Neurology_Adams

Neurology_Adams. The many mental and behavioral aberrations that are seen in confused patients, and their occurrence in various combinations and clinical contexts, make it unlikely that all forms of confusion derive from a single elementary mental or neurobiological abnormality. While attention is certainly near the core of confusion, and is considered the germinal feature by some investigators, phenomena as diverse as drowsiness and stupor, hallucinations and delusions, disorders of perception and registration, impersistence and perseveration, and so forth are not easily reduced to one mechanism. It seems more likely that a number of separable or overlapping disorders of function are involved. Indeed, one view of the confusional state that we find attractive conceptualizes confusion as a loss of the integrative functions among all the elementary and localizable cerebral functions such as symbolic language, memory retrieval, and apperception (the interpretation of primary perceptions). All of these


Neurology_Adams

Neurology_Adams. functions among all the elementary and localizable cerebral functions such as symbolic language, memory retrieval, and apperception (the interpretation of primary perceptions). All of these are included under the rubric of the confusional state, for want of a better term.


Neurology_Adams

Neurology_Adams. As commented, we prefer to use the term delirium to denote a highly recognizable agitated and hypersympathetic form of confusion. In addition to many of the negative elements of incoherent thinking mentioned above, delirium defined this way is characterized by a prominent disorder of perception; hallucinations and vivid dreams; a kaleidoscopic array of strange and absurd fantasies and delusions; inability to sleep; a tendency to twitch, tremble, and convulse; and intense fear or other emotional reactions. Delirium is distinguished not only by extreme inattentiveness but also by a state of heightened alertness—an increased readiness to respond to stimuli—and by overactivity of psychomotor and autonomic nervous system functions, sometimes striking in degree. Implicit in the term delirium are its nonmedical connotations as well—namely, intense agitation, or frenzied excitement, and trembling. This distinction between delirium and other acute confusional states is not universally


Neurology_Adams

Neurology_Adams. are its nonmedical connotations as well—namely, intense agitation, or frenzied excitement, and trembling. This distinction between delirium and other acute confusional states is not universally accepted. Many authors attach no particular significance to the autonomic and psychomotor overactivity and the hallucinatory and dream-like features of delirium, or to the underactivity and somnolence that characterize most other confusional states. We continue to find it useful to set delirium apart from other nondescript confusional states, if only for instructional purposes, because the two are manifestly different and occur in different clinical contexts. Engel and Romano called delirium “a state of cerebral insufficiency” and provided one of the fullest clinical descriptions of the syndrome and the monograph by Lipowski may be consulted. Implicit in both designations is the idea of an acute, transient, and usually relatively reversible disorder.


Neurology_Adams

Neurology_Adams. Impairment of memory is often included among the symptoms of delirium and other confusional states. Registration and recall are indeed greatly reduced in the states under discussion, but they are affected in proportion to the degree of inattention and the inability to register new material. The term amnesia, refers more precisely to an isolated loss of past memories as well as to an inability to form new ones, despite an alert state of mind and normal attentiveness. Amnesia further presupposes an ability of the patient to grasp the meaning of what is going on around him. The failure in the amnesic state is one of retention, recall, and reproduction and must be distinguished from states of drowsiness, acute confusion, and delirium, in which information and events seem never to have been adequately perceived and registered in the first place. In both a confusional state and in amnesia, the patient is left with a permanent gap in memory for his acute illness.


Neurology_Adams

Neurology_Adams. In a similar way, the term dementia (literally, an undoing of the mind) denotes a deterioration of all intellectual or cognitive functions with little or no disturbance of consciousness or perception. Implied in dementia is the idea of a gradual degradation of mental powers in a person who formerly possessed a normal mind. Amentia, by contrast, indicates a congenital feeblemindedness more commonly referred to as mental retardation, or more properly, developmental cognitive delay. Dementia and amnesia are discussed more explicitly in Chap. 20.


Neurology_Adams

Neurology_Adams. The intellectual, emotional, and behavioral activities of the human organism are so complex and varied that one may question the feasibility of analyzing these activities as reliable indicators of cerebral disease. Certainly they do not have the same tangibility and ease of anatomic and physiologic interpretation as sensory and motor paralysis or aphasia. Yet one observes certain patterns of disturbed higher cerebral function with such regularity as to make them clinically useful in identifying a number of diseases. Some of these disturbances gain specificity because they are combined in ways that form clinical syndromes.


Neurology_Adams

Neurology_Adams. The components of mentation and behavior that lend themselves to observation and examination are (1) attention; (2) perception and apperception (awareness and interpretation of sensory stimuli); (3) the capacity to form new memories and to recall events of the recent and distant past; (4) the ability to think and reason; (5) temperament, mood, and affect; (6) initiative, impulse, and drive; (7) social behavior; and (8) insight. Of these, the first two are sensory, the third and fourth are cognitive, the fifth is affective, the sixth is conative or volitional, the seventh refers to the patient’s relationships with those around him, and the last refers to the patient’s capacity to assess his own functioning. Each component of behavior and intellect has its objective side, expressed in the behavioral responses produced by certain stimuli, and its subjective side, expressed in the thinking and feeling described by the patient. Less accessible to the examiner, but nevertheless possible to


Neurology_Adams

Neurology_Adams. responses produced by certain stimuli, and its subjective side, expressed in the thinking and feeling described by the patient. Less accessible to the examiner, but nevertheless possible to study by questioning the patient, are the memory, planning, and other activities that continuously occupy the mind of an alert person. They, too, are disordered or quantitatively diminished by cerebral disease.


Neurology_Adams

Neurology_Adams. Disturbances of Attention Critical to clear thinking is a process of maintaining awareness of one or a limited number of external stimuli or internal thoughts for a fixed period of time and to simultaneously disregard the numerous distracting sensations and ideas that constantly bombard the nervous system. Without this ability to focus or “pay attention” and have an “attention span,” a coherent stream of thought or action is not possible. The undue interruption of these activities by the intrusion of other thoughts or actions is termed inattention, or distractibility. Two essential components are embodied in the attention mechanism: one, a continuous state of alertness that is normally present throughout waking life (and underlies self-awareness); the other, a process of selecting from the myriad sensations and thoughts those that are relevant to the immediate situation to the exclusion of others.


Neurology_Adams

Neurology_Adams. The confused patient may demonstrate inattention in almost every task undertaken. If the degree of confusion is slight, the patient may report a difficulty with concentration. If severe, there is a parallel lack of insight and the problem is evident by easy distractibility by ambient stimuli and by impersistence and perseveration in conversation and motor tasks. Restated, attention has such a pervasive effect on all other aspects of mental performance that it is often difficult to determine whether the confused patient also has primary disorders of memory, executive, or visuospatial function. Indeed, retentive memory may be severely reduced in confusional states. Furthermore, the ability to carry out a series of actions or mental operations wherein one is required to hold in memory the result of the previous operation (“working memory”) is intimately tied to attention and is particularly prone to disruption in confusional states.


Neurology_Adams

Neurology_Adams. The general ability to persist in a motor or mental task emphasizes an executive side of attention, but here one encounters a problem because the term attention has been applied to a number of seemingly different mental activities. One can view attention as a separate and unique cerebral function or simply a way of referring to the persistence or impersistence of any activity. We would argue that the entire cerebrum participates in attentiveness and the frontal and perhaps the parietal lobes are responsible for directing its content, but that the thalamocortical system is in a special way responsible for its raw maintenance. Mesulam, who has written substantially about this problem, considers the frontal and parietal lobes to be at the nexus of an “attentional matrix”; in his model, the prefrontal, parietal association, and limbic cortices direct and modulate attention in an executive manner. Certainly, the temporal lobes and other regions are involved as well.


Neurology_Adams

Neurology_Adams. Attention to a particular sensory modality requires the participation of the sensory cortex, which must simultaneously initiate the perceptive and apperceptive processes discussed later. What are called “modality” and “domain-specific” attentions (e.g., face or object recognition) are more complex, and disorders of these functions result in unique types of inattention, such as agnosia and anosognosia (lack of recognition of a part of the body, as discussed in Chap. 21). These are not derived from the all-encompassing loss of attention that is part of general confusional states but can instead be viewed as a restricted forms of disruption of insight for which reason they are not major components of the global confusional state. Disturbances of Perception


Neurology_Adams

Neurology_Adams. Disturbances of Perception The process of acquiring through the senses a knowledge of the world or, of one’s self by cohering what is sensed into giving meaning to what is experienced, which we have termed apperception, involves much more than being aware of the attributes of a stimulus. New visual stimuli, for example, activate the striate cortex and visual association areas, wherein are probably stored the coded past representations of these and similar classes of stimuli. Recognition involves the reactivation of this system by the same or similar stimuli at a later time. Essential elements in the perceptual process are the maintenance of attention, the selective focusing on a stimulus, elimination of all extraneous stimuli, and identification and naming of the stimulus by recognizing its relationship to remembered experience.


Neurology_Adams

Neurology_Adams. The perception of stimuli undergoes predictable disruption in disease. Most often there is a reduction in the number of perceptions in a given unit of time and a failure to synthesize them properly and to relate them to the ongoing activities of the mind. Part of this, as stated above, is due to distractibility (pertinent and irrelevant stimuli having equal value), and inability to persist in an assigned task. Together, these deficiencies lead to disorientation in time and place.


