NEUROLOGIC COMPLICATIONS
OF CRITICAL ILLNESS
SERIES EDITOR
Eva Feldman, MD, PhD, FAAN, FANA
Russell N. DeJong Professor of Neurology
University of Michigan
Contemporary Neurology Series
74 NEUROLOGIC COMPLICATIONS
OF CRITICAL ILLNESS
Third Edition
Eelco F.M. Wijdicks, MD, PhD
75 CLINICAL NEUROPHYSIOLOGY
Third Edition
Jasper R. Daube, MD, and
Devon I. Rubin, MD, Editors
76 PERIPHERAL NEUROPATHIES IN
CLINICAL PRACTICE
Steven Herskovitz, MD, Stephen N. Scelsa,
MD, and Herbert H. Schaumburg, MD
77 CLINICAL NEUROPHYSIOLIOGY OF
THE VESTIBULAR SYSTEM
Fourth Edition
Robert W. Baloh, MD, and
Kevin A. Kerber, MD
78 THE NEURONAL CEROID
LIPOFUSCINOSES (BATTEN DISEASE)
Second Edition
Sara E. Mole, PhD, Ruth D. Williams, MD,
and Hans H. Goebel, MD, Editors
79 PARANEOPLASTIC SYNDROMES
Robert B. Darnell, MD, PhD, and
Jerome B. Posner, MD
80 JASPER’S BASIC MECHANISMS OF
THE EPILEPSIES
Jeffrey L. Noebels, MD, PhD,
Massimo Avoli, MD, PhD,
Michael A. Rogawski, MD, PhD,
Richard W. Olsen, PhD, and
Antonio V. Delgado-Escueta, MD
81 MYASTHENIA GRAVIS AND
MYASTHENIC DISORDERS
Second Edition
Andrew G. Engel, MD
82 MOLECULAR PHYSIOLOGY
AND METABOLISM OF THE
NERVOUS SYSTEM
Gary A. Rosenberg, MD
83 SEIZURES AND EPILEPSY
Second Edition
Jerome Engel, Jr., MD, PhD
84 MULTIPLE SCLEROSIS
Moses Rodriguez, MD, Orhun H. Kantarci, MD,
and Istvan Pirko, MD
85 FRONTOTEMPORAL DEMENTIA
Bruce L. Miller, MD
86 AUTONOMIC NEUROLOGY
Eduardo E. Benarroch, MD
87 EVALUATION AND TREATMENT
OF MYOPATHIES
Second Edition
Emma Ciafaloni, MD, Patrick F. Chinnery,
FRCP, FMedSci, and
Robert C. Griggs, MD, Editors
88 MOTOR NEURON DISEASE IN ADULTS
Mark Bromberg, MD
89 HYPERKINETIC MOVEMENT
DISORDERS
Roger M. Kurlan, MD, Paul E. Green, MD,
and Kevin M. Biglan, MD, MPH
90 THE NEUROLOGY OF EYE MOVEMENTS
Fifth Edition
R. John Leigh, MD, FRCP, and
David S. Zee, MD
91 MIGRAINE
Third Edition
David W. Dodick, MD, and Stephen D.
Silberstein, MD
92 CLINICAL NEUROPHYSIOLOGY
Fourth Edition
Devon Rubin, MD and
Jasper Daube, MD, Editors
93 NEUROIMMUNOLOGY
Bibiana Bielekova, MD, Gary Birnbaum, MD,
and Robert P. Lisak, MD
94 PLUM AND POSNER’S DIAGNOSIS AND
TREATMENT OF STUPOR AND COMA
Fifth Edition
Jerome B. Posner, MD, Clifford B. Saper,
MD, PhD, Nicholas D. Schiff, MD,
and Jan Claassen, MD, PhD
95 CLINICAL NEUROPHYSIOLOGY
Fifth Edition
Devon I. Rubin, MD, Editor
96 PARKINSON DISEASE
Roger L. Albin, MD
97 NEUROLOGIC COMPLICATIONS
OF CRITICAL ILLNESS
Fourth Edition
Eelco F. M. Wijdicks, MD, PhD
NEUROLOGIC COMPLICATIONS
OF CRITICAL ILLNESS
Fourth Edition
Eelco F. M. Wijdicks, MD, PhD, FACP, FNCS
Professor of Neurology
Neurocritical Care Services
Department of Neurology, Mayo Clinic
Rochester, Minnesota
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Library of Congress Cataloging-in-Publication Data
Names: Wijdicks, Eelco F. M., 1954– author. |
Mayo Foundation for Medical Education and Research, sponsoring body.
