Apraxia

The Neuropsychology of Action

Leslie J. Gonzalez Rothi, Kenneth M. Heilman, Leslie J. Gonzalez Rothi, Kenneth M. Heilman

• Publisher: Psychology Press
• Year: 2014
• ISBN:
  9781317774853
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

The purpose of this book is to provide the reader with a perspective on apraxia that considers a link between the pathology of apraxia and normal motor skill. In addition, it is the intention of the authors to provide information that is theoretically interesting as well as clinically applicable. The book is a collection of papers by various authors working in the area of apraxia, almost exclusively with limb aparaxia specifically. Beginning with Hugo Liepman's work of the late 19th century, a cognitive neuropsychological model of limb apraxia is reviewed, the use of new technologies that are informative about the mechanisms of limb praxis are discussed, and issues related to research as well as clinical assessment/management of the disorder are provided. While acquired limb apraxia is the focus of the book, there are also chapters on handedness, developmental apraxia of speech, and disorders of handwriting.

1	Introduction to Limb Apraxia

Leslie J. Gonzalez Rothi and Kenneth M. Heilman

A DEFINITION OF APRAXIA

The term apraxia was coined by Steinthal in 1871. During the last century it has been used to describe a wide variety of neurologically induced, acquired, and developmental disorders including buccofacial apraxia, constructional apraxia, dressing apraxia, gait apraxia, gaze apraxia, limb apraxia, speech apraxia, truncal apraxia, and swallowing apraxia. Although the term apraxia is applied in each of these cases (and others), many of these disorders seem to be unrelated neurologically and psychologically. De Ajuriaguerra and Tissot (1969) therefore suggested that it may be necessary to abandon the general concept of apraxia as a class of disorders in favour of a description of various specific apraxias. But the term apraxia does have functional implications and we wondered about the attributes it implied to us. When Steinthal initially used this term apraxia it was not clear whether it reflected motor, sensory or gnosic deficits. Liepmann’s (1977) earliest writings at the turn of the century suggested that the term apraxia should be used when the genesis of the disorder was motor in nature.

The term apraxia is sometimes used to indicate a disorder of volitional movement where nonvolitional movement is spared. However, volition is operationally difficult to define and discriminate. Others describe apraxia as a disorder of movement from memory. For example, when a person is asked to “pretend to blow out a match” they fail to do so, but when a lit match is placed before them they blow it out successfully and efficiently because the presence of the lit match “made it possible to retrieve the movement memories.” These attributes of the disorder (i.e. failure with productions that are volitional or produced from memory), while probably the most consistently described attributes, are inconsistent with the movement behaviour found in some “apraxia” syndromes such as a few of those mentioned earlier. In other instances the “able/not able” distinction is less than absolute. For example, the long-held assumption that apraxic patients are only deficient in performing limb gestures to verbal command while they remain able to perform normally with actual tools and objects appears not to be correct. Whereas patients with limb apraxia may do better when using actual tools than they do with pantomime, they may also err when actually holding tools and objects (De Renzi, 1985) or when using tools and objects in their natural context (Foundas, Macauley, Raymer, Maher, Heilman, & Rothi, 1995).

The term apraxia also seems to have been used less discriminantly to refer to disorders of action where sensory-perceptual disorders have not been completely ruled out. One example is “constructional apraxia.” Since the constructive behaviour of these cases may not be entirely explained by the movement aspect of the deficit, the more accurate term of “visuoconstructive disability” is now used (Benton & Tranel, 1993).

Hughlings Jackson (1884) proposed that the central nervous system was hierarchically organised. At the lowest level the behavioural repertoire is limited and the responses are stereotypic. As the level heightens the behavioural repertoire becomes more complex and less stereotypic. Whereas the behaviours mediated at the lower levels cannot be modified and appear to be automatic or involuntary, the behaviours mediated at the highest levels are learned, can be modified, and appear to be voluntary. For an example at the lower level, the spinal cord is programmed to send an efferent volley of action potentials to a muscle when that muscle’s tendon is rapidly stretched. It is this program that gives us deep tendon reflexes. This simplest of motor programs cannot be modified by learning, is automatic, and is involuntary. At a higher level the brain stem, together with the basal ganglia, mediates righting reflexes such that, when there is rapid change in one’s position with respect to gravity, postural compensations are implemented. This principle is perhaps best illustrated when sitting on a chair which is tilting backward. If the chair started to fall backward one would automatically extend the lower extremities at the knee, flex the lower extremities at the hip, and lean forward with arms outstretched and positioned in front of the trunk. Although one can superimpose voluntary behaviours on these brain stem-, basal ganglia- and spinal cord-mediated behaviours, these automatic behaviours are not learned, cannot be modified, and therefore are frequently termed “reflexes.” The cerebral cortex is capable of programming both simple (e.g. finger flexion) and complex (e.g. using a pair of scissors to cut a piece of paper) behaviours. Almost all behaviours programmed by the cortex are voluntary (not automatic). In contrast to the primitive reflexes which may be motorically quite complex but not learned, the complex behaviours mediated by the cortex are almost always learned. A loss (as the result of neurologic disorder) of the ability to perforin these learned voluntary actions is what we term apraxia.

