The publication of the Vth International Symposium 1995 on "Mechanisms of Secondary Brain Damage" in Mauls/ltaly is a collection of focused reviews reaching from novel molecular- and cell biological findings to aspects of clinical management in head injury and cerebral ischemia. A specific purpose of these series of meetings introduced in 1984 is for an exchange on problems of mutual interest by international high ranking experts from the basic sciences and related clinical disciplines, such as intensive care medicine, neurology, or neurosurgery. The present volume covers three major areas: (a) Molecular and cell biological mechanisms including inflammation (b) Novel findings on mechanisms and treatment in cerebral ischemia (c) Secondary processes in head injury, regeneration and treatment Molecular-and cell biology is currently attracting attention towards activation of genomic processes associated with the demise of cells referred to as "programmed cell death" and "apoptosis" which, actually, might be distinguished from each other. Thus, the phenomenon of delayed neuronal death in selectively vulnerable brain areas following brief interruption of blood flow is scrutinized as to the contribution of the activation of suicide genes. The physiological role of such a response, among others, is removal of surplus neurons during ontogenesis of the brain. Yet, evidence is accumulating that similar mechanisms playa role in cerebral ischemia, probably also trauma, where nerve-and other cells demonstrate features of apoptosis. Observations on protection of neurons by administration of protein synthesis inhibitors in cerebral ischemia provide more direct support.

Brain Repair, addresses all relevant issues underlying the mechanisms of brain damage, brain plasticity and post-traumatic reorganisation after CNS lesions. This book is divided the three major sections that follow; cellular and molecular basis of brain repair, plasticity and reorganisation of neural networks, and experimental therapy strategies.

Brain Repair is written by high profile, international experts who describe in detail the newest results from basic research and highlight new model systems, techniques and therapy approaches. Based on a careful analysis of the cellular and molecular reaction patterns of the CNS to lesions, the contributions cover possibilities for endogenous reorganisation and repair as well as exciting new therapies emerging from basic research, some of which have already been introduced into the clinics. Thus, this book is unique in bridging the gap between basic and clinical research. It will be a valuable tool for all students, researchers and clinicians interested in understanding the brain's capacity to cope with lesions and interested in learning about emerging new therapy concepts.

Addressing disease of the frontal sinus successfully remains, perhaps, one of the most technically challenging issues encountered by otolaryngologists. The intricate anatomy, combined with a narrow aperture and relatively acute angle of approach, leads to complexity not encountered elsewhere in surgery of the sinuses. This comprehensive volume with contributions by over 30 of the world's leading rhinologists will help to shed light on this difficult topic. Thorough discussions of anatomy and pathophysiology of a variety of frontal sinus diseases provide a background for in-depth chapters on aspects of both medical and surgical management. A variety of surgical approaches are discussed, including the latest endoscopic techniques, as well as more traditional open and microscopic approaches. Heavily illustrated, this volume will be a "must have" for the rhinologist managing disease in the frontal sinus.

Statistically speaking, head and neck cancer per se (excluding melano ma and basal cell carcinoma) does not outwardly seem to pose a serious threat - 27,500/870,000 total cancer cases estimated for 1984 (or 3.2% of all cancers) and 9,350/450,000 total cancer deaths in 1984 (or 2.1 %) for the United States. Yet in clinical practice, by the time that diagnosis is made, more than 60% of oral cancers have already spread to the nearby lymph node system. And while the overall five-year survival rate for localized oral cancer is 67%, this rate decreases drastically to only 25% when the original cancer has metastasized. Scientific textbooks all too often are merely a compilation of dis crete parts, rather than a correlated, integrated whole. Dr. Hamner and his colleagues have achieved such an integrated, succinct version in The Management of Head and Neck Cancer. The outstanding group of contributors bring to the book a wealth of accumulated knowledge and expertise in their various cancer spe cialty disciplines. They are associated with some of the most distin guished cancer centers in the United States.

Tumours of the central nervous system in infancy and childhood show so many di verse pathomorphological characteristics and present so many diagnostic problems that a congress dealing specifically with the subject and thus bringing together a wide range of experts in the field seemed called for. The programme of the congress, . held in Mainz between 22 and 24 October 1981, was designed to provide compre hensive coverage of diagnosis and the various therapeutic procedures, as well as of basic research in the field. The various lectures given are contained in this book, which thus reflects the complete spectrum of topics discussed. The interest generated by the congress amply justified our decision to organize it. Representatives of various specialities, such as neuropathology, paediatrics, on cology, radiology, neurosurgery, paediatric surgery and neurology, and, last but not least, basic research, provided lively and interesting lectures which admittedly raised more problems than they solved. In addition to the actual papers presented, we attached considerable importance to the different opinions voiced during the congress, as reflected in the discussions included at the end of each chapter."