Title: Neurologic complications of critical illness / Eelco F.M. Wijdicks.
Other titles: Contemporary neurology series.
Description: 4. | New York, NY : Oxford University Press, [2023] |
Series: Contemporary neurology series | Includes bibliographical references and index.
Identifiers: LCCN 2022040676 (print) | LCCN 2022040677 (ebook) |
ISBN 9780197585016 (hardback) | ISBN 9780197585030 (epub) |
ISBN 9780197585047 (online)
Subjects: MESH: Critical Illness | Neurologic Manifestations | Critical Care
Classification: LCC RC350 .N49 (print) | LCC RC350 .N49 (ebook) |
NLM W1 CO769N | DDC 616.8/0428—dc23/eng/20230315
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DOI: 10.1093/med/9780197585016.001.0001
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Contents
Preface xiii
PART I
CRITERIA, URGENCY, AND IMPORTANCE
1. INDICATIONS FOR A NEUROLOGIC CONSULT IN
THE INTENSIVE CARE UNIT 3
CATEGORIES OF CONSULTS 4
BENEFITS OF A CONSULTATION
6
2. CONSULTING IN THE INTENSIVE CARE UNIT 9
PREPARATION AND HISTORY-TAKING 9
COMMON REQUESTS FOR CONSULTS IN THE ICU 10
PART II GENERAL CLINICAL NEUROLOGIC PROBLEMS IN
THE INTENSIVE CARE UNIT
3. ACUTE CONFUSIONAL STATE IN THE INTENSIVE CARE UNIT 19
TERMINOLOGY 20
ASSESSMENT OF DELIRIUM 21
NEUROLOGIC EXAMINATION OF THE ACUTELY CONFUSED PATIENT
23
MANAGEMENT OF DELIRIUM 24
4. COMA AND OTHER STATES OF ALTERED AWARENESS IN THE
INTENSIVE CARE UNIT 27
DEFINITIONS OF ALTERED STATES OF CONSCIOUSNESS 27
NEUROLOGIC EXAMINATION OF THE COMATOSE PATIENT 32
CAUSES OF COMA 39
NEUROLOGIC EXAMINATION IN BRAIN DEATH
39
v
vi
Contents
5. NEUROLOGIC MANIFESTATIONS OF MUSCLE RELAXANTS AND
DRUGS USED FOR ANALGESIA AND ANESTHESIA IN THE
INTENSIVE CARE UNIT 47
PRINCIPLES OF PHARMACODYNAMICS AND PHARMACOKINETICS IN
CRITICAL ILLNESS 48
EFFECT OF DRUGS ON NEUROMUSCULAR JUNCTION 51
EFFECT OF DRUGS ON LEVEL OF CONSCIOUSNESS 55
6. SEIZURES IN THE INTENSIVE CARE UNIT 63
GENERALIZED TONIC–CLONIC SEIZURES 64
DRUG-INDUCED AND DRUG-WITHDRAWAL SEIZURES 64
SEIZURES AND ACUTE METABOLIC DERANGEMENTS 67
SEIZURES AND STRUCTURAL CENTRAL NERVOUS SYSTEM
ABNORMALITIES 68
CONVULSIVE STATUS EPILEPTICUS 68
NONCONVULSIVE STATUS EPILEPTICUS 72
MANAGEMENT OF SEIZURES AND STATUS EPILEPTICUS 73
OUTCOME 79
7. GENERALIZED WEAKNESS IN THE INTENSIVE CARE UNIT 85
GENERAL CONSIDERATIONS
86
DISORDERS OF THE SPINAL CORD
86
DISORDERS OF PERIPHERAL NERVES
88
DISORDERS OF THE NEUROMUSCULAR JUNCTION 92
DISORDERS OF SKELETAL MUSCLE 93
8. ACUTE FOCAL NEUROLOGIC FINDINGS AND ASYMMETRIES IN
THE INTENSIVE CARE UNIT 103
GENERAL CONSIDERATIONS IN LESION LOCALIZATION 103
BRAIN INJURY PATTERNS 108
9. ACUTE MOVEMENT ABNORMALITIES IN THE INTENSIVE CARE UNIT 111
SEMIOLOGY 112
EMERGENT AND URGENT MOVEMENT ABNORMALITIES 115
Contents
vii
PART III NEUROLOGIC COMPLICATIONS IN MEDICAL AND SURGICAL
INTENSIVE CARE UNITS AND TRANSPLANTATION UNITS
10. NEUROLOGIC COMPLICATIONS OF INVASIVE PROCEDURES IN