Neurology_Adams

Neurology_Adams. Qualitative changes of perception also appear, mainly in the form of sensory distortions, causing misinterpretations of environmental stimuli (illusions) and misidentifications of persons; these, at least in part, form the basis of hallucinatory experience in which the patient reports and reacts to environmental stimuli that are not evident to the examiner. There is an inability to perceive simultaneously all elements of a large complex of stimuli, a defect that has been termed “failure of subjective organization.” More specific partial losses of perception are manifest in the “neglect syndromes.” The most dramatic examples are observed with right parietal lesions, which render a patient unaware of the left half of his body and the environment on the left side. There are numerous other examples of focal cerebral lesions that disturb or distort sensory perceptions, each subject to neurologic testing; these are discussed in Chap. 21. Their close connection to spatial experience makes


Neurology_Adams

Neurology_Adams. examples of focal cerebral lesions that disturb or distort sensory perceptions, each subject to neurologic testing; these are discussed in Chap. 21. Their close connection to spatial experience makes them understandable as alterations of apperception in the spatial-sensory sphere.


Neurology_Adams

Neurology_Adams. Disturbances of Memory The retention of learned information and experiences is involved in all mental activities. Memory may be arbitrarily subdivided into several parts: (1) registration; (2) fixation, mnemonic integration, and retention; (3) recognition and recall; and (4) reproduction. As stated above, there is a failure of learning and memory in patients with the global confusional state as a result of impaired attention because the material was never registered and assimilated in the first place. In almost all circumstances, the formation of new memories and the ability to recall old ones are disturbed in tandem.


Neurology_Adams

Neurology_Adams. In the Korsakoff amnesic syndrome, newly presented material appears to be correctly registered but cannot be retained for more than a few minutes (anterograde amnesia, or failure of learning). In this syndrome, there is always an associated defect in the recall and reproduction of memories that had been formed several days, weeks, or even years before the onset of the illness (retrograde amnesia). The fabrication of stories, called confabulation, constitutes a third feature of the syndrome but is neither specific nor invariably present. Intact retention with failure of recall (retrograde amnesia without anterograde amnesia) when it is severe and extends to all events of past life and even personal identity, is usually a manifestation of hysteria or malingering. Certain other characteristic defects occur in almost all memory disorders, for example, the relative retention of older memories in preference to newer ones (Ribot’s rule). Chapter 19 discusses this subject more fully.


Neurology_Adams

Disturbances of Thinking

Neurology_Adams. Disturbances of Thinking


Neurology_Adams

Neurology_Adams. Thinking, the highest order of intellectual activity, remains the most elusive of all mental operations. If by thinking one means the selective ordering of symbols for learning, organizing information, and problem solving, as well as the capacity to reason and form sound judgments, then the working units of this type of mental activity are words and numbers. The substitution of words and numbers for the objects for which they stand (symbolization) is a fundamental part of the process. These symbols are formed into ideas or concepts, and the arrangement of new and remembered ideas into certain orders or relationships constitutes an intricate part of thought, presently beyond the scope of analysis. Reference is made further on to Luria’s analysis of the steps involved in problem solving in connection with frontal lobe function, but actually, as he points out, the whole cerebrum is implicated in all forms of thinking. One may examine thinking in terms of its speed and efficiency,


Neurology_Adams

Neurology_Adams. in connection with frontal lobe function, but actually, as he points out, the whole cerebrum is implicated in all forms of thinking. One may examine thinking in terms of its speed and efficiency, ideational content, coherence and logical relationships of ideas, and the quantity and quality of associations to a given idea.


Neurology_Adams

Neurology_Adams. Aphasic disturbances are not prominent in global confusional and delirious states, but Geschwind discussed misnaming as an important feature among the “nonaphasic disorders of speech” in these conditions. Spontaneous speech is normal, but there may be inaccuracies in repetition that are most likely the result of inattention rather than a focal cerebral lesion.


Neurology_Adams

Neurology_Adams. Disorders of thinking are quite prominent in the global confusional state, in mania, dementia, and schizophrenia. In confusional states of all types, the organization of thought processes is disrupted, with fragmentation, repetition, and perseveration; this is spoken of as an “incoherence of thinking.” Derangements of thinking may also take the form of a flight of ideas; patients move too facilely from one idea to another, and their associations are numerous, and loosely linked. This is a common feature of hypomanic and manic states, and of some schizophrenic psychoses. The opposite condition, poverty of ideas, is characteristic both of depressive illnesses, in which it is combined with gloomy thoughts, of schizophrenia, and of dementing diseases, in which it is part of a reduction of all inner psychic intellectual activity. This overall reduction in thought and action is the most prominent feature of diseases that damage the frontal lobes.


Neurology_Adams

Neurology_Adams. A related condition of slowed thought, or bradyphrenia, is comparable to the bradykinesia of extrapyramidal disorders. The two often coexist and the patient, for example with Parkinson disease, can articulate that thinking is so slow as to be virtually blocked. The content of thought is not much altered, but it may be rendered almost useless when slowed to this degree. The outward manifestation of bradyphrenia is what one would expect, a delay in response and slowness in gathering one’s thoughts to express ideas.


Neurology_Adams

Neurology_Adams. Thinking may be distorted in such a way that ideas are not checked against reality. When a false belief is maintained in spite of convincing evidence to the contrary, the term delusion is used. This abnormality is common to bipolar, schizophrenic, and paranoid states, as well as the early stages of dementia. Often the story related by the patient has internal logic but is patently absurd. Psychotic patients may believe that ideas have been implanted in their minds by some outside agency, such as the internet, radio, television, or atomic energy; these thought control or “passivity feelings” are characteristic of schizophrenia, and sometimes of the psychosis of manic episodes. Also diagnostic of some forms of schizophrenia are distortions of logical thought, such as gaps in sequential thinking, intrusion of irrelevant ideas, and condensation of associations. Chapter 49 discusses these aspects of psychoses. Although mistaken notions along the lines of delusions do occur in the global


Neurology_Adams

Neurology_Adams. intrusion of irrelevant ideas, and condensation of associations. Chapter 49 discusses these aspects of psychoses. Although mistaken notions along the lines of delusions do occur in the global confusional state, they change from moment to moment and are not firmly held, quite in contrast to the psychotic states.


Neurology_Adams

Neurology_Adams. Disturbances of Emotion, Mood, and Affect The emotional life of an individual is expressed in a variety of ways. It is widely appreciated that there are marked individual differences in basic temperament. Throughout their lives some persons are cheerful, gregarious, optimistic, and free from worry, whereas others are just the opposite. The state of emotionality, and changes that are uncharacteristic to the individual lend themselves to observation and have clinical significance. Furthermore, some inherent personality traits may precede the development of overt mental disease. For example, the volatile, person is said to be liable to bipolar disease, and the suspicious, withdrawn, introverted person to schizophrenia and paranoia, but there are frequent exceptions to these statements.


Neurology_Adams

Neurology_Adams. Strong, persistent emotional states, such as fear and anxiety, may occur as reactions to life situations and are accompanied by numerous derangements of visceral function. If excessive, prolonged, and disproportionate to the stimulus, they are usually manifestations of an anxiety state or depression. In depression, almost all stimuli also tend to enhance the somber mood of unhappiness. Affective displays that are excessively labile and poorly controlled or uninhibited are a common manifestation of many cerebral diseases, particularly those involving the corticopontine and corticobulbar pathways. This disorder constitutes part of the syndrome of spastic bulbar (pseudobulbar) palsy, as discussed in Chaps. 22 and 24, but it may occur independently of any problem with brainstem function. Conversely, all emotional feeling and expression may be lacking, as in states of profound apathy or depression. Or excessive cheerfulness may be maintained in the face of serious, potentially fatal


Neurology_Adams

Neurology_Adams. Conversely, all emotional feeling and expression may be lacking, as in states of profound apathy or depression. Or excessive cheerfulness may be maintained in the face of serious, potentially fatal disease or other adversity—a pathologic euphoria. Finally, a patient’s emotional responses may be inappropriate to the stimulus, for example, a depressing or morbid thought may seem amusing and be attended by a smile, a bizarre affective state as in schizophrenia.


Neurology_Adams

Neurology_Adams. Temperament, mood, and other emotional experiences are evaluated by observing the patient’s behavior and appearance while questioning him about his feelings. For these purposes, it is convenient to divide emotionality into mood and affect. By mood is meant the prevailing internal emotional state of an individual. By contrast, affect (or feeling) refers to the outward emotional reactions evoked by a thought or an environmental stimulus. As such, it is the observable aspect of emotion. The patient’s language (e.g., the adjectives used), facial expression, attitude, posture, and speed of movement reflect prevailing mood. These distinctions are at times rather tenuous, but they are clinically valuable because pathologic processes may dissociate the two to an extreme degree. Disturbances of Impulse (Conation) and Activity


Neurology_Adams

Neurology_Adams. Reference was made in Chaps. 3 and 4 to weakness, akinesia, and bradykinesia as manifestations of corticospinal and extrapyramidal disease. Disorders of these parts of the motor system interfere with voluntary or automatic movements, much to the distress of the patient. But motility and activity can be impaired in more general ways in which the overall tone of the motor system is enhanced or diminished. One such disorder is a lack of conation, or impulse. These terms emphasize that the basic biologic urges, driving forces, or purposes by which every organism is motivated to achieve an endless series of objectives. Indeed, motor activity is ostensibly a necessary and satisfying objective in itself, for few individuals can remain still for long before they become fidgety or doodle, and the severely retarded apparently obtain gratification from certain rhythmic movements, such as rocking, head banging, and hand flapping. These are all presumed to be driven by mental impulses. As


Neurology_Adams

Neurology_Adams. and the severely retarded apparently obtain gratification from certain rhythmic movements, such as rocking, head banging, and hand flapping. These are all presumed to be driven by mental impulses. As discussed in Chap. 4, tics and compulsions apparently also represent the fulfillment of some psychic urge.