Recognized clinical leaders in neurosurgery and neuroradiology review the cutting-edge techniques and technologies now available and describe how minimally invasive techniques have influenced their subspecialties. On the radiology side, the authors explain the latest developments in magnetic resonance spectroscopy, functional imaging, and brain mapping, with emphasis on the application of image navigation directly in the operating room, using both preoperative and intraoperative systems. On the surgical side, some of the world's leading surgeons in pediatric neurosurgery, cerebrovascular surgery, neurosurgical oncology, spinal and peripheral nerve surgery, and trauma surgery detail how they use the powerful new minimally invasive techniques in the own practices. Among the novel approaches discussed are radiofrequency, radiosurgery, thermal therapy, and minimally invasive techniques that allow "molecular neurosurgery" via gene and viral vectors and local delivery systems.

Das Buch vermittelt dem in Praxis und Klinik tatigen Arzt die Grundlagen uber die mit Schwindel und Gleichgewichtsstoerungen einhergehenden Erkrankungen. Umfassend und praxisnah werden Diagnostik, Klinik und Therapie dieser komplexen Krankheitsbilder dargestellt. Im ersten Teil werden die anatomischen und physiologischen Grundlagen des Vestibularisapparates, die Nystagmusanalyse sowie die verschiedenen Untersuchungsmethoden abgehandelt. Im zweiten Teil werden die wichtigsten pathologischen Reaktionsmuster und Stadien von vestibularen Lasionen eroertert. Alle wichtigen vestibularen Erkrankungen werden ausfuhrlich und systematisch geordnet nach Symptomen, AEtiologie und Pathogenese, Komplikationen, Differentialdiagnose, interdisziplinaren Untersuchungsvorgangen, Ergebnisssen der Vestibularisprufung und Therapie einschliesslich zahlreicher Falldemonstrationen beschrieben. Spezielle Erfahrungen des Autors finden ihren Niederschlag in eigenen Analogschemen zur Erleichterung der Diagnostik, in einem Vestibularis-Index zur Erkennung der Schwere einer vestibularen Erkrankung sowie in eigenen diagnostischen und therapeutischen Konzepten.

Although in the last few years more experience in the field of epilepsy surgery with amygdalo-hippocampectomies was gained in several hos- pitals, a detailed microanatomical and microsurgical description meet- ing the requirements of the modern neurosurgeon has not been achieved so far. Recently the allocortex - the so-called "limbic system" - has doubtlessly received more attention, as can be gathered from the recently published monography by Duvernoy, which however only considers anatomical points of view. Lately not only epilepsies but also tumorsurgical operations on the border between temporal lobe and basal ganglia can be - thanks to modern MR-examinations - carried out more exactly. Here the tumor-conditioned deformations of the temporo-medial area and its connections with the adjacent basal gang- lia as well as their blood supply are of great importance. Using conven- tional techniques the postoperative morbidity was especially high until recently. The author has at the suggestion of his teacher G. M. Ya argil approached the problem first of all morphologically by developing his own techniques of brain dissection. After some developmental and topographic-anatomical descriptions he has described the vessel-supply by using injection-preparations. Particular aspects of A. chorioidea ant. with her lateral, medial and Tractus opticus penetrating perforat- ing arteries to the basal ganglia and Capsula into have never been described in such a convincing manner before. It is of great importance in the operative removal of the amygdalo- hippocampal area to realize that it is not sufficient to preserve the A.

