Plum and posner’s diagnosis of stupor and coma fourth Edition series editor sid Gilman, md, frcp
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Acute Toxic Encephalopathy During Viral Encephalitis
Parainfectious Encephalitis (Acute Disseminated Encephalomyelitis)
Cerebral Biopsy for Diagnosis of Encephalitis xii
Contents CEREBRAL VASCULITIS AND OTHER VASCULOPATHIES 273 Granulomatous Central Nervous System Angiitis
Systemic Lupus Erythematosus
Subacute Diencephalic Angioencephalopathy Varicella-Zoster Vasculitis
Behc¸et’s Syndrome Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy MISCELLANEOUS NEURONAL AND GLIAL DISORDERS 276 Prion Diseases
Adrenoleukodystrophy (Schilder’s Disease) Marchiafava-Bignami Disease
Progressive Multifocal Leukoencephalopathy
Epilepsy
Mixed Metabolic Encephalopathy ACUTE DELIRIOUS STATES 282 Drug Withdrawal Delirium (Delirium Tremens)
Postoperative Delirium Intensive Care Unit Delirium
Drug-Induced Delirium 6. PSYCHOGENIC UNRESPONSIVENESS 297 CONVERSION REACTIONS 299 CATATONIA 302 PSYCHOGENIC SEIZURES 304 CEREBELLAR COGNITIVE AFFECTIVE SYNDROME 306 ‘‘AMYTAL INTERVIEW’’ 307 7. APPROACH TO MANAGEMENT OF THE UNCONSCIOUS PATIENT 309 A CLINICAL REGIMEN FOR DIAGNOSIS AND MANAGEMENT 309 PRINCIPLES OF EMERGENCY MANAGEMENT 311 Ensure Oxygenation, Airway, and Ventilation
Maintain the Circulation Measure
the Glucose
Lower the Intracranial Pressure Stop Seizures
Treat Infection Restore
Acid-Base Balance
Adjust Body Temperature Administer Specific Antidotes
Control
Agitation
Protect the Eyes EXAMINATION OF THE PATIENT 317 Verbal Responses
Respiratory Pattern Eye Opening
Pupillary Reactions
Spontaneous Eye Movement Oculocephalic Responses
Caloric
Vestibulo-Ocular Responses
Corneal Responses Motor Responses
Tendon
Reflexes
Skeletal Muscle Tone GUIDES TO SPECIFIC MANAGEMENT 320 Supratentorial Mass Lesions
Infratentorial Mass Lesions Metabolic Encephalopathy
Psychogenic Unresponsiveness A FINAL WORD 327 8. BRAIN DEATH 331 DETERMINATION OF BRAIN DEATH 331 CLINICAL SIGNS OF BRAIN DEATH 333 Brainstem Function
Confirmatory Laboratory Tests and Diagnosis Diagnosis of Brain Death in Profound Anesthesia or Coma of Undetermined Etiology
Pitfalls in the Diagnosis of Brain Death Contents
xiii 9. PROGNOSIS IN COMA AND RELATED DISORDERS OF CONSCIOUSNESS, MECHANISMS UNDERLYING OUTCOMES, AND ETHICAL CONSIDERATIONS 341 INTRODUCTION 342 PROGNOSIS IN COMA 343 PROGNOSIS BY DISEASE STATE 344 Traumatic Brain Injury
Nontraumatic Coma Vascular Disease
Central Nervous System Infection
Acute Disseminated Encephalomyelitis Hepatic Coma
Depressant Drug Poisoning VEGETATIVE STATE 357 Clinical, Imaging, and Electrodiagnostic Correlates of Prognosis in the Vegetative State MINIMALLY CONSCIOUS STATE 360 Late Recoveries From the Minimally Conscious State LOCKED-IN STATE 363 MECHANISMS UNDERLYING OUTCOMES OF SEVERE BRAIN INJURY: NEUROIMAGING STUDIES AND CONCEPTUAL FRAMEWORKS 364 FUNCTIONAL IMAGING OF VEGETATIVE STATE AND MINIMALLY CONSCIOUS STATE 365 Atypical Behavioral Features in the Persistent Vegetative State
Neuroimaging of Isolated Cortical Responses in Persistent Vegetative State Patients POTENTIAL MECHANISMS UNDERLYING RESIDUAL FUNCTIONAL CAPACITY IN SEVERELY DISABLED PATIENTS 372 Variations of Structural Substrates Underlying Severe Disability
The Potential Role of the Metabolic ‘‘Baseline’’ in Recovery of Cognitive Function
The Potential Role of Regionally Selective Injuries Producing Widespread Effects on Brain Function ETHICS OF CLINICAL DECISION MAKING AND COMMUNICATION WITH SURROGATES (J.J. FINS) 376 Surrogate Decision Making, Perceptions, and Needs
Professional Obligations and Diagnostic Discernment
Time-Delimited Prognostication and Evolving Brain States: Framing the Conversation
Family Dynamics and Philosophic Considerations INDEX 387 xiv
Contents PLUM AND POSNER’S DIAGNOSIS OF STUPOR AND COMA Fourth Edition
Chapter 1 Pathophysiology of Signs and Symptoms of Coma ALTERED STATES OF CONSCIOUSNESS DEFINITIONS Consciousness Acutely Altered States of Consciousness Subacute or Chronic Alterations of Consciousness APPROACH TO THE DIAGNOSIS OF THE COMATOSE PATIENT PHYSIOLOGY AND PATHOPHYSIOLOGY OF CONSCIOUSNESS AND COMA The Ascending Arousal System Behavioral State Switching Relationship of Coma to Sleep The Cerebral Hemispheres and Conscious Behavior
