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Introduction to Speech-Language Neurology
1 KEY TERMS agnosias anterior aphasia apraxias association fiber tracts asymmetry behavioral neurology Carl Wernicke cephalic clinical neurology computed tomography (CT)
dorsal dysarthrias inferior localization of function Noam Chomsky Norman Geschwind Pierre Paul Broca plasticity posterior rostral superior ventral
Introduction to Speech-Language Neurology We must admit that the divine banquet of the brain was, and still is, a feast with dishes that remain elusive in their blending, and with sauces whose ingredients are even now a secret. MacDonald Critchley, The Divine Banquet of the Brain, 1979
CHAPTER OUTLINE Why Neurology? Recent Contributors to the Study of Neurologic Communication Disorders Historic Roots: Development of Speech-Language Pathology as a Brain Science Early Language Models World War I Modern Times Directions and Planes How to Study
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Why Neurology? The 1990s were labeled by the U.S. Congress as the Decade of the Brain. Likewise, 1990 was the year of the Americans with Disabilities Act (ADA). In 2006, American Speech-Language-Hearing Association (ASHA) members learned about the reauthorization of the IDEA (Individual Disability Education Act). Since the inception of the federal laws to help and protect Americans who have a variety of disabilities, including communication and hearing disorders, ASHA academic and clinical standards have undergone major changes as well. A tremendous expansion of knowledge has occurred in the neurosciences, including increased complexities of the types and severity of disorders treated by all speechlanguage pathologists (SLPs), from the school-based SLP and educational audiologist to the hospital-based certified SLP professional. ASHA has recognized these advances in neuroscience by realizing that an SLP or audiologist must have an expanded knowledge of neuroanatomy and physiology to remain a viable member of either the Individual Educational Plan (IEP) or the interdisciplinary team (IDT). That is why academic and clinical standards for all SLPs and audiologists underwent a major change in the early twenty-first century. For the student of speech-language pathology and audiology, these governmental reform acts and advances in neuroscience have played a significant role in forming the current academic and clinical standards used by ASHA. The new certification standards required as of July 2004 mandate particular knowledge and skills for students to be prepared to serve a variety of communication and hearing disorders in children and adults. From an undergraduate’s general education, which is now required to include biologic and physical sciences, to the graduate student’s in-depth study of stroke, traumatic brain injury (TBI), or autism, academic programs have had to increase neuroscience offerings. The work of the linguist, the cognitive psychologist, and the neuroscientist, as well as the SLP and audiologist, has brought to the field of communication sciences and disorders an accelerated knowledge of the specialized brain mechanisms that underlie speech, language, and hearing and their disorders. Specialists now possess the knowledge and skills to understand, implement, analyze, and synthesize the neurologic bases of speech, language, and hearing, as well as the skills required to meet the ADA, IDEA, and new ASHA standards. Widespread interest in the study of neurogenic issues has increased among speech and language students as opportunities for clinical experiences and employment in schools, hospitals, rehabilitation centers, and other health care agencies continue to increase. Increased longevity of human beings has caused a greater incidence
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of hearing, speech, and language disorders such as presbycusis, dementia, aphasia, dysarthria, and apraxia. With improving medical technology, traumatically braininjured infants, children, and adults are now saved from death much more frequently than in the past. The speech and language disorders of these survivors present new and greater challenges to the SLP and audiologist. In 1986, when the first edition of this text appeared, only half of undergraduate and graduate training programs in communication disorders offered specific coursework in neurology with an emphasis on speech and language mechanisms. As of this new edition, 30 years later, the majority of the 300 programs (www.asha.org) in the field provide such coursework. In 2004 Adler2 surveyed all accredited ASHA programs in Speech-Language Pathology and Audiology. The survey consisted of questions asking academic programs to give information about the anatomy and physiology (A&P) and neuroanatomy and physiology (N&P) courses required in their undergraduate and master’s degree course sequences. Results indicated that the A&P course is offered in every program, and more than 70% of the accredited programs offered N&P courses. Many of these courses in neuroanatomy are on the graduate level, and all respondents made it clear that the N&P course is quite relevant and is required for all students to meet the standards and prepare students for challenging SLP positions. Accompanying a growing interest among neurologists in communication sciences and disorders has been a parallel increase in the number of practicing SLPs. In the past 4 decades, membership in ASHA has risen from 2203 in 1952 to more than 173,000 members and affiliates in 2013 (www.asha.org). Although not all of these individuals are interested in neurologic disorders, many are, and for those who wish to study and specialize in neurologic speech and language disorders, a certification body, the Academy of Neurologic Communication Disorders and Sciences, accepts qualified members. Specialization in adult neurologic impairment, child neurologic impairment, or both is possible. In the past 5 to 10 years, ASHA special interest divisions have begun the process of specialization certifications in many areas, including child language, swallowing, fluency, and intraoperative monitoring. Most SLPs and audiologists work in schools, hospitals, or medical center or university clinics. All settings currently use an IDT approach and call the team a variety of names, including IDT, IEP team, clinical rounds team, or interdisciplinary management team (IMT). Regardless of name, the main function is to assess the client, discuss results from all disciplines, write a treatment plan that includes goals and objectives, and ensure that all goals and objectives have one outcome—the improvement of speech and language functioning for that client.
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The client might be seen in a school setting, a hospital, an outpatient clinic, a developmental center, through a home health agency, in a rehabilitation center, a university clinic, or in an office of a private practice. The SLP provides important information to what is usually a team of educational or medical professionals regarding a person’s speech and language deficits and assets as related to brain functioning.
Recent Contributors to the Study of Neurologic Communication Disorders During the past 4 decades, two towering figures have dominated the field of language and speech. One, a neurologist, was Norman Geschwind (1926-1984). He almost single-handedly resurrected the early neurologic literature of Europe focusing on language disorders and related deficits. Geschwind brought this body of knowledge to the attention of the American medical audience when interest in aphasia and related disorders was waning. He particularly highlighted the value of identifying lesions in the connective pathways of the brain, as well as diagnosing lesions in the traditional localized cortical areas of the brain that had been associated with language disorders for more than a century. His masterwork, “Disconnection Syndromes in Animals and Man,” was published in Brain more than 49 years ago.21 Geschwind taught brilliantly at Harvard University Medical School for many years and inspired generations of students to pursue neurology as a specialty and to concentrate on disorders of higher cerebral function. This area is now known as behavioral neurology. Aphasia and other related disorders, such as agnosia and apraxia, were considered minor aspects of a general neurologic practice until Geschwind highlighted them in neurology and related fields. Thanks to Geschwind’s original and incisive thinking, the study of language and its disorders returned to its rightful place of importance among the vast range of neurologic diseases. His thinking was so innovative that it influenced many other scientific disciplines, particularly linguistics, psychology, and philosophy. Geschwind is one of the few physicians who has been honored by having their scientific papers collected and published before their death.22 The second towering figure in the latter half of the twentieth century in the field of neurology of speech and language has been Noam Chomsky, a linguist of international renown. Chomsky is credited with creating a scientific revolution in the understanding of syntax and other components of language,28 and he has been called a major intellectual force, a “modern master” of creative and scientific thought.42
Beginning in 1957 with his monograph Syntactic Structures,10 Chomsky developed a theory of grammar, stressing mental processes that replaced the structural analysis of language based on the mechanistic and behavioral viewpoint exemplified by the writings of Bloomfield.4 Chomsky disputes the traditional idea that language is essentially a system of habits established by training and forcefully argues that every human being has the innate capacity to use language. Innate grammatical processes, he believes, are triggered by external stimuli but function autonomously. The concept of innateness implies a biologic, neurologic, and genetic basis for language. Chomsky’s definition of grammar differs from that of structuralist linguists in that it is concerned with a specific and formal description of language, as well as neurologic language processes as they work in the human brain. The details of these aspects of language, however, are not clearly explained in Chomsky’s writings, and it can be difficult, even with knowledge of transformational-generative grammar, to reconcile the details of the newer linguistic theory of Chomsky with the older neurologic theory of Geschwind and his followers. Box 1-1 BOX 1-1
Two Key Leaders in Speech and Language Norman Geschwind (1926-1984) • Revitalized early neurologic literature focusing on language disorders and related deficits • Brought body of knowledge to attention of American medical audience • Highlighted the value of identification and diagnosis of lesions in areas associated with language disorders • Published masterwork “Disconnection Syndromes in Animals and Man” (1965) in Brain • Largely founded the field of behavioral neurology • Influenced other disciplines such as linguistics, psychology, and philosophy
Noam Chomsky (1928-) • Created scientific revolution in understanding syntax and other components of language • Published Syntactic Structures in 1957, which outlined his theory of grammar • Argued the revolutionary notion that the capacity for language learning and usage is innate, not learned • Theorized that grammar includes neurologic language processes that parallel a formal description of language
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summarizes the work of both Geschwind and Chomsky in speech-language neurology. The more recent literature, however, is beginning to synthesize the linguistic and neurologic positions in explaining disordered communication. Steven Pinker, a cognitive psychologist and linguist, wrote that language may be considered an “instinct” in the same sense that Charles Darwin conceived of animal instincts. Pinker asserts that grammar is a perfect example of a biologic trait determined by the Darwinian principle of natural selection and that it is genetically based. In addition, Pinker stated that the intricately structured neural circuits that support language and speech are “laid down by a cascade of precisely timed genetic events.”45 A genetic nature of language is supported by cases of inherited disturbance that appear to be accompanied by specific defects of grammar.25Even earlier than Pinker’s work, a biologic defense of Chomsky’s concept of innateness appeared in a well-known but somewhat controversial book by Eric Lenneberg (1921-1975), The Biological Foundations of Language.36 Lenneberg clearly placed language development in a developmental neurology context. One of the highlights of this book was Lenneberg’s attempt to define a critical period for the acquisition of early language. Lenneberg maintained that the acquisition of syntax was paced by the rate of cerebral maturation and the lateralization of language mechanisms. He asserted that the rapid acquisition of language starts at approximately 2 years of age, as the brain begins to grow rapidly, and slows at puberty (at approximately 12 years of age), when cerebral growth reaches a plateau. Although often criticized, the concept of critical periods is consistent with the importance of biologic and neurologic mechanisms for language development, and some have supported Lenneberg’s claims.34 Although the concepts of Lenneberg, Geschwind, and particularly Chomsky concerning neurologic aspects of language have been widely criticized, they have focused interest on the need to understand brain function in detail when studying speech and language disorders. Not all biologic and neurologic theories of language have come from linguists or cognitive-behavioral psychologists. Harold Goodglass and Edith Kaplan were neuropsychologists and students of Geschwind who worked together at the Boston Veterans Administration Hospital to develop diagnostic theories of aphasia and assessment protocols for testing aphasic language behaviors,24 thereby contributing to the SLP’s knowledge of language and neuroanatomy and neurology. SLPs have provided a vast amount of assessment and intervention insights into the field of neurologic
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communication disorders from the vantage point of the therapy room. Although many SLPs have collaborated with neurologists to make extremely important contributions, the work of Nancy Helm-Estabrooks serves as a focal model for clinicians. Helm-Estabrooks was employed at the Boston Veterans Administration Hospital for much of her career as an SLP. There she was strongly affected by the excitement generated by Norman Geschwind and his students as they developed the field of behavioral neurology. Helm-Estabrooks has worked closely with various neurologists and neuropsychologists and is recognized worldwide for her innovative contributions, particularly in testing and therapy techniques for patients with neurogenic disorders. An example of her work is the Manual of Aphasia Therapy30 written with the internationally known neurologist Martin L. Albert. The SLP must understand the results of speech and language assessment in terms of the underlying neurologic mechanisms. Further, the SLP should be able to be conversant with current methods of neurologic diagnosis and treatment as they apply to persons with communication disorders. The neurologist’s point of view toward speech and language disorders should be familiar to every clinician. In turn, neurologists must be knowledgeable about the assessment methods and therapy procedures of the communication disorders specialist. The understanding of each other’s work is particularly crucial because neurology and the study of speech and language disorders have developed independently for many years and are only now beginning to interact more closely. This increased interaction will certainly result in additional benefits for members of both professions and those they serve. The clinical neurologist must work closely with the SLP in evaluating the communication disorders of the neurologic client. The SLP is clearly not responsible for making the final diagnosis of a neurologic disorder. Nevertheless, the SLP is responsible for assessing all relevant aspects of speech, language, and related disorders in clients with a known or suspected neurologic disorder.
