Aphasia and Anosognosia PDF

CHAPTER 8 APHASIA AND ANOSOGNOSIA Since the inception of the discipline of neurology in the For most people, cerebral hemisphere dominance 19th century, neurologists have studied language, lan- extends to control of fine, precise, rapid hand movemen...

CHAPTER 8 APHASIA AND ANOSOGNOSIA Since the inception of the discipline of neurology in the For most people, cerebral hemisphere dominance 19th century, neurologists have studied language, lan- extends to control of fine, precise, rapid hand movements guage impairment (aphasia), and related disorders to (handedness) and, to a lesser degree, reception of vision deduce how the normal brain functions and to advance and hearing. For example, right-handed people not only linguistics studies. In practice, they test for language- use their right hand for writing and throwing a ball, they related disorders, often quite striking in their presenta- use their right foot for kicking, right eye when peering tion, to help localize and diagnose neurologic disease. through a telescope, and right ear for listening to words Aphasia appears prominently in many neurologic and spoken simultaneously in both ears (dichotic listening). psychiatric disorders, and can disrupt cognition and halt The superior temporal gyrus – the planum temporale fundamental mental functions. Nevertheless, it does not – is distinctive in its exception to the general left–right have a separate category in the Diagnostic and Statistical anatomic symmetry of the brain. Its cortex in the domi- Manual of Mental Disorders, 5th Edition (DSM-5). The nant hemisphere has a much greater area than its non- DSM-5 only includes Language Disorder as one of the dominant counterpart because it has more gyri and Neu­rodevelopmental Disorder and Aphasia as a potential deeper sulci. The relatively large cortical area of the component of Neurocognitive Disorders. dominant planum temporale provides greater language capacity. It probably also allows for greater musical ability because it is larger in musicians than nonmusicians, and LANGUAGE AND DOMINANCE largest in musicians with perfect pitch. However, this normal asymmetry is lacking or even reversed in many The dominant hemisphere, by definition, governs language individuals with dyslexia, autism, Tourette disorder, and function and houses the brain’s language centers. The chronic schizophrenia – conditions with prominent lan- dominant hemisphere’s perisylvian language arc (see later) guage abnormalities. processes the most basic aspects of language, including language production and comprehension, reading, and writing. In its association areas, the dominant hemisphere HANDEDNESS also integrates language with intellect, emotion, and somatic, auditory, and visual sensations. Because of these About 85% of all people are right-handed and corre- crucial roles, the dominant hemisphere serves as the spondingly left hemisphere-dominant. In addition, most brain’s main portal for comprehension and expression of left-handed people are actually left hemisphere-dominant cognitive activity and emotions. or have mixed dominance. Language development begins in infancy, which is also Of people who are left-handed (old English lyft, weak, the period of greatest brain plasticity (ability to undergo foolish; compare Latin sinister and French gauche), some remodeling). By 5 years of age, the brain establishes have sustained an often undiagnosed congenital injury to dominance for language. Afterwards, as vocabulary, their left hemisphere that forced their right hemisphere verbal nuance, and intellectual complexity increase, plas- to assume dominance. Compared to right-handed people, ticity declines. For example, once past puberty, children left-handed ones are over-represented among individuals usually cannot learn a new (second) language without with overt neurologic impairment, such as intellectual dis- preserving traces of their native (primary) language. Also ability and epilepsy, and certain major psychiatric disor- once a person has reached this stage, the nondominant ders, such as schizophrenia and autism spectrum disorder. hemisphere can no longer assume a meaningful role in Moreover, left-handed children are over-represented language recovery following injury of the dominant among those with many neuropsychologic abnormalities, hemisphere. including dyslexia, other learning disabilities, and stutter- The dominant hemisphere controls languages learned ing. Economic studies have found that left-handed in infancy, but it does not necessarily control those workers earn approximately 10% less than right- learned as adults, including a second language. Nor does handed ones. Psychologic studies have found that left- it monitor obscenities, which are usually expressions handed compared to right-handed individuals scored of emotion. The nondominant hemisphere governs approximately 10% lower on cognitive testing except if prosody, which consists of speech’s inflection, rhythm, and the individual’s mother was also left-handed, in which tone. Prosody is closely related to speech’s affective com- case the left-handed ones showed no difference. ponent (see later). Interestingly, certain prosodic and However, in certain endeavors, being left-handed seems visual-spatial aspects of language, which are critical to confer some advantages. Left-handed people are dispro- in tone-dependent languages (such as many East Asian portionately over-represented among musicians, artists, and African languages) and sign language, respectively, mathematicians, athletes, and recent US presidents. In the depend on the dominant hemisphere. last several decades, left-handed presidents have included 151 152 SECTION 2 MAJOR NEUROLOGIC SYMPTOMS Gerald Ford, George H. Bush, Bill Clinton, Barack Obama, an observation that has been utilized in approaches to and, on most occasions, Ronald Reagan. In contrast, Jimmy rehabilitation of aphasia (melodic intonation therapy). Carter and George W. Bush were right-handed. Also, left- handed athletes tend to perform better than right-handed ones in sports involving direct confrontation, such as base- APHASIA ball, tennis, table tennis, fencing, and boxing. Only a small fraction of their benefit comes from tactical advantages, The Perisylvian Language Arc such as a left-handed batter standing one or two steps closer to first base. However, left-handed athletes achieve Impulses conveying speech, music, and other sounds no greater success in sports without direct confrontation, travel from the ears along the acoustic (eighth cranial) such as swimming and running. nerves into the brainstem where they synapse in the Unlike right-handed individuals, left-handed ones can medial geniculate body. Crossed and uncrossed brain- develop aphasia after injury to either cerebral hemi- stem tracts bring the postsynaptic impulses to the primary sphere. In addition, if left-handed individuals develop auditory cortex, Heschl’s gyri, in each temporal lobe (see aphasia, its subtype relates less closely to the specific Fig. 4.16). Most music and some other sounds are pro- injury site (see later), and their prognosis is better than if cessed in the nondominant hemisphere. In contrast, the right-handed individuals develop a comparable aphasia. brain transmits language impulses to Wernicke’s area, These observations support the idea of mixed hemi- which is situated in the dominant temporal lobe. From spheric dominance in left-handed individuals. there, they travel in the arcuate fasciculus, coursing poste- Ambidextrous individuals, who presumably have mixed riorly through the temporal and parietal lobes, and then dominance and are endowed with language, music, and anteriorly to Broca’s area in the frontal lobe. During its motor skill function in both hemispheres, tend to excel loop, the arcuate fasciculus allows communication with in sports and performing with musical instruments. areas of the brain involved in all other functions. Broca’s Sometimes neurologists need to determine a patient’s area, its terminus, is a vital language center located imme- cerebral dominance. For example, when neurosurgeons diately anterior to the motor center cortex representing must resect a portion of the dominant temporal lobe the right face, larynx, pharynx, and arm (Fig. 8.1). It because it houses a tumor or generates focal seizures (see receives processed, integrated language impulses, con- Chapter 10), they must avoid resecting language and verts them to speech, and activates the adjacent motor memory areas. A devastating aphasia or memory impair- cortex. Wernicke’s area, the arcuate