Neurology_Adams

Neurology_Adams. However, in reference to the confusional states, a quantitative reduction in all spontaneous activity, that is, in the amount of activity per unit of time, is one of the most frequent manifestations of cerebral disease. An important aspect of this state, called abulia, is a prominent delay in producing movement, speech, ideation, and emotional reaction, together observed as a kind of apathy. The terms bradyphrenia, and “psychomotor retardation,” referred to above may be a related or perhaps identical phenomena. With certain cerebral diseases the disinclination to move and act may reach an extreme degree, to a point where a person who is wide awake and perceptive of the environment does not speak or move for weeks on end (akinetic mutism). Such patients seem indifferent to what is happening around them, and unconcerned about the consequences of their inactivity.


Neurology_Adams

Neurology_Adams. Abulia and akinetic mutism must be distinguished from catatonia. Kahlbaum, who first used the term catatonia in 1874, described it as a condition in which the patient sits or lies silent and motionless, with a staring countenance, completely without volition and without reaction to sensory impressions. Sometimes there is resistance to the examiner’s efforts to move the patient, or the patient repeats certain movements or phrases hour after hour. If the limbs are moved passively, they may retain their new position for a prolonged period (flexibilitas cerea, or “waxy flexibility”), but more often there is no actual motor rigidity except that of voluntary resistance, termed paratonia. Profound depression or other psychosis is the usual cause of catatonia. The psychomotor retardation of psychosis may be so profound that the patient makes no attempt to help himself in any way and ultimately starves unless fed with a nasogastric tube.


Neurology_Adams

Neurology_Adams. Less easy to understand is a form of “lethal catatonia,” originally described by Stauder, in which the completely inert catatonic patient develops a high fever, collapses, and dies. In some respects, this state resembles the neuroleptic malignant syndrome, an idiosyncratic consequence of intoxication with neuroleptic drugs. In abulia, catatonia, and depression, the mind is usually sufficiently alert to record events and later to recount them, which differentiates these states from stupor and the vegetative state. But these distinctions are not always valid, for there are catatonic schizophrenic and depressive patients who could not recall what had happened during the period of illness.


Neurology_Adams

Neurology_Adams. Pathologic degrees of motor or mental restlessness and hyperactivity, seen characteristically in delirium tremens, represent the opposite extreme from abulia. Akathisia refers to constant restless movements and inability to sit still; in some patients, this is a consequence of the prolonged use of phenothiazines, butyrophenones, newer antipsychosis drugs, and l-dopa, but it is also seen in a major feature of agitated depressions. Hyperactivity-inattention disorders describe yet another form of excessive motor activity that usually accompanies an attention deficit syndrome of children, mostly boys (attention-deficit hyperactivity disorder [ADHD]). In the manic form of bipolar disease (and to a lesser extent in hypomania), continuous activity and insomnia are added to the flight of ideas and the euphoric (although somewhat irritable) mood. Following certain cerebral diseases, notably some forms of encephalitis and during recovery from traumatic lesions of the frontal lobes, the patient


Neurology_Adams

Neurology_Adams. the euphoric (although somewhat irritable) mood. Following certain cerebral diseases, notably some forms of encephalitis and during recovery from traumatic lesions of the frontal lobes, the patient may remain in a state of constant uncontrollable and sometimes destructive activity. Kahn referred to this state as “organic drivenness.”


Neurology_Adams

Disorders of Social Behavior

Neurology_Adams. Disorders of Social Behavior


Neurology_Adams

Neurology_Adams. Behavioral disturbances are common manifestations of all delirious–confusional states, particularly those of toxic–metabolic origin, but also those caused by more obvious structural disease of the brain. The patient may be completely indifferent to all persons around him, or the opposite, when any approach may excite anger and aggressive action. Family members may be treated with disrespect, regarded with suspicion, or falsely accused of harming the patient, stealing his possessions, or trying to poison him. The embarrassment consequent to urinating in public or soiling the bed may be absent and, particularly in men, there may be lewd behavior toward the opposite sex. In its most extreme form, usually seen in the later stages of dementing diseases, irascible behavior degenerates to kicking, screaming, biting, spitting, and an aversion to being touched, making it entirely impossible to approach the patient. These aspects of disordered mental function are the most alarming to the family


Neurology_Adams

Neurology_Adams. screaming, biting, spitting, and an aversion to being touched, making it entirely impossible to approach the patient. These aspects of disordered mental function are the most alarming to the family and are difficult to manage in the hospital. Previously upstanding, socially appropriate, and abstemious persons may lose all regard for their actions and become profligate, gamblers, or alcoholics. In cases of damage to the frontal lobes, even beyond a neglect for social conventions, there can be an indifference to others and to the consequences of the patient’s actions on other members of society.


Neurology_Adams

Neurology_Adams. In contrast, docility and amiable social behavior characterize certain conditions such as Down and Williams syndromes, and social indifference and a lack of ability to interpret the emotional state of others are major features of autism (see “Delirium” later on). Loss of Insight


Neurology_Adams

Neurology_Adams. Loss of Insight The state of being aware of the nature and degree of one’s deficits and their consequences becomes manifestly impaired or abolished in relation to many cerebral diseases, not just those of the frontal lobes. It is common in all but the mildest confusional states. This is reflected by the observation that patients with confusional or dementing states rarely seek advice or help for their illnesses; instead, the family usually brings the patient to the physician or some behavioral anomaly causes police or social services to refer the patients to medical care. And, after the diagnosis has been made, the loss of insight may be reflected in a lack of compliance with planned therapy. It is apparent that diseases that produce abnormalities of insight also reduce the patient’s capacity to make accurate introspections concerning his psychic function.


Neurology_Adams

Neurology_Adams. Lack of insight is a far more complex phenomenon than the operational definition given above suggests. In particular, there are many restricted forms of unawareness of gross neurologic deficits. These are the agnosias, discussed in Chap. 21.


Neurology_Adams

Neurology_Adams. To summarize, the entire group of acute confusional and delirious states is characterized principally by an alteration of consciousness and by prominent disorders of attention and perception, which interfere with the speed, clarity, and coherence of thinking, the formation of memories, and the capacity for performance of self-directed and commanded activities. Three major clinical syndromes can be recognized. One is an acute confusional state in which there is manifest reduction in alertness and psychomotor activity. A second syndrome, alluded to as a special form of confusion, delirium, is marked by overactivity, sleeplessness, tremulousness, and prominence of vivid hallucinations, sometimes with excessive sympathetic activity. These two illnesses tend to develop acutely, to have multiple causes and, except for a few cerebral diseases, to remit within a relatively short period of time of days to weeks, leaving the patient without residual damage. The third syndrome is one in which a


Neurology_Adams

Neurology_Adams. causes and, except for a few cerebral diseases, to remit within a relatively short period of time of days to weeks, leaving the patient without residual damage. The third syndrome is one in which a confusional state occurs in persons with an underlying chronic cerebral disease, particularly a dementia. Dr. Raymond Adams designated this frequently encountered disposition to a superimposed acute confusional state in the context of dementia as a beclouded dementia but the term, while apt, seems not to have caught on.


Neurology_Adams

Neurology_Adams. From the neurologic perspective, the generic term psychosis applies to states of confusion in which elements of hallucinations, delusions, and disordered thinking comprise the prominent features. An important point to be made here is that psychoses typically leave the sensorium relatively unclouded and allow for normal attentions and high-level performance of many mental tasks. These syndromes and some aspects of psychotic confusion are elaborated below.


Neurology_Adams

Neurology_Adams. Characteristically, the confusional states fluctuate in severity, typically being worse at night (“sundowning”). In the mildest form, the patient appears alert and may even pass for normal; only the failure to recollect and accurately reproduce happenings of the past few hours or days reveals the subtle inadequacy of his mental function. The more obviously confused patient spends much of his time in idleness, and what he does may be inappropriate and annoying to others. Only the more automatic acts and verbal responses are performed properly, but these may permit the examiner to obtain a number of relevant replies to questions about age, occupation, and residence. Orientation to the date, day of the week, and place is imprecise, often with the date being off by several days, the year being given as several years or one decade previous, or with the last two numbers transposed, for example, 2015 given as 2051. Such patients may, before answering, repeat every question that is put to


Neurology_Adams

Neurology_Adams. given as several years or one decade previous, or with the last two numbers transposed, for example, 2015 given as 2051. Such patients may, before answering, repeat every question that is put to them, and their responses tend to be brief and mechanical. It is difficult or impossible for them to sustain a conversation. Their attention wanders and they constantly have to be brought back to the subject at hand. They may even fall asleep during the interview, and if left alone are observed to sleep more hours each day than is natural or to sleep at irregular intervals.


Neurology_Adams

Neurology_Adams. As the confusion deepens, conversation becomes more difficult, and at a certain stage these patients no longer notice or respond too much of what is happening around them. Questions may be answered with a single word or a short phrase, spoken in a soft tremulous voice or whisper, or the patient may be mute. Asterixis is a common feature if a metabolic or toxic encephalopathy is responsible for the confusional state. In the most advanced stages of the illness, confusion gives way to stupor and, finally, to coma (see Chap. 16). With improvement in the underlying condition, they may pass again through the stages of stupor and confusion in the reverse order. All this informs us that at least one category of confusion is but a manifestation of the same disease processes that affect awakeness and alertness and, in their severest form, cause coma.


Neurology_Adams

Neurology_Adams. Table 19-1 lists some of the many causes of the common type of global confusional state. The most frequent in general practice are drug intoxications and endogenous metabolic encephalopathies, mainly electrolyte and water imbalance (hypoand hypernatremia, hyperosmolarity), hypercalcemia, disorders of acid–base balance, renal and hepatic failure, hyperand hypoglycemia, febrile and septic states (“septic encephalopathy” discussed further on), and chronic cardiac and pulmonary insufficiency.