Historic Roots: Development of Speech-Language Pathology as a Brain Science Speech-language pathology traces many of its roots to clinical neurology. In 1861 the French physician Pierre Paul Broca (1824-1880) studied the brains of two patients who had sustained language loss and motor speech disorders.5 This study allowed him to localize human language to a definite circumscribed area of
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the left hemisphere, thereby laying the foundation for a brain science of speech and language. Broca’s discovery went far beyond the now-classic description of an interesting brain disorder called aphasia. Possibly foremost among his conclusions were the assertions that the two hemispheres of the brain are asymmetric in function and that the left cerebral hemisphere contains the language center in most human beings. Important implications of brain asymmetry are even now coming to light some 130 years later. Asymmetry of function is more pervasive than originally thought. It extends well beyond language to other brain areas and their functions. Another conclusion that has had lasting importance for neurology since Broca’s death is that specific behavioral functions appear to be associated with clearly localized sites in the brain. The corollary of this observation is that behavioral dysfunction can point to lesions at specific sites in the nervous system. The concept of localization of function in the nervous system has been repeatedly demonstrated by clinical and research methods since Broca first articulated it more than a century ago. This observation was so profound that it became a significant historic force in the establishment of the medical discipline of clinical neurology. Much of clinical neurology depends on the physician’s ability to lateralize and localize a lesion in the nervous system. An important fact for speech-language pathology was that Broca’s discovery stimulated a period of intensive search for a workable explanation of the brain mechanisms of speech and language. Probably no period in the history of neurologic science has so advanced the understanding of communication and its disorders as those years between Broca’s discovery and World War I. An overview of Broca’s life work can be found in Box 1-2.
BOX 1-2
The Work of Pierre Paul Broca (1824-1880) • Touchstone study in 1861 allowed Broca to localize human language to a specific region of the left hemisphere, suggesting that the two hemispheres of the brain are asymmetric in function • First to identify the brain disorder aphasia • Articulated localization of function, leading to the establishment of the medical discipline of clinical neurology • Stimulated intensive research into a workable explanation of the brain mechanisms of speech and language
One of the first and foremost outcomes of this intensive study of speech-language brain mechanisms was the establishment of neurologic substrata for modalities of language deficit other than the expressive oral language described by Broca. In 1867 William Ogle published a case that demonstrated that a cerebral writing center was independent of Broca’s center for oral language.39 In 1874 Carl Wernicke (1848-1905) identified an auditory speech center in the temporal lobe associated with comprehension of speech, as opposed to Broca’s area in the frontal lobe that was an expressive speech center.50 In the terminology of that time, lesions in Broca’s area produced a motor aphasia, and one in Wernicke’s area produced a sensory aphasia. These terms are no longer used in medical terminology. The very general descriptor terms now used are expressive (motor) and receptive (sensory) aphasia. In 1892 Joseph Dejerine identified mechanisms underlying reading disorders.16 Disorders of cortical sensory recognition, or the agnosias, were named by Sigmund Freud in 1891,19 and in 1900 Hugo Liepmann comprehensively analyzed the apraxias, disorders of executing motor acts resulting from brain lesions.37
EARLY LANGUAGE MODELS Of the many neurologic models of the cerebral language mechanisms generated soon after Broca’s great discovery, Wernicke’s 1874 model has best withstood the test of time. Wernicke stressed the importance of cortical language centers associated with the various language modalities, but he also emphasized the importance of association fiber tracts connecting areas or centers. Like his teacher Theodore Meynert (1833-1892), he understood that the connections in the brain were just as important as the centers for a complete picture of language performance.38 In addition, Wernicke organized the symptoms of language disturbance in such a way that they could be used diagnostically to predict the lesion site in either connective pathways or centers in the language system. Ironically, the Wernicke model was eclipsed until the last half of the twentieth century, when it was revitalized and expanded by Norman Geschwind and his followers.21 Wernicke’s model came under criticism by the English neurologist Henry Head in 1926.29 He lumped Wernicke with a cadre of early neurologists he considered the more flagrant of the “diagram makers,” implying that they constructed language models that were highly speculative and not supported by empirical evidence. Current methods of neurologic investigation, including electrical cortical stimulation, isotope localization of lesions, computed tomography (CT), and regional blood flow studies in the brain.
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Neurologic speech mechanisms, as opposed to language mechanisms, also received attention in the late nineteenth century. In 1871 the famous French neurologist Jean Charcot (1825-1893) described the “scanning speech” that he associated with “disseminated sclerosis,” now known as multiple sclerosis.8 The term scanning, probably inappropriate, has also been widely used to describe speech with cerebellar or cerebellar pathway lesions (see Chapter 8). In 1888 an English neurologist, William Gowers (1846-1915), surveyed the neurologic speech disorders, known as dysarthrias, in a well-known book titled A Manual of Diseases of the Nervous System.26
WORLD WAR I World War I had a profound influence on the study of speech and language mechanisms resulting from neurologic insult. With a large population of headinjured young men with penetrating skull wounds, some neurologists felt an urgency for treatment. A handful of dedicated neurologists provided therapy for these traumatic language disorders because the profession of speech pathology was not yet born. Not until the next decade did the profession really begin. Lee Edward Travis has the distinction of being the first individual in the United States to specialize in the field of speech and language disorders at the doctoral level. In 1927 he became the first director of the speech clinic at the University of Iowa. His special interest was in stuttering, which he began to study in a neurologic context. Influenced by the neuropsychiatrist Samuel Terry Orton (1879-1948), Travis researched the hypothesis that stuttering was the result of brain dysfunction,47 specifically an imbalance or competition between the two cerebral hemispheres to control the normal bilateral functioning of the speech musculature. Orton’s hypothesis of dysfunctioning neural control of the speech musculature40 has generally been discredited, but his hemisphere competition theory of stuttering still surfaces from time to time in different guises to explain certain communication disorders. Although several of the founders of speech-language pathology in the United States believed that psychological explanations were more rewarding for understanding speech and language problems, notable exceptions existed. In particular, Harold Westlake of Northwestern University; Robert West of the University of Wisconsin; Jon Eisenson, formerly of California State University; and Joseph Wepman of the University of Chicago were all advocates of neurologic principles in communication disorders.
