Handbook of Electronic Assistive Technology

By Ladan Najafi and Donna Cowan

Electronic Assistive Technology (EAT) is a subset of a wider range of products and services known as Assistive Technology (AT). AT is designed to support and enable people with disabilities, either acquired or congenital, to participate in activities with greater independence and safety. With a global aging population, it has an important role to play in enabling and supporting those with disability and their carers.

Handbook of Electronic Assistive Technology discusses a range of commonly available or emerging electronic assistive technologies. It provides historical background, advice when assessing for these devices and references different models of provision. It includes both medical and engineering aspects of provision. It is anticipated that the book will support students, trainees, and newly qualified Assistive Technology Practitioners to develop their understanding of the field, by considering the variables that could potentially influence the decision-making process when assessing for and providing this equipment. It also provides a reference point for those already practicing in this field and offers coverage of a broader range of technologies than clinicians may be exposed to, in their daily work

This is the first reference book to focus on a comprehensive set of electronic assistive technologies and discuss their clinical application.

• Provides comprehensive coverage of electronic assistive devices
• Gives an overview of physical and cognitive pathologies and approaches for utilizing electronic assistive devices for individuals affected by these pathologies
• Covers essentials for assistive technology practitioners, human factors and technologies

• Language: English
• Publisher: Academic Press
• Release date: Nov 15, 2018
• ISBN: 9780128124888

Ladan Najafi

Ladan Najafi is a Clinical Scientist and a Chartered Engineer. She has a degree in Medical Engineering and MSc in Bio-Medical Engineering. She has specialised in Electronic Assistive Technology (EAT) and has experience of working with both adults and pediatrics. Ladan joined the East Kent Adult Communication and Assistive Technology (ACAT) Service in 2011 as the head of the service. This service is a section of the Medical Physics department of the East Kent Hospitals University Foundation Trust. She successfully expanded the ACAT service across Kent and Medway in 2015.

Book preview

Handbook of Electronic Assistive Technology

Editors

Donna Cowan

Ladan Najafi

Table of Contents

Cover image

Title page

Copyright

List of Contributors

Foreword

Preface

Acknowledgement

Glossary

1. Basic Neurosciences With Relevance to Electronic Assistive Technology

Introduction

Concepts of Impairment Function and Participation

Basic Neurosciences

How the Central Nervous System Is Made – Neuroembryology

Blood Supply

Basic Structural Anatomy and Physiology

When Things Don’t Work

2. Cognitive Impairment and EAT

Introduction

Developmental, Acquired and Progressive Cognitive Impairment

Specific Versus Generalised Cognitive Impairment

Other Neuropsychological Factors

Executive Functioning

Memory

Attention

Implications for Technology Use

Conclusions

3. Functional Posture

Introduction

What Is Posture and Postural Control?

The Postural Control System

Impairment of Postural Control

What Is a Functional Posture?

Assessment of Postural Ability for Functional Positioning Solutions

Case Studies

4. Assessment and Outcomes

What Is Assistive Technology?