Neurology_Adams

Neurology_Adams. Diffuse or multifocal disease of the cerebral hemispheres is another class of transient or persisting confusional states. Concussion and seizures, especially petit mal or temporal lobe status epilepticus or the postictal state, and certain focal (e.g., right parietal and temporal) cerebral lesions may also be followed by a period of confusion. Focal lesions, most often infarctions but also hemorrhages, of the right cerebral hemisphere may evoke an acute confusional state. Such syndromes have been described with strokes mainly in the territory of the right middle cerebral artery (Mesulam et al; Caplan et al; Mori and Yamadori); usually the infarcts have involved the posterior parietal lobe or inferior frontostriatal regions, but they have also occurred with strokes in the territory of one posterior cerebral artery. A variety of more generalized or multifocal cerebral diseases may be associated with transient or persistent confusional states. Among these are meningitis, encephalitis,


Neurology_Adams

Neurology_Adams. posterior cerebral artery. A variety of more generalized or multifocal cerebral diseases may be associated with transient or persistent confusional states. Among these are meningitis, encephalitis, thrombotic thrombocytopenic purpura (TTP), disseminated intravascular coagulation, tumors, subdural hematoma, and cranial trauma.


Neurology_Adams

Neurology_Adams. A more restricted group of focal cerebral diseases, including drug and alcohol withdrawal and systemic infections cause delirium, as discussed below. Pathophysiology of Confusional States


Neurology_Adams

Neurology_Adams. All that has been said on this subject in Chap. 16 regarding coma is applicable to at least one subgroup of the confusional states. In most cases, no consistent pathologic change is found because the abnormalities are metabolic and subcellular. As discussed in Chap. 2, the electroencephalogram (EEG) is almost invariably abnormal in even mild forms of this syndrome, in contrast to delirium tremens, where the changes may be relatively minor. Bilateral high-voltage slow waves in the range of 2 to 4 per second (delta) or 5 to 7 per second (theta) are the usual findings with confusion. These changes surely reflect one aspect of the central problem—the diffuse impairment of the cerebral mechanisms governing alertness and attention and the property of coherence imparted by these functions. If only theoretically, mental incoherence and the disorganized thinking and behavior of the confusional states reflect the loss of integrated activity of all of the associative regions of the cortex as


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Neurology_Adams. only theoretically, mental incoherence and the disorganized thinking and behavior of the confusional states reflect the loss of integrated activity of all of the associative regions of the cortex as mentioned earlier in the chapter.


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Neurology_Adams. This is best depicted in the patient undergoing withdrawal from alcohol after a sustained period of intoxication, that is, delirium tremens. The symptoms usually develop over a period of 2 or 3 days. The first indications are difficulty in concentration, restless irritability, increasing tremulousness, and insomnia. There may be momentary disorientation, an occasional inappropriate remark, or transient illusions or hallucinations.


Neurology_Adams

Neurology_Adams. These initial symptoms rapidly give way to a clinical picture that is one of the most colorful in medicine. The patient is inattentive and unable to perceive the elements of his situation. He may talk incessantly and incoherently, and look distressed and perplexed; his expression may be in keeping with vague notions of being annoyed or threatened by someone. From his manner and the content of speech, it is evident that he misinterprets the meaning of ordinary objects and sounds, misidentifies the people around him, and is experiencing vivid visual, auditory, and tactile hallucinations, often of a most unpleasant type. At first the patient can be brought into touch with reality and may identify the examiner and answer other questions correctly; but almost at once he relapses into a preoccupied, confused state, giving incorrect answers and being unable to think coherently. As the process evolves, the patient cannot shake off his hallucinations and is unable to make meaningful responses


Neurology_Adams

Neurology_Adams. confused state, giving incorrect answers and being unable to think coherently. As the process evolves, the patient cannot shake off his hallucinations and is unable to make meaningful responses to the simplest questions and is profoundly distracted and disoriented. Sleep is impossible or occurs only in brief naps. Speech is reduced to unintelligible muttering.


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Neurology_Adams. The signs of overactivity of the autonomic nervous system, more than any others, distinguish delirium from other confusional states. Tremor of fast frequency and jerky restless movements are practically always present and may be of high amplitude. The face is flushed, the pupils are dilated, and the conjunctivae are injected; the pulse is rapid, blood pressure elevated, and the temperature may be raised. There is excessive sweating. Most of these signs are reflections of overactivity of the sympathetic nervous system. The most certain indication of the subsidence of the attack is the occurrence of lucid intervals of increasing length and sound sleep. Recovery is usually complete. In retrospect, the patient has only a few vague memories of his illness or none at all. Single seizures may punctuate the syndrome at any time, including before its development.


Neurology_Adams

Neurology_Adams. Fragments of the full syndrome are common. Brief disorientation, isolated hallucinations, or restlessness with mild hypersympathetic features all occur in withdrawal states from sedative medications, febrile illnesses, and with various intoxications as well as with the syndrome associated with antibodies to the NMDA receptor of the type associated with ovarian teratoma, with overdosage from sympathetic drugs such as the selective serotonin reuptake inhibitors or those with atropinic effects (see below), and from ingestion of psychoactive substances such as phencyclidine (PCP). Delirium may also occur in association with a number of recognizable cerebral diseases, such as viral (herpes) encephalitis or meningoencephalitis, cerebral trauma, cerebral hemorrhage after surgery for craniopharyngioma or other tumors in the same region, or multiple embolic strokes caused by subacute bacterial endocarditis, cholesterol or fat embolism, or following cardiac or other surgery.


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Neurology_Adams. The brains of patients who have died in delirium tremens from alcohol withdrawal without associated disease or injury usually show no pathologic changes of significance. The topography of the lesions in most of the deliriums that are symptomatic of underlying destructive processes is of interest; they tend to be localized in the rostral midbrain and hypothalamus or in the temporal lobes, where they involve the reticular activating and limbic systems. Involvement of the hypothalamus perhaps accounts for the autonomic hyperactivity that characterizes delirium in some cases of cerebral disease and the autoantibody condition. That these are not the only sites implicated is emphasized by the observations that an acute agitated delirium has occurred, albeit infrequently, with lesions involving the fusiform and lingual gyri and the calcarine cortex (Horenstein et al); the hippocampal and lingual gyri (Medina et al); or the middle temporal gyrus (Mori and Yamadori).


Neurology_Adams

Neurology_Adams. Electrical stimulation studies of the human cerebral cortex during surgical exploration and studies by positron emission tomography (PET) have emphasized the importance of the temporal lobe in the genesis of complex visual, auditory, and olfactory hallucinations. Subthalamic and midbrain lesions may give rise to visual hallucinations that are not unpleasant and are accompanied by good insight (“peduncular hallucinosis” of Lhermitte). For reasons not easily explained, with pontine-midbrain lesions, there may be unformed auditory hallucinations. The EEG in delirium may show symmetrical mild generalized slow activity in the range of 5 to 10 per second. In milder degrees of delirium, there is usually no abnormality at all; this is in stark contrast to the generalized slowing and disruption of EEG activity that accompany most other forms of confusion in proportion to the severity of the clinical state.


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Neurology_Adams. Analysis of the conditions conducive to delirium suggests several physiologic mechanisms. Alcohol and sedative drugs are known to have a strong depressant effect on certain regions of the central nervous system; presumably, the disinhibition and overactivity of these parts after withdrawal of the drug are the basis of delirium. Another mechanism is operative in the case of bacterial infections with sepsis and poisoning by certain drugs, such as atropine and scopolamine, in which visual hallucinations are a prominent feature. Here the delirious state probably results from the direct action of the toxin or chemical agent on the same parts of the brain. It has long been suggested that some persons are much more liable to delirium than others, but there is reason to doubt this. Many years ago, Wolff and Curran showed that randomly selected persons developed delirium if the causative mechanisms were strongly operative. This is not surprising, for any normal person may, under certain


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Neurology_Adams. ago, Wolff and Curran showed that randomly selected persons developed delirium if the causative mechanisms were strongly operative. This is not surprising, for any normal person may, under certain circumstances, experience phenomena akin to those of delirium. A healthy person can be induced to hallucinate by being isolated for several days in an environment free of sensory stimulation (sensory deprivation). A relationship of delirium to dream states has also been postulated; both are characterized by a loss of appreciation of time, a richness of visual imagery, indifference to inconsistencies, and “defective reality testing.” Formulations in the field of dynamic psychiatry seem more reasonably to explain the topical content of delirium than its occurrence. Wolff and Curran, having observed the same content in repeated attacks of delirium from different causes, concluded that the content depends more on the age, gender, intellectual endowment, occupation, personality traits, and past


Neurology_Adams

Neurology_Adams. the same content in repeated attacks of delirium from different causes, concluded that the content depends more on the age, gender, intellectual endowment, occupation, personality traits, and past experiences than on the cause of the delirium.


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(See Also Chap. 42)

Neurology_Adams. (See Also Chap. 42)


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Neurology_Adams. In considering the pathophysiology of confusion, it must be again emphasized that drug intoxication—including from drugs prescribed by physicians—is among the most common causes in practice. The most distinctive syndromes are those from drugs that have direct or indirect anticholinergic properties. The delirium associated with these agents is centrally mediated but may be accompanied by peripheral anticholinergic manifestations. This point is critical in the differential assessment of agitated confusional states because other compounds, particularly serotonergic agents used to treat depression, also can produce delirium. Thus, in addition to confusion, toxic levels of anticholinergic compounds typically cause dry skin, dry mouth, diminished bowel motility, and urinary hesitancy, if not frank retention. (The clinical maxim that applies is “red as a beet, dry as a bone, blind as a bat, hot as a hare, and mad as a hatter.” The last part of this mnemonic has been also attached to the


Neurology_Adams

Neurology_Adams. frank retention. (The clinical maxim that applies is “red as a beet, dry as a bone, blind as a bat, hot as a hare, and mad as a hatter.” The last part of this mnemonic has been also attached to the dementia of mercury intoxication [see Mintzer and Burns].) By contrast, in the toxic serotonergic syndrome associated with excessive doses of the antidepressant drugs, salivation is normal, sweating is increased, and the gut is hyperactive; diarrhea is common. Moreover, the deep tendon reflexes may be exaggerated, and there is often clonus or myoclonus as described by


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Neurology_Adams. Birmes and associates. Drugs with dopaminergic activity used in the treatment of Parkinson disease are notorious for the induction of confusion or delirium, but it appears that the underlying disease provides an important substrate. Allied compounds with sympathomimetic actions such as cocaine and phencyclidine produce a hallucinatory delirium and yet others with different pharmacologic properties such as glutaminergic activity may result in a variety of delirious fragments or pure hallucinosis. Another entity that arises in this context is the neuroleptic malignant syndrome, a state associated with an agitated confusion followed by stupor. However, the characteristic features in neuroleptic malignant syndrome (NMS) are progressive muscle rigidity and evidence of myonecrosis as indicated by elevations of the serum creatine kinase; usually there is in addition some elevation of body temperature. The clinical examination and a thorough history aid greatly in determining which category


Neurology_Adams

Neurology_Adams. by elevations of the serum creatine kinase; usually there is in addition some elevation of body temperature. The clinical examination and a thorough history aid greatly in determining which category of drug is implicated.