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MODERN TIMES During World War II, which brought in its wake thousands of injured soldiers and other military personnel with traumatic aphasia, neurologists, psychologists, and SLPs were used in treatment programs for the first time. This effort produced a series of books and articles on aphasia rehabilitation; perhaps the most notable for the neurologically oriented SLP was Wepman’s Recovery from Aphasia (1951).49 It served as a textbook of language disorders for the growing number of students in the field and often served as their first introduction to the study of a major neurologic communication disorder. The study of neurologic speech mechanisms was greatly advanced after World War II by the work of Wilder G. Penfield (1891-1976) and his colleagues in Canada. Penfield, a neurosurgeon, used the technique of electrical cortical stimulation to map cortical areas directly, particularly speech and language centers. In 1959 in Speech and Brain Mechanisms41 (written with Lamar Roberts), he documented his observations on cerebral control of speech and language function and wrote on the concepts of subcortical speech mechanisms and infantile cerebral plasticity. The 1960s and 1970s were marked by several advances of neurologic concepts in communication and its disorders. As already mentioned, newer linguistic theory, particularly that proposed by Noam Chomsky,11,12 emphasized the universal features and innate mechanisms reflected in language. The biologic aspects of language and speech were highlighted by the linguist and psychologist Eric Lenneberg, who specifically placed language acquisition in the context of developmental neurology.36 The split-brain studies reported by Roger Sperry and his colleagues,44 in which the commissural tracts between the hemispheres were severed, indicated specific functions of the right hemisphere were different from the left. Major anatomic differences in the right and left language centers were also demonstrated in the human brain. Most significant for SLPs and audiologists are larger areas in the left temporal lobe in the fetus, infant, and adult.23,48,51 These differences suggest an anatomic basis for cerebral dominance for language and appear to contradict a theory of progressive lateralization of speech centers. Throughout the 1960s and 1970s considerable attention was paid to neurologic speech disorders. Neurologists and SLPs in the Mayo Clinic Neurology Department13-15 documented the acoustic-perceptual characteristics of the major dysarthrias in a viable
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classification scheme. This work has stimulated widespread study of the various adult dysarthrias in speech science laboratories around the country. The 1960s and 1970s were also marked by the development of two psychometrically sound and widely used aphasia tests: the Minnesota Test of Differential Diagnosis of Aphasia43 and the Boston Diagnostic Aphasia Examination.24 The 1980s found researchers talking about the importance of early stimulation and experience for brain and language development.27 The 1980s also brought further advances in aphasia diagnostic testing when the Western Aphasia Battery33 and the first edition of the Communication Activities in Daily Living32 were published. By the 1990s further advances in assessment for aphasia, TBI, and, for the first time, language and communication problems caused by dementia produced the Scales of Cognitive Abilities for Traumatic Brain Injury,1 the Arizona Battery for Communication Disorders of Dementia,3 the third edition of Examining for Aphasia,17 the Burns Brief Inventory of Communication and Cognition,6 the second edition of the Communication Activities in Daily Living,32 the Comprehensive Aphasia Test,45 and the second edition of the Frenchay Aphasia Screening Test.18 The 1990s saw significant advances in knowledge about language development and the brain with the publication of The Language Instinct.42 In 1997 Dr. Martha Taylor Sarno completed a 5-year study funded by National Institutes of Health on the effects of aphasia secondary to stroke on the quality of life in middle-aged and older people. Findings indicated that age was not a major factor in the recovery and quality of life of individuals with aphasia.46 During the decade of the 1990s, research into the incidence, prevalence, and rehabilitation needs of persons with TBI proliferated, and in 1999 a report to Congress was made highlighting the need for further research and rehabilitation funding for persons affected by TBI.7 And now we find ourselves in the twenty-first century! A few of the more recent tests published related to neurologic basis of communication or disorders include the Cognitive Linguistic Quick Test (CLQT)31 and the Multimodal Communication Screening Test for Persons with Aphasia (MCST-A).35 Research and treatment have taken giant steps forward into the twenty-first century incorporating the use of advanced technology. Many SLPs are experimenting with, refining, and documenting positive outcomes of service delivery models that incorporate telehealth in treatment of patients with neurogenic communication disorders.9 Research designs developed by SLPs such as Dr. Julius
Fridriksson, as well as many others, have resulted in collaboration with neurologists and radiologists to utilize advanced technology such as functional magnetic resonance imaging (fMRI) or transcranial stimulation to expand our knowledge of how neurodevelopmental problems or acquired brain damage alters language, speech, and/or swallowing.20
Directions and Planes This text uses many drawings and photographs to aid in visualization. The human body itself may be defined in terms of a standard anatomic position, one in which the body is erect and the head, eyes, and toes are pointed forward. The limbs are at the side of the body, and the palms face forward (Fig. 1-1). When viewing drawings in texts or creating anatomic sketches, constantly orient yourself in terms of the standard anatomic positions and planes. From this fundamental position other positions, planes, and directions are defined (Fig. 1-2). Box 1-3 summarizes the major planes or sections used in anatomic drawings to orient the reader to the view that was used. The orienting directional terms that may be used when navigating around an illustration of the brain may be slightly different because the brain itself is tilted inside our skull. Figure 1-3 illustrates the anatomic planes of the brain. To understand what you are reading as well as the drawings and pictures you will be seeing when studying neuroanatomy, it is imperative that you understand the directional terms and the different planes in which the views may be pictured. Conventional textbooks are only two-dimensional, and thus it is of excellent benefit to the student to use websites that are designed to picture anatomic structures with three-dimensional reconstruction technique. Several terms are used to designate direction in neuroanatomy (Figs. 1-1 and 1-2). Some of these terms are used synonymously. Anterior and ventral mean toward the front or in front of when any part of the body (including the spinal cord) except the brain is illustrated. However, note in Figure 1-3 that if it is the brain that is being discussed or illustrated, ventral means inferior. When orienting in the brain, rostral is the synonymous term for anterior (Fig. 1-3). P osterior or dorsal indicates toward the back or behind for both. Superior refers to above or upward in both; inferior means below or downward in both but is synonymous with ventral in the brain. The terms cranial and cephalic can be used in place of superior when orienting direction in the body.
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FIGURE 1-1 Standard anatomic position for study of the human body with anatomic planes and terms for type or direction of movement included. (From Standring, S. [2016]. Gray’s Anatomy: The Anatomical Basis of Clinical Practice, [41st ed.]. London: Churchill Livingstone.)
How to Study Most students in speech-language pathology receive a limited introduction to the neurosciences in their undergraduate careers. The majority of students are
enrolled in courses designed to acquaint them with the anatomy and physiology of speech, but these courses usually focus on speech musculature. Students often do not receive an adequate introduction to neuroanatomy and neurophysiology of speech and language.
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Coronal plane
Median or sagittal plane Transverse or horizontal plane
Medial rotation
Lateral rotation
Adduct
Abduct Supination
Proximally Pronation
Flexion Distally Extension
Inversion
Eversion
FIGURE 1-2 Directional references for the human body. (Reprinted from Blaussen.com staff. “Blaussen gallery 2014.” Wikiversity Journal of Medicine. https://en.wikiversity.org/wiki/ Wikiversity_Journal_of_Medicine/Blausen_gallery_2014#Other_anatomy) BOX 1-3
Standard Anatomic Positions and Planes • The median plane, or section, passes longitudinally through the brain and divides the right hemisphere from the left hemisphere. • The sagittal plane divides the brain vertically at any point and parallels the medial plane. • A coronal, or frontal, section is any vertical cut that separates the brain into front and back halves. • A horizontal plane divides the brain into upper and lower halves and is at right angles to the median and coronal planes. • A transverse cut is any section that is at right angles to the longitudinal axis of the structure.
It is assumed that students will learn these details in courses in aphasia, adult dysarthria, and rehabilitation of speech in cerebral palsy. Students find that neuroscience courses taken as advanced undergraduates or beginning graduate students are difficult. Students often say that neurology courses are difficult because they believe they must learn the technical term for each hill and valley in the complex anatomy of the brain. In addition, the technical terms are unfamiliar, usually derived from Greek and Roman word roots. This text concentrates on crucial terminology for an understanding of speech and language and the diseases and conditions that result in communication disorders. The number of terms
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Superior Dorsal
Rostral (anterior)
Posterior
Ventral (inferior)
Ventral (anterior)
Dorsal (posterior)
Caudal
FIGURE 1-3 Axes of the human brain. (Reprinted from Martin, J. G. [1989]. Neuroanatomy. New York: Elsevier.)
believed to be important has increased over the various editions of this text as the scope of practice for SLPs has expanded. Because of the crucial role that SLPs now play on many medical, rehabilitation, and educational teams, they also must be familiar with terminology used by other health professionals when discussing the client’s condition. A glossary is provided at the end of the text. Part of the strategy in mastering any text in the biologic sciences is to give the study of drawings, diagrams, and tables in the text as much time as the narrative sections. If the reader can come away from a study of this text with a set of working mental images of the structures and pathways of the nervous system that are important to communication and can recall them at critical times, then one of the purposes of the authors will be realized. With an emphasis on imagery as one of the better ways to learn neurology, it should be no surprise that the authors urge readers to use as a teaching aid their own drawings of structures and pathways. Even crude sketches, carefully labeled, teach the necessary anatomic relations and fix pathways, structures, and names in the mind. Students (and instructors!) are also encouraged to use the vast resource of the Internet. There are now literally thousands of photos, illustrations, and videos dealing with neuroanatomy, neuroscience, and neurology on various websites sponsored by universities, government agencies, and research institutes. I encourage you to be careful; choose sites that are well established in terms of the credentials for providing such technical information. Because of the
precipitous manner in which websites and the information contained on them changes, only a few sites are recommended or referenced in these chapters. Your instructor is likely to be able to recommend or help you find valuable sites to assist your exploration of the nervous system. Chapters 2 and 3 provide an overview of the nervous system in total. Subsequent chapters often refer back to certain sections of these chapters to review the written information and the illustrations that provide a beginning foundation of knowledge regarding the neurologic characteristics of the communicative nervous system. Chapters 4, 5, and 6 expand teaching on the structure and physiology of neurons; the sensory systems of touch, vision, and hearing; and the motor system. Chapters 7 and 8 discuss cranial nerves and the disorders of speech production that SLPs commonly assess and treat in adults. Chapter 9 deals with the anatomy and physiology of the parts of the nervous system primarily concerned with language and learning, and Chapter 10 discusses acquired language disorders in adults. The last three chapters of this text are dedicated to learning how the brain develops from birth (Chapter 11), to pediatric speech (Chapter 12), and to language (Chapter 13) disorders. A synopsis of facts and clinical applications important to the SLP are presented at the end of each chapter. Students should be aware that these are not the only important facts in the chapter! This synopsis should not be the only thing you study for your examinations because your task is not to memorize a lot of facts with little understanding as to how they relate to the human communication nervous system. Chapters 5 through 8, 10, 12, and 13 also provide case studies, that is, a description of a patient and the signs and symptoms of his or her disorder. Questions are provided to consider regarding the patient’s symptoms. Answers can be found on the Evolve website. The reader is encouraged to attempt to integrate verbal material with eidetic imagery, as well as with thoughtful consideration of what patients with these conditions experience. Students must call on all their brainpower, bringing into play the special capacities of both the right and left hemispheres of the brain. The left hemisphere is specialized for its capacities of verbal analysis and reasoning, whereas the right hemisphere is specialized for its visual-spatial functions. However, it will become clear to you that, though this specialization exists, the right and the left hemispheres are integrated in communication and cognition. Both hemispheres also use subcortical areas to retrieve memories and empathize with others. Therefore, readers will use their whole brain to learn about the whole brain!