The dawn of neurosurgery can be traced back to the first description preserved in the Edwin Smith papyrus' (3000 Be) which dealt with head and spinal injury. In the course of 5000 years, since the first record in Egypt, advances in lifestyle and technology have brought about our modern civilized society. However, as a result of civilization, currently the total number of severe head injuries worldwide is believed to exceed 10000000 and the number of severe spinal injuries is believed to be more than 75 000 each year. This means that central nervous system injury is not only the oldest topic in neurosurgery, but that it is also of critical importance in modern life. Taking these problems into consideration, the International Neurotraumatology Committee was organized in 1965 as an affiliated Committee of the World Federation of Neurosurgical Societies. The first scientific meeting was convened by the Committee in Marseilles in 1970. Nine further meetings were subsequently held, in Europe, Africa, and South America. The meeting was first named "International Conference on Recent Advances in Neurotrauma tology" (ICRAN) by Professor Phillip Harris, when the scientific meeting was held in Edinburgh in 1982. The tenth meeting, (ICRAN 1992), the first one in Asia, was held at Karuizawa, Japan, from September 23rd to 26th, 1992."

The 4th Advanced Seminar in Neurosurgical Research was held on May 17th-18th, 1989 in the Abbey of Praglia, a XIIth century Benedictine Monastery, near Padua, Italy, and was devoted to "Neurosurgical Aspects of Epilepsy." The general aim of these Advanced Seminars is to bring together European Neurosurgeons interested or involved in research, either clinically, experimentally or both, in a given field in order to achieve in-depth informal discussions not possible in the more conventional large congress. In particular, these Advanced Seminars seek to provide high level teaching by experienced basic scientists, to provide "state of the art" assessment of the subject and to highlight areas of controversy that might be suitable for future research. A special effort is made to identify younger Neurosurgeons, partly through the auspices of the European Directory of Neurosurgical Research, who have a particular interest in the subject under discussion, not all of whom will have immediate access to the most advanced, modern technology. Surgical treatment of epilepsy is an expanding area of endeavour and an expertise that remains underutilized in many countries. The programme for this Seminar was designed to paint the broad background, moving from basic membrane electrophysiology through to cost benefit analysis and rehabilitation. The perspectives of neu ropathology, neurology, neuroradiology, nuclear medicine, neuropsychology, neurophysiology and the drug in dustry are all included."

This monograph presents a comprehensive review of the clinical experience in surgical repair of cranial defects which the author has gained during a period of over ten years. Particular problems of patients undergoing cranioplasty, such as neurological impairments, EEG changes, variations of intracranial pressure, and sinking skin flap syndrome are described and discussed. The author presents convincing evidence of the importance of cranioplasty in improving the quality of life of patients with large and disfiguring cranial defects. Unfortunately, cranioplasty still ameliorates only to a minimal extent the general condition in patients suffering of major cerebral lesions. I am convinced that this volume will serve the purpose it was designed for : that it will be a most helpful introduction into the problems related to reconstructive surgery. Basel, August 1984 Otmar Gratzl Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A. History of Cranioplasty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 B. Clinical Aspects of Cranial Bone Defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 I. Origin of Cranial Defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Acquired Defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Congenital Defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3. Demographic and Other Characteristics of Patients . . . . . . . . . . . . . . . . . 9 II. Neurological and Psychic Changes Before and After Cranioplasty . . . . . . . 11 1. Classification of Neurological Deficits and of the Skin Flap Types . . . . . 13 2. The "Sinking Skin Flap Syndrome" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3. The Influence of Cranioplasty Upon Neurological and Psychic Changes 17 III. Electroencephalographic (EEG) Changes in Patients with Cranial Defects 21 1. EEG Recordings and Casuistic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2. Evaluation of EEG Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 IV. Scintigraphy Findings in Patients with Cranial Bone Defects . . . . . . . . . . . . 26 1. Casuistic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2. Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

This book contains the papers delivered at the Fourth International Symposium on Intracranial Pressure, held at Williamsburg, Virginia, USA, June 10-14, 1979. Divided into 12 sessions, they reflect the most recent developments in areas such as head injuries, pressure volume studies, cerebrovascular complications, intracranial hemor rhage, brain edema, systemic factors and infectious processes, data recording and analysis, CSF formation and absorption, hydroce phalus, clinical aspects of ICP monitoring, anesthesia and intra cranial pressure, treatment with barbiturates and steroids, and os motherapy. The book concludes with a summary of the present state-of-the-art in the field as a whole by Dr. Langfitt. There were two innovations at this Symposium. The first of these was poster sessions, the second, breakfast seminars. This volume contains all papers read plus all those presented as posters, and for this reason contains more pages than the three previous volumes. The organizers wish to thank the Advisory Committee for the work done in paper selection and focus of the Conference. Appreciation is also given to the Chairmen and Co-chairmen of the sessions for the preparation of summary statements. Manuscript preparation was performed by Ms. Lucille Browne, and gratitude is expressed to her. The next Symposium, the Fifth International Conference on ICP, will be held in Japan in 1982. We also wish to acknowledge the technical help of Springer-Verlag and their celerity in producing this volume. The Editors VII Contents Session I. Head Injury Chairman: D. P. BECKER; Co-chairman: I. PAPO 3 Summary . . . . . . . . . . . .."