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Neurology_Adams. Dementing Disease Complicated by Confusional States and Delirium in the Elderly


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Neurology_Adams. Physicians are all too familiar with the situation of an elderly patient who enters the hospital with a medical or surgical illness or begins a prescribed course of medication and displays a newly acquired mental confusion. Presumably, the liability to this state is determined by preexisting brain disease, most often Alzheimer disease but sometimes Parkinson disease, multiple small deep cerebral infarctions, or another dementing process, which may or may not have been obvious to the family before. All the clinical features that one observes in the acute confusional states may be present, but their severity varies greatly. Confusion may be reflected only in the patient’s inability to relate the history of the illness sequentially, or it may be so severe that the patient is virtually non compos mentis. An analysis of other studies by Witlox and colleagues has estimated that the risk of dementia in persons over 85 years if an episode of global confusion has occurred is almost 9 times the


Neurology_Adams

Neurology_Adams. mentis. An analysis of other studies by Witlox and colleagues has estimated that the risk of dementia in persons over 85 years if an episode of global confusion has occurred is almost 9 times the rate in others of the same age. Authoritative writers have suggested that confusion is causal to subsequent dementia but evidence for this is so far lacking.


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Neurology_Adams. The family and even the primary physician often identify the problem as abrupt in onset and having no precedent as the patient seemingly functioned well previously. However, careful questioning about the patient’s independent capability in handling of finances and shopping, organization of household matters, driving, relating to neighbors or family, and even previous episodes of confusion to which the family paid little heed, are usually uncovered.


Neurology_Adams

Neurology_Adams. Although almost any complicating illness may bring out a confusional state in an elderly person, the most common are febrile infectious diseases; trauma, notably concussive brain injuries; surgical operations, general anesthesia and preand postoperative medication; even small amounts of pain or sedative medications used for any cause; and congestive heart failure, chronic respiratory disease, and severe anemia, especially pernicious anemia. With regard to medications, those even seemingly innocuous ones, may cause the syndrome (e.g., histamine blockers used to reduce gastric acid, anticonvulsants, corticosteroids, and l-dopa, and certain antibiotics). Often, a “multifactorial” etiology is implicated by physicians and writers in this field and poor eyesight and hearing are included in this ambiguous and unsatisfactory term, especially when moderately severe electrolyte imbalance or renal failure are added implicated in the mix of other factors. Admittedly, it is difficult to determine


Neurology_Adams

Neurology_Adams. ambiguous and unsatisfactory term, especially when moderately severe electrolyte imbalance or renal failure are added implicated in the mix of other factors. Admittedly, it is difficult to determine which of several possible factors is responsible for the patient’s confusion, and often there may be more than one. In a cardiac patient, for example, fever, hypoxia or hypercarbia, one or more drugs, and electrolyte imbalance each may contribute. For a perspective on the relative contributions to confusion in the elderly of various medical and pharmacologic factors, the reader may consult the review by Inouye and colleagues.


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Neurology_Adams. In the instance of fever and confusion, particularly in the elderly person, the problem of “septic encephalopathy” is offered as an explanation, but it may simply be a rephrasing of the well-known problem of infection such as pneumonia leading to a global confusion or delirium that was extensively discussed in the older literature by Osler. Young has called attention to the high frequency of this disorder in critically ill patients, 70 percent of their bacteremic patients, and its accompaniment by a polyneuropathy in a high proportion of cases. Paratonic rigidity of the limbs (an oppositional action on the patient’s part that is proportioned to the effort of the examiner in moving the limbs) is an almost universal accompaniment; according to these authors, focal cerebral or cranial nerve signs are not encountered. All other potential causes of a confusional state must, of course, be excluded before attributing the state to an underlying infection.


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Neurology_Adams. The EEG is slowed in proportion to the level of consciousness, but it shows mild changes even in the bacteremic patient who is fully alert. The spinal fluid is normal or has a slightly elevated protein concentration. While there is no doubt that young and healthy patients may become confused when affected with high fever and overwhelming infections such as pneumonia, most cases of septic encephalopathy are of the “beclouded dementia” type in the older patient. The point made by Young is that subtle degrees of confusion are ubiquitous with serious infections of many varieties. Among the most perplexing cases of this type have been healthy older persons we have observed who acquired an agitated delirium following spinal column infection after surgery. The delirium ceased within hours of drainage of an abscess. The older literature contains similar examples with closed space infection in other locations. The chapter by Young can be consulted for an exposition of the various theories of


Neurology_Adams

Neurology_Adams. of an abscess. The older literature contains similar examples with closed space infection in other locations. The chapter by Young can be consulted for an exposition of the various theories of pathogenesis of this state. High fever itself (above 40.6°C [105°F]) is probably an adequate explanation for confusion in some cases. A similar global confusional state occurs in patients with severe burns (burn encephalopathy).


Neurology_Adams

Neurology_Adams. All that has been stated above is true of the patient with a nondescript postoperative confusional state, in which a number of factors, such as fever, infection, dehydration, and drug and anesthetic effects, are implicated. In a study of 1,218 postoperative patients by Moller and colleagues, older age was by far the most important factor associated with persistent confusion after an operation; but a number of other factors—including the duration of anesthesia, need for a second operation soon after the first, postoperative infection, and respiratory complications—were also predictive of mental difficulty in the days after the procedure. As discussed further on, confusion appearing after a surgical procedure may suggest an underlying dementia or be predictive of the future development of dementia. What is as important is the confusional episode may not entirely resolve for weeks or months as commented below. Careful questioning of the family often reveals subtle decline is daily


Neurology_Adams

Neurology_Adams. of dementia. What is as important is the confusional episode may not entirely resolve for weeks or months as commented below. Careful questioning of the family often reveals subtle decline is daily functioning over the prior months or years. Unacknowledged alcoholism and withdrawal effects undoubtedly cause the same problem quite often on surgical services (see also “Stroke with Cardiac Surgery” in Chap. 33).


Neurology_Adams

Neurology_Adams. When such patients recover from the medical or surgical illness, they usually return to their premorbid state, though their shortcomings, now drawn to the attention of the family and physician, are far more obvious than before. For this reason, families will date the onset of a dementia to the time of the medical illness or surgical procedure, and continue to minimize the previous gradual decline in cognition. In other cases, however, the acute medical illness seemingly marks the beginning of a persistent decline in mental clarity that over time can be identified as a dementing illness. A related problem that has come under study is persistent cognitive loss after critical illness. The rates of this irreversible change are apparently high, up to one-quarter of severely ill patients in some series, but accurate estimates are difficult to obtain because of the lack of pre-illness psychometric testing.


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Neurology_Adams. This problem has attracted increasing attention in the past decades as a cause of otherwise obscure confusional states. It is discussed in Chaps. 15 and 16, but here we only comment that the process may be portrayed clinically only because of small myoclonic twitches or eyelid fluttering. The only certain way to arrive at, or exclude the diagnosis is with EEG monitoring for more than the usual 30 min recording if possible. One suspects nonconvulsive seizures particularly in known epileptics, septic patients, and in certain medical diseases such as TTP.


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Neurology_Adams. A small proportion of psychoses of schizophrenic or bipolar type first become manifest during an acute medical illness or following an operation or parturition and need to be distinguished from an acute confusional state. The manic state in particular can produce an overtly confusional state but the patient sleeps little, is prone to excessive writing and, unlike the patient with a global confusional state, flits from one topic to the next in a vaguely pertinent way, makes bizarre or unusual misidentifications of people, and is reluctant to let the examiner out of the room or the opposite, is rude and requests that the physician or an entourage leave immediately. Rarely, a catatonic state will make its first appearance in these circumstances. A causal relationship between the psychosis and medical illness is sought but cannot be established. The psychosis may have preceded the medical illness but was not recognized. The diagnostic study of the psychiatric illness must then proceed


Neurology_Adams

Neurology_Adams. and medical illness is sought but cannot be established. The psychosis may have preceded the medical illness but was not recognized. The diagnostic study of the psychiatric illness must then proceed along the lines suggested in Chap. 48. Close observation will usually disclose a clear sensorium and relatively intact memory, features that permit differentiation from an acute confusional or delirious state or dementia.


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Neurology_Adams. The syndromes themselves and their main clinical causes are the only satisfactory basis for classification until such time as their actual causes and pathophysiology are discovered (see Table 19-1).