Structural Lesions That Cause Altered Consciousness in Humans ALTERED STATES OF CONSCIOUSNESS And men should know that from nothing else but from the brain came joys, delights, laughter and jests, and sorrows, griefs, despondency and lamen- tations. And by this, in an especial manner, we ac- quire wisdom and knowledge, and see and hear and know what are foul, and what are fair, what sweet and what unsavory . . . —The Hippocratic Writings Impaired consciousness is among the most diffi- cult and dramatic of clinical problems. The an- cient Greeks knew that normal consciousness depends on an intact brain, and that impaired consciousness signifies brain failure. The brain tolerates only limited physical or metabolic in- jury, so that impaired consciousness is often a sign of impending irreparable damage to the brain. Stupor and coma imply advanced brain failure, just as, for example, uremia means renal failure, and the longer such brain failure lasts, 3
the narrower the margin between recovery and the development of permanent neurologic in- jury. The limited time for action and the mul- tiplicity of potential causes of brain failure challenge the physician and frighten both the physician and the family; only the patient es- capes anxiety. Many conditions cause coma. Table 1–1 lists some of the common and often perplexing causes of unconsciousness that the physician may encounter in the emergency department of a general hospital. The purpose of this mono- graph is to describe a systematic approach to the diagnosis of the patient with reduced con- sciousness, stupor, or coma based on anatomic and physiologic principles. Accordingly, this book divides the causes of unconsciousness into two major categories: structural and meta- bolic. Chapter 1 provides background informa- tion on the pathophysiology of impaired con- sciousness, as well as the signs and symptoms that accompany it. In Chapter 2 this infor- mation is used to define a brief but informa- tive neurologic examination that is necessary to Table 1–1 Cause of Stupor or Coma in 500 Patients Initially Diagnosed as ‘‘Coma of Unknown Etiology’’* Subtotals I. Supratentorial lesions 101 A. Rhinencephalic and subcortical destructive lesions 2 1. Thalamic infarcts 2 B. Supratentorial mass lesions 99 1. Hemorrhage 76 a. Intracerebral 44 (1) Hypertensive 36 (2) Vascular anomaly 5 (3) Other 3 b. Epidural 4 c. Subdural 26 d. Pituitary apoplexy 2 2. Infarction 9 a. Arterial occlusions 7 (1) Thrombotic 5 (2) Embolic 2 b. Venous occlusions 2 3. Tumors 7 a. Primary 2 b. Metastatic 5 4. Abscess 6 a. Intracerebral 5 b. Subdural 1 5. Closed head injury 1 II. Subtentorial lesions 65 A. Compressive lesions 12 1. Cerebellar hemorrhage 5 2. Posterior fossa subdural or extradural hemorrhage 1 3. Cerebellar infarct 2 4. Cerebellar tumor 3 5. Cerebellar abscess 1 6. Basilar aneurysm 0 Subtotals B. Destructive or ischemic lesions 53 1. Pontine hemorrhage 11 2. Brainstem infarct 40 3. Basilar migraine 1 4. Brainstem demyelination 1 III. Diffuse and/or metabolic brain dysfunction 326
A. Diffuse intrinsic disorders of brain 38 1. ‘‘Encephalitis’’ or encephalomyelitis 14 2. Subarachnoid hemorrhage 13 3. Concussion, nonconvulsive seizures, and postictal states 9 4. Primary neuronal disorders 2 B. Extrinsic and metabolic disorders 288
1. Anoxia or ischemia 10 2. Hypoglycemia 16 3. Nutritional 1 4. Hepatic encephalopathy 17 5. Uremia and dialysis 8 6. Pulmonary disease 3 7. Endocrine disorders (including diabetes) 12 8. Remote effects of cancer 0 9. Drug poisons 149 10. Ionic and acid-base disorders 12 11. Temperature regulation 9 12. Mixed or nonspecific metabolic coma 1 IV. Psychiatric ‘‘coma’’ 8 A. Conversion reactions 4 B. Depression 2 C. Catatonic stupor 2 *Represents only patients for whom a neurologist was consulted because the initial diagnosis was uncertain and in whom a final diagnosis was established. Thus, obvious diagnoses such as known poisonings, meningitis, and closed head injuries, and cases of mixed metabolic encephalopathies in which a specific etiologic diagnosis was never established are under- represented. 4 Plum and Posner’s Diagnosis of Stupor and Coma determine if the reduced consciousness has a structural cause (and therefore may require im- mediate imaging and perhaps surgical treat- ment) or a metabolic cause (in which case the diagnostic approach can be more lengthy and extensive). Chapters 3 and 4 discuss patho- physiology and specific causes of structural in- jury to the brain that result in defects of con- sciousness. Chapter 5 examines the broad range of metabolic causes of unconsciousness, and the specific treatments they require. Chapter 6 explores psychiatric causes of unresponsive- ness, which must be differentiated from or- ganic causes of stupor and coma. Chapter 7 provides a systematic discussion of the treat- ment of both structural and metabolic