Endovascular Neurosurgery represents a unique collaboration between contributors from a number of specialties, all of whom are concerned with the management of cerebrovascular disease. This provides a balanced account of the efficacy of interventional endovascular techniques in this group of conditions. As a result, Endovascular Neurosurgery will prove an invaluable account of a relatively new specialty and will be essential reading for neurosurgeons, neurologists, neuroradiologists, neurophysiologists and neuroanaesthetists.

This is the first book to cover minimal-invasive treatment of osteoporotic, tumorous and traumatic vertebral fractures in the English language. In addition to detailed descriptions of the techniques, including tips and tricks from experts, the book contains a chapter about the medical treatment of osteoporosis, which is indispensable in the interdisciplinary approach to osteoporosis. This acclaimed innovative concept unites several treatment aspects. More conservative treatment methods are also presented in this work.

All chapters reflect new developments and clinical findings in the field of orthopaedics, surgery, traumatology and neurosurgery.

During the last decade a multitude of studies concerning the dynamic changes in cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and intracranial pressure (ICP) in the acute phase after head injury have been published. These studies have been supplemented with studies of cerebral autoregulation, CO2 reactivity and barbiturate reactivity. Other investigations include studies of cerebrospinal fluid pH, bicarbonate, lactate and pyruvate. In this book experimental and clinical studies of the dynamic changes in CBF, CMRO2, CO2 reactivity and barbiturate reactivity are reviewed. The author's own clinical studies of the dynamic changes in CBF and cerebral metabolism are summarized and discussed, and the therapeutical implication as regards the use of artificial hyperventilation, sedation with barbiturate and mannitol treatment are discussed.

1 2 3 O. D. Wiestler , U. Schlege1 , andJ. Schramm lInstitut flir Neuropathologie, Universitatskliniken Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany 2Neurologische Universitatsklinik, Sigmund-Freud-Str. 25, 53127 Bonn, Germany 3Neurochirurgische Universitatsklinik, Sigmund-Freud-Str. 25,53127 Bonn, Germany In contrast to various other neoplastic disorders, there has still been no dramatic progress in the treatment of gliomas. Modem microsurgical and imaging techniques have made more tumors surgically accessible and have allowed a more extensive surgical resection. However, these new developments have not improved the clinical outcome. Recently, molecular biological studies on genes and genetic loci affected in tumors of the nervous system have yielded significant new insights into pathoge- netic machanisms. Many neuro-oncologists are therefore looking forward to transla- ting molecular genetic findings into novel diagnostic and therapeutic strategies for the management of these devastating neoplasms. We have produced this volume with the intention of highlighting major developments in both molecular and clinical neuro-oncology and of stimulating the communication and cooperation between these two fields. Two major families of growth-controlling genes have emerged from the past decade of intense research on the molecular genetics of tumors: oncogenes and tumor suppressor genes. Oncogenes are characterized by their potential to stimulate the growth of susceptible cells whereas tumor suppressor genes share a growth-inhibi- ting property. A stringently controlled interplay between these two regulatory me- chanisms is required to maintain a stable composition of tissues.

"Child development" has always been a traditional component of well child care and a particular area of interest for pediatricians, child neu rologists, and psychologists. However, it was not until the early 1960s that children with developmental disabilities (i. e. , chronic handicapping disorders) became a major focus of public and professional attention. During this period, children with "special needs" were dramatically catapulted into the limelight and "exceptional" became the buzzword of the day. Public and professional awareness of these issues reached new peaks and recognition of the potential psychosocial impairments of chil dren with developmental disabilities created national anxiety. A variety of factors contributed to an unprecedented societal advocacy for chil dren with developmental problems: (1) a national concern generated by President Kennedy'S particular interest in mental retardation; (2) in creased activity and visibility of parent advocacy/lobbying groups (e. g. , the Association for Children with Learning Disabilities); (3) the enact ment of federal legislation designed to protect the rights of the handi capped (e. g. , PL94-142); and (4) the popularization of developmental behavioral disabilities by the various communications media. Cumulatively these events precipitated a redefinition of the real mean ing of "comprehensive health care for children," resulting in an empha sis on the child's neurodevelopmental, educational, psychological, and social needs. For the pediatrician, a myriad of new management respon sibilities were mandated, in addition to the traditional health care con cerns.