fasciculus, and Broca’s ment may complicate resection of an incorrect or too area form a horseshoe-shaped region of cerebral cortex large an area. Using the Wada test – essentially injections surrounding the Sylvian fissure that neurologists call the of amobarbital directly into a carotid artery – neurolo- perisylvian language arc. gists can establish which hemisphere is dominant. When Using the perisylvian language arc model, researchers the amobarbital perfuses the dominant hemisphere, it have established normal and abnormal language patterns. renders the patient temporarily aphasic. Similarly, perfu- Under normal circumstances, when people repeat aloud sion of one temporal lobe may cause temporary amnesia what they hear, auditory impulses go first to Wernicke’s if the other temporal lobe is already damaged. A more area, then pass through the arcuate fasciculus, and finally recent alternative, functional magnetic resonance imaging arrive in Broca’s area for speech production (Fig. 8.2A). (fMRI), which uses MRI to detect blood flow to a par- Reading aloud is a complicated variation of repeating ticular brain area while subjects perform a linguistic task, aloud because it requires both hemispheres and a learned may indicate which hemisphere is dominant. The rest system of transforming written symbols into sounds. As of this chapter assumes that the left hemisphere is people read, their visual pathways transmit impulses to dominant. the calcarine (visual) cortex in both the left and right occipital lobes (see Fig. 4.1). Impulses from the left visual field go to the right occipital cortex. Then those impulses MUSIC must travel through the posterior corpus callosum to reach the left (dominant) cerebral hemisphere. The Musically gifted people generally tend to process music, impulses that have crossed from the right visual cortex like language, in their dominant hemisphere. Those merge with those already in the left hemisphere’s parietal having perfect pitch – the ability to identify a tone in the lobe. Decoded, coherent language information then absence of a reference tone – display distinctive fMRI travels from the left parietal lobe via the arcuate fascicu- patterns when listening to music. If these people develop lus to Broca’s area for articulation (Fig. 8.2B). aphasia, they also lose a great deal of their musical ability. All along its path, the language arc maintains recipro- In contrast, the great majority of individuals possess- cal connections with cerebral cortical areas for memory, ing no particular musical ability rely on their nondomi- emotion, and other neuropsychologic domains. It also nant hemisphere to carry a tune. The proximity of their has strong connections with the thalamus, basal ganglia, musical and emotional systems, both in the nondominant and other subcortical structures. hemisphere, may explain the emotional effects music has on them. The primary location of music in the nondomi- nant hemisphere for most people may also explain Clinical Evaluation why many aphasic individuals, handicapped in language, Before diagnosing aphasia, the clinician must keep in often retain their ability to recognize music and to sing, mind normal language variations when examining a  8 APHASIA AND ANOSOGNOSIA 153 Motor strip Broca’s area Broca’s Motor area strip Angular gyrus Arcuate fasciculus Wernicke’s area FIGURE 8.1 In the standard model of language function, the dominant (left) cerebral hemisphere contains Wernicke’s area in the tem- poral lobe and Broca’s area in the frontal lobe. The arcuate fasciculus, the “language superhighway,” which connects these areas, curves posteriorly from the temporal lobe to the parietal lobe. It then passes through the angular gyrus and anteriorly to the frontal lobe. These structures surrounding the Sylvian fissure, which comprise the perisylvian language arc, form the central processing unit of the language system. Note the proximity of Broca’s area to the motor strip that innervates the muscles of the face, throat, arm, and hand. speaking, consider each word and formulate every phrase as though carefully considering which item to choose from a menu, but some blurt out the first thing that comes to their mind. In diagnosing aphasia, the clinician can use various classifications. One distinguishes receptive (sensory) from expressive (motor) aphasia based on relative impairment of language production versus comprehension. However, a A major drawback of that classification is that most aphasic patients display a mixture of impairments that does not permit a strict classification. The most useful classification of the aphasias, nonfluent versus fluent, rests on the quantity and grammatical cor- rectness of the patient’s verbal output (Table 8.1A). It suffices for clinical evaluations and roughly correlates with imaging studies. Aphasia pundits subdivide nonflu- ent aphasia and fluent aphasia each into four categories based primarily on the patient’s ability to comprehend, B repeat, and name objects. When repetition ability remains intact in either nonfluent or fluent category, neurologists FIGURE 8.2 A, When people repeat words aloud, language signals arrive in Wernicke’s area, located adjacent to Heschl’s add the designation transcortical. gyrus (see Fig. 4.16), and then travel through the parietal lobe in Clinicians usually detect aphasia in a patient during the the arcuate fasciculus to Broca’s area. This area innervates the introductory conversation, history taking, or mental status adjacent cerebral cortex for the tongue, lips, larynx, and pharynx. examination. They then perform a standard series of B, When people read aloud, visual signals travel to the left and right occipital visual cortex regions. Both regions send signals to simple verbal tests to identify and classify the aphasia. The a left parietal lobe association region (the oval), which converts tests systematically evaluate three basic language functions: text to language. Signals from the left visual field, which have comprehension, naming, and repetition (Box 8.1). Mildly initially traveled to the right cortex, must pass through the poste- affected patients may perform well with simple items but rior corpus callosum to reach the language centers (see Fig. 8.4). show difficulty with comprehension of more demanding materials, naming more uncommon objects, or repeating patient. Normal individuals may struggle and stammer more complicated phrases. The examiner may also perform when confronted with a novel experience, particularly a the same testing with written requests and responses; neurologic examination. Many people have their own however, with one notable exception, alexia without style and rhythm of speaking. Some may be reticent, agraphia (see later), defects in written communication gen- uneducated, intimidated, or hostile. Others, before erally parallel those in verbal communication. 154 SECTION 2 MAJOR NEUROLOGIC SYMPTOMS TABLE 8.1A Salient Features of the Nonfluent TABLE 8.1B Nonfluent Aphasias and Fluent Aphasias Comprehension Repetition Feature Nonfluent Fluent Broca’s Intact Lost Other terms Expressive Receptive Transcortical motor Intact Intact Motor Sensory Broca’s Wernicke’s Mixed transcortical (Isolation) Lost Intact Content Paucity of words, Complete sentences Global Lost Lost mostly nouns with normal and verbs syntax Articulation Dysarthric, slow, Good stuttering slow, effortful manner. Excessive pauses interrupt the Errors Telegraphic Paraphasic errors, flow of nonfluent speech. Neurologists sometimes speech circumlocutions, tangentialities, describe its jerky rhythm as “telegraphic.” For example, clang associations in response to a question about food, a patient might stammer “fork... steak... eat... no.” Depending on Associated Right hemiparesis Hemianopia, the variety of nonfluent aphasia, patients cannot repeat deficits (arm, face>leg) hemisensory loss simple phrases or name common objects. In contrast, Localization Frontal lobe Temporal or most patients with nonfluent aphasia retain relatively of lesion parietal lobe normal comprehension that can be illustrated by their Occasionally diffuse ability to follow simple verbal requests, such as “Please close your eyes” or “Raise your left hand, please.” Nonfluent aphasia’s four major subdivisions are the following (Table 8.1B): Broca’s aphasia: commonly occurring, classic nonflu- BOX 8.1 Clinical Evaluation for Aphasia ent aphasia with comprehension intact and repeti- Spontaneous speech: fluent versus nonfluent tion lost Verbal tests Transcortical motor aphasia: similar to Broca’s, but Comprehension repetition remains intact Ability