Neurology_Adams

Neurology_Adams. The first step in diagnosis is to recognize that the patient is confused. This is obvious in most cases but, as pointed out earlier, the mildest forms, particularly when some other alteration of personality is prominent, may be overlooked. Sometimes, the patient’s attention can be best engaged by speaking softly or whispering rather than shouting or using a conversational amplitude of voice. A subtle disorder of orientation may be betrayed by an incorrect response regarding dates (off by more than one day of the month or day of the week), or in misnaming the hospital. The ability to retain a span of digits forward (normally 7) and backward (normally 5), spelling a word such as “world” or “earth” forward and then backward, reciting the months of the year in their reverse order, and serial subtraction of 3s from 30 or 7s from 100 are useful bedside tests of the patient’s capacity for attentiveness and sustained mental activity, though some of these presuppose that the patient is


Neurology_Adams

Neurology_Adams. serial subtraction of 3s from 30 or 7s from 100 are useful bedside tests of the patient’s capacity for attentiveness and sustained mental activity, though some of these presuppose that the patient is literate or has a knowledge of mathematics. Another is the efficiency in performing dual tasks such as tapping alternately with each hand while reading aloud. Memory of recent events is one of the most delicate tests of adequate mental function and is readily accomplished by having the patient relate the details of entry to the hospital; examinations undertaken in the previous days; naming the president, vice president; and summarizing major current events, as outlined in Chap. 21. Errors in performance should not be minimized or attributed to age, for they may presage serious upcoming problems during the hospitalization.


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Neurology_Adams. Once it is established that the patient is confused, the differential diagnosis must be made between an acute confusional state associated with psychomotor underactivity, delirium, a beclouded dementia, and a confusional state that complicates focal cerebral disease. This is done by taking into account the degree of the patient’s alertness, wakefulness, psychomotor and hallucinatory activity, and disturbances of memory and impulse, as well as the presence or absence of asterixis or myoclonus or signs of overactivity of the autonomic nervous system and of generalized or focal cerebral disease. In the neurologic examination, particular attention should be given to the presence or absence of focal neurologic signs and to asterixis, myoclonus, and seizures.


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Neurology_Adams. In the chronically demented patient, there are usually a number of “frontal release” signs, such as picking at the bedsheets and clothes, grasping, groping, sucking, and paratonic rigidity of the limbs. However, some demented patients are as bewildered as those with confusional psychosis, and the two conditions are distinguishable only by differences in their mode of onset and chronicity. This suggests that the affected parts of the nervous system may be the same in both conditions.


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Neurology_Adams. At times, a left hemispheral lesion causing a mild Wernicke’s aphasia resembles a confusional state in that the stream of speech and thought are incoherent. The prominence of paraphasias and neologisms in spontaneous speech, difficulties in auditory comprehension, and normal nonverbal behavior mark the disorder as aphasic in nature. However, a problem with naming may be more common in nonaphasic global confusional states, as alluded to earlier in the chapter and emphasized in a brief piece by Geschwind. Spontaneous speech in these circumstances is unaffected.


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Neurology_Adams. The distinction between an acute confusional state and dementia is difficult at times, particularly if the mode of onset and the course of the mental decline are not known. The patient with an acute confusional state is said to have a “clouded sensorium” (an ambiguous term referring to a symptom complex of inattention, disorientation, perhaps drowsiness, and an inclination to inaccurate perceptions and sometimes to hallucinations and delusions), whereas the patient with dementia usually has a clear sensorium. As indicated earlier, schizophrenia and bipolar psychosis, particularly with mania can usually be separated from the confusional states by the presence of a clear sensorium and relatively intact memory function.


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Neurology_Adams. A thorough medical and neurologic examination, CT or MRI, and—in cases with fever or with no other apparent cause—blood count, chest x-ray, and lumbar puncture should be performed. The medical, neurologic, and laboratory findings (including measurements of Na, Ca, CO2, blood urea nitrogen [BUN], NH3, calcium, glucose, Pao2, Pco2, “toxic screen”) determine the underlying disease and its treatment, and they also give information concerning prognosis. An approach to the laboratory tests that are useful in revealing the common conditions that give rise to the confusional state, when the cause is not self-evident from the history and physical examination, is given in Table 19-2; but as always, the choice of tests is governed by the clinical circumstances.


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Neurology_Adams. Table 19-2; but as always, the choice of tests is governed by the clinical circumstances. These details are of the utmost importance. It has been estimated that 20 to 25 percent of medically ill hospital inpatients will experience some degree of confusion; moreover, elderly patients who are delirious have a significant level of mortality, variously estimated at 22 to 76 percent according to Weber and colleagues. Optimal care begins with the identification of individuals at risk for delirium, including those who have an underlying dementia, preexisting medical illnesses, or a history of alcoholism or serious depression. Furthermore, delirium is more common in males and, not surprisingly, is more likely when sensory function is already impaired (loss of vision and hearing) (Burns et al; Weber et al).


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Neurology_Adams. The primary effort is directed toward elimination of the underlying medical problem, particularly to discontinuing offending drugs or toxic agents. Other important objectives are to quiet the agitated patient and protect him from injury. A nurse, attendant, or member of the family should be with a seriously confused patient if this can be arranged. A room with adequate natural lighting will aid in creating a diurnal rhythm of activity and reduce “sundowning.” It is often better to let an agitated patient walk about the room than to restrain him in bed, which may increase his fright or excitement and cause him to struggle to the point of exhaustion, collapse, or self-harm. The less-active patient can be kept in bed by side rails, wrist restraints, or a restraining sheet or vest. Sensitive explanations of these restraints to the family should be made in terms that emphasize the patient’s health and safety. The fully awake but mildly confused patient should be permitted to sit up or walk


Neurology_Adams

Neurology_Adams. of these restraints to the family should be made in terms that emphasize the patient’s health and safety. The fully awake but mildly confused patient should be permitted to sit up or walk about part of the day unless the primary disease contraindicates this.


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Neurology_Adams. All drugs that could possibly be responsible for the acute confusional state or delirium should be discontinued if this can be done safely. These include sedating, antianxiety, narcotic, anticholinergic, antispasticity, and corticosteroid medications, l-dopa, metoclopramide, and cimetidine, as well as antidepressants, antiarrhythmics, antiepileptics, and antibiotics. Despite the need to be sparing with medications in these circumstances, haloperidol, quetiapine, and risperidone are helpful in calming the severely agitated and hallucinating patient, but they too should be used in the lowest effective doses. An exception is alcohol or sedative withdrawal, in which chlordiazepoxide or other diazepines are favored by most physicians (see Chap. 41). In delirious patients, the purpose of sedation is to assure rest and sleep, avoid exhaustion, and facilitate nursing care, but one must be cautious in attempting to suppress delirium completely. Warm baths were also known in the past to be


Neurology_Adams

Neurology_Adams. is to assure rest and sleep, avoid exhaustion, and facilitate nursing care, but one must be cautious in attempting to suppress delirium completely. Warm baths were also known in the past to be effective in quieting the delirious patient, but hospitals no longer have facilities for this valuable method of treatment.


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Neurology_Adams. It would seem obvious that attempts should be made to preempt the problem of confusion in the hospitalized elderly patient that includes early identification of those at risk, particularly individuals with incipient dementia, frequent reorientation to the surroundings with signs, verbal reminders, and a clock; mentally stimulating activities; ambulation several times a day or similar exercises when possible; and attention to providing visual and hearing aids in patients with these impairments. They recorded a 40 percent reduction in the frequency of a confusional illness in comparison to patients who did not receive this type of organized program. Preventive strategies of the type they outline are most important in the elderly, even those without overt dementia, but a routine plan is advisable so that nurses and ancillary staff are able to apply them consistently.


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Neurology_Adams. Finally, the physician should be aware of the benefit of many small therapeutic measures that allay fear and suspicion and reduce the tendency to hallucinations. The room should be kept dimly lighted at night, and, if possible, the patient should not be moved from one room to another. Every procedure should be explained to the patient, even such simple ones as the taking of blood pressure or temperature. It may be some consolation and also a source of professional satisfaction to remember that most confused and delirious patients recover if they receive competent medical and nursing care (and are almost always amnestic for the ordeal). The family may be reassured on this point but forewarned that improvement may take several days or weeks and that episodes of confusion may be exposing an underlying dementia. They must also understand that the patient’s abnormal behavior is not willful but rather symptomatic of a transitory brain disease. (See also Chap. 41 for specific aspects of


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Neurology_Adams. an underlying dementia. They must also understand that the patient’s abnormal behavior is not willful but rather symptomatic of a transitory brain disease. (See also Chap. 41 for specific aspects of management of delirium due to withdrawal of alcohol and other sedative-hypnotic drugs.)


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Neurology_Adams. Birmes P, Coppin D, Schmitt L, et al: Serotonin syndrome: a brief review. CMAJ 168:1439, 2003. Burns A, Gallagley A, Byrne J: Delirium. J Neurol Neurosurg Psychiatry 75:362, 2004. Caplan LR, Kelly M, Kase CS, et al: Mirror image of Wernicke’s aphasia. Neurology 36:1015, 1986. Engel GL, Romano J: Delirium: a syndrome of cerebral insufficiency. J Chronic Dis 9:260, 1959. Geschwind N: Non-aphasic disorders of speech. Int J Neurol 4:207, 1964. Horenstein S, Chamberlin W, Conomy T: Infarction of the fusiform and calcarine regions: agitated delirium and hemianopia. Trans Am Neurol Assoc 92:85, 1967. Inouye SK, Bogardus ST, Charpentier PA, et al: A multicomponent intervention to prevent delirium in hospitalized older patients. N Engl J Med 340:669, 1999. Inouye SK, Westendorp GJ, Saczynksi JS: Delirium in elderly people. Lancet 383:911, 2014. Kahlbaum KL: Catatonia (Die Katatonie oder das spannungsirresein). Johns Hopkins University Press, Baltimore, 1973.