Our common interest in surgery of the vertebral artery was born in 1976, when as residents in the same hospital, we attended an attempt by two senior surgeons to treat an aneurysm of the vertebral artery at the C 3 level. Long discussions had preceded this unsuccessful trial, to decide if surgery was indicated and to choose the surgical route. Finally a direct lateral approach was performed, but access was difficult and correct treatment was impossible, resulting in only partial reduction of the aneurysmal pouch. Following this experience, we decided to seek a regular and well defined approach for exposition of the vertebral artery. Review of the literature indicated some surgical attempts, but the descriptions did not give the impression of safety and reproducibility. No landmark on the described surgical route appeared sufficiently reliable. Henry's anatomical work (1917) gave the only accurate description on vertebral artery anatomy, and it became the basis for our work. When the same patient was referred again one year later, after a new stroke in the vertebro-basilar system, we had behind us repetitive experience on cadavers of an original approach to the distal vertebral artery.

As an addition to the European postgraduate training system for young neurosurgeons we began to publish in 1974 this series devoted to Advances and Technical Standards in Neurosurgery which was later sponsored by the European Association of Neurosurgical Societies. The fact that the English language is well on the way to becoming the international medium at European scientific conferences is a great asset in terms of mutual understanding. Therefore we have decided to publish all contributions in English, regardless of the native language of the authors. All contributions are submitted to the entire editorial board before publication of any volume. Our series is not intended to compete with the publications of original scientific papers in other neurosurgical journals. Our intention is, rather, to present fields of neurosurgery and related areas in which important recent advances have been made. The contributions are written by specialists in the given fields and constitute the first part of each volume. In the second part of each volume, we publish detailed descriptions Of standard operative procedures, furnished by experienced clinicians; in these articles the authors describe the techniques they employ and explain the advantages, difficulties and risks involved in the various procedures. This part is intended primarily to assist young neurosurgeons in their post graduate training. However, we are convinced that it will also be useful to experienced, fully trained neurosurgeons."

The rapid development of diagnostic and therapeutic procedures in the management of spinal angiomas has opened up new possibilities and provided better chances for the patients concerned. The greatest impetus to this pro gress was given by the introduction of selective and superselective spinal angiography, microsurgical technique, and embolization. These sophisticated techniques and the skill required for their use are far from being routine in the neurosurgical and neuroradiologic departments. In spite of the rarity of spinal angiomas, the application of the above-mentioned procedures is the prerequisite for improving early diagnosis and giving timely adequate treat ment. Delay in diagnosis and treatment are still the main cause of unsatisfac tory results. In the last 10 -20 years, several groups in Europe and the USA have done important and fundamental work in introducing and developing the diganos tic and therapeutic armamentarium. Based on the pioneering work of their teachers and the classic contribution of Wyburn - Mason in 1943, they simultaneously improved the morphologic, physiologic, and clinical basis of our knowledge. Although progress is going on and many problems have to be solved, the general principles of clinical diagnosis, operative treatment, and embolization have been laid down and are to be published in a special monograph on this topic."

The blood-brain barrier is still not completely understood and therefore the subject of fascinating study. How are endogenous substances transported through the blood-brain barrier? What are the known therapeutic and toxic agents? How are they transported across cerebral microvessels? The discussion of these and other questions with far-reaching consequences for all neuroscientists can be found in this volume. This authoritative and up-to-date review of the blood-brain barrier gives a proper understanding of the topic. The experimental principles, the results of very recent research, as well as the implications that experimental research has for clinical treatment are thoroughly covered. Information is given on: - new findings based on classical physiological and pharmacological techniques, - results obtained from brain capillaries in vitro and in culture, - results obtained from the new scanning techniques (PET and MRI), - the immunology of the blood-brain barrier, - trace metal transport, - the pathological breakdown of the barrier and - the modification of drugs to increase their entry into the brain. Here is a source of information that is invaluable to specialists concerned with basic research in the neurosciences, with the design of neuropharmacological agents, with the radiological diagnosis of cerebral pathology or with the treatment of cerebral lesions!