to follow simple requests, “Please pick up your Mixed transcortical or isolation aphasia: with loss of hand.” comprehension but repetition remains intact Ability to follow complex requests, “Please show me Global aphasia: devastating, with loss of both com- your left ring finger and stick out your tongue.” prehension and repetition (see later). Naming Common objects: tie, keys, pen Uncommon objects: watchband, belt buckle Localization and Etiology Repetition Simple phrases: “The boy went to the store.” Lesions responsible for nonfluent aphasias usually Complex phrases: “No ifs, ands, or buts” encompass, surround, or sit near Broca’s area (Fig. 8.3A). Reading and writing tests Their etiology is usually a middle cerebral artery stroke or another discrete structural lesion. Their location, not their pathology, produces the aphasia. Whatever the eti- ology, these lesions tend to be so extensive that they damage neighboring structures, particularly the motor Nonfluent Aphasia cortex and posterior sensory cortex. Moreover, because Characteristics the lesions are usually spherical or conical, rather than superficial and two-dimensional, they damage underlying Paucity of speech characterizes nonfluent aphasia. white matter tracts, including the visual pathway. Diffuse Patients say little and usually only speak in response to cerebral injuries, such as anoxia, metabolic disturbances, direct questions. Whatever speech they produce consists or Alzheimer disease, rarely cause nonfluent aphasia. almost exclusively of single words and short phrases. They rely on basic words, particularly nouns and verbs Associated Deficits without proper conjugation. They cannot use the con- nective tissue of language, such as adjectives, adverbs, and Because the lesion causing nonfluent aphasia usually conjunctions. Their longer phrases typically consist of damages the adjacent motor cortex, right hemiparesis stock phrases or sound bites, such as, “Not so bad” or usually accompanies this aphasia. In such cases, the hemi- “Get out of here.” Synonyms for nonfluent aphasia paresis predominately affects the arm and lower face, and include “expressive” or “motor” aphasia because of the causes poor articulation (dysarthria). Deeper lesions also prominent impairment in language production. sever the visual pathway and can cause a right homony- Patients’ speech typically contains fewer than 50 mous hemianopia (see Chapter 12). One of the most words-per-minute, which is much slower than the normal common syndromes in neurology is an occlusion of the 100 to 150 words-per-minute, and they produce it in a left middle cerebral artery producing the combination of  8 APHASIA AND ANOSOGNOSIA 155 A B C D FIGURE 8.3 A, Lesions causing nonfluent aphasia are typically located in the frontal lobe and encompass Broca’s area and the adjacent cortex motor strip. B, Those causing fluent aphasia are in the temporoparietal region. Neurodegenerative illnesses may damage Wernicke’s areas and more posterior regions and cause fluent aphasia. C, Lesions causing conduction aphasia, which are relatively small, interrupt the arcuate fasciculus in the parietal or posterior temporal lobe. D, Those causing mixed transcortical (isolation) aphasia involve the watershed region, which encircles the perisylvian language arc. nonfluent aphasia and right-sided hemiparesis and hom- The signature of isolation aphasia is this disparity onymous hemianopia. between patients’ seeming muteness and their preserved Another nonlanguage consequence of the lesions is ability to repeat long and complex sentences. Patients buccofacial apraxia, also called “oral apraxia.” This apraxia who display such repetition, echolalia, mindlessly reiterate consists of the inability to execute normal voluntary visitors’ words readily, involuntarily, and sometimes com- movements of the face, lip, and tongue. When buccofa- pulsively. A cursory evaluation could understandably cial apraxia occurs in conjunction with nonfluent aphasia, confuse this disturbance with irrational jargon. it adds to the dysarthria. This aphasia usually stems from the loss of the precari- To test for buccofacial apraxia, the clinician might ask ous blood supply of the cerebral cortex. While major patients to say, “La.. Pa.. La.. Pa.. La.. Pa”; protrude branches of left middle cerebral artery perfuse the their tongue in different directions and pretend to blow perisylvian arc, only thin, fragile, distal branches of out a match and suck through a straw. Patients with buc- middle, anterior, and posterior cerebral arteries perfuse cofacial apraxia will be unable to comply, but they may its border with the surrounding cortex (watershed area). be able to use the same muscles reflexively or when pro- When these vessels deliver insufficient blood to this vided with cues. For example, patients who cannot speak portion of the cortex, it suffers a watershed infarction might sing, and those who cannot pretend to use a straw (Fig. 8.3D). Thus, cardiac or respiratory arrest, suicide might be able to suck water through an actual one. attempts using carbon monoxide, and hypoxic episodes Patients who suffer aphasia due to stroke or traumatic cause isolation aphasia. brain injury (TBI) generally improve to some extent. Damage to the entire remaining cortex usually causes Presumably, at least some ischemic areas of the brain cognitive impairment, usually to the point of dementia. recover and surviving neurons form new connections. It also usually causes decorticate posture (see Fig. 11.5). Mixed Transcortical or Isolation Aphasia Global Aphasia Some lesions, which must be diffuse and extensive, Extensive dominant hemisphere damage abolishes so damage the cerebral cortex surrounding the language arc. much language function that it results in an extreme form By sparing the language pathway, these lesions leave basic of nonfluent aphasia, known as global aphasia. Aside from language function intact but removed from other cogni- uttering some unintelligible sounds, patients with global tive functions. In mixed transcortical or isolation aphasia, aphasia remain mute. Although they can follow some which stems from such a cerebral injury, patients retain gestured requests, which bypass the language arc, they their ability to repeat whatever they hear; however, they cannot comply with verbal ones. They also lack emo- cannot interact in a conversation, follow requests, or tional responsiveness. name objects. Because these patients can characteristi- Comparably severe physical deficits – right hemiple- cally only duplicate long strings of syllables, neurologists gia, right homonymous hemianopia, and conjugate devia- consider them to have nonfluent aphasia. tion of the eyes toward the left – parallel the extensive 156 SECTION 2 MAJOR NEUROLOGIC SYMPTOMS language deficits. Causes frequently include internal tend toward tangential diversions or tangentialities, as carotid artery occlusions with extensive cerebral ische- though once having spoken the wrong word, they pursue mia, dominant hemisphere tumors, cerebral hemor- the idea triggered by their error. These patients, caught rhages, and gun-shot wounds. in a tangentiality, may string together meaningfully Global aphasia patients can sometimes express them- related words until they reach an absurd point. For selves with left-hand gestures and shoulder shrugs. They example, when attempting to name a pencil, the patient may even be able to comply with some nonverbal requests, may say, “pen … pence … paper … papal …” such as gestures. Their communication, albeit limited Despite their loss of verbal communication, patients’ and silent, distinguishes them from patients with psycho- nonverbal expressions are preserved because nondomi- genic mutism. nant hemisphere functions remain unaffected. For example, patients’ prosody remains consistent with their mood. Patients continue to express their feelings through Fluent Aphasia facial gestures, body movements, and cursing. Similarly, Fluent aphasia’s four major subdivisions are the following most patients retain their ability to produce a melody (Table 8.1C): even though they may be unable to repeat the lyrics. For Wernicke’s aphasia: common, with loss of compre- example, patients might hum a tune, such as “Jingle hension, naming, and repetition Bells,” but if they attempt to sing it, paraphasias crop up Transcortical sensory aphasia: similar to Wernicke’s in the middle of the lyrics. except repetition remains intact Anomic aphasia: inability to name objects Associated Deficits Conduction aphasia: inability to repeat. Of them, Wernicke’s aphasia is the epitome and