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Neurology_Adams. Kahlbaum KL: Catatonia (Die Katatonie oder das spannungsirresein). Johns Hopkins University Press, Baltimore, 1973. Kahn E: Psychopathic Personalities. New Haven, CT, Yale University Press, 1931. Lipowski ZJ: Delirium: Acute Confusional States. New York, Oxford University Press, 1990. Medina JL, Rubino FA, Ross A: Agitated delirium caused by infarction of the hippocampal formation, fusiform and lingual gyri. Neurology 24:1181, 1974. Mesulam MM: Attentional networks, confusional states, and neglect syndromes. In: Mesulam MM (ed): Principles of Behavioral and Cognitive Neurology. Oxford, UK, Oxford University Press, 2000, pp 174–256. Mesulam MM, Waxman SG, Geschwind N, et al: Acute confusional states with right middle cerebral infarctions. J Neurol Neurosurg Psychiatry 39:84, 1976. Mintzer J, Burns A: Anticholinergic side effects of drugs in elderly people. J R Soc Med 93:457, 2000.


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Neurology_Adams. Mintzer J, Burns A: Anticholinergic side effects of drugs in elderly people. J R Soc Med 93:457, 2000. Moller JT, Cluitmans P, Rasmussen LS: Long-term postoperative cognitive dysfunction in the elderly: ISPOCD1 study. Lancet 351:857, 1998. Mori E, Yamadori A: Acute confusional state and acute agitated delirium. Arch Neurol 44:1139, 1987. Stauder HK: Die todliche Katatonie. Arch Psychiatr Nervenkrankh 102:614, 1934. Weber JB, Coverdale JH, Kunik ME: Delirium: current trends in prevention and treatment. Intern Med J 34:115, 2004. Witlox J, Eurelings LS, de Jonghe JF, et al: Delirium in elderly patients and the risk of postdischarge mortality, institutionalization, and dementia. JAMA 304:443, 2010. Wolff HG, Curran D: Nature of delirium and allied states. Arch Neurol Psychiatry 33:1175, 1935. Young GB: Other inflammatory disorders. In: Young GB, Ropper AH, Bolton CF (eds): Coma and Impaired Consciousness. McGraw-Hill, New York, 1998, pp 271–303.


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Neurology_Adams. Young GB: Other inflammatory disorders. In: Young GB, Ropper AH, Bolton CF (eds): Coma and Impaired Consciousness. McGraw-Hill, New York, 1998, pp 271–303. Dementia, the Amnesic Syndrome, and the Neurology of Intelligence and Memory


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Neurology_Adams. Dementia, the Amnesic Syndrome, and the Neurology of Intelligence and Memory Increasingly, as the population of elderly rises, the neurologist is consulted because an otherwise healthy person begins to fail mentally and loses his capacity to function effectively at work or in the home. This may indicate the development of a degenerative brain disease, a brain tumor, multiple strokes, chronic subdural hematomas, drug intoxication, chronic meningoencephalitis (such as caused by HIV or syphilis), normal-pressure hydrocephalus, or a depressive illness. Formerly, there was little that could be done about these clinical states, but there are now effective means of treating several of these conditions, and in some instances, of restoring the patient to normal competence. Moreover, diagnostic technologies allow earlier recognition of the underlying pathologic process, thus improving the chances of recovery or of preventing the disease’s progression.


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Neurology_Adams. The definitions of normal and abnormal states of mind were considered in Chap. 19, where it was pointed out that the term dementia denotes a persistent deterioration of intellectual or cognitive function with little or no disturbance of consciousness or perception. In current medical parlance, the term is used to designate a syndrome of failing memory and of other intellectual functions as a result of chronic progressive degenerative disease of the brain. Such a definition may be too narrow. The term more accurately includes a number of closely related syndromes characterized not only by intellectual deterioration but also by certain behavioral abnormalities and changes in personality. Furthermore, dementia can be the result of a static encephalopathy such as head trauma or cerebral anoxia or of a progressive degenerative disease, but it differs from the global confusional state, or encephalopathy, in its chronicity. Thus, it is not possible to determine if a confused, amnestic person


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Neurology_Adams. or of a progressive degenerative disease, but it differs from the global confusional state, or encephalopathy, in its chronicity. Thus, it is not possible to determine if a confused, amnestic person is demented until some time has passed and the deficits have persisted, marking a dementia, or abated, signifying an encephalopathy. Beyond the need to properly define these terms, the two entities have different causes. There are several states of dementia of differing causes and mechanisms and degeneration of systems of cerebral neurons, albeit common, is only one of the many causes. Similarly, as discussed in previous chapters, there are myriad intrinsic (metabolic) and extrinsic (toxic) causes of encephalopathy.


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Neurology_Adams. To understand the phenomenon of intellectual deterioration, it is helpful to have some idea of how intellectual functions, particularly intelligence and memory, are normally organized and sustained, and the manner in which diffuse and focal cerebral lesions cause deficits in these functions. The neurology of intelligence is considered in this chapter as a prelude to a discussion of the dementias and the neurology of memory.


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Neurology_Adams. Intelligence, or intelligent behavior, has been variously defined as a “general mental efficiency,” as “innate cognitive ability,” or as “the aggregate or global capacity of an individual to act purposefully, to think rationally, and to deal effectively with his environment” (Wechsler), in other words, the capacity to have ideas and reason about them. It is global because it characterizes an individual’s behavior as a whole; it is an aggregate in the sense that it is composed of a number of independent and qualitatively distinguishable cognitive abilities. This topic should be of interest to neurologists because intelligence is disturbed by many disorders of the brain but cannot be easily attributed to any cerebral region or particular cognitive function. Indeed, the dementias and developmental delays, affect intelligence in a way that cannot be explained except by some widely distributed aspect of brain function.


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Neurology_Adams. As every educated person recognizes, intelligence has something to do with normal cerebral function. It is also apparent that the level of intelligence differs from one person to another, and members of certain families are exceptionally bright and intellectually accomplished, whereas members of other families are just the opposite. If properly motivated, intelligent children excel in school and score high on intelligence tests, although this may be tautologic as the tests are designed specially to measure certain aspects of performance. Furthermore, the first intelligence tests, devised by Binet and Simon in 1905, were for the purpose of predicting scholastic success. The term intelligence quotient, or IQ, was introduced by the German psychologist Stern and used by Terman in 1916 for the development of intelligence testing. It denotes the figure that is obtained by dividing the subject’s mental age (as determined by the Binet-Simon scale) by his chronologic age (up to the 14th year)


Neurology_Adams

Neurology_Adams. development of intelligence testing. It denotes the figure that is obtained by dividing the subject’s mental age (as determined by the Binet-Simon scale) by his chronologic age (up to the 14th year) and multiplying the result by 100. The IQ correlates, but only broadly, with achievement in school and to a lesser extent with eventual success in professional work. An individual IQ increases with age up to the 14th to 16th years and then remains stable, at least until late adult life. At any age, a large sample of normal children attains test scores of a normal, or gaussian, distribution.


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Neurology_Adams. The original studies of pedigrees of highly intelligent and mentally less able families, which revealed a striking concordance between parent and child, lent support to the idea that intelligence is to a large extent inherited. However, it became evident that the tests used were also greatly influenced by the environment in which the child was reared. Moreover, tests were less reliable in identifying talented children who were not offered optimal opportunities. This led to the equally polarized but widespread belief that intelligence tests are only achievement tests and that environmental factors fostering high performance are the important factors determining intelligence.


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Neurology_Adams. Neither of these views is likely to be entirely correct. Past studies of monozygotic and dizygotic twins raised in the same or different families put the matter in a clearer light. Identical twins reared together or apart are more alike in intelligence than nonidentical twins brought up in the same home (see reviews of Willerman, of Shields, and of Slater and Cowie). A study of elderly twins by McClearn and colleagues is further instructive; even in twins who were older than 80 years of age, a substantial part (an estimated 62 percent) of cognitive performance could be accounted for by shared genetic traits. These findings suggest that life experience alters intelligence, but in a modest way. There is therefore a strong suggestion that genetic endowment is the more important factor—a view that was championed by Piercy and more recently by Herrnstein and Murray. However, there is equally valid evidence that early learning modifies the level of ability that is finally attained. In this


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Neurology_Adams. that was championed by Piercy and more recently by Herrnstein and Murray. However, there is equally valid evidence that early learning modifies the level of ability that is finally attained. In this way, intelligence may be looked upon not as the sum of genetic and environmental factors but as the product of the two. More importantly, it is generally appreciated that nonscholastic achievement or success is governed by factors other than intellectual ones, such as curiosity, a readiness to learn, interest, persistence, sociability, and ambition or motivation—factors that vary considerably from person to person and are not at all measured by tests of intelligence.


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Neurology_Adams. As to the genetic mechanisms involved in the inheritance of intelligence, a limited amount is known. There is an excess of males with what was previously called mental retardation, and now less pejoratively “developmental delay,” and there are several well-characterized syndromes in which the inheritance of mental retardation is X-linked as described in Chaps. 27 and 37. Also notable are the somewhat different patterns of performance between males and females on subtests of the various intelligence tests (males perform better in spatial ability and certain mathematical tasks). Males are more likely to be affected by advantageous or by aberrant genes on their single X chromosome, whereas females benefit from the mosaic provided by two X chromosomes. In some families, high intelligence segregates to certain individuals through an X-linked pattern. Further study will determine the validity of these views and of what will certainly prove to be a polygenic inheritance of intelligence and


Neurology_Adams

Neurology_Adams. to certain individuals through an X-linked pattern. Further study will determine the validity of these views and of what will certainly prove to be a polygenic inheritance of intelligence and intellectual traits.


