Topics in Behavioral Neurology and Neuropsychology

With Key References

Daniel B. Hier, Philip B Gorelick, Andrea Gellin Shindler

• Publisher: Butterworth-Heinemann
• Year: 2013
• Print ISBN: 9780409951653
• eBook ISBN: 9781483192710
• Topic: Medicine
• Subtopic: Clinical Medicine

Topics in Behavioral Neurology and Neuropsychology provides information pertinent to neuropsychology and behavioral neurology. This book serves as a guide to those caring for patients with disorders of higher cortical function. Organized into 18 chapters, this book begins with an overview of the classes of disorders of higher cortical function according to major behavioral disturbance. This text then presents the various classification schemes for aphasic syndromes. Other chapters consider the multidimensional process of the analysis of various speech disorders, including dysprosody, dysarthria, hysteria, anomia, and aphasia. This book discusses as well the various forms of alexia, including pure alexia, alexia, alexia with agraphia, and frontal alexia. The final chapter deals with stroke and other brain disorders. This book is a valuable resource for neurologists, psychiatrists, neuroscientists, neuropsychologists, neurology residents, speech pathologists, and rehabilitation medicine specialists. Readers who are interested in the study of the disorders of the higher cortical function will also find this book useful.

1

Cerebral Organization

Publisher Summary

This chapter discusses the classification and different aspects of cerebral organization. A large number of disorders of higher cortical function are now recognized, but no completely satisfactory schema exists for categorizing them. Conduction aphasia may follow injury to the left insula. The term cerebral dominance reflects the observation that language functions are usually lateralized to the left hemisphere and visual-spatial functions are usually lateralized to the right hemisphere. Dichotic listening studies suggest that speech is less firmly lateralized to the left hemisphere in left-handers than in right-handers. Left-handedness appears to predict the anomalous patterns of cerebral organization. The transfer of language from the left to right hemisphere has a number of consequences. A variety of behavioral syndromes may occur after the interruption of the corpus callosum, which is the most important commissure connecting the cerebral hemispheres. The corpus callosum is occasionally sectioned to control intractable epilepsy. Partial sectioning may occur after cerebral infarction or when tumors are surgically removed from the vicinity of the corpus callosum.

CLASSIFICATION OF DISORDERS OF HIGHER CORTICAL FUNCTION

A large number of disorders of higher cortical function are now recognized, but no completely satisfactory schema exists for categorizing them. Traditionally, disorders of higher cortical function have been grouped according to major behavioral disturbance:

Aphasias: disorders of language

Apraxias: disorders of skilled movement

Agnosias: nonperceptual disorders of recognition

Alexias: disorders of reading

Agraphias: disorders of writing

Acalculias: disorders of calculating

Dementias: global disorders of intellect

Amnesias: disorders of memory

Unfortunately this schema is not complete, and many disorders are difficult to classify (e.g., right-left confusion, confabulation). Disorders may also be grouped by the main modality affected (e.g., visual, auditory, or somesthetic), by whether they are motor (executive) or sensory (receptive), and by whether they are developmental or acquired. Unfortunately, none of these schemas permits easy classification of all disorders. Classification of disorders by major site of involvement (e.g., frontal, parietal) is useful (see below), but for many disorders (e.g., amusia, anosognosia) the exact site of the injury responsible for the disorder is uncertain.

Within both hemispheres, certain general patterns of intrahemispheric organization exist. Brain mass anterior to the central sulcus (rolandic sulcus) subserves motor (executive) functions, whereas brain mass posterior to the central sulcus subserves sensory (receptive) functions. The frontal lobe is involved not only in the execution of motor acts but in generating much of the motivation that drives these acts. A variety of higher cortical deficits may follow frontal lobe injury (Table 1.1).

Table 1.1

Frontal Lobe Disorders

Left	Right	Bilateral
Broca’s aphasia	Impersistence	Abulia
Oral apraxia	Neglect	Perseveration
Dysprosody	Extinction	Confabulation
Transcortical motor aphasia	Reduplication	Moria
		Rigidity
Callosal apraxia
Depression (?)

Parietal cortex subserves tactile sensation (somatesthesis). The inferior parietal lobule (angular gyrus region) serves to integrate sensory information (thereby permitting visual, auditory, and tactile cross-modal associations). The left temporal-parietal-occipital junction, unlike the homologous area in the right hemisphere, must also integrate linguistic with sensory information. Hence, damage to this critical junction on the left produces a unique set of deficits that are both quasi-linguistic and quasi-perceptual (right-left confusion, alexia, agraphia, finger agnosia, and dyscalculia). Spatial and quasi-spatial mapping of sensory input occurs in both the left and right parietal lobes; however, the right parietal lobe appears more efficient for many of these operations. Deficits associated with parietal lobe injury are summarized in Table 1.2.

Table 1.2

Parietal Lobe Disorders

Left	Right	Bilateral
Constructional apraxia	Constructional apraxia	Ideational apraxia (?)
Dyscalculia	Dressing apraxia
Agraphia	Aprosody (?)
Alexia	Neglect
Semantic aphasia	Extinction
Anomic aphasia	Topographical disorientation
Gerstmann’s syndrome	Anosognosia
Conduction aphasia	Affective agnosia (?)
Ideomotor apraxia	Left astereognosis
Right astereognosis

The temporal lobes have prominent olfactory and auditory functions and, because of their proximity to the underlying limbic system, have important modulating effects on emotion. The dominant left temporal lobe is the site of much of the primary language cortex within the brain. Deficits associated with temporal-lobe injury are shown in Table 1.3, and visual disturbances that follow injury to the occipital lobes are listed in Table 1.4.

Table 1.3

Temporal Lobe Disorders

Left	Right	Bilateral
Amnesia (verbal)	Amnesia (visual)	Cortical deafness
Amusia (?)	Amusia (?)	Auditory agnosia
Jargonaphasia	Agitation (?)	Klüver-Bucy syndrome
Wernicke’s aphasia	Confusion (?)	Global amnesia
Anomic aphasia	Synesthesia (?)
Catastrophic reaction
Synesthesia (?)
Agitation (?)

Table 1.4

Temporal Lobe Disorders

Left	Right	Bilateral
Simultanagnosia	Palinopsia	Cortical blindness
Alexia	Metamorphopsia	Visual agnosia
Color anomia	Left achromatopsia	Prosopagnosia
Optic aphasia		Anton’s syndrome
Right achromatopsia		Balint’s syndrome

The role of the insula remains largely a mystery. Conduction aphasia may follow injury to the left insula. Deep structures (especially the thalamus) subserve alerting functions for both hemispheres and act as a condu...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Preface
• Note to Readers
• Chapter 1: Cerebral Organization
• Chapter 2: Aphasia
• Chapter 3: Speech Disorders
• Chapter 4: Alexia and Agraphia
• Chapter 5: Apraxia
• Chapter 6: Agnosia
• Chapter 7: Amnesia
• Chapter 8: Dementia
• Chapter 9: Childhood Disorders
• Chapter 10: Visual-Spatial Disorders
• Chapter 11: Auditory Disorders
• Chapter 12: Frontal Lobe Disorders
• Chapter 13: Right-Hemisphere Disorders
• Chapter 14: Left Parietal Disorders
• Chapter 15: Disorders of Affect and Emotion
• Chapter 16: Miscellaneous Disorders
• Chapter 17: Recovery
• Chapter 18: Stroke and Other Brain Disorders
• Index of First Authors
• Subject Index