THE INTENSIVE CARE UNIT 123
NEUROTOXICITY OF RADIOLOGIC CONTRAST AGENTS 124
CHOLESTEROL EMBOLIZATION 124
AIR EMBOLISM 126
NEUROLOGIC COMPLICATIONS ASSOCIATED WITH SPECIFIC
PROCEDURES 127
11. NEUROLOGIC MANIFESTATIONS OF ACUTE BACTERIAL INFECTIONS
AND SEPSIS 147
BACTERIAL MENINGITIS 147
SPINAL EPIDURAL ABSCESS 151
INFECTIVE ENDOCARDITIS 154
CLOSTRIDIAL SYNDROMES 161
SEPSIS 164
12. NEUROLOGIC MANIFESTATIONS OF VIRAL OUTBREAKS 175
WEST NILE VIRUS NEUROINVASIVE DISEASE 176
TICK- AND MOSQUITO-BORNE ENCEPHALITIS 179
ENDEMIC INFLUENZA 180
SARS-COV-2 (COVID-19) PANDEMIC 183
13. NEUROLOGIC COMPLICATIONS OF CARDIAC ARREST 189
GENERAL CONSIDERATIONS IN RESUSCITATION MEDICINE 190
POSTRESUSCITATION ENCEPHALOPATHY
SUPPORTIVE CARE
193
203
SPECIFIC TREATMENT AND TARGETED TEMPERATURE MANAGEMENT 204
14. NEUROLOGIC MANIFESTATIONS OF ACID–BASE DERANGEMENTS,
ELECTROLYTE DISORDERS, AND ENDOCRINE CRISES 215
ACID–BASE DISORDERS
215
ELECTROLYTE DISORDERS 219
ENDOCRINE EMERGENCIES 232
viii
Contents
15. NEUROLOGIC COMPLICATIONS OF ACUTE RENAL DISEASE 249
UREMIC ENCEPHALOPATHY
249
DIALYSIS DYSEQUILIBRIUM SYNDROME 253
POSTERIOR REVERSIBLE ENCEPHALOPATHY SYNDROME 255
NEUROMUSCULAR DISORDERS 260
16. NEUROLOGIC MANIFESTATIONS OF ACUTE HEPATIC FAILURE
GENERAL CONSIDERATIONS
270
HEPATIC ENCEPHALOPATHY
270
269
BRAIN EDEMA IN FULMINANT HEPATIC FAILURE 275
17. NEUROLOGIC COMPLICATIONS ASSOCIATED WITH DISORDERS
OF THROMBOSIS AND HEMOSTASIS 289
GENERAL CONSIDERATIONS
289
DISSEMINATED INTRAVASCULAR COAGULATION
THROMBOLYSIS AND ANTICOAGULATION
290
291
NEOPLASTIC COAGULOPATHIES 295
THROMBOTIC THROMBOCYTOPENIC PURPURA 297
18. NEUROLOGIC COMPLICATIONS OF ACUTE VASCULITIS SYNDROMES 305
GENERAL CONSIDERATIONS
305
LARGE-VESSEL VASCULITIS 307
POLYARTERITIS NODOSA 308
CHURG-STRAUSS SYNDROME 312
GRANULOMATOSIS WITH POLYANGIITIS
313
DRUG-INDUCED VASCULITIS 315
19. NEUROLOGIC COMPLICATIONS IN THE CRITICALLY ILL
PREGNANT PATIENT 321
NEUROLOGY OF PREGNANCY
321
ECLAMPSIA 323
HELLP SYNDROME 326
AMNIOTIC FLUID EMBOLISM 328
NEUROLOGIC COMPLICATIONS OF TOCOLYTIC AGENTS 328
Contents
20. NEUROLOGIC COMPLICATIONS OF CANCER IN THE ICU 333
GOALS OF CARE IN CRITICAL ILLNESS AND ADVANCED CANCER 334
NEURO-ONCOLOGIC EMERGENCIES 334
PARANEOPLASTIC ENCEPHALITIS 336
COMPLICATIONS OF RADIATION AND CHEMOTHERAPY 338
COMPLICATIONS OF CANCER IMMUNOTHERAPY 340
21. NEUROLOGIC COMPLICATIONS OF AORTIC SURGERY
343
SCOPE OF THE PROBLEM 344
VASCULAR ANATOMY OF THE SPINAL CORD 346
NEUROLOGIC FEATURES OF SPINAL CORD INFARCTION 348
DIAGNOSTIC EVALUATION OF SPINAL CORD INFARCTION 350
THERAPEUTIC OPTIONS 353
PLEXOPATHIES 354
AORTIC DISSECTION 354
22. NEUROLOGIC COMPLICATIONS OF CARDIAC SURGERY
GENERAL CONSIDERATIONS
361
362
ISCHEMIC STROKE 366
NEUROPSYCHOLOGIC IMPAIRMENT 373
SEIZURES 374
RETINAL DAMAGE 374
PERIPHERAL NERVE DAMAGE 375
23. NEUROLOGIC COMPLICATIONS OF ACUTE ENVIRONMENTAL
INJURIES 385
