INTENSIVE CARE in NEUROLOGY and NEUROSURGERY Pathophysiological Basis for the Management of Acute Cerebral Injury

Home , Neurointensive care, Neurology, Neurosurgery

Daniel Agustín Godoy INTENSIVE CARE IN NEUROLOGY AND NEUROSURGERY Pathophysiological Basis for the Management of Acute Cerebral Injury

VOLUME 1 Head Editor Daniel Agustín Godoy, MD, FCCM Neurointensive Care Unit- Sanatorio Pasteur Intensive Care Unit Hospital Interzonal de Agudos ‘’San Juan Bautista’’ Catamarca. Argentina

Associate Editor Gustavo Rene Piñero, MD, FCCM Intensive Care Unit Hospital Municipal ‘’Leonidas Lucero’’ Assistant Professor Critical and Emergency MedicineHealth Sciences Department - South University Bahia Blanca, Buenos Aires. Argentina

First edition February 2013

VOLUME 1 ISBN 978-88-9741-939-6

Printed on acid-free paper by Tipografia Graphot, Torino (Italy)

Although the information about medication given in this book has been carefully checked, the author and publisher accept no liability for the accuracy of this information. In every individual case the user must check such information by consulting the relevant literature.

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To my parents Mirtha and Justino for giving me the life, education and the opportunity to study and acquire this wonderful profession.

To my kids, Facundo, Luciano, Josefina and Alvaro who have suffered my absences and for all the love given me every day.

To Veronica, my love, my friend, my support, guidance, and containment with whom if God willing I share what I have left.

To all my colleagues and friends who have shared with me over than 23 years of hard and tireless work, uncertainties, anxieties, sorrows and joys in the Intensive Care Units where I have worked.

To the life... Table of Contents

Prologue...... XV Preface...... XVII References...... XVII

SECTION 1. Introduction to Neuroinjury

1 Neuroscience Critical Care: Two Experts’ Point of View...... 3 1.1 History, Organization, and Vision for the Future: Prof. Mirski’s Point of View...... 3 1.2 NICU Organization: Past, Present and Future: Prof. Robertson’s Point of View... 10 References...... 20

2 Basic Anatomy Applied to the Interpretation of Axial Tomography of the Brain in Emergency Medicine...... 27 2.1 Introduction...... 27 2.2 Development...... 27 2.3 Key Concepts...... 36 2.4 Appendix: Images...... 36 References...... 51 General References...... 51

3 Physiological Basis for the Correct Interpretation of Different Situations in Acute Cerebral Injury...... 53 3.1 Functional and Structural Organization of the Nervous System...... 53 3.2 The Blood-Brain Barrier (BBB)...... 55 3.3 Cerebrospinal Fluid (CSF)...... 56 3.4 Aquaporins (AQP)...... 57 3.5 Intracranial Pressure...... 58 3.6 Cerebral Volume/Pressure Curve (V/P). Cerebral Compliance...... 59 3.7 Intracranial Pressure Curve...... 60 3.8 Cerebral Oxygen Metabolism...... 61 3.9 Cerebral Blood Flow (CBF)...... 62

3.10 Oxygen Tissue Pressure (ptiO2)...... 64 3.11 Cerebral Glucose Metabolism...... 65 3.12 Cerebral Temperature...... 65 3.13 Brain-systemic Temperature Gradient...... 66 3.14 Concept of Primary and Secondary Injury...... 68 General References...... 68

4 Examination of the Critically Ill Neurological Patient...... 71 4.1 Clinical Evaluation (or Examination) of the Critically Ill Neurological Patient...... 71 4.2 General Examination...... 72 4.3 Comprehensive Neurological Examination...... 74 4.4 Routine Investigations of the Neurocritical Patient...... 74

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4.5 Focused Neurological Examination of Selected Topics ...... 75 References...... 101 General References...... 102 5 Evaluation Scales in Neurocritically Ill Patients...... 105 5.1 Objectives...... 105 5.2 Introduction...... 105 5.3 Evaluation in the Acute Phase...... 105 5.4 Imaging-based Assessment Scales...... 114 5.5 Scale of Evolution, Evaluation of Consciousness in Advanced Stages of Brain Injury Outcome Scales...... 123 General References...... 129