This volume is a compilation of papers presented at the Tenth International Symposium on Brain Edema held on October 20-23, 1996, in San Diego, California. This follows the sequence of meetings that was initiated 31 years ago in the First International Symposium held in Vienna. Subsequent symposiums were held in Mainz, Montreal, Berlin, Groningen, Tokyo, Baltimore, Bern, and Tokyo CY okohama). A considerable number of papers was chosen from over 100 papers that were received. The organizers wish to thank the Advisory Committee for the excellent work done in selection of the papers. We also wish to thank all the persons who contributed to the success of the Tenth International Symposium, especially the staff who worked behind the scenes. These papers were reviewed, edited, approved or disapproved by the Editorial Board. Those manuscripts that were felt not pertinent to this publication were not accepted by the Editorial Board. Therefore, the excellent quality of those that are in the book are a reflection of the authors' dedication and work and that of those of the Editorial Board in their review process. For the reader's convenience, the papers are structured according to the various disease processes which are associated with the primary topic: hypertension, hydrocephalus, infection, ischemia, tumor, etc. We do hope that the reader will enjoy the articles and that they will provide an impetus and insight for future work.

Distinguished medical researchers from around the world review novel neural reconstructive techniques that appear to be beneficial for Parkinson's disease and hold promise for treating Huntington's disease, pain, demyelinating diseases, and stroke. The contributors focus on those diseases for which clinical trials are either ongoing or likely to occur in the near future. Among the topics reviewed are results and rationale for some of the leading transplant programs for the treatment of Parkinson's disease, the use of PET scanning for patient evaluation, autopsy studies of transplant recipients, transplant immunology, fetal tissue transplantation for Huntington's disease, cellular transplantation for the treatment of pain and stroke, and transplantation of myelinating cells. A full discussion of the important ethical issues surrounding the use of fetal tissue for transplantation purposes is also included.

The cerebello-pontine angle has always posed a challenge to the neurosurgeon, the otoneurosurgeon, and the neuroradiologist. Angle masses which are very small and difficult to detect frequently produce symptoms, but may remain silent while growing to exceptional size. The neuroradiologist must have firm knowl edge of the clinical manifestations of the diverse angle lesions in order to tailor his studies to the patients' needs. The majority of angle lesions are benign; thus successful surgery has the potential for complete cure. Angle lesions typically arise in conjunction with vital neurovascular structures, and often displace these away from their expected positions. Large lesions may attenuate the vestibulocochlear and facial nerves and thin them over their dome. Since the nerves often remain functional, the surgeon then faces the need to separate the tumor from the contiguous nerve, with preservation of neurological function. Depending on the exact location and extension of the lesion, resection may best be attempted via otologic or neurosurgical approaches. The neuroradiologist must determine - precisely -the presence, site, size, and extension( s) of the lesion and the displacement of vital neurovascular structures as a guide to selecting the line of surgical attack. Since the arteries, veins, and nerves that traverse the angle are fine structures, the neuroradiologist must perform studies of the highest quality to do his job effectively."

The two International Symposia on Spinal Cord Monitoring, held in Tokyo in 1981 [Homma S, Tamaki T (eds) (1984) Fundamentals and clinical appli- cation of spinal cord monitoring. Saikon Publishing, Tokyo] and Erlangen in 1984, were remarkable in that they stimulated a gathering of electro- encephalographic, neurophysiological, orthopaedic, neurosurgical, anaes- thetic and pathological practitioners, presenting experimental, clinical and surgical experiences. The factor held in common was an understanding of the need to reduce the incidence and severity of iatrogenic neurological im- pairment associated with certain surgical and radiographic procedures. In the past there has been a tendency for the study of human evoked poten- tials (EPs) to be regarded as an end in itself, or at best a discipline which can be of limited assistance in certain problems of neurological diagnosis. Symposia such as these serve the valuable function of opening electro- physiological eyes to the problems to which EP techniques might usefully be devoted in other medical spheres. They also help those who practise electrophysiology as an adjunct to their speciality to comprehend such of the more complex properties of EPs as are relevant to their particular interests. The title of the Symposia and of this volume arose as a result of an his- torical accident. The pioneers of intraoperative neuronal monitoring were mostly surgeons specialising in the correction of spinal deformities or the removal of tumours.