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Synopsis of Clinical Information and Applications for the Speech-Language Pathologist • The source of all speech and language behavior is the brain • 1990: Americans with Disabilities Act • 2004: New ASHA clinical and academic standards • 2005: IDEA was reauthorized • 2008: Revised ASHA clinical and academic standards • ASHA membership, 2013 = more than 173,000 • Norman Geschwind: First neurologist to outline the literature focusing on language disorders and related deficits • Geschwind influenced linguistics, psychology, and philosophy • Noam Chomsky: First international linguist to correlate language and speech with brain functioning • Chomsky: Language is innate and implies a biologic, neurologic, and genetic basis for language • Pinker: Synthesized the linguistic and neurologic bases of language • Lenneberg: Wrote The Biological Foundations of Language • Goodglass and Kaplan: Neuropsychologists and students of Geschwind • Broca: First to localize human language to the left hemisphere • Behavioral functions are attributed to specific sites in the brain
REFERENCES 1. Adamovich, B., & Henderson, J. (1992). Scales of Cognitive Abilities for Traumatic Brain Injury. Austin, TX: Pro-Ed. 2. Adler, R. K. (2004). The anatomy and physiology of speech and the neuroanatomy and physiology of speech courses: State of the art. Chicago: ASHA Convention. 3. Bayles, K., & Tomoeda, C. (1993). Arizona Battery for Communication Disorders of Dementia. Austin, TX: Pro-Ed. 4. Bloomfield, L. (1933). Language. New York: Holt, Rinehart and Winston. 5. Broca, P. (1861). Remarques sur le siége de la faculté du langage articulé, suivies d’une observation d’aphémie (perte de la parole). Bulletin: Société. 6. Burns, M. (1997). Burns Brief Inventory of Communication and Cognition. San Antonio, TX: Psychological Corporation. 7. Centers for Disease Control and Prevention website. Traumatic brain injury in the United States: A report to Congress. Available at: http://www.cdc.gov/traumaticbra ininjury/pubs/tbi_report_to_congress.html. 8. Charcot, J. M. (1890). Oeuvres compléte de J. M. Charcot. Paris: Lecrosnier et Babe. 9. Cherney, L. R., & van Vuuren, S. (2012). Telerehabilitation, virtual therapists and acquired neurologic speech and language disorders. Seminars in Speech and Language, 33, 243–257.
• Ogle: Identified a writing center in the brain independent of Broca’s area • Carl Wernicke: Identified an auditory center for speech associated with comprehension of speech, opposing Broca, who identified the expressive center • The temporal lobe has become identified with language and speech comprehension and the frontal lobe with language and speech expression • Freud: First to identify cortical sensory areas or agnosias • Liepmann: First to identify the apraxias of motor execution • Travis: First identified stuttering to be the result of brain dysfunction, specifically the imbalance between the two hemispheres • Neurologic aspects of communication disorders by Harold Westlake, Joseph Wepman, Robert West, and Jon Eisenson • Wepman’s Recovery from Aphasia served as the first textbook of language disorders in the field of speech pathology • Penfield: First to use cortical mapping for identifying areas of language and speech functions in the brain • Directions and planes help orient you to identify structures and site of lesions and injuries 10. Chomsky, N. (1957). Syntactic structures. The Hague: Mouton. 11. Chomsky, N. (1972). Language and mind. New York: Harcourt and Brace. 12. Chomsky, N. (1975). Reflections on language. New York: Pantheon Books. 13. Darley, F. L., Aronson, A. E., & Brown, J. R. (1969a). Differential diagnostic patterns of dysarthria. Journal of Speech and Hearing Research, 12, 246–249. 14. Darley, F. L., Aronson, A. E., & Brown, J. R. (1969b). Clusters of deviant speech dimensions in the dysarthrias. Journal of Speech and Hearing Research, 12, 462–469. 15. Darley, F. L., Aronson, A. E., & Brown, J. R. (1975). Motor speech disorders. Philadelphia: W. B. Saunders. 16. Dejerine, J. (1892). Contribution a etude anatomopathologique et clinique des differentes varietes de cectie verbal. Mémoires de la Société de Biologie, 27, 1–330. 17. Eisenson, J. (1994). Examining for aphasia (3rd ed.). Austin, TX: Pro-Ed. 18. Enderby, P., Wood, V., & Wade, D. (2006). Frenchay Aphasia Screening Test. Hoboken, NJ: Wiley Publishers. 19. Freud, S. (1953). On aphasia: A critical study. Translated by F. Stengel. New York: International Universities Press. 20. Fridriksson, J. (2011). Measuring and inducing brain plasticity in chronic aphasia. Journal of Communication Disorders, 44, 557–563.
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21. Geschwind, N. (1965). Disconnection syndromes in animals and man. Brain, 88, 237–294, 585–644. 22. Geschwind, N. (1974). Selected papers on language and the brain. Boston: D. Reidel. 23. Geschwind, N., & Levitsky, W. (1968). Human brain: Right-left asymmetries in temporal speech region. Science, 168, 186–187. 24. Goodglass, H., & Kaplan, E. (1972). Assessment of aphasia and related disorders. Philadelphia: Lea & Febiger. 25. Gopnik, M., & Crago, M. (1991). Family aggregation of developmental language disorder. Cognition, 39, 1–50. 26. Gowers, W. R. (1888). A manual of diseases of the nervous system. Philadelphia: Blakiston. 27. Greenough, W. T., Black, J. E., & Wallace, C. S. (1987). Experience and brain development. Developmental Psychobiology, 22, 727–252. 28. Harris, R. A. (1993). The linguistics wars. New York: Oxford University Press. 29. Head, H. (1926). Aphasia and kindred disorders. (2 vols). London: Cambridge University Press. 30. Helm-Estabrooks, N., & Albert, M. L. (1991). Manual of aphasia therapy. Austin, TX: Pro-Ed. 31. Helm-Estabrooks, N. (2001). Cognitive Linguistic Quick Test. Menlo Park, CA: Pearson. 32. Holland, A., Frattali, C., & Fromm, D. (1999). Communication activities in daily living (2nd ed.). Austin, TX: Pro-Ed. 33. Kertesz, A. (1982). Western Aphasia Battery. Austin, TX: Pro-Ed. 34. Kolb, B., & Gibb, R. (2011). Brain plasticity and behavior in the developing brain. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 20, 265–277. 35. Lasker, J. P., & Garrett, K. L. (2006). Using the Multimodal Communication Screening Test for Persons with Aphasia (MCST-A) to guide the selection of alternative communication strategies for people with aphasia. Aphasiology, 20, 2–4. 36. Lenneberg, E. (1967). Biological foundations of language. New York: Wiley.
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37. Liepmann, H. (1900). Das Krankheitbild der apraxie (“motorischen asymbolie”). Monatsschrift fur Psychiatrie und Neurologie, 8, 15–40. 38. Meynert, T. (1885). Psychiatry. Translated by B. Sachs. New York: Putnam. 39. Ogle, W. (1867). Aphasia and agraphia. St. George’s Hospital Reports, 2, 83–122. 40. Orton, S. T. (1937). Reading, writing and speech problems in children. New York: W. W. Norton. 41. Penfield, W., & Roberts, L. (1959). Speech and brain mechanisms. Princeton, NJ: Princeton University Press. 42. Pinker, S. (1994). The language instinct. New York: William Morrow. 43. Schuell, H. (1965). The Minnesota Test for Differential Diagnosis of Aphasia. Minneapolis: University of Minnesota Press. 44. Sperry, R. W., Gazzaniga, M. S., & Bogen, J. E. (1969). Interhemispheric relationships: The neocortical commissures; syndromes of hemispheric disconnection. In P. J. Vinken, & G. W. Bruyn (Eds.), Handbook of clinical neurology. vol. 4. Amsterdam: North Holland. 45. Swinburn, K., Porter, G., & Howard, D. (2004). Comprehensive Aphasia Test. New York: Psychology Press. 46. Taylor-Sarno, M. (1997). Quality of life in the first poststroke year. Aphasiology, 11(7), 665–679. 47. Travis, L. E. (1931). Speech pathology. New York: AppletonCentury-Crofts. 48. Wada, J. A., Clark, R., & Hamm, A. (1975). Cerebral asymmetry in humans. Archives of Neurology, 2, 239–246. 49. Wepman, J. (1951). Recovery from aphasia. New York: The Ronald Press. 50. Wernicke, C. (1874). Der aphasische symptomenkomplex. Breslau: Cohn and Weigert. Translated in Eggert, G. H. (1977). Wernicke’s works on aphasia. A sourcebook and review. The Hague: Mouton. 51. Whitelson, S. F., & Pallie, W. (1973). Left hemisphere specialization for language in the newborn: Neuroanatomical evidence of asymmetry. Brain, 96, 641–647.