Hughlings Jackson (1878) noted that, even when a specific body part may be unable to carry out a volitional act, that same body part may still be able to make the same movements when carrying out nonintentional or reflexive acts. The opposite may also occur such that an individual who can no longer perform an automatic involuntary behaviour may be able to perform voluntary behaviours with the same body parts. Although some term the loss of the ability to perform automatic behaviours apraxia (e.g. optic and swallowing apraxia), we use the term apraxia to denote a loss of learned behaviours. Therefore, we define apraxia simply as a neurological disorder of learned purposive movement skill that is not explained by deficits of elemental motor or sensory systems.

RELEVANCE

Almost 20 years ago we began our collaboration in research in limb apraxia. We have been asked many times by students, colleagues, and, most acutely, by grant reviewers: “Why is the study of apraxia of interest?”. While it is a commonly held notion that apraxia is of theoretical interest without being of any practical import, we disagree. Although we did not have experimental data to support our position, it was not uncommon for patients’ families to tell us that they had to remove access to dangerous tools and objects from the patients’ environment because they were concerned that these patients might hurt themselves. In addition, because we see many patients who are aphasic, we commonly look to gesture in the form of Amer-ind (Skelly, 1979) as an alternative form of communication. Amer-ind is a gestural system that can be performed with a single hand. Amer-ind gestures are relatively transparent in terms of meaning and can be interpreted by most untrained viewers. However, because limb apraxia commonly co-occurs (Kertesz, Ferro, & Shewan, 1984) with aphasia, we found limited success with the ability of patients with both disorders to acquire this gestural system. Most recently, the work of Schwartz and colleagues (described in Chapter 14 of this book) as well as our own work looking at the ability of patients with limb apraxia to use tools and objects in natural contexts (Foundas et al., 1995) have confirmed our impression that apraxia is not a trivial behavioural disorder only of theoretical interest, but instead apraxia is a common and disabling disorder.

DOMAIN OF INTEREST

Unfortunately, interest in apraxia has been limited to a small group of neurologists, psychologists, and speech–language pathologists. However, because apraxia is of both theoretical and practical importance, we believe that many professions (from anthropologists to occupational therapists) should find this topic of interest as well. For example, several phylogenetic levels of animals are known to use tools and to learn to use body movements meaningfully and skilfully. Tool manufacture and complex tool use, while noted in rare examples, are less well developed in animals than man. The development of tool use in man is, of course, of interest anthropologically. Therefore what is learned from comparative psychological and anthropological studies of the development of tool use and “gesture” across species and across human history with specific reference to changes in relevant brain structures should be consistent or compatible with what is known about the cognitive neuropsychology of human praxis using an ablation paradigm of study.

Additionally, as pointed out by Morris in Chapter 13, how children learn to use tools and gesture with each hand is poorly understood. Knowledge of how the praxis system is acquired should inform us not only of the neural substrates of skill acquisition but also about which portions of a componential system of limb praxis are modular and which are not by virtue of their dependence on development of others. Studying developmental models of normal praxis may also help us understand developmental disorders of praxis.

Neuropsychologically, the study of how one loses a previously attained level of movement skill as the result of brain impairments allows us to study how the adult human brain instantiates planned movements. The principles of movement processing, such as those learned by use of the ablation paradigm of neuropsychology, must be reconciled with those learned by using the paradigms of cognitive psychology, such as the study of normal reaching patterns, etc. (for example, see Chapter 9 by Harrington and Haaland). In turn, the interest of the physician is to use the knowledge gained from neuropsychological evaluation to assist in diagnosis, lesion localisation and patient care.

Finally, information regarding praxis processing and deficiencies should be of interest to rehabilitation clinicians such as speech-language pathologists, clinical neuropsychologists, occupational therapists and physical therapists for a number of reasons. For one, these clinicians need to advise their clients of potential environmental dangers. In addition, there is a need to develop efficacious and theoretically informed treatment and rehabilitative strategies (see Chapter 7, by Maher and Ochipa, for examples).