THERMAL BURNS 385
SMOKE INHALATION 389
ELECTRICAL BURNS 392
LIGHTNING INJURY
393
ACCIDENTAL HYPOTHERMIA 395
HEAT STROKE 397
NEAR-DROWNING 399
ix
x
Contents
24. NEUROLOGIC COMPLICATIONS OF DRUG OVERDOSE, POISONING,
AND TERRORISM 407
THE PRESENTING EMERGENCY AND PRINCIPLES OF TREATMENT
408
SPECIFIC POISONINGS 410
BIOLOGICAL AND CHEMICAL WARFARE 419
25. NEUROLOGIC COMPLICATIONS OF TRAUMATIC BRAIN INJURY
429
CLINICAL SPECTRUM OF HEAD INJURY 430
NEURORADIOLOGIC FINDINGS IN HEAD INJURY 430
GENERAL PRINCIPLES OF MANAGEMENT 440
MANAGEMENT OF INCREASED INTRACRANIAL PRESSURE 442
MANAGEMENT OF TRAUMATIC INTRACRANIAL HEMATOMAS
444
WAR-RELATED BRAIN INJURY 446
MANAGEMENT OF TRAUMATIC CEREBRAL ANEURYSM
446
26. NEUROLOGIC COMPLICATIONS OF TRAUMA TO THE SPINE,
SPINAL CORD, AND NERVES 455
TRAUMA OF SPINE AND SPINAL CORD 455
ACUTE SPINAL CORD INJURY
464
POSTTRAUMATIC NEUROPATHIES ASSOCIATED WITH FRACTURES 467
FAT EMBOLISM SYNDROME 468
27. NEUROLOGIC COMPLICATIONS OF ORGAN TRANSPLANTATION
473
SURGICAL TECHNIQUES OF ORGAN TRANSPLANTATION 474
NEUROLOGIC COMPLICATIONS IN TRANSPLANT RECIPIENTS 479
NEUROLOGIC COMPLICATIONS OF GRAFT-VERSUS-HOST DISEASE 501
PART IV
OUTCOME IN CENTRAL NERVOUS SYSTEM CATASTROPHES
28. OUTCOME OF ACUTE INJURY TO THE CENTRAL NERVOUS SYSTEM 513
DESCRIPTION OF OUTCOME CATEGORIES
OUTCOME IN ENCEPHALOPATHIES 516
OUTCOME IN STROKE 522
OUTCOME IN HEAD INJURY
524
514
Contents
OUTCOME IN TRAUMATIC SPINE INJURY
525
OUTCOME IN CENTRAL NERVOUS SYSTEM INFECTIONS 525
PART V
CONSULTATIVE NEUROLOGY AND END-OF-LIFE CARE IN
THE INTENSIVE CARE UNIT
29. THE NEUROLOGIST AND END-OF-LIFE CARE IN THE INTENSIVE
CARE UNIT 533
GENERAL CONSIDERATIONS
534
LEGAL ASPECTS OF WITHDRAWAL OF TREATMENT 534
DECISIONS IN WITHDRAWAL OF TREATMENT
535
WITHDRAWAL OF TREATMENT 536
WITHDRAWAL OF TREATMENT IN SPECIAL NEUROLOGIC
CIRCUMSTANCES 537
BRAIN DEATH AND ORGAN DONATION 538
CARDIAC DEATH AND ORGAN DONATION 539
30. THE NEUROLOGIST AND ICU ETHICAL DILEMMAS 545
PRINCIPLES OF COMMUNICATION WITH FAMILIES 546
HOPE
547
FUTILITY 548
GUIDING A FAMILY CONFERENCE
548
THE ETHICS OF COMPASSIONATE SEDATION
THE COURTS 550
Index 553
550
xi
Preface
Writ large in this book is the premise that the evaluation of a critically ill patient with a neurologic
manifestation or complication is the most demanding neurology consultation. This book, when
first published in 1995, provided a practical guide for every disquieted neurologist who entered
the intensive care unit (ICU). Just about what, as a young neurologist, I would have liked to have
known. Keeping this book up to date requires multiple editions because intensive care is one of
the fastest growing and changing specialties. Now, more than 25 years later, we can look back at
the extraordinary expansion in knowledge of critical illness and better understanding of this field