dorsal dysarthrias inferior localization of function Noam Chomsky Norman Geschwind Pierre Paul Broca plasticity posterior rostral superior ventral
Introduction to Speech-Language Neurology We must admit that the divine banquet of the brain was, and still is, a feast with dishes that remain elusive in their blending, and with sauces whose ingredients are even now a secret. MacDonald Critchley, The Divine Banquet of the Brain, 1979
CHAPTER OUTLINE Why Neurology? Recent Contributors to the Study of Neurologic Communication Disorders Historic Roots: Development of Speech-Language Pathology as a Brain Science Early Language Models World War I Modern Times Directions and Planes How to Study
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Why Neurology? The 1990s were labeled by the U.S. Congress as the Decade of the Brain. Likewise, 1990 was the year of the Americans with Disabilities Act (ADA). In 2006, American Speech-Language-Hearing Association (ASHA) members learned about the reauthorization of the IDEA (Individual Disability Education Act). Since the inception of the federal laws to help and protect Americans who have a variety of disabilities, including communication and hearing disorders, ASHA academic and clinical standards have undergone major changes as well. A tremendous expansion of knowledge has occurred in the neurosciences, including increased complexities of the types and severity of disorders treated by all speechlanguage pathologists (SLPs), from the school-based SLP and educational audiologist to the hospital-based certified SLP professional. ASHA has recognized these advances in neuroscience by realizing that an SLP or audiologist must have an expanded knowledge of neuroanatomy and physiology to remain a viable member of either the Individual Educational Plan (IEP) or the interdisciplinary team (IDT). That is why academic and clinical standards for all SLPs and audiologists underwent a major change in the early twenty-first century. For the student of speech-language pathology and audiology, these governmental reform acts and advances in neuroscience have played a significant role in forming the current academic and clinical standards used by ASHA. The new certification standards required as of July 2004 mandate particular knowledge and skills for students to be prepared to serve a variety of communication and hearing disorders in children and adults. From an undergraduate’s general education, which is now required to include biologic and physical sciences, to the graduate student’s in-depth study of stroke, traumatic brain injury (TBI), or autism, academic programs have had to increase neuroscience offerings. The work of the linguist, the cognitive psychologist, and the neuroscientist, as well as the SLP and audiologist, has brought to the field of communication sciences and disorders an accelerated knowledge of the specialized brain mechanisms that underlie speech, language, and hearing and their disorders. Specialists now possess the knowledge and skills to understand, implement, analyze, and synthesize the neurologic bases of speech, language, and hearing, as well as the skills required to meet the ADA, IDEA, and new ASHA standards. Widespread interest in the study of neurogenic issues has increased among speech and language students as opportunities for clinical experiences and employment in schools, hospitals, rehabilitation centers, and other health care agencies continue to increase. Increased longevity of human beings has caused a greater incidence
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of hearing, speech, and language disorders such as presbycusis, dementia, aphasia, dysarthria, and apraxia. With improving medical technology, traumatically braininjured infants, children, and adults are now saved from death much more frequently than in the past. The speech and language disorders of these survivors present new and greater challenges to the SLP and audiologist. In 1986, when the first edition of this text appeared, only half of undergraduate and graduate training programs in communication disorders offered specific coursework in neurology with an emphasis on speech and language mechanisms. As of this new edition, 30 years later, the majority of the 300 programs (www.asha.org) in the field provide such coursework. In 2004 Adler2 surveyed all accredited ASHA programs in Speech-Language Pathology and Audiology. The survey consisted of questions asking academic programs to give information about the anatomy and physiology (A&P) and neuroanatomy and physiology (N&P) courses required in their undergraduate and master’s degree course sequences. Results indicated that the A&P course is offered in every program, and more than 70% of the accredited programs offered N&P courses. Many of these courses in neuroanatomy are on the graduate level, and all respondents made it clear that the N&P course is quite relevant and is required for all students to meet the standards and prepare students for challenging SLP positions. Accompanying a growing interest among neurologists in communication sciences and disorders has been a parallel increase in the number of practicing SLPs. In the past 4 decades, membership in ASHA has risen from 2203 in 1952 to more than 173,000 members and affiliates in 2013 (www.asha.org). Although not all of these individuals are interested in neurologic disorders, many are, and for those who wish to study and specialize in neurologic speech and language disorders, a certification body, the Academy of Neurologic Communication Disorders and Sciences, accepts qualified members. Specialization in adult neurologic impairment, child neurologic impairment, or both is possible. In the past 5 to 10 years, ASHA special interest divisions have begun the process of specialization certifications in many areas, including child language, swallowing, fluency, and intraoperative monitoring. Most SLPs and audiologists work in schools, hospitals, or medical center or university clinics. All settings currently use an IDT approach and call the team a variety of names, including IDT, IEP team, clinical rounds team, or interdisciplinary management team (IMT). Regardless of name, the main function is to assess the client, discuss results from all disciplines, write a treatment plan that includes goals and objectives, and ensure that all goals and objectives have one outcome—the improvement of speech and language functioning for that client.
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The client might be seen in a school setting, a hospital, an outpatient clinic, a developmental center, through a home health agency, in a rehabilitation center, a university clinic, or in an office of a private practice. The SLP provides important information to what is usually a team of educational or medical professionals regarding a person’s speech and language deficits and assets as related to brain functioning.
Recent Contributors to the Study of Neurologic Communication Disorders During the past 4 decades, two towering figures have dominated the field of language and speech. One, a neurologist, was Norman Geschwind (1926-1984). He almost single-handedly resurrected the early neurologic literature of Europe focusing on language disorders and related deficits. Geschwind brought this body of knowledge to the attention of the American medical audience when interest in aphasia and related disorders was waning. He particularly highlighted the value of identifying lesions in the connective pathways of the brain, as well as diagnosing lesions in the traditional localized cortical areas of the brain that had been associated with language disorders for more than a century. His masterwork, “Disconnection Syndromes in Animals and Man,” was published in Brain more than 49 years ago.21 Geschwind taught brilliantly at Harvard University Medical School for many years and inspired generations of students to pursue neurology as a specialty and to concentrate on disorders of higher cerebral function. This area is now known as behavioral neurology. Aphasia and other related disorders, such as agnosia and apraxia, were considered minor aspects of a general neurologic practice until Geschwind highlighted them in neurology and related fields. Thanks to Geschwind’s original and incisive thinking, the study of language and its disorders returned to its rightful place of importance among the vast range of neurologic diseases. His thinking was so innovative that it influenced many other scientific disciplines, particularly linguistics, psychology, and philosophy. Geschwind is one of the few physicians who has been honored by having their scientific papers collected and published before their death.22 The second towering figure in the latter half of the twentieth century in the field of neurology of speech and language has been Noam Chomsky, a linguist of international renown. Chomsky is credited with creating a scientific revolution in the understanding of syntax and other components of language,28 and he has been called a major intellectual force, a “modern master” of creative and scientific thought.42
Beginning in 1957 with his monograph Syntactic Structures,10 Chomsky developed a theory of grammar, stressing mental processes that replaced the structural analysis of language based on the mechanistic and behavioral viewpoint exemplified by the writings of Bloomfield.4 Chomsky disputes the traditional idea that language is essentially a system of habits established by training and forcefully argues that every human being has the innate capacity to use language. Innate grammatical processes, he believes, are triggered by external stimuli but function autonomously. The concept of innateness implies a biologic, neurologic, and genetic basis for language. Chomsky’s definition of grammar differs from that of structuralist linguists in that it is concerned with a specific and formal description of language, as well as neurologic language processes as they work in the human brain. The details of these aspects of language, however, are not clearly explained in Chomsky’s writings, and it can be difficult, even with knowledge of transformational-generative grammar, to reconcile the details of the newer linguistic theory of Chomsky with the older neurologic theory of Geschwind and his followers. Box 1-1 BOX 1-1
Two Key Leaders in Speech and Language Norman Geschwind (1926-1984) • Revitalized early neurologic literature focusing on language disorders and related deficits • Brought body of knowledge to attention of American medical audience • Highlighted the value of identification and diagnosis of lesions in areas associated with language disorders • Published masterwork “Disconnection Syndromes in Animals and Man” (1965) in Brain • Largely founded the field of behavioral neurology • Influenced other disciplines such as linguistics, psychology, and philosophy
Noam Chomsky (1928-) • Created scientific revolution in understanding syntax and other components of language • Published Syntactic Structures in 1957, which outlined his theory of grammar • Argued the revolutionary notion that the capacity for language learning and usage is innate, not learned • Theorized that grammar includes neurologic language processes that parallel a formal description of language
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summarizes the work of both Geschwind and Chomsky in speech-language neurology. The more recent literature, however, is beginning to synthesize the linguistic and neurologic positions in explaining disordered communication. Steven Pinker, a cognitive psychologist and linguist, wrote that language may be considered an “instinct” in the same sense that Charles Darwin conceived of animal instincts. Pinker asserts that grammar is a perfect example of a biologic trait determined by the Darwinian principle of natural selection and that it is genetically based. In addition, Pinker stated that the intricately structured neural circuits that support language and speech are “laid down by a cascade of precisely timed genetic events.”45 A genetic nature of language is supported by cases of inherited disturbance that appear to be accompanied by specific defects of grammar.25Even earlier than Pinker’s work, a biologic defense of Chomsky’s concept of innateness appeared in a well-known but somewhat controversial book by Eric Lenneberg (1921-1975), The Biological Foundations of Language.36 Lenneberg clearly placed language development in a developmental neurology context. One of the highlights of this book was Lenneberg’s attempt to define a critical period for the acquisition of early language. Lenneberg maintained that the acquisition of syntax was paced by the rate of cerebral maturation and the lateralization of language mechanisms. He asserted that the rapid acquisition of language starts at approximately 2 years of age, as the brain begins to grow rapidly, and slows at puberty (at approximately 12 years of age), when cerebral growth reaches a plateau. Although often criticized, the concept of critical periods is consistent with the importance of biologic and neurologic mechanisms for language development, and some have supported Lenneberg’s claims.34 Although the concepts of Lenneberg, Geschwind, and particularly Chomsky concerning neurologic aspects of language have been widely criticized, they have focused interest on the need to understand brain function in detail when studying speech and language disorders. Not all biologic and neurologic theories of language have come from linguists or cognitive-behavioral psychologists. Harold Goodglass and Edith Kaplan were neuropsychologists and students of Geschwind who worked together at the Boston Veterans Administration Hospital to develop diagnostic theories of aphasia and assessment protocols for testing aphasic language behaviors,24 thereby contributing to the SLP’s knowledge of language and neuroanatomy and neurology. SLPs have provided a vast amount of assessment and intervention insights into the field of neurologic
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communication disorders from the vantage point of the therapy room. Although many SLPs have collaborated with neurologists to make extremely important contributions, the work of Nancy Helm-Estabrooks serves as a focal model for clinicians. Helm-Estabrooks was employed at the Boston Veterans Administration Hospital for much of her career as an SLP. There she was strongly affected by the excitement generated by Norman Geschwind and his students as they developed the field of behavioral neurology. Helm-Estabrooks has worked closely with various neurologists and neuropsychologists and is recognized worldwide for her innovative contributions, particularly in testing and therapy techniques for patients with neurogenic disorders. An example of her work is the Manual of Aphasia Therapy30 written with the internationally known neurologist Martin L. Albert. The SLP must understand the results of speech and language assessment in terms of the underlying neurologic mechanisms. Further, the SLP should be able to be conversant with current methods of neurologic diagnosis and treatment as they apply to persons with communication disorders. The neurologist’s point of view toward speech and language disorders should be familiar to every clinician. In turn, neurologists must be knowledgeable about the assessment methods and therapy procedures of the communication disorders specialist. The understanding of each other’s work is particularly crucial because neurology and the study of speech and language disorders have developed independently for many years and are only now beginning to interact more closely. This increased interaction will certainly result in additional benefits for members of both professions and those they serve. The clinical neurologist must work closely with the SLP in evaluating the communication disorders of the neurologic client. The SLP is clearly not responsible for making the final diagnosis of a neurologic disorder. Nevertheless, the SLP is responsible for assessing all relevant aspects of speech, language, and related disorders in clients with a known or suspected neurologic disorder.