most Unlike in nonfluent aphasia, hemiparesis and other cor- common subdivision. Its characteristic is paraphasic errors ticospinal tract signs do not accompany fluent aphasia or paraphasias, which are incorrect, meaningless, or even because the responsible lesion is distant from the cerebral nonsensical words. Patients insert paraphasias into rela- cortex motor strip. For example, neurologists typically tively complete, well-articulated, grammatically correct elicit right-sided hyperactive deep tendon reflexes (DTRs) sentences that are spoken at a normal rate. However, para- and a Babinski sign, but not hemiparesis, in fluent aphasia phasias may render their conversation unintelligible. More- patients. However, they may detect a right-sided sensory over, patients typically cannot fully comprehend language impairment or visual field cut because the underlying nor repeat simple phrases. Patients with its less severe lesions often interrupt sensory or visual cerebral path- variant, transcortical sensory aphasia, can repeat phrases, but ways in the parietal lobe. otherwise their language impediments are similar. Fluent aphasia patients are often strikingly unaware of Paraphasias most often consist of a word substitution, their paraphasias, unable to edit them, and oblivious to such as “clock” for “watch” or “spoon” for “fork” (related their listener’s consternation. Sometimes these patients, or semantic paraphasia), in which the substitute word arises frustrated by their inability to communicate, develop from the same category. Less commonly, the words anxiety, agitation, or paranoia. Clinicians not finding any involved have little relation, such as “glove” for “knife” hemiparesis and unable to capture the patient’s attention (unrelated paraphasia); or a nonspecific relation, such as for sensory or visual field testing often do not appreciate “that” for any object (generic substitution). Paraphasias the neurologic basis of their patient’s abnormal language, may also consist of altered words, such as “bed” for thought, or behavior. For many psychiatry liaison con- “bread” (phonemic paraphasia). sultations, the sudden onset of fluent aphasia often Furthermore, paraphasias may include nonsensical explains a patient’s anger, acute psychosis, consternation, coinages (neologisms), such as “I want to fin the gunt in change in behavior, or management confrontations. Con- the fark.” Patients can bounce from one word to another versely, the “gibberish” of fluent aphasia may mimic the with a similar sound, but one with little or no shared speech of a psychotic patient (see later). meaning (clang associations, from the German klang, sound). For example, a patient making a clang association Localization and Etiology might ask, “What’s for dinner, diner, slimmer, thinner?” As if to circumvent their word-finding difficulty, fluent Small discrete structural lesions, such as strokes, in the tem- aphasia patients often speak in circumlocutions. They also poroparietal region are the usual cause of Wernicke aphasia and fluent aphasias in general (see Figs. 8.3B and 20.16). In addition, neurodegenerative illnesses, particularly Alzheimer disease and neurocognitive disorder due to frontotemporal lobar TABLE 8.1C Fluent Aphasias degeneration (frontotemporal dementia, see Chapter 7), often cause fluent aphasia among other symptoms. Comprehension Repetition Wernicke’s Lost Lost Anomic Aphasia Transcortical sensory Lost Intact A variety of fluent aphasia, anomic aphasia or anomia, is Conduction Intact Lost simply inability to name objects. Patients often cannot Anomic Intact Intact name objects, but at times, using a paraphasia, they offer substitutes and they usually can demonstrate the function  8 APHASIA AND ANOSOGNOSIA 157 of the object. For example, they can use a pencil or a routine communications – saying the date and place, comb, but cannot say that it is a pencil or a comb. Com- repeating a series of numbers, and following requests – it prehension and repetition remain intact. mimics dementia. At times, patients with aphasia seem so Small strokes, because they are so common, are the bizarre that they appear incoherent. Because people think most frequent causes of anomic aphasia. Less often, neu- in words, aphasia also clouds cognition and memory. rodegenerative illnesses cause it. For patients with neu- Dementia and aphasia also differ in their time course. rodegenerative illnesses, anomic aphasia rather than Dementia develops slowly, but aphasia begins abruptly, dementia or simply memory impairment sometimes except in the infrequent case when it heralds a neurode- explains inability to name the current month or familiar generative illness. Nonfluent aphasia further differs from places, objects, and people. Thus, these patients may dementia in its accompanying physical aspects: dysarthria perform poorly on a mental status test because of aphasia and obvious lateralized signs, such as a right-sided hemi- rather than dementia. paresis and homonymous hemianopia. Moreover, para- phasias occur frequently in fluent aphasia but rarely in dementia. Conduction Aphasia Nevertheless, patients occasionally have both aphasia In contrast to lesions that damage Broca’s or Wernicke’s and dementia. This combination occurs with one or more areas, lesions occasionally damage only the tract – the strokes superimposed on neurocognitive disorder due to arcuate fasciculus – that connects them. Such a critically Alzheimer disease. It routinely develops in frontotemporal situated lesion interrupts the language arc and produces lobar degeneration. These situations defy classification conduction aphasia. (Neurologists consider conduction because aphasia usually invalidates standard cognitive aphasia as one of the disconnection syndromes [see later].) testing. Conduction aphasia patients, who remain fluent and Distinguishing aphasia from dementia and recogniz- retain comprehension, cannot repeat short sentences or ing when the two conditions coexist are more than aca- even short phrases. Their deficit is the opposite of patients demic exercises. A diagnosis of aphasia usually suggests with isolation aphasia. that a patient has had a discrete dominant cerebral hemi- The most frequent cause of conduction aphasia is an sphere injury. Because a stroke or other structural lesion embolic stroke in the parietal or posterior temporal would be the most likely cause, the appropriate evalua- lobe (Fig. 8.3C). Infarctions that cause conduction tion would include a computed tomography (CT) or aphasia are usually so small that they produce little or no magnetic resonance imaging (MRI). In contrast, a physical deficit. At worst, patients show right lower facial diagnosis of dementia suggests that the most likely weakness. cause would be a neurodegenerative illness and the evaluation would include various blood tests as well as a CT or MRI. MENTAL ABNORMALITIES WITH LANGUAGE IMPAIRMENT Schizophrenia Distinguishing fluent aphasia from schizophrenic speech Comorbid Depression can, theoretically at least, prove even more troublesome. Psychiatrists face obstacles when assessing the mood of Circumlocutions, tangential diversions, clang associa- aphasic patients because they tend to appear apathetic, tions, and neologisms are common manifestations. As cannot freely communicate, and offer potentially mis- the thought disorder of schizophrenia develops, its leading facial expressions. Aphasic patients who appear language abnormalities increase in frequency and simi- depressed may actually be manifesting underlying demen- larity to aphasia. In a different situation, previously tia or pseudobulbar palsy. For example, following one or healthy people suddenly developing aphasia can be so more strokes, patients may have aphasia along with frightened and confused that they become agitated and dementia or poststroke depression (see Chapter 11). In irrational. another example, lesions damaging both frontal lobes Despite these confounding elements, clinicians can reduce patients’ expression to a paucity of speech, discern many differences. Schizophrenic speech generally emotion, and responsiveness. develops gradually in patients who are usually in their However, physicians cannot attribute depression with third through fifth decades and have had long-standing comorbid aphasia entirely to brain damage. Most nonflu- psychiatric illness. Their neologisms and other parapha- ent aphasia patients remain aware of their impairments. sias occur infrequently and tend toward the inconspicu- They have suddenly lost their ability to communicate – a ous. Unlike most patients with fluent