SECTION 2. Neuromonitoring 6 Neuroimage Monitoring in the Management of Neurocritical Care Patients...... 135 6.1 Introduction...... 135 6.2 CT in Head-injured Patients...... 137 6.3 CT in Patients With Cerebrovascular Hemorrhagic Disease...... 145 6.4 CT in the Diagnosis of Acute Ischemic Cerebrovascular Diseases ...... 152 6.5 Conclusions...... 156 References...... 156 7 Intracranial Pressure Monitoring. Acute Cerebral Injury: the First 48 Hours...... 159 7.1 Intracranial Pressure...... 159 7.2 Techniques for Monitoring Intracranial Pressure...... 160 7.3 The ICP Waveform...... 161 7.4 Elevated Intracranial Pressure and Pressure Waves...... 163 7.5 Cerebral Perfusion Pressure...... 165 7.6 Cerebral Autoregulation...... 165 7.7 Indications for ICP Monitoring...... 166 7.8 Conclusions...... 166 References...... 166 8 Update on Brain Tissue Oxygen Monitoring in TBI and Other Acute Cerebral Disorders...... 169 8.1 Introduction...... 169 8.2 Approaches to Monitoring Cerebral Oxygenation...... 170

8.3 Hyperemia and Arterial pCO2 ...... 178 8.4 Approaches to Treatment...... 181 8.5 Early Detection and Treatment of Ischemia...... 206 8.6 Suggestions and Limitations...... 211 8.7 Conclusions...... 212 References...... 213 9 Monitoring Cerebral Blood Flow and Cerebral Autoregulation: Basic Principles, Techniques, Common Patterns and Interpretation of Results...... 225 9.1 Introduction...... 225 9.2 Physiology of Cerebral Circulation...... 225 9.3 Techniques to Measure Cerebral Blood Flow...... 227 9.4 CBF in Pathological Conditions...... 229 9.5 Key Concepts...... 230 References...... 231

VI Table of contents 10 The Current Role of Transcranial Doppler in the Intensive Care Unit. Indications, Bases for Its Correct Interpretation, Most Frequent Applications and Patterns...... 233 10.1 CBF Monitoring at the Bedside. Transcranial Doppler Ultrasound...... 233 10.2 Flow Velocity and Pulsatility Index. Normal Range and its Variations ...... 235 10.3 Clinical Applications of Transcranial Doppler in Intensive Care Medicine...... 235 10.4 Transcranial Ultrasonographic Abnormalities in Neurocritical Patients...... 237 10.5 Extreme Expression of Intracranial Hypertension: Cerebral Circulatory Arrest...... 242 10.6 TCD as a Complementary (Auxiliary) Diagnostic Technique in Determining Brain Death...... 242 10.7 Summary of Changes in Cerebral Hemodynamics: Muñoz Chard...... 243 10.8 Assessment of Cerebrovascular Reactivity...... 244 10.9 Appendix...... 252 10.10 TCD in Evaluating Hemodynamics...... 256 10.11 Relationship Between CBF and CPP...... 258 References...... 259

11 Neurophysiologic Monitoring in Neurointensive Care: EEG, EMG, and Evoked Potentials...... 265 11.1 Introduction...... 265 11.2 Electroencephalography...... 265 11.3 Evoked Potential...... 266 11.4 Continuous Neurophysiological Monitoring (EEG-SEP) in the ICU...... 275 11.5 EMG in the ICU...... 279 References...... 281

12 Monitoring Brain Chemistry by Microdialysis During Neurointensive Care...... 285 12.1 Introduction...... 285 12.2 The Microdialysis Technique...... 285 12.3 Biochemical Markers of Ischemia and Cell Damage...... 287 12.4 Lactate/Pyruvate Ratio...... 288 12.5 Glycerol...... 288 12.6 Glutamate...... 289 12.7 Glucose...... 289 12.8 Implanting and Positioning of Microdialysis Catheters...... 290 12.9 Selecting Perfusion Flow...... 293 12.10 Multimodal Monitoring...... 293 12.11 Interpreting Microdialysis Data...... 293 12.12 Clinical Studies...... 294 12.13 Conclusions...... 298 References...... 299