The Growing Need for Assistive Technology

Assessment and Provision of AT

Assessment Models

The Assessment Team

Referral Forms

Assessment Time

Physical Skills

Sensory Skills

Follow-Ups and Reviews

Outcome Measures for Assistive Technology

5. Alternative Access Technologies

Introduction

Keyboards

Touchscreens

Pointing Devices

Eye-Gaze Access

Switch Access

Speech Recognition

Brain–Computer Interface

Key Points

6. Environmental Control

Introduction

Environmental Control Systems

Alternative Access to Computer Technologies

Assessment for EC Provision

Summary

7. Alternative and Augmentative Communication

Introduction

A History of AAC

Prevalence of Need

Defining and Classifying AAC Systems

Components of an AAC System

Assessment

Communicative Competence

Evidence-Based Practice in AAC

AAC Service Delivery in the United Kingdom

Conclusion

8. Assisted Living

Definition of Assisted Living

Smart Homes

The Technology

Smart Homes in the United Kingdom

Automation

Safety Monitoring

Active Support of Lifestyle

Lifestyle Monitoring

Carer Support

The Use of Telecare and Telehealth in Assisted Living

The Internet of Health

Concluding Remarks

9. Powered Mobility

Introduction

Assessment

Control Systems

Powered Wheelchair Selection

Summary

10. Assistive Technology Integration and Accessibility

Overview

Introduction

History and Research into Integration

Factors to Consider When Recommending Integration

Models of Integration

Conclusions

11. Robotics

Background

A Brief History of Robotics

Emergence of Assistive Robots

Application of Robotics in Rehabilitation

Design Considerations for Robotic Exoskeletons

Roboethics

Future of Robotics

Index

Copyright

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This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

Notices

Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.

Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.

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A catalog record for this book is available from the Library of Congress

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library

ISBN: 978-0-12-812487-1

For information on all Academic Press publications visit our website at https://www.elsevier.com/books-and-journals

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List of Contributors

Steven Bloch,     Division of Psychology and Language Sciences, University College London (UCL), London, United Kingdom

Jane Chantry,     Chailey Clinical Services, Sussex Community NHS Foundation Trust, East Sussex, United Kingdom

Michael Clarke,     Division of Psychology and Language Sciences, University College London (UCL), London, United Kingdom

Donna Cowan,     Chailey Clinical Services, Rehabilitation Engineering Services, Sussex Community NHS Foundation Trust, Chailey, United Kingdom

Sarah Crombie,     Chailey Clinical Services, Sussex Community NHS Foundation Trust, East Sussex, United Kingdom

Sara da Silva Ramos,     Brain Injury Rehabilitation Trust, The Disabilities Trust, Horsham, United Kingdom

Guy Dewsbury,     Independent Research Consultant, Peterborough, United Kingdom

Charlie Fairhurst,     Paediatric Neurosciences, Evelina London Children’s Hospital, Guys and Saint Thomas’ NHS Foundation Trust, London, United Kingdom

Tom Griffiths

Communication Aid Service East of England (CASEE), Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom

Division of Psychology and Language Sciences, University College London (UCL), London, United Kingdom

Geoff Harbach,     Birmingham Community Healthcare NHS Foundation Trust, United Kingdom

Matthew Jamieson,     Computer and Information Sciences, University of Strathclyde, Glasgow, United Kingdom

Simon Judge,     Barnsley Hospital, Barnsley Assistive Technology Team, University of Sheffield, School of Health and Related Research, Rehabilitation and Assistive Technology Group, BARNSLEY, United Kingdom

Lakshmi Krisha Kanumuru,     Intelligent Interactions Group, School of Engineering and Digital Arts, University of Kent, Canterbury, Kent, United Kingdom

Layla Bashir Larsen

Intelligent Interactions Group, School of Engineering and Digital Arts, University of Kent, Canterbury, Kent, United Kingdom

East Kent Hospitals University Foundation Trust, Department of Medical Physics, Kent and Canterbury Hospital, Ethelbert Road, Canterbury, Kent, United Kingdom

Jeremy Linskell,     NHS Tayside, Dundee, Scotland

Dave Long

AJM Healthcare, United Kingdom

Oxford University Hospitals NHS Foundation Trust, United Kingdom

Joanne McConnell

Oxford University Hospitals NHS Foundation Trust, United Kingdom

R82, United Kingdom

Ladan Najafi,     Medical Physics, East Kent Hospitals University NHS Foundation Trust, Canterbury, United Kingdom

Jemma Newman,     Electronic Assistive Technology South West, North Bristol NHS Trust, Bristol, United Kingdom

Paul Nisbet,     CALL Scotland (Communication, Access, Language and Literacy), The University of Edinburgh, Edinburgh, United Kingdom

Paul Oprea,     Intelligent Interactions Group, School of Engineering and Digital Arts, University of Kent, Canterbury, Kent, United Kingdom