Historic Roots: Development of Speech-Language Pathology as a Brain Science Speech-language pathology traces many of its roots to clinical neurology. In 1861 the French physician Pierre Paul Broca (1824-1880) studied the brains of two patients who had sustained language loss and motor speech disorders.5 This study allowed him to localize human language to a definite circumscribed area of
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the left hemisphere, thereby laying the foundation for a brain science of speech and language. Broca’s discovery went far beyond the now-classic description of an interesting brain disorder called aphasia. Possibly foremost among his conclusions were the assertions that the two hemispheres of the brain are asymmetric in function and that the left cerebral hemisphere contains the language center in most human beings. Important implications of brain asymmetry are even now coming to light some 130 years later. Asymmetry of function is more pervasive than originally thought. It extends well beyond language to other brain areas and their functions. Another conclusion that has had lasting importance for neurology since Broca’s death is that specific behavioral functions appear to be associated with clearly localized sites in the brain. The corollary of this observation is that behavioral dysfunction can point to lesions at specific sites in the nervous system. The concept of localization of function in the nervous system has been repeatedly demonstrated by clinical and research methods since Broca first articulated it more than a century ago. This observation was so profound that it became a significant historic force in the establishment of the medical discipline of clinical neurology. Much of clinical neurology depends on the physician’s ability to lateralize and localize a lesion in the nervous system. An important fact for speech-language pathology was that Broca’s discovery stimulated a period of intensive search for a workable explanation of the brain mechanisms of speech and language. Probably no period in the history of neurologic science has so advanced the understanding of communication and its disorders as those years between Broca’s discovery and World War I. An overview of Broca’s life work can be found in Box 1-2.
BOX 1-2
The Work of Pierre Paul Broca (1824-1880) • Touchstone study in 1861 allowed Broca to localize human language to a specific region of the left hemisphere, suggesting that the two hemispheres of the brain are asymmetric in function • First to identify the brain disorder aphasia • Articulated localization of function, leading to the establishment of the medical discipline of clinical neurology • Stimulated intensive research into a workable explanation of the brain mechanisms of speech and language
One of the first and foremost outcomes of this intensive study of speech-language brain mechanisms was the establishment of neurologic substrata for modalities of language deficit other than the expressive oral language described by Broca. In 1867 William Ogle published a case that demonstrated that a cerebral writing center was independent of Broca’s center for oral language.39 In 1874 Carl Wernicke (1848-1905) identified an auditory speech center in the temporal lobe associated with comprehension of speech, as opposed to Broca’s area in the frontal lobe that was an expressive speech center.50 In the terminology of that time, lesions in Broca’s area produced a motor aphasia, and one in Wernicke’s area produced a sensory aphasia. These terms are no longer used in medical terminology. The very general descriptor terms now used are expressive (motor) and receptive (sensory) aphasia. In 1892 Joseph Dejerine identified mechanisms underlying reading disorders.16 Disorders of cortical sensory recognition, or the agnosias, were named by Sigmund Freud in 1891,19 and in 1900 Hugo Liepmann comprehensively analyzed the apraxias, disorders of executing motor acts resulting from brain lesions.37
EARLY LANGUAGE MODELS Of the many neurologic models of the cerebral language mechanisms generated soon after Broca’s great discovery, Wernicke’s 1874 model has best withstood the test of time. Wernicke stressed the importance of cortical language centers associated with the various language modalities, but he also emphasized the importance of association fiber tracts connecting areas or centers. Like his teacher Theodore Meynert (1833-1892), he understood that the connections in the brain were just as important as the centers for a complete picture of language performance.38 In addition, Wernicke organized the symptoms of language disturbance in such a way that they could be used diagnostically to predict the lesion site in either connective pathways or centers in the language system. Ironically, the Wernicke model was eclipsed until the last half of the twentieth century, when it was revitalized and expanded by Norman Geschwind and his followers.21 Wernicke’s model came under criticism by the English neurologist Henry Head in 1926.29 He lumped Wernicke with a cadre of early neurologists he considered the more flagrant of the “diagram makers,” implying that they constructed language models that were highly speculative and not supported by empirical evidence. Current methods of neurologic investigation, including electrical cortical stimulation, isotope localization of lesions, computed tomography (CT), and regional blood flow studies in the brain.
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Neurologic speech mechanisms, as opposed to language mechanisms, also received attention in the late nineteenth century. In 1871 the famous French neurologist Jean Charcot (1825-1893) described the “scanning speech” that he associated with “disseminated sclerosis,” now known as multiple sclerosis.8 The term scanning, probably inappropriate, has also been widely used to describe speech with cerebellar or cerebellar pathway lesions (see Chapter 8). In 1888 an English neurologist, William Gowers (1846-1915), surveyed the neurologic speech disorders, known as dysarthrias, in a well-known book titled A Manual of Diseases of the Nervous System.26
WORLD WAR I World War I had a profound influence on the study of speech and language mechanisms resulting from neurologic insult. With a large population of headinjured young men with penetrating skull wounds, some neurologists felt an urgency for treatment. A handful of dedicated neurologists provided therapy for these traumatic language disorders because the profession of speech pathology was not yet born. Not until the next decade did the profession really begin. Lee Edward Travis has the distinction of being the first individual in the United States to specialize in the field of speech and language disorders at the doctoral level. In 1927 he became the first director of the speech clinic at the University of Iowa. His special interest was in stuttering, which he began to study in a neurologic context. Influenced by the neuropsychiatrist Samuel Terry Orton (1879-1948), Travis researched the hypothesis that stuttering was the result of brain dysfunction,47 specifically an imbalance or competition between the two cerebral hemispheres to control the normal bilateral functioning of the speech musculature. Orton’s hypothesis of dysfunctioning neural control of the speech musculature40 has generally been discredited, but his hemisphere competition theory of stuttering still surfaces from time to time in different guises to explain certain communication disorders. Although several of the founders of speech-language pathology in the United States believed that psychological explanations were more rewarding for understanding speech and language problems, notable exceptions existed. In particular, Harold Westlake of Northwestern University; Robert West of the University of Wisconsin; Jon Eisenson, formerly of California State University; and Joseph Wepman of the University of Chicago were all advocates of neurologic principles in communication disorders.