of neurology. Intensivists understand the issues involved and appreciate that a neurologic complication in any medical or surgically critically ill patient is a major cause of mortality and later
morbidity. If recognized in time, treatment of a neurologic complication may greatly improve the
outcome. But neurocritical care in all its forms is also at times informed uncertainty, and many
clinical observations are not understood.
The framework of consults has also changed. New diseases have appeared, such as neurologic
complications of cancer immunotherapy, and older diseases, such as cyclosporine neurotoxicity
in transplant patients, have become rare occurrences. Neurotoxicities of drugs are better understood (e.g., serotonin syndrome and cefepime neurotoxicity). Recent mosquito- and tick-borne
illness (e.g., Zika virus, Chikungunya, and Eastern equine encephalitis) in the United States has
resulted in intensive care admissions. The world since 2019 has been shaken by the SARS-CoV-2
pandemic with its multiple surges and no ICU spared. The pandemic has been a revelation,
certainly since the end of 2021, when ICUs (and morale) were at a breaking point as a result of
treating an unacceptably large number of unvaccinated patients who became infected with the
delta variant. Neurologic complications of SARS-CoV-2 infection have emerged, and this damaging
respiratory virus became the most common reason to consult neurologists, who, like their colleagues
in other specialties, had the disadvantage of dealing with a new disease. It is a prime example of how
suddenly ICU populations can change and have changed again in 2023.
The new edition has responded to changes in ICU care and changes in the ICU population and
is now thoroughly updated. I have added criteria for consultation and how to co-manage patients.
A consultation is often contingent on the following five perceptions: (1) an evolving situation that
requires neurologic expertise; (2) “something” might not be recognized; (3) an unusual CT scan
that does not appear to explain the condition; (4) movements that could indicate seizures requiring
expert evaluation and electroencephalography (EEG); and (5) the patient’s condition looks grim
but needs corroboration, and the family may request a neurologic opinion. All this is addressed.
Neurologic consultations are often requested when patients remain comatose after CPR, and the
neurologist is asked to have the last word. Failure to awaken after surgery or after extended sedation has been discontinued are other typical examples that trigger a request. We have an obligation
to provide the best evaluation and management when the outcome can go either way. We also
have an obligation to evaluate for futility. Neurologic consultation not only provides diagnostic,
therapeutic, and prognostic advice but may also change the approach to the patient. This is a major
responsibility and not one to be taken lightly.
