Chapter 027. Aphasia, Memory Loss, and Other Focal Cerebral Disorders (Part 7)

Gerstmanns SyndromeThe combination of acalculia (impairment of simple arithmetic), dysgraphia (impaired writing), finger anomia (an inability to name individual fingers such as the index or thumb), and right-left confusion (an inability to tell whether a hand, foot, or arm of the patient or examiner is on the right or left side of the body) is known as Gerstmanns syndrome. In making this diagnosis it is important to establish that the finger and left-right naming deficits are not part of a more generalized anomia and that the patient is not otherwise aphasic. When Gerstmanns syndrome is seen in isolation, it...
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Chapter 027. Aphasia, Memory Loss, and Other Focal Cerebral Disorders (Part 7) Chapter 027. Aphasia, Memory Loss, and Other Focal Cerebral Disorders (Part 7) Gerstmanns Syndrome The combination of acalculia (impairment of simple arithmetic),dysgraphia (impaired writing), finger anomia (an inability to name individualfingers such as the index or thumb), and right-left confusion (an inability to tellwhether a hand, foot, or arm of the patient or examiner is on the right or left sideof the body) is known as Gerstmanns syndrome. In making this diagnosis it isimportant to establish that the finger and left-right naming deficits are not part of amore generalized anomia and that the patient is not otherwise aphasic. WhenGerstmanns syndrome is seen in isolation, it is commonly associated with damageto the inferior parietal lobule (especially the angular gyrus) in the left hemisphere. Aprosodia Variations of melodic stress and intonation influence the meaning andimpact of spoken language. For example, the two statements He is clever. andHe is clever? contain an identical word choice and syntax but convey vastlydifferent messages because of differences in the intonation and stress with whichthe statements are uttered. This aspect of language is known as prosody. Damageto perisylvian areas in the right hemisphere can interfere with speech prosody andcan lead to syndromes of aprosodia. Damage to right hemisphere regionscorresponding to Wernickes area can selectively impair decoding of speechprosody, whereas damage to right hemisphere regions corresponding to Brocasarea yields a greater impairment in the ability to introduce meaning-appropriateprosody into spoken language. The latter deficit is the most common type ofaprosodia identified in clinical practice—the patient produces grammaticallycorrect language with accurate word choice but the statements are uttered in amonotone that interferes with the ability to convey the intended stress and affect.Patients with this type of aprosodia give the mistaken impression of beingdepressed or indifferent. Subcortical Aphasia Damage to subcortical components of the language network (e.g., thestriatum and thalamus of the left hemisphere) can also lead to aphasia. Theresulting syndromes contain combinations of deficits in the various aspects oflanguage but rarely fit the specific patterns described in Table 27-1. In a patientwith a CVA, an anomic aphasia accompanied by dysarthria or a fluent aphasiawith hemiparesis should raise the suspicion of a subcortical lesion site. Progressive Aphasias In clinical practice, acquired aphasias are most commonly encountered inone of two contexts: CVAs and degenerative diseases. Aphasias caused by CVAsstart suddenly and display maximal deficits at the onset. The underlying lesion isrelatively circumscribed and associated with a total loss of neural function at thelesion site. These are the classic aphasias described above where relativelyreproducible relationships between lesion site and aphasia pattern can bediscerned. Aphasias caused by neurodegenerative diseases have an insidious onsetand relentless progression so that the symptomatology changes over time. Sincethe neuronal loss within the areas encompassed by the neurodegeneration is partialand since it tends to include multiple components of the language network,distinctive clinical patterns and clinico-anatomic correlations are less obvious. Dementia is a generic term used to designate a neurodegenerative diseasethat impairs intellect and behavior to the point where customary daily livingactivities become compromised (Chap. 365). Alzheimers disease is the singlemost common cause of dementia. The neuropathology of Alzheimers diseasecauses the earliest and most profound neuronal loss in memory-related parts of thebrain such as the entorhinal cortex and the hippocampus. This is why progressiveforgetfulness for recent events and experiences is the cardinal feature ofAlzheimers disease. In time, the neuronal pathology in Alzheimers diseasespreads to the language network and a progressive aphasia, usually of the anomictype, becomes added to the progressive amnesia. There are other patterns ofdementia, however, where neurodegeneration initially targets the language ratherthan memory network of the brain, leading to the emergence of a progressiveaphasia that becomes the most prominent aspect of the clinical picture during theinitial phases of the disease. Primary progressive aphasia (PPA) is the most widelyrecognized syndrome with this pattern of selective language impairment. Clinical Presentation and Diagnosis of PPA The patient with PPA comes to medical attention because of word-find ...