THE BOOK

This book is a compilation of the works of many clinical investigators working on different praxis problems. We are indebted to these authors for their contributions, their guidance, and their support. While certainly not an exhaustive review of the various perspectives currently available in the study of limb apraxia, we have included these 14 chapters because we feel they provide a reasonably cohesive and compatible statement collectively. In Chapter 2, Heilman and Rothi provide a selected history of the re-emergence of interest in the psychology of limb apraxia largely as a result of Geschwind’s articles of 1965 entitled “Disconnexion syndromes in animals and man.” Serving as one of Heilman’s professors during his clinical training, Geschwind was influential in encouraging Heilman to read Liepmann’s writings of the turn of the century regarding limb apraxia. Because hand preference and hand skill are so closely linked functionally, theories accounting for hand preference are reviewed, prior to a discussion of the mechanism of hand skill (limb praxis) in subsequent chapters. Then, utilising the discoveries of Liepmann (and the reformulations of Geschwind) and recruiting parallels found in the cognitive neuropsychology of language, Rothi, Ochipa, and Heilman (1991) proposed a cognitive neuropsychological model of limb praxis and cited cases in the literature supporting its structure. An updated, but fundamentally unaltered reiteration of that 1991 paper is presented in Chapter 4 and forms the basis of many of the subsequent chapters of this book. For example, Chapter 5 by Raymer and Ochipa expands upon the issue of action semantics raised in Chapter 4 by Rothi, Ochipa, and Heilman and enlists many of the same methodologies that have become the hallmark of the cognitive neuropsychological approach. Similarly, in Chapter 6 Rothi, Raymer, and Heilman provide the interested clinician and researcher with attributes of test construction that would allow one to assess a patient in a manner compatible with the fractionation of praxis functions implied by the model described in Chapters 4 and embellished in Chapter 5. While relatively little is known about the neurology of the praxis system based on this functional approach, Crosson in Chapter 12 embraces the challenge of parallels between language and praxis modelled in Chapter 4 and applies these notions to what the role of the subcortical structures might be in praxis programming. As a result, seven hypotheses are generated to challenge future research. Poizner and colleagues in Chapter 8 describe a technology used to analyse the spatiotemporal characteristics of skilled limb movement as applied to patients with ideomotor limb apraxia and, with this technology, confirms Liepmann’s hypothesis of apraxia resulting from a failure of stored movement representations. Explicating the nature of information in and structure of these “movement representations” as proposed by Liepmann is the challenge approached in Chapter 9 by Harrington and Haaland, whereas a higher order perspective on praxis processing is the perspective provided in Chapter 14 by Schwartz and Buxbaum in their work on action pragmatics or how actions are used in natural contexts. Finally, Chapters 10 and 11 represent interesting reviews of praxis systems closely linked to limb praxis specifically: notably, writing and speaking. For example, it is a commonly held (but inaccurate) notion that failure to write legibly as the result of brain damage is the result of a coexisting limb apraxia (Zangwill, 1954). In Chapter 10 Rapcsak reviews the cognitive neuropsychological model specific to peripheral agraphias that is compatible but distinctive from that which is proposed for limb apraxia. Regarding apraxia of speech, Square, Roy and Martin review in Chapter 11 the controversy that continues to rage over the existence of a defect of motor planning of speech and its potential relationship to limb and buccofacial apraxias.

Thus, the chapters that follow provide the reader with a perspective of limb apraxia that expands upon Hugo Liepmann’s vision that is almost 100 years old. The reader may be a clinician looking for theoretical underpinnings that might provide greater precision to clinical interventions for this disorder while the reader who is a researcher of normal motor skill acquisition may find concurrence in principle...

Table of contents

• Cover
• Title Page
• Copyright Page
• Table of Contents
• Contributors
• Brain Damage Behaviour and Cognition
• Series Preface
• Chapter 1. Introduction to Limb Apraxia
• Chapter 2. Limb Apraxia: A Look Back
• Chapter 3. Handedness
• Chapter 4. A Cognitive Neuropsychological Model of Limb Praxis and Apraxia
• Chapter 5. Conceptual Praxis
• Chapter 6. Limb Praxis Assessment
• Chapter 7. Management and Treatment of Limb Apraxia
• Chapter 8. Kinematic Approaches to the Study of Apraxie Disorders
• Chapter 9. Representations of Actions in Ideomotor Limb Apraxia: Clues from Motor Programming and Control
• Chapter 10. Disorders of Writing
• Chapter 11. Apraxia of Speech: Another Form of Praxis Disruption
• Chapter 12. Subcortical Limb Apraxia
• Chapter 13. Developmental Dyspraxia
• Chapter 14. Naturalistic Action
• Glossary
• Author Index
• Subject Index