SECTION 3. General Support

13 Fluid Therapy in Acute Brain Injury...... 305 13.1 Introduction...... 305 13.2 Fluids Commonly Used in Neurocritical Care...... 306 13.3 Use of Fluids in Neurocritical Care...... 310 13.4 Conclusions...... 312 References...... 312

VII Intensive Care in Neurology and Neurosurgery 14 The Metabolism of Sodium and Its Effect on the Brain...... 317 14.1 Introduction...... 317 14.2 Hyponatremia...... 318 14.3 Hypernatremia...... 325 14.4 Clinical Management and Treatment...... 326 General References...... 326

15 Hemodynamic Monitoring...... 329 15.1 Introduction...... 329 15.2 Indications and Complexity of Hemodynamic Monitoring...... 330 15.3 Definitions and Hemodynamic Parameters...... 330 15.4 Pressure Monitoring...... 332 15.5 Pulmonary Artery Pressure and the Swan-Ganz Catheter...... 334 References...... 345

16 Cardiac Arrhythmias in Nervous System Disorders...... 347 16.1 Introduction...... 347 16.2 Stroke...... 347 16.3 Paroxysmal Essential Hyper- and Hypopothassemia (Periodic Paralysis)...... 348 16.4 Dystrophy...... 349 16.5 Myotonic Muscular Dystrophy...... 350 16.6 Steinert Myotonic Dystrophy...... 350 16.7 Emery-Dreyfuss Muscular Dystrophy...... 351 16.8 Muscular Dystrophy of the Extremities and the Waist...... 351 16.9 Friederich’s Ataxia...... 351 16.10 Kearns-Sayre Syndrome...... 352 16.11 Leber’s Hereditary Optical Neuropathy...... 353 16.12 Guillain-Barré Syndrome...... 353 16.13 Myasthenia Gravis...... 353 16.14 Epilepsy...... 353 General References...... 358

17 Mechanical Ventilation in the Neurologic Critically Ill Patient...... 359 17.1 Introduction...... 359 17.2 Breathing Control and Respiratory Depression...... 359 17.3 Sedation...... 363 17.4 Hyperventilation...... 364 17.5 Lung Recruitability and Use of PEEP...... 367 17.6 ALI/ARDS and Ventilator-induced Lung Injury...... 369 17.7 Weaning...... 370 17.8 Tracheostomy...... 372 17.9 Conclusions...... 372 General References...... 372

18 Surgical Airway Management in the Neurocritically Ill Patient: Timing, Technique, and Complications...... 375 18.1 Introduction...... 375 18.2 Surgical Airway Management...... 375 18.3 Conclusions...... 379 References...... 380

VIII Table of contents 19 Gastrointestinal Disorders in the Neurocritical Patient...... 381 19.1 Gastrointestinal Motility Disorders in the Neurocritical Patient...... 381 19.2 Common Gastroenterological Disorders in Severe Acute Neurological Illness..... 385 General References...... 393

20 Nutritional Support in Critically Ill Patients...... 395 20.1 Introduction...... 395 20.2 Metabolism During Injury...... 395 20.3 Assessment of Nutritional Status...... 397 20.4 Anthropometric Measurement...... 397 20.5 Biochemical Measures (Biological Indicators)...... 400 20.6 Nutritional Requirements...... 405 20.7 Artificial Nutrition...... 408 20.8 Enteral Nutrition...... 409 20.9 Parenteral Nutrition...... 414 20.10 Assessment and Monitoring of Artificial Nutrition...... 420 20.11 Is There a Specific Nutritional Formulation for Patients with Brain Injury?...... 421 General References...... 423

21 Acute Renal Injury in the Neurocritical Patient...... 425 21.1 Introduction...... 425 21.2 Epidemiology of Acute Kidney Injury...... 425 21.3 Definition of AKI in Critically Ill Patients...... 425 21.4 Diagnosis of AKI in Critically Ill Patients...... 428 21.5 Common Causes of AKI in Critically Ill Patients...... 431 21.6 Prevention and Management of AKI in Critically Ill Patients...... 432 21.7 Indications and Initiation of Renal Replacement Therapy in AKI...... 437 21.8 Dose of Renal Replacement Therapy in Acute Kidney Injury...... 440 21.9 Methods of Renal Replacement Therapy in Acute Kidney Injury...... 442 21.10 Conclusions...... 444 General References...... 445