aphasia, those major loss. They naturally feel sad, hopeless, and frus- with schizophrenia can repeat polysyllabic words and trated. Treatment of depression comorbid with aphasia complex phrases. should follow the same strategies as treatment of depres- In contrast, aphasia usually appears suddenly in indi- sion without the comorbidity. viduals in their seventh or eighth decade, often with other risk factors for stroke. Except for some patients with fluent aphasia, most patients with aphasia retain aware- Dementia ness that they cannot communicate and they very often Although aphasia is not equivalent to dementia, it can request help. Also, possibly because of self-monitoring, mimic dementia. For example, when aphasia impairs patients with aphasia keep their responses short and 158 SECTION 2 MAJOR NEUROLOGIC SYMPTOMS pointed. Any right-sided hemiparesis or hemianopia more complexities (irregular verbs, multiple tenses) clinches the diagnosis. produce the greatest prevalence of dyslexia. Therefore, developmental dyslexia is most prevalent in English- speaking children, less prevalent in French-speaking chil- Other Disorders dren, and even less so in Italian-speaking children. Children with autism may demonstrate language impair- Moreover, developmental dyslexia occurs in 80% of all ment – not only in their verbal expression, but also in children with learning disabilities. Teachers usually detect their facial and bodily communication, such as failure to it when children first try to read, but mild forms may point. In many cases, nonsensical repetitions (stereoty- escape detection until high school or college when stu- pies), idiosyncrasies, and echolalia overwhelm their dents confront complicated reading tasks. In up to about speech. Also, they often fail to appreciate the nuance and 25% of children and, to a lesser extent, in some adults, affective components of language. developmental dyslexia is co-morbid with attention- Several clear-cut pediatric neurologic illnesses may deficit/hyperactivity disorder (ADHD). Developmental present with language impairment in children and must dyslexia persists throughout life, but some strategies ame- be considered when assessing children for autism. In girls liorate or circumvent the problem. with Rett syndrome, language characteristically regresses Developmental dyslexia affects boys with dispropor- after several years of normal development (see Chapter tionate severity and frequency, such that the boy : girl 13). Similarly, language regression accompanied by ratio lies between 2 : 1 and 5 : 1. Most dyslexic children seizures characterizes Landau–Kleffner syndrome (see come from families where other members also have Chapter 13). the disorder. In general, the incidence of dyslexia in Mutism and other apparent language abnormalities children is 25% if a sibling has the disorder, 50% if are frequently manifestations of conversion disorder and one parent has it, and 75% if both parents have it. related disturbances (see Chapter 3). In these cases, the Studies have implicated autosomal dominant and sex- apparent language impairment is usually inconsistent and linked genes. Imaging and pathologic studies reveal amenable to suggestion. Acquired stuttering also often that the brains of some dyslexic individuals, especially indicates a psychogenic disturbance. For example, a boys, lack the normal planum temporale asymmetry. patient with psychogenic aphasia might stutter and seem In other words, their brains are symmetric, which to be at a loss for words, but communicate normally by is abnormal. writing. An amobarbital interview might reveal perfectly In older children and adults, strokes, trauma, or other intact language function. lesions of the dominant hemisphere may suddenly impair A common psychogenic aphasia-like condition is the reading ability. Neurologists call this condition acquired sudden, unexpected difficulty in recalling the name dyslexia. In contrast to developmental dyslexia, acquired (blocking) of someone who triggers a strong emotional dyslexia is usually a component of aphasia. Thus, right- response. The classic aphasia-like condition remains sided motor deficits including agraphia (inability to write) the Freudian slip, originally known as a parapraxis. Freud’s accompany acquired dyslexia (but see the next section for work on aphasia, which presaged his exploration of an important exception). Also, schizophrenic patients the unconscious, described his view of language circuitry have a significant incidence of dyslexia. and then words spoken “in error” actually as a manifesta- tion of a repressed wish or conflict. Depending on Alexia and Agraphia their viewpoint, clinicians who assess everyday word substitutions may term them either paraphasias or In the exception, alexia without agraphia (Fig. 8.4), patients insights into the unconscious. For example, when a physi- suddenly find that they can no longer read. Despite this cian’s former secretary, suspected of harboring a neuro- deficit, they have little or no impairment in comprehend- logic disorder, says that she has been Dr. So-and-So’s ing speech or expressing themselves verbally or by “medical cemetery,” a clinician could interpret the writing. They can transcribe another person’s dictation comment as either her feelings about the competence of and write their own thoughts, but then they cannot read the doctor, an indication of the patient’s own fears of their own handwriting. Alexia without agraphia (which death, or a paraphasia referable to a dominant hemi- should be called “alexia with intact graphia” to avoid the sphere lesion. double negative) usually results from a stroke or other destructive lesion encompassing the dominant (left) occipital lobe and adjacent posterior corpus callosum (the DISORDERS RELATED TO APHASIA splenium). Aside from having a right homonymous hemi- anopia, patients remain physically intact. In contrast, Dyslexia agraphia almost always accompanies alexia in develop- mental dyslexia. In most cases, reading impairment despite normal or near-normal intelligence and education represents a developmental disorder, Developmental Dyslexia (Greek, Gerstmann Syndrome lexis, word or phrase), which falls into the DSM-5 cate- Gerstmann syndrome, a classic disorder that may appear in gory of Specific Learning Disorders. When tested, children and adults, consists of four neuropsychologic approximately 10% of all United States schoolchildren disturbances: acalculia (impaired arithmetic skills), finger display some developmental dyslexia. Languages with agnosia (inability to identify fingers), left/right confusion,  8 APHASIA AND ANOSOGNOSIA 159 TABLE 8.2 Testing for Ideomotor Apraxia Action Gesture* Imagined Real Buccofacial Kiss the Pretend to blow Blow out a air out a match match L R Repeat Pretend to suck Drink water “Pa” on a straw through a straw Limb Salute Pretend to use Comb the hair a comb Stop Pretend to Write with a traffic write pencil or pen *Symbolic acts FIGURE 8.4 Lesions that damage the left occipital lobe and the posterior corpus callosum (the splenium) cause alexia without objects (pantomime) and then on actual ones. After seeing agraphia. Patients are unable to see anything in their right visual field because of the left occipital cortex damage. Images in their the examiner perform an action, patients with apraxia left visual field still reach their right cortex, but their signals typically can copy it. For example, a patient with apraxia cannot reach the left cerebral language centers because the might be unable to follow the request, “Please pretend damaged splenium blocks neurotransmission. With obstacles in to salute an officer,” but after the examiner demonstrates both information routes (the right visual field cut and transfer the salute, the patient will duplicate it. Similarly, when of information to the dominant hemisphere), patients cannot read written material presented to either visual field. In contrast, patients with apraxia are handed an actual object, which they can still write full sentences from memory, imagination, or gives them a cue, they can often perform the object’s dictation because these forms of information still reach the intended action. For example, a patient with apraxia language centers. might be unable to pretend to use a comb, but when presented with one, the patient will readily comb his hair. As a general rule, inability to use a common tool, such and agraphia. When all four elements occur, neurologists as a comb or spoon, most reliably demonstrates apraxia. usually attribute the syndrome to a stroke or other lesion Further testing, depending