coma. Chapter 8 explores the outcomes of coma of different causes, including the prognosis for useful recovery and the states of long-term im- pairment of consciousness. Chapter 9 reviews some ethical problems encountered in treating unconscious individuals. DEFINITIONS Consciousness Consciousness is the state of full awareness of the self and one’s relationship to the environ- ment. Clinically, the level of consciousness of a patient is defined operationally at the bedside by the responses of the patient to the examiner. It is clear from this definition that it is possi- ble for a patient to be conscious yet not respon- sive to the examiner, for example, if the patient lacks sensory inputs, is paralyzed (see locked- in syndrome, page 7), or for psychologic reasons decides not to respond. Thus, the determina- tion of the state of consciousness can be a technically challenging exercise. In the defini- tions that follow, we assume that the patient is not unresponsive due to sensory or motor im- pairment or psychiatric disease. Consciousness has two major components: content and arousal. The content of conscious- ness represents the sum of all functions medi- ated at a cerebral cortical level, including both cognitive and affective responses. These func- tions are subserved by unique networks of cor- tical neurons, and it is possible for a lesion that is strategically placed to disrupt one of the net- works, causing a fractional loss of conscious- ness.
1 Such patients may have preserved aware- ness of most stimuli, but having suffered the loss of a critical population of neurons (e.g., for recognizing language symbol content, differ- ences between colors or faces, or the presence of the left side of space), the patient literally becomes unconscious of that class of stimuli. Patients with these deficits are often charac- terized as ‘‘confused’’ by inexperienced exam- iners, because they do not respond as expected to behavioral stimuli. More experienced clini- cians recognize the focal cognitive deficits and that the alteration of consciousness is confined to one class of stimuli. Occasionally, patients with right parietotemporal lesions may be sufficiently inattentive as to appear to be globally confused, but they are not sleepy and are, in fact, usually agitated. 2 Thus, unless the damage to cortical net- works is diffuse or very widespread, the level of consciousness is not reduced. For example, pa- tients with advanced Alzheimer’s disease may lose memory and other cognitive functions, but remain awake and alert until the damage is so extensive and severe that response to stimuli is reduced as well (see vegetative state, page 8). Hence, a reduced level of consciousness is not due to focal impairments of cognitive function, but rather to a global reduction in the level of behavioral responsiveness. In addition to being caused by widespread cortical impairment, a reduced level of consciousness can result from injury to a specific set of brainstem and di- encephalic pathways that regulate the overall level of cortical function, and hence conscious- ness (Figure 1–1). The normal activity of this arousal system is linked behaviorally to the appearance of wakefulness. It should be appar- ent that cognition is not possible without a rea- sonable degree of arousal. Sleep is a recurrent, physiologic, but not path- ologic, form of reduced consciousness in which the responsiveness of brain systems responsible for cognitive function is globally reduced, so that the brain does not respond readily to environ- mental stimuli. Pathologic alteration of the re- lationships between the brain systems that are responsible for wakefulness and sleep can im- pair consciousness. The systems subserving nor- mal sleep and wakefulness are reviewed later in this chapter. A key difference between sleep and coma is that sleep is intrinsically reversible: sufficient stimulation will return the individual to a normal waking state. In contrast, if patients Pathophysiology of Signs and Symptoms of Coma 5