22 The Brain and the Abdomen: Closer Than You Think...... 451 22.1 Introduction...... 451 22.2 The Relationship Between IAP and ICP...... 451 22.3 Clinical Importance of IAH in Patients at Risk for ICH...... 456 22.4 Treatment Options...... 458 22.5 Clinical Recommendations...... 459 22.6 Conclusions...... 460 References...... 460

23 Endocrinology of Acute Brain Injury...... 465 23.1 Basic Anatomy, Physiology and Changes in Acute Brain Injuries...... 465 23.2 Endocrinology of Acute Brain Injury Secondary to Traumatic Brain Injury (TBI) and Subarachnoid Hemorrhage (SAH)...... 477 General References...... 483

24 Coagulation Disorders in the Neurocritical Patient...... 485 24.1 Introduction...... 485 24.2 Pathophysiology...... 485 24.3 Traumatic Brain Injury...... 485 24.4 Spontaneous Intracranial Hemorrhage...... 487

IX Intensive Care in Neurology and Neurosurgery

24.5 Ischemic Stroke...... 489 24.6 Subarachnoid Hemorrhage...... 489 24.7 Prophylaxis of Pulmonary Thromboembolism in Neurocritical Patients...... 489 General References...... 493

SECTION 4. Intracranial Hypertension

25 Pathophysiology of Intracranial Hypertension...... 497 25.1 General Concepts...... 497 25.2 Compliance...... 499 25.3 ICP Waves...... 500 25.4 Factors Which the ICP Depends on...... 501 25.5 Intracranial Hypertension Compensating Mechanisms...... 501 25.6 Effects of Intracranial Hypertension...... 502 25.7 Intracranial Pressure Gradients...... 503 25.8 Herniaton Syndrome...... 504 25.9 Elevated ICP...... 504 25.10 Hydrocephalus...... 504 General References...... 508

26 Cerebral Edema: State of the Art...... 511 26.1 Introduction...... 511 26.2 Causes of Edema...... 512 26.3 Methods to Measure Edema...... 515 26.4 Treatment...... 516 26.5 Conclusions...... 519 References...... 519

27 The Treatment of Intracranial Hypertension. Algorithm of Treatment and First Level Therapeutic Measures...... 521 27.1 Introduction...... 521 27.2 Neurotraumatic Patient Treatment in the Hospital...... 522 27.3 Multimodal Monitoring in Patients With Severe Traumatic Brain Injury...... 524 27.4 General Measures for Treating Brain Injured Patients...... 525 27.5 Specific Treatment of Intracranial Hypertension...... 526 27.6 Muscle Relaxation...... 527 27.7 Evacuation of Cerebrospinal Fluid...... 528 27.8 Hyperosmolar Solutions...... 530 27.9 Hyperventilation...... 532 27.10 Therapeutic Alternatives in the Treatment of Intracranial Hypertension. Second Level Measures: How Often do We Use Them?...... 535 27.11 Quantification of Intensity of Treatment Applied to Control Intracranial Pressure: The Extended Therapy Intensity Level Scale...... 536 27.12 The Withdrawal of Treatment: A Reverse Stepwise Process...... 537 27.13 Case Report...... 538 27.14 Key Concepts...... 541 27.15 Acknowledgements...... 542 References...... 542