on circumstances, includes in the angular gyrus of the dominant parietal lobe (see performing a series of steps, copying figures, arranging Fig. 8.1). matchsticks, walking, or dressing. Some neurologists question the existence of this syn- Patients typically remain unaware of their apraxia drome as a distinct clinical entity, because patients rarely because they usually do not spontaneously attempt the display all of its components and those with three or all various tests, such as saluting an unseen officer or using four components usually also have aphasia or other neu- an imaginary screwdriver. Moreover, an unsophisticated ropsychologic impairment. Nevertheless, even if the four clinician might incorrectly attribute the impairment to elements do not constitute a syndrome, they are fre- paresis, incoordination, or dementia. quently comorbid with each other and with subtle phys- Despite its complexity, neurologists designate several ical signs of dominant hemisphere injury, such as clinically useful categories of apraxia. Ideomotor apraxia, right-sided hyperactive DTRs and a Babinski sign. the most common category, consists essentially of the inability to convert an idea into an action. For example, Apraxia patients with ideomotor apraxia cannot pantomime despite possessing a clear understanding and retaining Apraxia, the motor system’s rough equivalent of aphasia, the physical ability to comply. Clinicians might envision is inability to execute learned actions despite normal ideomotor apraxia as the result of a disconnection between strength, sensation, and coordination. Neurologists attri- cognitive or language regions and motor regions bute apraxia to disruption of links between the cere- (Fig. 8.5). Almost invariably, a left-sided frontal or pari- brum’s motor and neuropsychologic centers, particularly etal lobe lesion is responsible for this variety of apraxia. the perisylvian language arc and frontal lobe executive Thus, ideomotor apraxia often coexists with aphasia, par- centers. ticularly nonfluent aphasia, and inability of the right hand Although apraxia can be readily differentiated from to pantomime. simple paresis, it is often comorbid with aphasia or Another variety, buccofacial apraxia, as previously dis- dementia. In fact, apraxia often appears as a symptom of cussed, is a feature of nonfluent aphasia. In limb apraxia, Alzheimer disease and other cortical dementias (see patients cannot execute simple requests usually involving Chapter 7). their right arm or leg. They cannot pretend to brush their In assessing patients for apraxia, the examiner usually teeth, turn a key, comb their hair, or kick a ball. When first tests their buccofacial (lips, face, tongue) and limb asked to pretend to use an object, these patients charac- movements when they attempt to make gestures or teristically use their hand as though it were the actual perform “symbolic acts” (Table 8.2). Next, the examiner object. For example, they will brush their teeth with their asks them to perform certain actions, first on pretend forefinger instead of pretending to hold a toothbrush. 160 SECTION 2 MAJOR NEUROLOGIC SYMPTOMS The onset of nondominant hemisphere syndromes often leaves patients perplexed because they cannot appreciate their situation. More than with other cerebral injuries, patients with nondominant hemisphere lesions turn to classic defense mechanisms. Most often, they deny – implicitly or explicitly – that they have hemipare- sis, visual loss, or other neurologic deficit. For example, patients who have just developed left hemiplegia will L R continue to use their left hand despite its uselessness and either say that they do not know why their actions are not producing any effect or claim that they are perform- ing the task. Using projection in a conflict between their own self-image and the reality of having a brain tumor- induced hemiparesis, such patients may declare that their deficit is really a roommate’s who sustained a stroke. Patients may also rationalize their problem. For example, when asked why he did not move his left arm, one patient FIGURE 8.5 In a schematic axial view, requests for normal stated, “I don’t want to. If I wanted to move it, I would.” movements travel to Wernicke’s area in the left posterior tem- Another stroke victim explained that she did not move poral lobe. They then travel anteriorly to the motor regions and, her arm because of pain, not paresis, and that if her through the anterior corpus callosum, to the contralateral motor doctors gave her adequate pain relief, she would be able strip. Interruptions of the path within the left cerebral hemi- sphere result in bilateral ideomotor limb apraxia. Lesions in the to move it. Sometimes laughing off the deficit, patients anterior corpus callosum interrupt only those signals destined dispassionately avoid dealing with their loss of body func- to control left arm and leg movements, which causes unilateral tion and its implications. left arm and leg ideomotor apraxia. Whatever the reason that patients cannot accept a neurologic deficit, their misperceptions prevent them from complying with hospital routines. Patients with In ideational apraxia, patients cannot conceive and then nondominant hemisphere syndromes frequently refuse to perform a sequence of steps. For example, they cannot participate in rehabilitation programs because they feel pretend to fold a letter, place it into an envelope, address no need for them and participating would force them to the envelope, and then affix a stamp. In contrast to ideo- confront their deficits. Implicitly or explicitly denying motor apraxia, which is associated with nonfluent aphasia, their deficits also leads to potentially dangerous behavior, ideational apraxia is almost inseparable from dementia. such as when patients with a left homonymous hemiano- In particular, ideational apraxia is a hallmark of frontotem- pia plan to drive home. Patients often refuse to make poral lobar degeneration where it reflects executive dys- realistic discharge plans and insist on premature hospital function. Alzheimer disease and multiple strokes, because discharge. Even if encounters with medical staff and they lead to dementia and impaired planning and execu- family do not precipitate a catastrophic reaction, patients tion, typically cause ideational apraxia. with nondominant disorders tend to be bellicose when In the next section of this chapter, this book covers conversations address their illness, deficit, and need for construction apraxia and dressing apraxia, which are typi- realistic plans. cally manifestations of nondominant hemisphere lesions. It has already covered gait apraxia in the discussion of normal-pressure hydrocephalus (see Fig. 7.8). Hemi-Inattention A patient with nondominant hemisphere damage may ignore visual, tactile, and other sensory stimuli that origi- NONDOMINANT HEMISPHERE SYNDROMES nate from their left side (Fig. 8.6). For example, visual inattention, a variety of hemi-inattention or hemineglect, Symptoms arising from nondominant hemisphere injury occurs when patients disregard, fail to perceive, or mis- tend to be subtle, predominantly neuropsychologic, and interpret objects in their left visual field (Fig. 8.7). Some- apparent in several well-known syndromes. Detecting times people leave food on the left side of plates, and men them requires considerable clinical acumen and gentle with this condition leave the left side of their face probing. Physicians confronting patients risk precipitat- unshaven. A patient asked to draw a clock may place all ing a catastrophic reaction. 