This edition also has new chapters on the interpretation of focal findings, acute movement
disorders in critical illness, cancer immunotherapy, and ethical dilemmas. A separate section
on interpretation of EEG requests (and how to use it in critically ill patients) is added. Several
new drugs (direct oral anticoagulants [DOACs] and chimeric antigen receptor T-cell therapy
[CAR-T]) have made their way into the ICU and are discussed in detail because their side effects
require specific intervention. There is a wealth of new tables, algorithms, and neuroimaging. I
have added a new section of advice for practical management to each chapter to reconcile theory
and practice.
xiii
xiv
Preface
ICUs are challenged with an increasingly growing (and aging) population, and admissions are
increasing. Neurologic complications will increase, too. This clinical text will be helpful to a very
wide audience of healthcare providers and, in particular, for any intensivist and general neurologist
who must manage these patients with extremely complex medical disorders, surgeries, comorbidity, and with different clinical trajectories. The book is also aimed at neurointensivists who consult
in ICUs other than their own. This book reaches beyond neurology and additionally targets emergency physicians, neurosurgeons, transplant and vascular surgeons, internal medicine hospitalists,
pharmacists, allied healthcare providers, and ICU nursing staff.
I appreciate the help of so many. Lea Dacy not only dutifully edited the full manuscript, but
she has always been absolutely necessary to improve the prose. I am grateful for the work by the
illustrators of Mayo Clinic Media Support service and, in particular, David Factor, who predictably
provided beautiful and informative drawings. I appreciate my long-time working relationship with
Oxford University Press, and they are peerless when it comes to academic work.
The interest in the acute neurosciences in practice is the unexpected. I have lived the subject
matter for several decades, and our neurocritical care group sees several hundred patients in ICUs
other than our own Neurosciences ICU each year. I hope the book I set out to write reflects that
experience. The diagnosis and management of neurologic complications in critical illness, in my view,
has always been one of the major pillars of neurocritical care.
March 2023
Eelco Wijdicks
PART I
Criteria, Urgency, and
Importance
Chapter 1
Indications for a Neurologic Consult
in the Intensive Care Unit
CATEGORIES OF CONSULTS
BENEFITS OF A CONSULTATION
Teams working in intensive care units (ICUs) may
bring in a neurologist and for all kinds of reasons.1
When called to action, most neurologists entering an ICU are immediately confronted with the
complexity of critical illness. The modern ICU is
a unique place, with patients presenting with an
array of different conditions and with consultants
having specific expertise in handling critical illness. Patients enter the ICU in a life-threatening
state with failing organ systems and become
hypotensive, hypoxemic, hypercapnic, and tachycardic; the initial resuscitation generally does not
concentrate on neurologic manifestations. Most
intensivists briefly check for pupil responses or
major asymmetries, but they accept an altered
level of consciousness as a common consequence
of an evolving critical illness. Some manifestations may not be considered atypical enough
for an urgent neurologic consult. This logically
implies that neurologists will see a selection of
neurologic manifestations in critical illness.
ICU consultative neurology focuses on those
patients admitted to medical and surgical ICUs
presenting with a de novo neurological problem related to their illness—questions . . . and
issues concerning the effects of antiseizure and
antiparkinson medication for prior diagnosed
illness are entirely different. These patients
are seen in consultation for diagnosis and
management—often expediently—but remain
under the care of intensivists and surgeons.
The complications observed may be quite specific (or mundane), but intensivists may intuitively feel uncomfortable in overseeing these
new neurologic conditions themselves. They
request not only assistance in identifying the
neurologic disorder but also help in management. This is particularly pertinent with recurrent seizures or progressive neurologic decline.
Once the patient is seen, continuous attention
is necessary, which may involve prolonged bedside care and, later, calls at night from nursing
staff or attending intensivists and, ultimately,
direct management. Interpretation of electroencephalograms and neuroimaging is often
repeatedly required.2
3
4
Part I Criteria, Urgency, and Importance
More than in any place in the hospital, ICU
consultations involve questions about de-escalating
care. The attending team and family may consider
withdrawing intensive care or, at least, consider
a do-not-resuscitate status and thus need a neurologist’s input. This involvement partly reflects
the high prevalence of neurologic catastrophes
in patients with a critical illness. Frequently, the
clinical situation is clear, as in persistently comatose survivors after prolonged cardiopulmonary
arrest and in elderly patients with polytrauma
and severe traumatic brain injury; in other situations, the degree of brain injury may be more
difficult to ascertain. Neurologists are asked
to participate in family conferences, and they
can be helpful in clarifying the bigger picture.