X Table of contents 28 Second Level Measures for the Treatment of Intracranial Hypertension in Traumatic Brain Injury...... 547 28.1 Introduction...... 547 28.2 Etiology of Intracranial Hypertension...... 549 28.3 Intracranial Pressure Monitoring...... 549 28.4 Clinical Significance of the Pressure-Volume Curve...... 549 28.5 Where to Monitor ICP? The Problem of Intracranial Pressure Gradients...... 551 28.6 Stepped Versus Individualized Treatment...... 552 28.7 Types of the Therapeutic Measures...... 552 28.8 Barbiturates...... 554 28.9 Moderate Hypothermia...... 557 28.10 Decompressive Craniectomy...... 559 28.11 Acknowledgements...... 562 References...... 562 29 Non-conventional Therapeutics for the Treatment of Elevated Intracranial Pressure: Indomethacin and THAM...... 567 29.1 Indomethacin...... 567 29.2 Tromethamine (THAM or TRIS)...... 569 29.3 References...... 572 30 A Different Point of View in Intracranial Hypertension Management: the Lund Therapy...... 573 30.1 Introduction...... 573 30.2 Pathophysiology After Brain Trauma...... 574 30.3 Measures to Reduce Vasogenic Brain Edema...... 574 30.4 Decompressive Craniotomy and Other Surgical Measures...... 576 30.5 Microcirculation Around Contusions...... 576 30.6 Maintenance of Normovolemia to Improve Cerebral Microcirculation...... 576 30.7 Arterial Pressure and Plasma Volume Expanders...... 577 30.8 Albumin and Erythrocytes as Blood Volume Expanders...... 578 30.9 How to Determine Whether Intravascular Volume is Adequate...... 579 30.10 Other Measures to Improve Cerebral Microcirculation...... 579 30.11 Arterial, Plasma Oncotic and Cerebral Perfusion Pressure...... 580 30.12 Body Temperature Control...... 581 30.13 Nutrition...... 582 30.14 Clinical Application...... 582 References...... 584 31 A Critical Point of View in the Management of Intracranial Hypertension: Are All Therapeutic Tools Evidence Based?...... 587 31.1 Introduction...... 587 31.2 Sedation as a Therapy...... 588 31.3 Hyperventilation...... 589 31.4 Drainage of Cerebrospinal Fluid...... 589 31.5 Osmotherapy...... 590 31.6 Cerebral Perfusion Pressure...... 590 31.7 Hypothermia...... 591 31.8 Steroids...... 591 31.9 Albumin...... 593 31.10 Conclusions...... 593 References...... 593

XI Intensive Care in Neurology and Neurosurgery SECTION 5. Traumatic Injury

32 Mild Traumatic Brain Injury...... 599 32.1 Introduction...... 599 32.2 Epidemiology...... 599 32.3 Classification...... 600 32.4 Radiological Diagnosis...... 604 32.5 Timing of Hospital Discharge...... 605 32.6 Post-traumatic Sequelae...... 606 32.7 Key Concepts...... 607 Acknowledgements...... 607 General References...... 607

33 Moderate Traumatic Brain Injury...... 609 33.1 Introduction...... 609 33.2 Epidemiology...... 609 33.3 Baseline Evaluation...... 609 33.4 Management Issues...... 610 33.5 Computerized Tomography...... 611 33.6 Intracranial Pressure Monitoring...... 611 33.7 Results...... 611 33.8 Final Considerations...... 612 General References...... 612

34 Medical Treatment of Severe Traumatic Brain Injury...... 615 34.1 Introduction...... 615 34.2 Epidemiology...... 615 34.3 Classification...... 616 34.4 Pathology of Brain Damage...... 617 34.5 Pathophysiology...... 620 34.6 Diagnosis of TBI...... 622 34.7 Treatment of TBI...... 624 34.8 Conclusions...... 635 General References...... 636

35 Surgical Management of Severe Traumatic Brain Injury...... 639 35.1 Introduction ...... 639 35.2 Epidural Hematoma...... 639 35.3 Subdural Hematomas ...... 642 35.4 Intra-axial Lesions ...... 645 35.5 Contusion and Cerebral Hemorrhage...... 646 35.6 Delayed Intracerebral Hematoma...... 648 35.7 Lesions of the Posterior Fossa...... 648 35.8 Depressed Skull Fracture...... 649 35.9 Surgical Treatment of Increased ICP: Decompressive Craniectomy...... 650 References...... 655

36 Severe Traumatic Brain Injury: Pathophysiology and Management Guided by Multi-modal Monitoring...... 659 36.1 Introduction...... 659 36.2 Clinical and Cellular Pathophysiology of Severe Traumatic Brain Injury...... 659 36.3 Clinical Pathophysiology...... 661