12 numerals on the right side (see Chapter 7, Questions The cause is almost always a structural lesion, such as and Answer, Question 67). In contrast, patients with trauma, stroke, or malignant tumor that has rapidly homonymous hemianopia usually develop some aware- developed in the nondominant parietal or frontal lobe ness of their deficit and make compensatory eye move- cortex, underlying thalamus, and reticular activating ments to keep objects in the preserved visual field. system. Corticobasal degeneration, a rare neurodegen- Another manifestation of hemi-inattention – extinction erative illness, also may attack these regions and cause the on double simultaneous stimulation (DSS) – occurs when an symptoms. Alternatively, corpus callosum lesions may examiner touches both sides of a patient’s body, but the produce some symptoms. Whatever the pathology, it patient pays no attention to the left-sided stimulation. impairs spatial attention. For example, when the examiner touches the left arm, the  8 APHASIA AND ANOSOGNOSIA 161 A A B G K A K Y P A U P W A L H F A P B A M A Y G J V D A L V A J A K F S T E C I B S A D A U B C A E A C FIGURE 8.6 Simple bedside tests for hemi-inattention. A, The examiner has asked the patient, who has just sustained a right middle cerebral infarction, to bisect a horizontal line. The patient, neglecting a portion of the line’s left side, draws the vertical line off-center to the right and bisects only the line’s perceived segment. B, Then the examiner asks the patient to circle all the “A”s on the page. Again neglecting the left side of the page, the patient circles only those on the right. C, An examiner has asked a 4-year-old boy, recovering from right parietal trauma, to draw a man. Because of a combination of hemi-inattention and constructional apraxia (see later), he merely scribbles on the right side of the paper. (A normal 4-year-old’s drawing of a man is expected to a have a head, eyes, arms, and legs.) 162 SECTION 2 MAJOR NEUROLOGIC SYMPTOMS 2 And now? 1 What am I wearing? (still) White coat 3 Now? White coat You’ve removed the white coat. I see a striped shirt. FIGURE 8.7 In a classic demonstration of left visual inattention, in the “white coat test” the patient disregards the left-sided stimula- tion and perceives only the examiner’s clothing in his right visual field. If the patient’s problem were simply a left homonymous hemianopia, he still would have explored and discovered, with his intact right visual field, that the examiner was half-dressed. patient correctly reports that it was touched, but when undressed. In extreme cases, they completely fail to dress. the examiner touches both arms, the patient reports that Patients may not merely leave their left limbs out of their only the right one was touched. Another example of DSS shirts and pants, they may put both hands into one sleeve, can occur with visual stimulation. A patient might cor- misalign buttons, and become befuddled when presented rectly perceive hand movement in the left visual field, but with their clothing turned inside out (see Additional when the examiner simultaneously waves hands in both Review Questions and Answers, Question 299). More- visual fields, the patient would report seeing it only in the over, patients remain unaware that their clothing is right-sided field. disheveled. Even though their dressing apraxia includes hemi-inattention and other perceptual impairments, neu- rologists label it an apraxia because of the initial, obvious Constructional Apraxia problem with skilled movements. Another frequently occurring manifestation of nondomi- nant hemisphere injury is constructional apraxia, which is a visual-spatial perceptual impairment. Patients with this Alien Hand Syndrome disorder cannot organize visual information and integrate A remarkable form of hemi-inattention occurs in the alien it with fine motor skills. For example, they cannot hand (alien limb) syndrome. In this disorder, a patient’s left copy simple figures or arrange matchsticks in patterns hand usually retains at least rudimentary motor and (Fig. 8.8). However, clinicians cannot always attribute sensory functions, but the patient cannot control its constructional apraxia to a nondominant lesion. It also movements or appreciate its sensations. In classic cases, appears in tests of patients with intellectual disability, the hand moves semipurposefully, independently making diffuse cerebral dysfunction, and executive impairment autonomous explorations and performing simple tasks, from frontal lobe disease. such as scratching or unbuttoning pajamas without the patient’s awareness. It sometimes fondles the patient or reaches out to the examiner. It may counteract the right Dressing Apraxia hand’s actions (inter-manual conflict) or make uncharac- In dressing apraxia (impaired ability to dress), patients teristic movements. In an often-quoted example, a patient characteristically leave their left side partly or entirely reported that her left hand intermittently attempted to  8 APHASIA AND ANOSOGNOSIA 163 improbable explanation, such as that they merely fell asleep on it and its strength will return in a few hours, or that they simply do not wish to move it (rationalization). Anosognosia holds more than academic interest. It com- plicates and delays recovery from right hemisphere strokes and TBI. Physicians caring for patients with left hemiparesis and anosognosia for their deficit might tentatively introduce the idea that the patient has limitations, but with participa- tion in rehabilitation and the passage of time, improvement will occur. The patient’s realization will follow. Loss of afferent sensory input, particularly proprio- ception, is invariably present in anosognosia but is not sufficient to produce it. For example, patients with a thoracic spinal cord transection lose feeling in their lower trunk and legs, but they remain acutely aware of their paraparesis and sensory loss. Another theory attributes nondominant symptoms to disordered attentiveness and arousal stemming from damage of the underlying thala- mus and reticular activating system. In any case, patients’ premorbid personality and emotional state have no bearing on development of this condition. FIGURE 8.8 When asked to draw a clock, a patient with con- Aprosody structional apraxia drew an incomplete circle, repeated (perse- verated) the numerals, and placed them unevenly. When Prosody is the melodic contour of speech. Loss of attempting to copy the top left figure, the patient only repeated prosody, aprosody or aprosodia, results in the inability to several lines. The patient also misplaced and rotated the posi- tion of the bottom left figure (see also Fig. 2.8). Such abnormali- produce emotional or affective qualities in one’s speech ties also may be detected with instruments such as the WAIS or to recognize them in the speech of others. Thus, non- and Bender–Gestalt tests. dominant hemisphere lesions interfere with patients’ capacity to sense emotions in a speaker’s tone of voice. For example, a patient with aprosody would be unable to choke her. Patients may treat the hand as though it were appreciate the contrasting feelings in the question “Are an errant child and rebuke, slap, or chastise it. you going home?” asked first by a jealous hospital room- The alien hand syndrome definition technically mate and then by a gleeful child. In addition, aprosody requires that the patient reveal two misperceptions: (1) restricts the ability to impart emotional qualities to the patient does not possess the hand and (2) because the speech. With no inflection or style, patients’ speech hand’s movements take place without the patient’s knowl- sounds bland and unfeeling. edge and control, another person (the alien) governs To assess prosody, the examiner should note the the hand. Most patients simply feel estranged from patient’s variations in volume, pitch, and emphasis during their hand or accept only a tenuous relationship with casual conversation. The examiner might then have the it. For those patients who develop the alien hand syn- patient ask a question, such as “May I have the ball?” in drome following a corpus callosum injury, their situation the manner of a friend and then a stern schoolteacher is akin to their right hand not knowing what their left using appropriate vocal and facial expressions. The exam- hand is doing. iner then may ask the same question while the patient tries to identify the different tones. Loss of nonverbal communication tends to accompany Anosognosia aprosody. In particular, patients lose access to meaningful Anosognosia – a term constructed by Babinski (Greek, a, face and limb expressions, popularly called “body lan- without; noso, disease; gnosis, knowledge) – has come to guage” or technically called speech’s paralinguistic compo- describe patients’ inability to acknowledge a physical nent. These physical aspects of communication lend deficit or their denial of it. The classic example is anosog- conviction, emphasis, and affect to spoken words. Indeed, nosia for a left hemiparesis. Patients with anosognosia such physical expressions seem independent and some- typically cannot identify the affected part of their own times more credible than speech. Well-known examples body (somatotopagnosia or autotopagnosia). For example, are children crossing their fingers when promising, adults they might claim that the examiner’s limb is really theirs; who wink while they are telling an incredible story, and fail to recognize their own paretic limb; or refuse to accept people who smile while relating sad events. that the obviously paralyzed limb is even weak (denial). Sometimes they attribute the weakened limb to a third person, such as another patient (projection). This ploy DISCONNECTION SYNDROMES holds instant appeal if that person has an immobilized limb from a stroke or fracture. Alternatively, even while accept- Injuries that sever communication pathways between ing their hand’s weakness, patients might offer an cortical centers cause uncommon but interesting 164 SECTION 2 MAJOR NEUROLOGIC SYMPTOMS Requests shown in phenomena that neurologists call disconnection syndromes. left visual field Neurologists had predicted the existence of such syn- dromes before verifying them in patients, much as physi- 1. Raise your left hand. 2. Raise your right hand. cists have predicted certain subatomic particles before 3. “Copy this figure.” demonstrating them. This chapter has already discussed several disconnection syndromes: (1) alexia without agraphia; (2) conduction aphasia; and (3) ideomotor 4.