with pathologic alterations of consciousness can be awakened at all, they rapidly fall back into a sleep-like state when stimulation ceases. Patients who have a sleep-like appearance and remain behaviorally unresponsive to all external stimuli are unconscious by any defini- tion. However, continuous sleep-like coma as a result of brain injury rarely lasts more than 2 to 4 weeks. Acutely Altered States of Consciousness Clouding of consciousness is a term applied to minimally reduced wakefulness or awareness, which may include hyperexcitability and irrit- ability alternating with drowsiness. A key dis- tinction must be made in such patients between those who are confused (i.e., do not respond ap- propriately to their environment) because of a focal deficit of cognitive function versus those who have more global impairment. The beclou- ded patient is usually incompletely oriented to time and sometimes to place. Such patients are inattentive and perform poorly on repeating numbers backward (the normal range is at least four or five) and remembering details or even the meaning of stories. Drowsiness is often pro- minent during the day, but agitation may pre- dominate at night. The pathophysiology of brain function in such patients has rarely been studied, but Posner and Plum 3
had declined by 20% below normal levels in patients with hepatic encephalopathy with leth- argy and global confusion, and Shimojyo and colleagues noted similar reductions in patients with lethargy and global confusion due to Wer- nicke’s encephalopathy. 4 More recently, Trze- pacz and colleagues have identified decreased regional cerebral blood flow (CBF) bilaterally in the frontotemporal cortex and right basal gan- glia of patients with subclinical hepatic ence- phalopathy. 5 Increases in CBF during treatment of cobalamin deficiency correlate with clinical improvement. 6 Other studies have implicated reduced cholinergic function; excess release of dopamine, norepinephrine, and glutamate; and both decreased and increased serotonergic and gamma-aminobutyric acid (GABA) activity. 7 The pathogenesis of clouding of consciousness and delirium is discussed in more detail in Chapter 5. Delirium, from the Latin ‘‘to go out of the furrow,’’ is a more floridly abnormal mental state characterized by misperception of sensory stimuli and, often, vivid hallucinations. Deli- rium is defined by the Diagnostic and Statisti- cal Manual of Mental Disorders, 4th edition (DSM-IV), 8 as follows: ‘‘A. Disturbance of con- sciousness (i.e., reduced clarity of awareness of the environment) with reduced ability to focus, sustain or shift attention. B. A change in cog- nition (such as memory deficit, disorientation, language disturbance) or the development of a perceptual disturbance that is not better ac- counted for by a pre-existing, established or evolving dementia. C. The disturbance devel- ops over a short period of time (usually hours to days) and tends to fluctuate during the course of the day.’’ Delirious patients are disoriented, first to time, next to place, and then to persons in their environment. Rarely are patients unaware of who they are, although sometimes married women will revert to their maiden name. Pa- tients are often fearful or irritable and may overreact or misinterpret normal activities of physicians and nurses. Delusions or hallucina- tions may place the patient completely out of contact with the environment and the exam- iner. Full-blown delirious states tend to come on rapidly and rarely last more than 4 to 7 days. However, fragments of misperceptions may persist for several weeks, especially among al- coholics and patients with cerebral involvement from collagen vascular diseases. Delirium with agitation occasionally may be seen as a consequence of focal lesions of the right parieto-occipitotemporal cortex, 2,9 but
generally is indicative of bilateral impairment of cortical function in toxic-metabolic states, such as atropine poisoning, alcohol or seda- tive drug (e.g., benzodiazepine) withdrawal, acute porphyria, or hepatic or renal failure. It also occurs with systemic infectious processes or as a component of encephalitis, during which immune mediators such as cytokines and eicosanoid derivatives may cloud mental function. Obtundation, from the Latin ‘‘to beat against or blunt,’’ literally means mental blunting or torpidity. In a medical setting, such patients have a mild to moderate reduction in alertness, ac- companied by a lesser interest in the environ- ment. Such patients have slower psychologic responses to stimulation. They may have an 6 Plum and Posner’s Diagnosis of Stupor and Coma increased number of hours of sleep and may be drowsy between sleep bouts. Stupor, from the Latin ‘‘to be stunned,’’ is a condition of deep sleep or similar behavioral unresponsiveness from which the subject can be aroused only with vigorous and continuous stimulation. Even when maximally aroused, the level of cognitive function may be impaired. Such patients can be differentiated from those with psychiatric impairment, such as catato- Yüklə 9,02 Mb. Dostları ilə paylaş:
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