XII Table of contents

36.4 Autoregulation...... 661 36.5 Secondary Brain Injury...... 663 36.6 Intracranial Pressure...... 663 36.7 Intracranial Hypertension, Monitoring Modalities, and Treatment Strategies....664 36.8 Conclusions...... 673 References...... 674

37 Prognosis in Traumatic Brain Injury...... 679 37.1 Introduction...... 679 37.2 Prognosis...... 681 37.3 Prognosis in Traumatic Brain Injury...... 683 37.4 Prognostic Models...... 686 37.5 CRASH Prognostic Models...... 687 37.6 Individual Predictors...... 688 37.7 Comparison With Previous Studies...... 691 37.8 Strengths and Weaknesses of This Study...... 692 37.9 Implications...... 693 37.10 Future Research...... 693 References...... 694

38 Surgical Treatment of Spinal Cord Injury...... 703 38.1 Introduction...... 703 38.2 Terminology...... 704 38.3 Initial Treatment...... 708 38.4 Spine Immobilization...... 708 38.5 Maintenance of Blood Pressure...... 709 38.6 Maintenance of Oxygenation...... 710 38.7 General Care of SCI Patients...... 711 38.8 Laboratory Evaluations...... 712 38.9 Surgical Treatment...... 715 38.10 Functional Independence Measure (FIM)...... 716 General References...... 718

39 Acute Spinal Cord Injury: Pathophysiology and Intensive Care Management...... 721 39.1 Introduction...... 721 39.2 Pathophysiology of Spinal Cord Injury...... 721 39.3 Acute Management of the Patient With Spinal Cord Injury...... 724 39.4 Conclusion...... 728 References...... 729

XIII Prologue

This book deserves to my gratitude, more than my prologue. Many years ago, when this project started, its aim was simple: to provide the physician with a quick and practical tool for consultation. However, the enormous generosity, self- lessness and spirit of collaboration of great teachers and world opinion leaders in this subspecialty made it possible to transform it in what it is today. Some time ago (I still remember well his e-mail), Prof. Stephan Mayer of Columbia, New York, in that period President of the Neurocritical Care Society, described the book as “magnum opus”. In my humble opinion this definition was very exaggerated, but his words were like a shot of optimism that undoubtedly lead the way. My teachers and friends encouraged me, helped me, I held back, and therefore they all have my eternal gratitude. In particular, I’d like to mention two persons who had a great role in my professional life, with whom I shared most of my professional life, two great friends: Este- ban Piacenza, who taught me how to take my first steps in intensive care, and Prof. Wal- ter Nigri, neurosurgeon, who introduced me into the neurocritical care. Of course it was not so easy. Editing a book of this magnitude is a Herculean task, only understandable by those who have done something similar. In addition, during its prep- aration I had to overcome a rough and long illness (and this is the reason for its delay). However, like everything one undertakes in life, it has a special flavor when the effort needed has been intense. So I’d like to recommend to potential readers two sentenc- es that accompanied me throughout my life, especially during difficult periods and ob- viously while editing this book: «Persistence is the key to success» and «What’s to come is better». Simply thanks to all those who made possible to make this dream come true.

Daniel A. Godoy

XV Preface

«During revolutions scientists see new and different things when looking with familiar instruments in places they have looked before. It is rather as if the professional community had been suddenly transported to another planet where familiar objects are seen in a different light…» [1] Thomas S. Kuhn