Sometimes, the neurologic complication is a
defining moment, and little more can be done for
the patient. Neurologists can be conclusive and
advise the managing ICU team against treating
a patient in a futile situation. In other situations
the neurologic situation could be misjudged as
irrecoverably poor while there is a possibility for
another more favorable trajectory. This is not an
uncommon scenario, and neurologists can shed
more light on why they think that way. Another
fundamental rule of ICU consultation is to prognosticate decisively when certain but to hold back
when information is incomplete or the clinical
situation is not fully understood.
Critical illness increases the probability of
a neurologic complication, and, according to
current best estimates and excluding pervasive delirious states, approximately 10–20% of
patients will develop some sort of neurologic
manifestation. The neurology of critical illness
is an important field that requires more prospective research. The rationale for neurologic
Table 1.1 The field of neurology of
critical illness
Neurologic consultation in the ICU requires a
broad base of medical knowledge
Neurologic consultation provides diagnostic,
therapeutic, and prognostic advice
Neurologic consultation often involves assessment
of abnormalities of responsiveness or seizures
Neurologic consultation may detect an unsuspected
neurologic disorder
Neurologic consultation in the ICU may change
approach to the patient
Neurologic consultation involves end-of-life
decisions for patients
consultation is summarized in Table 1.1 and
shows common clinical neurologic problems
facing the intensive care specialist and consulting neurologist in everyday decisions.
CATEGORIES OF CONSULTS
We must assume that ICU consults are urgent
or emergent. The urgency is often determined
by an inability to understand the full clinical picture and particularly when the initial presentation is disturbing. Examples are ICU consults for
acutely impaired consciousness, which require
a quick but comprehensive assessment of the
cause of coma and whether it can be immediately
reversed. Upon receiving a call to consult in the
ICU, we typically expect three clinical scenarios:
acute loss of consciousness, failure of patients
to awaken fully after recuperation from a major
surgical procedure, and occasionally, coma in a
developing but undiagnosed critical illness. We
are often consulted to evaluate and treat delirium,
and we now have a better sense of what this acute
brain dysfunction could entail.3–6
Any consult in a critically ill neurologic
patient must proceed through the steps outlined in Table 1.2. Any consult in a critically
ill patient may lead to a diagnosis not initially
considered by the managing team; in our experience, this occurs rather frequently.7 These
recognized neurologic disorders may all have
major consequences diagnostically, prognostically, and therapeutically.
Consultations may have a varying degree of
complexity and may involve management of
major acute neurologic injury. Consultation
may evolve from a simple question, to being
physically present, to continuously managing
Table 1.2 Essentials of a neurology
consult in the intensive care unit
Assess details on severity of critical illness
Assess blood pressure and extent of blood pressure
support
Assess drug administration over 5–7 days
Verify onset of symptoms with nursing staff
Assess major confounders
Assess for focal localizing sign
Assess for movements, twitching, new rigidity
Assess for drugs strongly related to movement
disorders
1
Table 1.3 Reasons for a consult in the
intensive care unit
Acutely comatose
Failure to awaken after resuscitation
Acute focal deficit
Acute agitation
New seizure(s)
Acute repetitive movements
Generalized weakness
Abnormal neuroimaging
Abnormal EEG
an acute injury to the brain or spine and, as
such, may even involve palliation and end-oflife discussions (Table 1.3).
There is a spectrum of close participation
with the consulting neurologist (Figure 1.1).
In some cases, a consult consists of picking up
the phone and asking an expert, and in many
Figure 1.1. Types of consultations.
Indications for a Neurologic Consult
5
intensive care practices, it is often easier to call
a consultant rather than to ask for a formal consult. Both parties often agree that some type of
advice will pragmatically direct testing or treatment. For the intensivist, there may be other
immediately pressing priorities in the complex
care of the patient, and a new neurologic problem is best solved quickly. Many of the neurology
“curbsides” in the ICU are indeed simple phone
calls to ask a simple question, but some questions should probably generate a formal consult.