Katie Price,     Division of Psychology and Language Sciences, University College London (UCL), London, United Kingdom

Konstantinos Sirlantzis,     Intelligent Interactions Group, School of Engineering and Digital Arts, University of Kent, Canterbury, Kent, United Kingdom

Alan Woodcock,     Medical Engineering Physics - Rehabilitation Engineering Division, King’s College Hospital NHS Foundation Trust, London, United Kingdom

Foreword

Assistive technology is more important than ever. Growing numbers of people with care and support needs challenge us to think of new ways to care for and offer support to them. Technology can and will be an important part of these new ways, because it is necessary – our present way of doing it is simply insufficient and not sustainable – but also because it is possible. Never before in history has technology developed as fast as today and this will generate new things that will prove to be of great value. Harnessing that potential for the benefit of people who need care and support in such a way that it really helps and offers meaningful support is the challenge. To do this, professionals in health and social care will have to obtain knowledge about these new technologies and about the needs and requirements of their clients, so that they can support them in finding the optimal match between technology and their clients.

This is why this handbook of electronic assistive technology (EAT) is timely and important. It offers a guide to the complex and rapidly developing landscape of technologies that have the potential to improve people’s lives. It will raise health and social care professionals’ awareness of the potential of technology and take away some of the fears many of them have when it comes to applying these new technologies. I hope it will also help the people who may benefit most from using these technologies to discuss the possibilities and to negotiate optimal solutions that give them the opportunities to live the life they want.

Of course there are many complex issues to be solved when EAT becomes more usual: questions about quality and safety, privacy, liability, financial issues, etc. But don’t let these issues stand in the way of using the great potential that new technologies offer; as with all new developments, they will be solved.

Luc de Witte,     Professor of Health Services Research, Centre for Assistive Technology and Connected Healthcare, University of Sheffield, UK,     President of the Association for the Advancement of Assistive Technology in Europe

Preface

Both the editors are leads of assistive technology services who regularly train engineers and therapists in the assessment, prescription and provision of electronic assistive technology (EAT). They identified that there was a gap in the market for a book specifically concerning EATs to support the new entrant to the field. The Handbook of Electronic Assistive Technology is a text intended for engineering and therapy students, healthcare trainees, professionals working in allied fields and academics working and teaching these topics. The authors are all experienced practising clinicians and academics working in this field.

The book starts with chapters on the basics of neuroanatomy and physiology, cognition and postural management because understanding these areas in practice is a prerequisite to any EAT intervention. The most commonly found EATs are then described with some background as to how these devices have evolved, how they are provided in the United Kingdom and essential assessment considerations. Some chapters are supported by real life case studies that are intended to support the reader by demonstrating how theories have been put into practice.

Emerging areas of assistive technology are also covered such as robotics and assisted living because these are likely to develop and become an accepted part of a range of strategies used to support people with disabilities and the older person to remain independent in their own homes.

The book was commissioned following both editors contributing to another Elsevier text, Clinical Engineering: A Handbook for Clinical and Biomedical Engineers. This covered many fundamental engineering areas and for this reason basic clinical engineering subjects are not included in this EAT handbook. The editors would recommend it to therapists and other clinicians who wish to expand their knowledge base, or engineers unfamiliar with medical device management.

As demonstrated by the many disciplines of the authors who took part in the writing of this book, EAT is a multi-disciplinary subject area and so this handbook is intended for a range of disciplines. While this book is about technology the focus is given to the underlying principles and how they are applied, rather than to the specifics of a technology because this is rapidly changing. It is anticipated that most readers will have some understanding of the topic and are familiar with the terminologies mentioned. However, readers without any background should also be able to gain from this book and find it a valuable reference.

Acknowledgement

Compiling this book has been an amazing journey, bringing clinicians, service leads, academics and researchers together. We are indebted to all authors and those supporting them who responded to all our deadlines in a timely manner despite all their work pressures. We understand how difficult it is for those in various sectors and mostly in senior positions to allocate time to projects like this.