This volume, which we have the honor to introduce, presents the work of a group of international experts in neurocritical care. Dr. Daniel Godoy has completed thedaunting task of introducing the beginner and updating the specialist on current knowledge in brain injury. Anyone who has been involved in editorial projects will have experienced the trials and tribulations of uniting the efforts of many; Dr. Godoy’s book is no excep- tion. He has met this challenge patiently and tenaciously. Having known him for many years, we feel he is to be commended for his devotion and drive. His extraordinary interest in science has made him a well-known expert his field bringing about an ever-in- creasing level of activity in neurointensive care in Argentina. Many of the contributors to this book are known personally to us, colleagues with different specialties who we also consider friends, having come together through a shared fascination with an undoubtedly complex and heterogeneous medical challenge: neurocritical care. This book is dedicated to brain-injured and neurocritically ill patients. The management of these patients constitutes a growing subspecialty that remains unrecognized by many international medical associations but has played a prominent role in intensive care over the last two decades. Neurocritical care as a subspecialty evolved from the need to provide highly specialized care to neurosurgical patients. Later, patients with severe traumatic brain injury (TBI), hemorrhagic stroke, and acute central nervous system disorders were included in this line of care. Each of these patients requires specialists who are knowledgeable of their particular clinical situations in addition to rapid and often complex management of intracranial hypertension, technical equipment, and skilled nurses [2]. Indeed, specialized nursing forms the backbone of modern neurocritical care units. As with the management of other complex pathologies (e.g. neurovascular disorders, endoscopic surgery, skull base fractures, and pediatric neurology), subspecialization in neurosurgery is essential to improving outcome and reducing complications. In neurosurgery, outcome is always improved when the patient is in the hands of an expert instead of a general, though versatile, neurosurgeon. However, some sectors of the

XVII Intensive Care in Neurology and Neurosurgery international intensive care societies still view neurocritical care subspecialization with skepticism, if not with mistrust. In our opinion, these attitudes reflect irrational fears and are at odds with scientific evidence in support of subspecialization. Several studies have shown that neurocritical care specialization reduces mortality, improves functional outcome in almost all diseases studied, and is cost-effective for the health care system [3]. This has been demonstrated in patients with severe TBI, spontaneous subarachnoid hemorrhage, intracerebral hematoma, and ischemic stroke [3-5]. Admittedly, in some cases it is not easy to discern whether the determinants of improved results are the specialized units themselves or the well-structured clinical management protocols. In patients with severe TBI, the rigorous application of the Brain Trauma Foundation guide- lines has been shown to significantly reduce mortality [6]. What should be remembered, however, is that such protocols have been created using procedures designed by neurocritical care specialists. What has brought added value to subspecialization most is the human factor, as noted by Smith: “Members of a multidisciplinary team who care regu- larly for patients with acute brain injury are more likely to be aware of the adverse impact on the brain of secondary physiological insults and to be more obsessional about their prevention, recognition and treatment” [2]. Despite contradictions, doubts, and disagreements, neurointensive care has reached or- ganizational levels unthinkable just a decade ago and neurointensive care units can now be found in nearly all countries. Nonetheless, the tempo of change varies and the models are diverse. The Neurocritical Care Society in the United States and the Canadian Neurocritical Care Society were founded in 2003 [3]. The European Society of Intensive Care Medicine has also established a neurointensive care section, the Neuro-Intensive Care and Emergency Medicine Section. Access to specialized accreditation is homoge- neous, however, following several models and using methods of access, while in other countries no models have been implemented at all. In our opinion, and contrary to popular belief, a well-planned subspecialization based on competencies as well as generic and specific skills will not restrict but rather widen the viewpoint of the specialist and add value to the care of neurocritically injured patients. This provides a driving force for translational research, an indispensable tool in the 21st century that increases knowledge and improves mid-term therapeutic strategies and prognosis. Translational research, which is promoted by the US National Institutes of Health (http://commonfund.nih.gov), is only feasible with a therapeutic approach using multidisciplinary teams with different perspectives and methodologies to obtain a comprehensive understanding of these patients. This allows new therapeutic strategies to move from bench to bedside and back again. To be successful, this kind of research requires teams to work in an atmosphere that fosters collegial effort among neurointen- sivists, neurosurgeons, and neurologists with a vocation for research in collaboration with basic researchers. This ideal scenario is only possible within the context of neurocritical care units. Who should lead these units would be a side issue were it not for con- tentious debate in some countries and in certain scientific societies. We feel that intensive care experts are the most qualified professionals to lead these groups and facilitate the collaboration of different specialists with the common goal of improving prognosis in neurocritically ill patients. The many research projects carried out during the Decade of the Brain (1990-2000) have produced an enormous wealth of information, and our ability to understand the under- lying pathophysiology of many of the conditions affecting TBI patients is challenged, even for our colleagues in neurocritical care. These rapid advances in neuroscience over the past 20 years have led to difficulties in filtering, reading, understanding, and assim- ilating the latest findings. One of the great advantages of this book is that it may serve both those wishing to enter the field of neurocritical care and specialists seeking a time-