Consultants should generally and deliberately
avoid a practice of mostly taking phone calls for
curbsides, which are a set of quick questions that
pertain to critical illness. These include interpretation of a CT scan of the brain, a question about
electroencephalograph (EEG) interpretation, or
the need for EEG monitoring. Other common
questions are how to manage neurologic medication such as antiepileptic drugs, assess the risk
of anticoagulation, or interpret specific neurologic manifestations of acute neurologic disease.
It is often better to see the patient briefly and
then determine if a formal consult can be helpful.
The consulting neurologists will also have
to consider the following questions. How can
I best ask pointed questions? Am I able to
provide advice with limited information and
without having the opportunity to examine
the patient in detail? Am I confident enough
to dismiss or diagnose certain CT scan abnormalities? Does this clinical problem require a
close follow-up and thus a formal consultation?
Acute (STAT) consults in the ICU are the
most challenging in the hospital because (1)
decisions may have to be made in an evolving
situation; (2) the primary diagnosis may be
unclear and puzzling; (3) neurologic examination can be compromised when patients
are markedly swollen, jaundiced, immobile,
bruised, or have major operation sites or an
open chest; and (4) none of the neuroimaging
and electrophysiology results may be particularly helpful. Any consulting neurologist will
ask him- or herself the following additional
questions: Are the neurologic findings commensurate with the cause and degree of critical illness? Are the focal findings significant
or difficult to judge? How is neuroimaging or
electrophysiology best interpreted in the setting of critical illness?2,8–10 Are there urgent
treatment options or treatment adjustments
that have not been considered? Will this neurologic manifestation set the patient back
6
Part I Criteria, Urgency, and Importance
permanently? Can I provide a reliable opinion on the future likelihood of full dependence for the patient, and could this opinion
put an end to the aggressive, constantly escalating care?
BENEFITS OF A CONSULTATION
The need for broad knowledge of critical care
could argue for a separate hospital service
staffed by experienced neurohospitalists or
neurointensivists. It goes to the heart of a longstanding academic and clinical question (and,
in some centers, a charged debate): Who is
best qualified to see these patients? Many of
us are caught unaware by a variety of presentations, and as long as experience is gained, it is
better gained by a specialized group. We have
seen several conditions emerge more clearly
as a result of covering all ICU consults with
our neurocritical care services in both Mayoaffiliated hospitals.
Telemedicine could be ideal for these consults,11–16 but accurate metrics will need to be
developed to show benefit. These could include
(1) seizure control, (2) acute stroke care, (3)
neurosurgical intervention, (4) control of intracranial pressure, and (5) limiting potent sedative drugs and avoiding drug-drug interactions.
Ultimately, a full neurologic examination
leads to new tests (EEG, somatosensory evoked
potential [SSEP], CT scan, MRI, and CSF). All
these tests are highly neurospecific, and recommendations of what to test or add to routine
orders require good communication and, most
importantly, accurate interpretation.
PRACTICAL ADVICE
• A major principle of consultation in the
ICU is to see the patient immediately rather
than paying a belated visit. A serious neurologic illness requiring immediate intervention might go unrecognized. Moreover, the
entire clinical picture may be unclear and
evolving, and neurologic expertise may point
toward the right direction.
• Treatments may be inappropriate, incomplete, and incorrect. Errors happen easily
even in the best-equipped, well-staffed ICUs.
• Neurologists should appreciate the pharmacology of sedative drugs and use of analgesic
drugs to provide a better assessment.
• Direct communication with the intensivist
might provide a comprehensive clinical course
and timeline of when events occurred.
• Direct communication with the surgeon on
the surgical procedure and possible intraoperative events can decrease evaluation time
and capture important intraoperative complications such as hypotension or even CPR.
• The circumstances surrounding critical illness could make the patient vulnerable to
seizures. However, few patients in the ICU
have seizures; many more undergo EEGs.
Proportionality is necessary.
• A universal question is whether failure to
wean from a ventilator is due to a previously
unappreciated and undiagnosed neurologic
disorder. Early diffuse weakness in ICU may
be undiagnosed amyotrophic lateral sclerosis. Late diffuse weakness in ICU is often
sepsis-related or critical illness–associated
polyneuromyopathy.
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