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MODERN TIMES During World War II, which brought in its wake thousands of injured soldiers and other military personnel with traumatic aphasia, neurologists, psychologists, and SLPs were used in treatment programs for the first time. This effort produced a series of books and articles on aphasia rehabilitation; perhaps the most notable for the neurologically oriented SLP was Wepman’s Recovery from Aphasia (1951).49 It served as a textbook of language disorders for the growing number of students in the field and often served as their first introduction to the study of a major neurologic communication disorder. The study of neurologic speech mechanisms was greatly advanced after World War II by the work of Wilder G. Penfield (1891-1976) and his colleagues in Canada. Penfield, a neurosurgeon, used the technique of electrical cortical stimulation to map cortical areas directly, particularly speech and language centers. In 1959 in Speech and Brain Mechanisms41 (written with Lamar Roberts), he documented his observations on cerebral control of speech and language function and wrote on the concepts of subcortical speech mechanisms and infantile cerebral plasticity. The 1960s and 1970s were marked by several advances of neurologic concepts in communication and its disorders. As already mentioned, newer linguistic theory, particularly that proposed by Noam Chomsky,11,12 emphasized the universal features and innate mechanisms reflected in language. The biologic aspects of language and speech were highlighted by the linguist and psychologist Eric Lenneberg, who specifically placed language acquisition in the context of developmental neurology.36 The split-brain studies reported by Roger Sperry and his colleagues,44 in which the commissural tracts between the hemispheres were severed, indicated specific functions of the right hemisphere were different from the left. Major anatomic differences in the right and left language centers were also demonstrated in the human brain. Most significant for SLPs and audiologists are larger areas in the left temporal lobe in the fetus, infant, and adult.23,48,51 These differences suggest an anatomic basis for cerebral dominance for language and appear to contradict a theory of progressive lateralization of speech centers. Throughout the 1960s and 1970s considerable attention was paid to neurologic speech disorders. Neurologists and SLPs in the Mayo Clinic Neurology Department13-15 documented the acoustic-perceptual characteristics of the major dysarthrias in a viable
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classification scheme. This work has stimulated widespread study of the various adult dysarthrias in speech science laboratories around the country. The 1960s and 1970s were also marked by the development of two psychometrically sound and widely used aphasia tests: the Minnesota Test of Differential Diagnosis of Aphasia43 and the Boston Diagnostic Aphasia Examination.24 The 1980s found researchers talking about the importance of early stimulation and experience for brain and language development.27 The 1980s also brought further advances in aphasia diagnostic testing when the Western Aphasia Battery33 and the first edition of the Communication Activities in Daily Living32 were published. By the 1990s further advances in assessment for aphasia, TBI, and, for the first time, language and communication problems caused by dementia produced the Scales of Cognitive Abilities for Traumatic Brain Injury,1 the Arizona Battery for Communication Disorders of Dementia,3 the third edition of Examining for Aphasia,17 the Burns Brief Inventory of Communication and Cognition,6 the second edition of the Communication Activities in Daily Living,32 the Comprehensive Aphasia Test,45 and the second edition of the Frenchay Aphasia Screening Test.18 The 1990s saw significant advances in knowledge about language development and the brain with the publication of The Language Instinct.42 In 1997 Dr. Martha Taylor Sarno completed a 5-year study funded by National Institutes of Health on the effects of aphasia secondary to stroke on the quality of life in middle-aged and older people. Findings indicated that age was not a major factor in the recovery and quality of life of individuals with aphasia.46 During the decade of the 1990s, research into the incidence, prevalence, and rehabilitation needs of persons with TBI proliferated, and in 1999 a report to Congress was made highlighting the need for further research and rehabilitation funding for persons affected by TBI.7 And now we find ourselves in the twenty-first century! A few of the more recent tests published related to neurologic basis of communication or disorders include the Cognitive Linguistic Quick Test (CLQT)31 and the Multimodal Communication Screening Test for Persons with Aphasia (MCST-A).35 Research and treatment have taken giant steps forward into the twenty-first century incorporating the use of advanced technology. Many SLPs are experimenting with, refining, and documenting positive outcomes of service delivery models that incorporate telehealth in treatment of patients with neurogenic communication disorders.9 Research designs developed by SLPs such as Dr. Julius
Fridriksson, as well as many others, have resulted in collaboration with neurologists and radiologists to utilize advanced technology such as functional magnetic resonance imaging (fMRI) or transcranial stimulation to expand our knowledge of how neurodevelopmental problems or acquired brain damage alters language, speech, and/or swallowing.20
Directions and Planes This text uses many drawings and photographs to aid in visualization. The human body itself may be defined in terms of a standard anatomic position, one in which the body is erect and the head, eyes, and toes are pointed forward. The limbs are at the side of the body, and the palms face forward (Fig. 1-1). When viewing drawings in texts or creating anatomic sketches, constantly orient yourself in terms of the standard anatomic positions and planes. From this fundamental position other positions, planes, and directions are defined (Fig. 1-2). Box 1-3 summarizes the major planes or sections used in anatomic drawings to orient the reader to the view that was used. The orienting directional terms that may be used when navigating around an illustration of the brain may be slightly different because the brain itself is tilted inside our skull. Figure 1-3 illustrates the anatomic planes of the brain. To understand what you are reading as well as the drawings and pictures you will be seeing when studying neuroanatomy, it is imperative that you understand the directional terms and the different planes in which the views may be pictured. Conventional textbooks are only two-dimensional, and thus it is of excellent benefit to the student to use websites that are designed to picture anatomic structures with three-dimensional reconstruction technique. Several terms are used to designate direction in neuroanatomy (Figs. 1-1 and 1-2). Some of these terms are used synonymously. Anterior and ventral mean toward the front or in front of when any part of the body (including the spinal cord) except the brain is illustrated. However, note in Figure 1-3 that if it is the brain that is being discussed or illustrated, ventral means inferior. When orienting in the brain, rostral is the synonymous term for anterior (Fig. 1-3). P osterior or dorsal indicates toward the back or behind for both. Superior refers to above or upward in both; inferior means below or downward in both but is synonymous with ventral in the brain. The terms cranial and cephalic can be used in place of superior when orienting direction in the body.
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INTRODUCTION TO SPEECH-LANGUAGE NEUROLOGY CHAPTER ONE
FIGURE 1-1 Standard anatomic position for study of the human body with anatomic planes and terms for type or direction of movement included. (From Standring, S. [2016]. Gray’s Anatomy: The Anatomical Basis of Clinical Practice, [41st ed.]. London: Churchill Livingstone.)
How to Study Most students in speech-language pathology receive a limited introduction to the neurosciences in their undergraduate careers. The majority of students are
enrolled in courses designed to acquaint them with the anatomy and physiology of speech, but these courses usually focus on speech musculature. Students often do not receive an adequate introduction to neuroanatomy and neurophysiology of speech and language.
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INTRODUCTION TO SPEECH-LANGUAGE NEUROLOGY CHAPTER ONE
Coronal plane
Median or sagittal plane Transverse or horizontal plane
Medial rotation
Lateral rotation
Adduct
Abduct Supination
Proximally Pronation
Flexion Distally Extension
Inversion
Eversion
FIGURE 1-2 Directional references for the human body. (Reprinted from Blaussen.com staff. “Blaussen gallery 2014.” Wikiversity Journal of Medicine. https://en.wikiversity.org/wiki/ Wikiversity_Journal_of_Medicine/Blausen_gallery_2014#Other_anatomy) BOX 1-3
Standard Anatomic Positions and Planes • The median plane, or section, passes longitudinally through the brain and divides the right hemisphere from the left hemisphere. • The sagittal plane divides the brain vertically at any point and parallels the medial plane. • A coronal, or frontal, section is any vertical cut that separates the brain into front and back halves. • A horizontal plane divides the brain into upper and lower halves and is at right angles to the median and coronal planes. • A transverse cut is any section that is at right angles to the longitudinal axis of the structure.
It is assumed that students will learn these details in courses in aphasia, adult dysarthria, and rehabilitation of speech in cerebral palsy. Students find that neuroscience courses taken as advanced undergraduates or beginning graduate students are difficult. Students often say that neurology courses are difficult because they believe they must learn the technical term for each hill and valley in the complex anatomy of the brain. In addition, the technical terms are unfamiliar, usually derived from Greek and Roman word roots. This text concentrates on crucial terminology for an understanding of speech and language and the diseases and conditions that result in communication disorders. The number of terms
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INTRODUCTION TO SPEECH-LANGUAGE NEUROLOGY CHAPTER ONE
Superior Dorsal
Rostral (anterior)
Posterior
Ventral (inferior)
Ventral (anterior)
Dorsal (posterior)
Caudal
FIGURE 1-3 Axes of the human brain. (Reprinted from Martin, J. G. [1989]. Neuroanatomy. New York: Elsevier.)
believed to be important has increased over the various editions of this text as the scope of practice for SLPs has expanded. Because of the crucial role that SLPs now play on many medical, rehabilitation, and educational teams, they also must be familiar with terminology used by other health professionals when discussing the client’s condition. A glossary is provided at the end of the text. Part of the strategy in mastering any text in the biologic sciences is to give the study of drawings, diagrams, and tables in the text as much time as the narrative sections. If the reader can come away from a study of this text with a set of working mental images of the structures and pathways of the nervous system that are important to communication and can recall them at critical times, then one of the purposes of the authors will be realized. With an emphasis on imagery as one of the better ways to learn neurology, it should be no surprise that the authors urge readers to use as a teaching aid their own drawings of structures and pathways. Even crude sketches, carefully labeled, teach the necessary anatomic relations and fix pathways, structures, and names in the mind. Students (and instructors!) are also encouraged to use the vast resource of the Internet. There are now literally thousands of photos, illustrations, and videos dealing with neuroanatomy, neuroscience, and neurology on various websites sponsored by universities, government agencies, and research institutes. I encourage you to be careful; choose sites that are well established in terms of the credentials for providing such technical information. Because of the
precipitous manner in which websites and the information contained on them changes, only a few sites are recommended or referenced in these chapters. Your instructor is likely to be able to recommend or help you find valuable sites to assist your exploration of the nervous system. Chapters 2 and 3 provide an overview of the nervous system in total. Subsequent chapters often refer back to certain sections of these chapters to review the written information and the illustrations that provide a beginning foundation of knowledge regarding the neurologic characteristics of the communicative nervous system. Chapters 4, 5, and 6 expand teaching on the structure and physiology of neurons; the sensory systems of touch, vision, and hearing; and the motor system. Chapters 7 and 8 discuss cranial nerves and the disorders of speech production that SLPs commonly assess and treat in adults. Chapter 9 deals with the anatomy and physiology of the parts of the nervous system primarily concerned with language and learning, and Chapter 10 discusses acquired language disorders in adults. The last three chapters of this text are dedicated to learning how the brain develops from birth (Chapter 11), to pediatric speech (Chapter 12), and to language (Chapter 13) disorders. A synopsis of facts and clinical applications important to the SLP are presented at the end of each chapter. Students should be aware that these are not the only important facts in the chapter! This synopsis should not be the only thing you study for your examinations because your task is not to memorize a lot of facts with little understanding as to how they relate to the human communication nervous system. Chapters 5 through 8, 10, 12, and 13 also provide case studies, that is, a description of a patient and the signs and symptoms of his or her disorder. Questions are provided to consider regarding the patient’s symptoms. Answers can be found on the Evolve website. The reader is encouraged to attempt to integrate verbal material with eidetic imagery, as well as with thoughtful consideration of what patients with these conditions experience. Students must call on all their brainpower, bringing into play the special capacities of both the right and left hemispheres of the brain. The left hemisphere is specialized for its capacities of verbal analysis and reasoning, whereas the right hemisphere is specialized for its visual-spatial functions. However, it will become clear to you that, though this specialization exists, the right and the left hemispheres are integrated in communication and cognition. Both hemispheres also use subcortical areas to retrieve memories and empathize with others. Therefore, readers will use their whole brain to learn about the whole brain!