Dr Donna Cowan: I would like to thank all those who have inspired and mentored me throughout my career in rehabilitation engineering, in particular Professor Colin Roberts, Dr Alan Turner-Smith and Dr Terry Pountney. I have learned that you need to do the things that interest you and to enjoy what you do. I have had the good fortune, most of the time, to be able to do just that.

I would like to thank my family Sean, Jack and Kate for the endless patience, love and inspiration they provide, and my sister Cheryl for always providing a plan.

Thank you to my colleagues and the families and children at Chailey Clinical Services who have taught me so much.

Finally, thank you to Ladan for inviting me to join her as editor for this book. As always, it has been a pleasure to work with her.

Ladan Najafi: First and foremost I would like to thank my family for their support, love and encouragement throughout my career.

I would like to express my gratitude to my colleagues in the Kent and Medway Communication and Assistive Technology (KM CAT) Service-Adult Team for their support and understanding during the time I spent editing this book. I am also very thankful for all I have learned by working with them, and those working at Chailey Clinical Services, where I started my career as a trainee in electronic assistive technology under Dr Cowan’s supervision and management.

I am grateful to Julie Bradford (KM CAT-Adult Team) for providing a case study at the last minute. Last but not the least I would also like to thank one of our service users, Martin Page, for his support and input with the case study.

Glossary

AAL   Ambient assisted living (AAL) comprises concepts, products, and services that combine new technologies and the social environment in order to improve quality of life during all periods of life.

Abduction   Movement away from the midline of the body (e.g., abduction of the hip is moving the knee outward).

Accessibility framework   Set of tools and standards built into an operating system with the aim of making the operating system and software built to run on this operating system more accessible to those with disabilities.

Actuator   Mechanism by which a control system acts on an environment.

Adduction   Movement toward the midline of the body (e.g., adduction of the hip squeezes the legs together).

Anterior cingulate   Frontal part of the cingulate cortex, which surrounds the frontal part of the corpus callosum. This area is involved in the regulation of heart rate and blood pressure, other autonomic functions, and high-level functions like making decisions, impulse and emotional control, and anticipation of rewards.

Apathy   Lack of emotion or interest in life. An apathetic presentation in a neurological patient refers to the long-term, often debilitating, state of reduced emotional experience, low motivation, and drive as a result of the neurological condition.

Aphasia   Language disorder in which there is absence of ability to form or comprehend speech or language i.e., where thoughts cannot be converted into verbal language. The word is often used when dysphasia is intended where dysphasia includes moderate language impairments.

API   Application programming interface (API) is a set of clearly defined methods of communication between various software components.

Apraxia   Motor disorder in which there is difficulty motor planning to perform tasks or movements but where the individual understands what is being asked.

Attenuation   Reduction of the force, effect, or value of something. In the attenuation model of selective attention, information that enters the senses is preconsciously either attended to or attenuated depending on its physical properties and activation threshold.

Autonomic function   Function controlled by the autonomic nervous system. That is largely unconscious functions such as heart rate, digestion, respiratory rate etc.

BACNet   Communications protocol for building automation and control networks that leverage the ASHRAE, ANSI, and ISO 16484-5 standard protocol.

Bit   Basic unit of information used in computing and digital communications.

Bluetooth   Wireless technology standard for exchanging data over short distances from fixed and mobile devices and for building personal area networks (PANs).

Bluetooth   Short-range radiofrequency protocol for interdevice communication, used on most current mobile phones, tablets, and computers.

Byte   Unit of digital information that most commonly consists of 8  bits.