“When you see this face (Visual fixation point) apraxia with its varieties, buccofacial and limb apraxia. are you happy or sad?” Subsequent chapters will present other disconnection syndromes, including the medial longitudinal fasciculus (MLF) syndrome, also known as internuclear ophthal- moplegia (INO) (see Chapters 12 and 15). Another disconnection syndrome, the anterior cerebral artery syndrome, results from an occlusion of both anterior cerebral arteries that causes an infarction of both frontal lobes and the anterior corpus callosum (the genu). In this syndrome, information cannot pass between the left hemisphere language centers and the right hemisphere motor centers. Although the patient’s left arm and leg will have normal spontaneous movement, those limbs fail to follow an examiner’s verbal or written requests to move them. In other words, the patient will have unilateral (left-sided) limb apraxia (see Fig. 8.5). Other injuries of the corpus callosum may surprisingly not produce disconnection syndromes. For example, Raise individuals with a congenital absence of the corpus cal- losum may show no overt impairment. In Marchiafava– Bignami syndrome, which has been attributed in a minority Requests shown in right visual field of cases to excessive consumption of Italian red wine, patients show disconnection signs, but only as part of 1. Raise your right hand. extensive cerebral dysfunction. 2. Raise your left hand. 3. “Copy this figure.” Split-Brain Syndrome The most important disconnection syndrome referable 4. “When you see this face to the corpus callosum is the split-brain syndrome. This are you happy or sad?” condition most often results from a longitudinal surgical division of the corpus callosum (commissurotomy) per- formed by neurosurgeons in an effort to control intrac- table epilepsy (see Chapter 10). Rarely performed nowadays, the commissurotomy almost completely iso- lates each cerebral hemisphere. This isolation permits examiners to present information to only a single, iso- lated hemisphere. For example, examiners can show pic- Left Rig tures, writing, and other visual information in one of the ht patient’s visual fields, presenting information only to the contralateral hemisphere (Fig. 8.9). Likewise, by having a blindfolded patient touch objects with the one hand, examiners can present tactile information to only one hemisphere. Raise governs language function, patients cannot read the requests or describe the objects. Although patients cannot speak of the feelings evoked by emotionally laden pictures shown in their FIGURE 8.9 A commissurotomy typically leaves patients with left visual field, they have sympathetic nonverbal responses. the split-brain syndrome. Each of their hemispheres can be Bottom, The left hemisphere perceives written requests and tested individually by showing requests, objects, and pictures objects shown in the right visual field. Patients can read those in the contralateral visual field. Top, Objects and written requests written requests, copy those objects with the right hand, and shown in the left visual field are perceived by the right visual comply with the requests; however, because the language areas field. Since connections to the ipsilateral motor area are intact, cannot send information through the corpus callosum, the left the left hand can copy figures. However, since the right hemi- hand cannot comply. When patients describe emotions por- sphere is unable to transmit information through the corpus trayed in a picture, their language lacks affect, derived from the callosum to the dominant left cerebral hemisphere, which nondominant hemisphere.  8 APHASIA AND ANOSOGNOSIA 165 For example, if an object is placed in a blindfolded Brust, J. C. (2001). Music and the neurologist. Annals of the New York patient’s left hand, the patient cannot name or describe Academy of Sciences, 930, 143–152. Buxbaum, L. J., Ferraro, M. K., Veramonti, T., et al. (2004). Hemispa- it (because the information does not reach the dominant tial neglect. Neurology, 62, 749–756. hemisphere), and the right hand cannot choose an identi- Croquelois, A., & Bogousslavsky, J. (2011). Stroke aphasia. Cerebrovas- cal object. Similarly, if one hand learns to follow a maze, cular Diseases, 31, 392–399. the other hand will have to be taught separately. Faber, R., Abrams, R., Taylor, M. A., et al. (1983). Comparison of schizophrenic patients with formal thought disorder and neurologi- However, auditory information cannot be presented cally impaired patients with aphasia. The American Journal of Psychia- exclusively – only predominantly – to one hemisphere. try, 140, 1348–1351. (Because pathways are duplicated in the brainstem [see Gokhale, S., Lahoti, S., & Caplan, L. R. (2013). The neglected neglect: Fig. 4.16], sounds presented to one ear travel, after the Auditory neglect. Journal of the American Medical Association Neurol- medial geniculate synapse, to both hemispheres, but pre- ogy, 70, 1065–1069. Goodman, J. (2014). The wages of sinistrality: Handedness, brain struc- dominantly to the contralateral one.) ture, and human capital accumulation. Journal of Economic Perspectives, The interruption of the corpus callosum prevents the 193–212. right hemisphere from sharing most information with the Greenberg, V. D. (1998). 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Delirium Case 5 Case 1 A 54-year-old salesman, over the course of 8 months, has A 68-year-old retired waiter suddenly developed right developed difficulty closing sales and memory impair- hemiparesis. On examination, he only utters “Oh, Oh!” ment particularly for words and customers’ names. He when stimulated. He remains impassive, mute to ques- has difficulty completing his paperwork, but he has tions, and unresponsive when asked to move. Although remained friendly, fully conversant, and articulate. He is his palpebral fissures are symmetric and he spontaneously able to name six objects, follow double requests, and closes his eyelids, his right lower face sags downward, repeat complex phrases; however, he has difficulty recall- flattening his nasolabial fold, and his right arm and leg ing six digits and three objects after 3 minutes, and recent have no muscle tone or movement. He makes no response events. to objects placed in his right visual field. Answers: 1–5. Case 1: a. He has loss of expressive language function Case 2 accompanied by right hemiplegia and homonymous A 70-year-old retired high-school science teacher, since hemianopia. The language loss is so severe and suffering a stroke the previous year, can only say “weak, extensive that many neurologists would describe it arm,” “go away,” and “give… supper me.” His speech is as a variety of nonfluent aphasia known as global slurred. When requested by an examiner, he can raise his aphasia. In this man’s case, an occlusion of the left left arm, protrude his tongue, and close his eyes. However, internal carotid artery probably caused an infarction he cannot name objects or repeat phrases. His right arm of the entire left hemisphere. is paretic, but he can walk. Case 2: a. This man can say only a few phrases or several words in a telegraphic pattern, but he is able to comply with verbal requests, which indi- Case 3 cates that his comprehension is intact. Although Over a period of 6 weeks, a previously healthy 64-year- neurologists can neatly characterize only about old state senator has developed headaches, progressively one-third of cases of aphasia, this man has a text- severe difficulty in finding words, and confusion. She book case of the Broca’s variety of nonfluent speaks continuously and incoherently: “Go to