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INTRODUCTION TO SPEECH-LANGUAGE NEUROLOGY CHAPTER ONE
Synopsis of Clinical Information and Applications for the Speech-Language Pathologist • The source of all speech and language behavior is the brain • 1990: Americans with Disabilities Act • 2004: New ASHA clinical and academic standards • 2005: IDEA was reauthorized • 2008: Revised ASHA clinical and academic standards • ASHA membership, 2013 = more than 173,000 • Norman Geschwind: First neurologist to outline the literature focusing on language disorders and related deficits • Geschwind influenced linguistics, psychology, and philosophy • Noam Chomsky: First international linguist to correlate language and speech with brain functioning • Chomsky: Language is innate and implies a biologic, neurologic, and genetic basis for language • Pinker: Synthesized the linguistic and neurologic bases of language • Lenneberg: Wrote The Biological Foundations of Language • Goodglass and Kaplan: Neuropsychologists and students of Geschwind • Broca: First to localize human language to the left hemisphere • Behavioral functions are attributed to specific sites in the brain
REFERENCES 1. Adamovich, B., & Henderson, J. (1992). Scales of Cognitive Abilities for Traumatic Brain Injury. Austin, TX: Pro-Ed. 2. Adler, R. K. (2004). The anatomy and physiology of speech and the neuroanatomy and physiology of speech courses: State of the art. Chicago: ASHA Convention. 3. Bayles, K., & Tomoeda, C. (1993). Arizona Battery for Communication Disorders of Dementia. Austin, TX: Pro-Ed. 4. Bloomfield, L. (1933). Language. New York: Holt, Rinehart and Winston. 5. Broca, P. (1861). Remarques sur le siége de la faculté du langage articulé, suivies d’une observation d’aphémie (perte de la parole). Bulletin: Société. 6. Burns, M. (1997). Burns Brief Inventory of Communication and Cognition. San Antonio, TX: Psychological Corporation. 7. Centers for Disease Control and Prevention website. Traumatic brain injury in the United States: A report to Congress. Available at: http://www.cdc.gov/traumaticbra ininjury/pubs/tbi_report_to_congress.html. 8. Charcot, J. M. (1890). Oeuvres compléte de J. M. Charcot. Paris: Lecrosnier et Babe. 9. Cherney, L. R., & van Vuuren, S. (2012). Telerehabilitation, virtual therapists and acquired neurologic speech and language disorders. Seminars in Speech and Language, 33, 243–257.
• Ogle: Identified a writing center in the brain independent of Broca’s area • Carl Wernicke: Identified an auditory center for speech associated with comprehension of speech, opposing Broca, who identified the expressive center • The temporal lobe has become identified with language and speech comprehension and the frontal lobe with language and speech expression • Freud: First to identify cortical sensory areas or agnosias • Liepmann: First to identify the apraxias of motor execution • Travis: First identified stuttering to be the result of brain dysfunction, specifically the imbalance between the two hemispheres • Neurologic aspects of communication disorders by Harold Westlake, Joseph Wepman, Robert West, and Jon Eisenson • Wepman’s Recovery from Aphasia served as the first textbook of language disorders in the field of speech pathology • Penfield: First to use cortical mapping for identifying areas of language and speech functions in the brain • Directions and planes help orient you to identify structures and site of lesions and injuries 10. Chomsky, N. (1957). Syntactic structures. The Hague: Mouton. 11. Chomsky, N. (1972). Language and mind. New York: Harcourt and Brace. 12. Chomsky, N. (1975). Reflections on language. New York: Pantheon Books. 13. Darley, F. L., Aronson, A. E., & Brown, J. R. (1969a). Differential diagnostic patterns of dysarthria. Journal of Speech and Hearing Research, 12, 246–249. 14. Darley, F. L., Aronson, A. E., & Brown, J. R. (1969b). Clusters of deviant speech dimensions in the dysarthrias. Journal of Speech and Hearing Research, 12, 462–469. 15. Darley, F. L., Aronson, A. E., & Brown, J. R. (1975). Motor speech disorders. Philadelphia: W. B. Saunders. 16. Dejerine, J. (1892). Contribution a etude anatomopathologique et clinique des differentes varietes de cectie verbal. Mémoires de la Société de Biologie, 27, 1–330. 17. Eisenson, J. (1994). Examining for aphasia (3rd ed.). Austin, TX: Pro-Ed. 18. Enderby, P., Wood, V., & Wade, D. (2006). Frenchay Aphasia Screening Test. Hoboken, NJ: Wiley Publishers. 19. Freud, S. (1953). On aphasia: A critical study. Translated by F. Stengel. New York: International Universities Press. 20. Fridriksson, J. (2011). Measuring and inducing brain plasticity in chronic aphasia. Journal of Communication Disorders, 44, 557–563.
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21. Geschwind, N. (1965). Disconnection syndromes in animals and man. Brain, 88, 237–294, 585–644. 22. Geschwind, N. (1974). Selected papers on language and the brain. Boston: D. Reidel. 23. Geschwind, N., & Levitsky, W. (1968). Human brain: Right-left asymmetries in temporal speech region. Science, 168, 186–187. 24. Goodglass, H., & Kaplan, E. (1972). Assessment of aphasia and related disorders. Philadelphia: Lea & Febiger. 25. Gopnik, M., & Crago, M. (1991). Family aggregation of developmental language disorder. Cognition, 39, 1–50. 26. Gowers, W. R. (1888). A manual of diseases of the nervous system. Philadelphia: Blakiston. 27. Greenough, W. T., Black, J. E., & Wallace, C. S. (1987). Experience and brain development. Developmental Psychobiology, 22, 727–252. 28. Harris, R. A. (1993). The linguistics wars. New York: Oxford University Press. 29. Head, H. (1926). Aphasia and kindred disorders. (2 vols). London: Cambridge University Press. 30. Helm-Estabrooks, N., & Albert, M. L. (1991). Manual of aphasia therapy. Austin, TX: Pro-Ed. 31. Helm-Estabrooks, N. (2001). Cognitive Linguistic Quick Test. Menlo Park, CA: Pearson. 32. Holland, A., Frattali, C., & Fromm, D. (1999). Communication activities in daily living (2nd ed.). Austin, TX: Pro-Ed. 33. Kertesz, A. (1982). Western Aphasia Battery. Austin, TX: Pro-Ed. 34. Kolb, B., & Gibb, R. (2011). Brain plasticity and behavior in the developing brain. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 20, 265–277. 35. Lasker, J. P., & Garrett, K. L. (2006). Using the Multimodal Communication Screening Test for Persons with Aphasia (MCST-A) to guide the selection of alternative communication strategies for people with aphasia. Aphasiology, 20, 2–4. 36. Lenneberg, E. (1967). Biological foundations of language. New York: Wiley.
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37. Liepmann, H. (1900). Das Krankheitbild der apraxie (“motorischen asymbolie”). Monatsschrift fur Psychiatrie und Neurologie, 8, 15–40. 38. Meynert, T. (1885). Psychiatry. Translated by B. Sachs. New York: Putnam. 39. Ogle, W. (1867). Aphasia and agraphia. St. George’s Hospital Reports, 2, 83–122. 40. Orton, S. T. (1937). Reading, writing and speech problems in children. New York: W. W. Norton. 41. Penfield, W., & Roberts, L. (1959). Speech and brain mechanisms. Princeton, NJ: Princeton University Press. 42. Pinker, S. (1994). The language instinct. New York: William Morrow. 43. Schuell, H. (1965). The Minnesota Test for Differential Diagnosis of Aphasia. Minneapolis: University of Minnesota Press. 44. Sperry, R. W., Gazzaniga, M. S., & Bogen, J. E. (1969). Interhemispheric relationships: The neocortical commissures; syndromes of hemispheric disconnection. In P. J. Vinken, & G. W. Bruyn (Eds.), Handbook of clinical neurology. vol. 4. Amsterdam: North Holland. 45. Swinburn, K., Porter, G., & Howard, D. (2004). Comprehensive Aphasia Test. New York: Psychology Press. 46. Taylor-Sarno, M. (1997). Quality of life in the first poststroke year. Aphasiology, 11(7), 665–679. 47. Travis, L. E. (1931). Speech pathology. New York: AppletonCentury-Crofts. 48. Wada, J. A., Clark, R., & Hamm, A. (1975). Cerebral asymmetry in humans. Archives of Neurology, 2, 239–246. 49. Wepman, J. (1951). Recovery from aphasia. New York: The Ronald Press. 50. Wernicke, C. (1874). Der aphasische symptomenkomplex. Breslau: Cohn and Weigert. Translated in Eggert, G. H. (1977). Wernicke’s works on aphasia. A sourcebook and review. The Hague: Mouton. 51. Whitelson, S. F., & Pallie, W. (1973). Left hemisphere specialization for language in the newborn: Neuroanatomical evidence of asymmetry. Brain, 96, 641–647.