Cognitive reserve   Individual’s resilience to neurological damage through optimization of damaged neural resources (e.g., the extent to which the individual uses different neural networks or cognitive strategies to compensate for damage and to retain functional abilities). It is also often used in place of/interchangeably with the term brain reserve, which refers to the amount of damage a brain can endure while still functioning (with emphasis on the capacity; for example, larger brains or those with more neuronal connections can suffer more damage before reaching a threshold, below which functioning becomes impaired). Factors such as higher childhood cognition, higher educational attainment, and increased involvement in activities have been shown to contribute positively to cognitive reserve.

Compensatory strategies   In neuropsychological rehabilitation, this phrase means strategies used to compensate for functional abilities reduced as a consequence of neurological disability (e.g., use of a diary or calendar to help people organise their lives and remember activities). This is contrasted to remediation or training that aims to restore cognitive abilities to allow the patient to function independently of compensatory guidance (e.g., goal management training to help people stop and think about what they need to do).

Computer accessibility   Field and practice of making computing devices more accessible to those with disabilities.

Computed tomography (CT)   CT scan uses combinations X-ray measurements taken from different angles to provide cross sectional slices of areas of the scanned area. It provides details images of organs bones, soft tissue and blood vessels.

Concreteness   Impaired abstraction; a patient who meets this description in clinical neuropsychology may have difficulty detaching from the immediate stimuli or environment.

DECT   Digital enhanced cordless telecommunications.

Disinhibition   Inability to stop oneself from behaving in a certain way, usually impulsively and in a way that disregards social conventions. This is a common symptom of executive dysfunction after brain damage.

Dorsiflexion   Flexion movement that occurs at the ankle and is a movement of the toes toward the shin.

Dorsolateral pre-frontal cortex   Top of the frontal part of the human brain; important in executive functioning (e.g., planning, inhibition, cognitive flexibility, working memory).

Dwell select   Selection of an item on computer screen, by means of moving the cursor to rest or hover over it for a predetermined, but adjustable, time period.

Dysexecutive symptoms   These include cognitive symptoms (e.g., poor short-term memory and attention span), emotional symptoms (e.g., difficulty inhibiting or interpreting emotions), and behavioural symptoms (making poor judgements, breaking social conventions).

EADL   Electronic aids to daily living; an alternative term for environmental controls.

EC   Environmental control.

Echelon   American company responsible for design of LonWorks.

Electroencephalography (EEG)   Detection of electrical signals arising from brain activity.

Electromyography (EMG)   Detection of electrical signals arising from muscle activity.

EnOcean   Energy-harvesting wireless technology used primarily in building automation systems.

Environmental control system (ECS)   Form of electronic assistive technology that enables people with significant disabilities to independently access equipment in their environment.

Errorless learning   Rehabilitation technique that ensures the person always responds correctly. As each skill is taught, a prompt or cue is provided immediately following an instruction with the aim of preventing incorrect responses. This technique reduces the possibility of mistakenly learning incorrect responses in people with memory impairment.

European Home Systems (EHS)   Protocol aimed at home appliances control and communication using power line communication. It is one of the smart home systems that converged to form the KNX standard.

European Installation Bus (EIB)   One of the smart home systems that converged to form the KNX standard.

Executive functioning   Functioning of the various fractionated cognitive processes that contribute to cognitive control; includes inhibition, self-monitoring, cognitive flexibility, and working memory capacity.

Extension   Straightening movement that increases the angle between two body parts (e.g., when straightening the knee). When a joint can move forward and backward such as the neck and trunk, extension refers to movement in the posterior direction.

External rotation (sometimes termed lateral rotation)   Rotational movement away from midline (e.g., with a straight leg, by pointing the toe and turning the leg outwards, you are externally rotating the hip).

Fieldbus   Family of industrial computer network protocols used for real-time distributed control.

Flexion   Bending movement that decreases the angle between two body parts (e.g., flexing the knee is moving the foot toward the buttock and decreasing the angle at the knee joint). When a joint can move forward and backward, such as the neck and trunk, flexion refers to movement in the anterior direction.

Frontal lobes   Area at the front of the cortex in the human brain; this area is the most recently evolved and includes areas involved in executive functioning.