XVIII ly update. This volume originated in Latin America, where health systems are heterogeneous and free universal health coverage is not yet a constitutional right in some countries. It is therefore important to underscore that specialization in neurocritical care is only valid in certain socio-economic contexts where health care priorities are well de- fined. What is desirable in certain circumstances may not be so in others. The adequate context for subspecialization is perhaps more typical in developed countries, with high- tech hospitals or academic organizations that provide incentives for the management and maintenance of high-cost units. In such settings, treatment should be optimal and auditable, and serve as a guide for the design and validation of intervention protocols at other centers with fewer resources. It is a great honor for us to introduce readers to a work that will leave a significant mark on Latin American and international neurointensive care thanks to Dr. Godoy’s com- mendable effort to make an English version available. It is important that a project of this scale come from Latin America because it serves as a proof t ofthe enthusiasm for this subspecialization, which has been solidly established in that part of the world over the past 15 years. New generations of intensivists, neurosurgeons, neurologists, and anesthesiologists are facing new challenges. Perhaps the most difficult challenge is to modify the collec- tive consciousness with the idea that the optimal management of brain-injured patients cannot be carried out without a multidisciplinary approach. This is currently not be- ing taught during specialized training, nor is it accepted elsewhere in different scientific fields, where specialists perpetuate a sterile debate about their identities and delineate characteristics that divide rather than unite them. We believe we are witnessing what Kuhn called a “paradigm shift” or a turning point in neurocritical care. Kuhn also noted that such changes are almost never brought about by new findings but rather by the synthesis and critical review of what is already known. Frequently, it is the observer’s point of view, not the observed fact, that changes. Some evident examples in pathophysiology include cortical spreading depression described by Leão in 1944, basic concepts of brain edema first described by Klatzo in 1967, and the pathophysiology of cerebral vasospasm in spontaneous subarachnoid hemorrhage, all of which were far too summarily debated for decades. In the last five years, these three areas, to name just a few, have seen dramatic advancement in terms of knowledge about the mechanisms of brain injury that had long been elusive. Improved understanding has come about by re-examining long-cherished concepts through the use of new monitoring tools and methods in molecular biology. This increased knowledge opens new therapeutic expectations, an idea best summarized by Pang et al: “the application of what we know will have a greater impact on health and illness than any new drug or technology to be introduced in the next decade” [7]. Dr. Godoy has edited a volume that will serve as a starting point rather than a final goal, opening new inroads and stimulating the interest of readers in search of knowledge. We believe that the breadth of the topics covered, the careful selection of the authors, and the quality of each section will meet if not exceed expectations.

Juan Sahuquillo Department of Neurosurgery, Vall d’Hebron University Hospital, Barcelona, Spain

Alberto Biestro Intensive Treatment Center, Hospital de Clínicas Dr. Manuel Quintela, Montevideo, Uruguay

XIX Intensive Care in Neurology and Neurosurgery References

1. Kuhn TS. The structure of scientific revolutions. 3rd ed. Chicago, IL: University of Chicago Press, 1996 2. Smith M. Neurocritical care: has it come of age?Br J Anaesth 2004; 93: 753-5 3. Thenayan EA, Bolton C, Jichici D, et al. Neurocritical care in Canada: evolving streams in a new discipline. Can J Neurol Sci 2008; 35: 405-8 4. Diringer MN, Edwards DF. Admission to a neurologic/neurosurgical intensive care unit is associated with reduced mortality rate after intracerebral hemorrhage. Crit Care Med 2001; 29: 635-40 5. Kurtz P, Fitts V, Sumer Z, et al. How Does Care Differ for Neurological Patients Ad- mitted to a Neurocritical Care Unit Versus a General ICU?Neurocrit Care 2011; 15: 477-80 6. Petsas A, Waldmann C. Where should patients with severe traumatic brain injury be managed?: Patients can be safely managed in a nonspecialist center. J Neuro- surg Anesthesiol 2010; 22: 354-6 7. Pang T, Gray M, Evans T. A 15th grand challenge for global public health. The Lan- cet 2006; 367: 284-86