64.00,
U S $ 27.60. This volume has been prepared by editing the Proceedings of a Symposium on Thirst organised for the Union des Soci6t6s Suisses de Biologie Exp6rimentale. The papers which are included provide invaluable progress reports on the control of the intake of non-nutritive fluids. The sections conveniently cover the major areas of interest and controversy in water homeostasis. The sections on catecholaminergic mechanisms and peripheral aspects, and on central mechanisms in renin angiotensin induced drinking are of particular value and are particularly useful, providing reviews of the literature and some important new data. These new reports indicate the probable role of the renin-angiotensin system in the control of drinking in the intact animal. There is a useful section on oropharyngeal and gastric influences in drinking, which emphasises the importance of these influences (which has been much disputed in the past). The section on salt appetite usefully complements the other sections and is a timely reminder that the control of salt and water intake cannot be considered independently. It is unfortunate that one or two of the other sections are of less uniformly high quality and one or two of the contributions are frankly anecdotal. This slim, expensive volume is essential for all who study water (or salt) economy experimentally. It is difficult to believe, however, that it will reach a large general scientific audience. D. C. Evered