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Neurology_Adams. One would think that neurologic structure and function would correlate in some way with intelligence, but with the exception of the pathologically developmentally delayed (see Chaps. 27 and 37), such an association has been difficult to document. Brain weight and the complexity of the convolutional pattern are not correlated with intelligence—despite popular notions to the contrary, including a widely criticized analysis of the brain of Albert Einstein. (Witelson and colleagues proposed that an enlarged inferior parietal lobule, a crossmodal association area, accounted for Einstein’s visuospatial and mathematical genius, but this is certainly an oversimplification). Only laboratory measures of vigilance and facility of sensory registration (speed of motor responses/reaction time and rapid recognition of differences between lines, shapes, or pictures) have a consistent but still modest correlation with IQ. However, it is of interest that morphometric features of the regions of the


Neurology_Adams

Neurology_Adams. recognition of differences between lines, shapes, or pictures) have a consistent but still modest correlation with IQ. However, it is of interest that morphometric features of the regions of the cortex that are presumed to underlie IQ and verbal skills, such as the frontal and language areas, show a heritable component when measured on high-resolution MRI scans (see Thompson et al).


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Neurology_Adams. As to psychologic theories of intelligence, several have traditionally been influential at different historical periods. One is the two-factor theory of Spearman, who noted that all the separate tests of cognitive abilities correlated with each other, suggesting that a general factor (g factor) enters into all performance. Because none of the correlations between subtests approached unity, he postulated that each test measures not only this general ability (commonly identified with intelligence) but also a subsidiary factors specific to the individual tests, which he designated the s factors. A second theory, the multifactorial theory of Thurstone, proposed that intelligence consists of a number of entirely separable primary mental abilities, such as memory, verbal facility, numerical ability, visuospatial perception, and capacity for problem solving, all of them more or less equivalent. He proposed that these primary abilities, although correlated, are not subordinate to a more


Neurology_Adams

Neurology_Adams. ability, visuospatial perception, and capacity for problem solving, all of them more or less equivalent. He proposed that these primary abilities, although correlated, are not subordinate to a more general ability. For Eysenck, intelligence exists in three forms: biologic (the genetic component), social (development of the genetic component in relation to personal relationships), and a number of specific abilities subject to measurement by psychometric tests.


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Neurology_Adams. Thurstone’s multifactorial theory of intelligence has been periodically reframed, for example by Gardner, who separated six categories of high-order cerebral ability but restated them in more modern terms: linguistic (encompassing all language functions); musical (including composition and performance); logical–mathematical (the ideas and works of mathematicians); spatial (including artistic talent and the creation of visual impressions); bodily–kinesthetic (including dance and athletic performance); and the personal (consciousness of self and others in social interactions). He referred to each of these as intelligences, defined as the ability to solve problems or resolve difficulties and to be creative within the particular field. Several lines of evidence are marshaled in support of this parceling of skills and abilities: (1) each may be developed to an exceptionally high level in certain individuals, constituting virtuosity or genius; (2) each can be destroyed or spared in


Neurology_Adams

Neurology_Adams. of this parceling of skills and abilities: (1) each may be developed to an exceptionally high level in certain individuals, constituting virtuosity or genius; (2) each can be destroyed or spared in isolation as a consequence of a lesion in a certain part of the nervous system; (3) in certain individuals, that is, in prodigies, special competence in one of these abilities is evident at an unusually early age; (4) in the autism spectrum, one or more of these abilities may be selectively spared or developed to an abnormally high degree (idiot savant). Each of these entities appears to have a genetic basis in so far as musical, artistic, mathematical, and athletic ability often runs in families, but their full development is influenced by environmental factors.


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Neurology_Adams. There are only limited data regarding the highest levels of intelligence, identified as genius. Terman and Ogden’s longitudinal study of 1,500 California schoolchildren who were initially tested in 1921 supported the idea that an extremely high IQ predicted future scholastic accomplishments (though not occupational or life success). On the other hand, most individuals recognized as geniuses have been especially skilled in one domain—such as painting, linguistics, music, chess, or mathematics—and such “domain genius” is not necessarily predicated on high IQ scores, although certain individuals display crossmodal superiorities—particularly in mathematics and music.


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Neurology_Adams. Chapter 27 discusses the developmental aspects of intelligence in more detail. One of the leading theories had been that of Piaget, who proposed that the emergence of intelligence is accomplished in discrete stages related to age: sensorimotor, from 0 to 2 years; preconceptual thought, from 2 to 4 years; intuitive thought, from 4 to 7 years; concrete operations (conceptualization), from 7 to 11 years; and, finally, the period of “formal operations” (logical or abstract thought), from 11 years on. This scheme implies that the capacity for logical thought, developing as it does according to an orderly timetable, is coded in the genes. Surely, one can recognize these states of intellectual development in the child, but Piaget’s theory has been criticized as being anecdotal and lacking the quantitative validation that could be derived only from studies of a large normal population. Furthermore, it does not take into account an individual’s special abilities, which do not usually develop


Neurology_Adams

Neurology_Adams. validation that could be derived only from studies of a large normal population. Furthermore, it does not take into account an individual’s special abilities, which do not usually develop and reach their maximum at the same time as the more general intellectual capacities.


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Neurology_Adams. One would suppose that neurology, embodying an understanding of so many diseases affecting the cerebrum, might make it possible to verify one of these several theories of intelligence and to determine the anatomy of this cognitive entity. Presumably, Spearman’s g factor of intelligence would be maximally impaired, by diffuse lesions, in proportion to the mass of brain involved, an idea expressed by Lashley as the “mass-action principle.” Indeed, according to Chapman and Wolff, there is a correlation between the volume of brain tissue lost and a general deficit of cerebral function. Others disagree, claiming that no universal psychologic deficit can be linked to lesions affecting particular parts of the brain. Probably the truth lies between these two divergent points of view. According to Tomlinson and colleagues, who studied the effects of vascular lesions in the aging brain, lesions that involved more than 50 mL of tissue caused a moderate general reduction in performance,


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Neurology_Adams. to Tomlinson and colleagues, who studied the effects of vascular lesions in the aging brain, lesions that involved more than 50 mL of tissue caused a moderate general reduction in performance, especially in speed and capacity to solve problems. Piercy, on the other hand, found correlations only between specific intellectual deficits and lesions of particular parts of the left and right hemispheres. It is important to acknowledge, for example, that lesions of the frontal lobes, and particularly the prefrontal regions, which disorder planning and “executive” functions, do not measurably affect overall IQ but do, of course, slow mental processing and degrade subtests specific to these skills. These problems are discussed in Chap. 21 on the localized functions of the cerebral cortex.


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Neurology_Adams. The authors conclude from experience and from evidence provided by neurologic studies that intelligence consists of a combination of multiple primary abilities, each of which may be inherited and each of which has a separate but poorly delineated anatomical representation. Yet we would disagree with both Thurstone and Gardner that these special abilities are of equivalent weight with regard to what is generally considered as “intelligence.” When viewed in the light of the classics of literature, history, and science, some of them, namely linguistic and mathematical, and perhaps spatial–dimensional abilities, are more closely integral to ideation and problem solving. Furthermore, they are affected most in the developmentally delayed and lost early in dementing diseases. To the extent that facility with general mental performance, that requiring the manipulation of abstract symbols and thoughts, marks an individual as “intelligent” and that these correlate with each other, we find


Neurology_Adams

Neurology_Adams. that facility with general mental performance, that requiring the manipulation of abstract symbols and thoughts, marks an individual as “intelligent” and that these correlate with each other, we find Spearman’s g factor to be a credible but still not satisfying concept for intelligence.


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Neurology_Adams. Neurologic data, while unable to locate the sources of a general factor for intelligence certainly does not exclude its possibility—one that is unavoidably measured in many different tests of cerebral functions. It is expressed if the connections between the frontal lobes and other parts of the brain are intact as attention, drive, and motivation are noncognitive psychologic attributes of fundamental importance to performance reside in this lobe. It is also possible, if not likely, that the parietal lobe associative areas of the cerebrum are engaged in the processing of sensory experiences and their manipulation in symbolic form. This applies equally to the ability to relate thoughts to each other and to stored concepts, but here, memory, symbols, and names, requiring the full function of the temporal lobes, play a central role. The interrelationships between some of these special abilities had been thoughtfully analyzed by Luria (see also the section on frontal lobes in Chap. 21). An


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Neurology_Adams. the temporal lobes, play a central role. The interrelationships between some of these special abilities had been thoughtfully analyzed by Luria (see also the section on frontal lobes in Chap. 21). An account of the subject of IQ and intelligence can also be found in the monograph by Mackintosh.


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Neurology_Adams. An equivalently complex problem arises in the neurologic analysis of the highest human achievement and the method of human advancement, namely creativity. In some ways, creativity is tied to special skills along the lines of Gardner’s modality-based intelligence, particularly as it relates to artistic work, but the brain structures involved in aesthetics and abstraction are obscure, as Zeki points out. Some insight is gained from the fact that intelligence and problem-solving ability are only roughly tied to creativity and that there are congenital absences and deficiencies of appreciation of visual, artistic, or mathematical skills. The capacity to be creative may be inhibited by other functions of the brain, as exposed in the case described by Seeley and colleagues of a woman with frontotemporal dementia whose artistic abilities emerged as her facility with language deteriorated. As pointed out in the following chapter, like intelligence, traits such as creativity almost certainly


Neurology_Adams

Neurology_Adams. dementia whose artistic abilities emerged as her facility with language deteriorated. As pointed out in the following chapter, like intelligence, traits such as creativity almost certainly do not reside in a particular lobe or structure of the brain and may depend on the overdevelopment of certain associative areas, as well as on frontal lobe drive and, of course, are fully manifest only by exposure and encouragement.


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Neurology_Adams. Dementia is a syndrome comprising the loss of several separable but overlapping intellectual abilities. It therefore presents in a number of different combinations. These constellations of intellectual deficits constitute the preeminent clinical abnormalities of a large number of cerebral diseases and are sometimes virtually the only abnormalities. Table 20-1 lists the most common types of dementing diseases and their relative frequency.