Frontotemporal dementia   Form of dementia distinguished by its progression from the frontal and temporal areas of the brain. Dysexecutive symptoms or language deficits are often the earliest experienced by patients as areas responsible for emotional control, inhibition, and language processing.

Functional magnetic resonance imaging (fMRI)   Imaging technique that builds on the technique of MRI and measures brain activity by detecting changes in blood flow when an activity occurs. When an area of the brain is in use blood flow to that area increases. There are differences in the magnetic properties of arterial (oxygen rich) and venous (oxygen poor) blood. Deoxygenated blood is more magnetic than oxygenated blood. This difference lead to an improved MR signal as the oxygenated blood interferes less with the MR signal and this can be mapped to show neuron activity.

Gateway   Network node equipped for interfacing with another network that uses different protocols.

Hemianopia   Decreased vision or blindness in half the visual field, usually one side of the vertical midline. Both eyes are affected.

Huntington disease   Inherited disease that leads to brain cell death; problems with mood followed by coordination difficulties are often experienced as the earliest symptoms.

Inferior, middle, and superior frontal regions   Regions of the frontal part of the cortex that can be described in terms of their spatial relation to each other from top of the front of the brain (superior) down to middle (middle) and bottom (inferior) regions.

Infrared (IR)   Control signals in the infrared frequency range.

Integrated Assistive Technology   System designed to allow an individual with a disability access to and control of more than one function, which they would otherwise be unable to achieve.

Integrated circuit (IC)   Complex electronic circuitry built onto a single piece of semiconductor of very small dimensions.

Interfaces   Shared boundary across at which two or more distinct components of a system interact; for example, the user interface of a computer is where the computer’s hardware, software, and the human user interact.

Internal rotation (sometimes termed medial rotation)   Rotational movement toward midline e.g., with a straight leg, by pointing the toe and turning the leg inward, you are internally rotating the hip).

Internet of things (IoT)   Network of physical devices, vehicles, home appliances, and other items embedded with electronics that enable these objects to connect and exchange data.

Internet of Things (IoT)   Widespread use of internet for communication between devices and systems.

IoS   Apple operating system, or Apple device.

Keyguard   Raised grid over touch screen to differentiate the discrete selection areas of icons.

KNX   Standardised OSI-based network communications protocol for building automation.

Kyphosis   Abnormal outward curvature of the spine, usually of the upper back so that the spine is bent forward.

Learning difficulty   Developmental cognitive impairment in a specific domain (e.g., reading, arithmetic) and present in the context of neurotypical general intellectual development.

Learning disability   Reduced intellectual ability affecting all areas of cognitive functioning and accompanied by difficulties in everyday activities.

Local operating network (LONWorks)   Networking platform specifically created to address the needs of control applications.

Lordosis   Abnormal inward curvature of the lumbar spine.

Magnetic resonance imaging (MRI)   Field of imaging using magnetic fields, electric field gradients, and radio waves to generate detailed images of the body.

Master   Device or process that controls one or more other devices or processes (known as slaves).

Means of access   Device or method by which a person can operate and interact with an EC unit, computer, phone, or other; EAT examples are push button, touch screen, head tracking, and voice recognition.

Mesh Network   Local network topology in which the infrastructure nodes connect directly, dynamically, and nonhierarchically to as many other nodes as possible.

Microprompting   Assistive technology that guides the user through a task that can be split into several substeps; for example, a device that talks people through the recipe when cooking a meal.

Middleware   Computer software that provides services to software applications beyond those available from the operating system.

Neurocognitive   Cognitive abilities closely linked to the function of certain neural pathways or cortical areas.

Neurodegenerative   Progression of nerve cell damage and death; neurodegenerative diseases include dementias and other diseases such as Parkinson and Huntington diseases.

Neurorehabilitation   Medical process of aiding recovery from, and alleviating functional difficulties resulting from, injury to the nervous system.

NHS   National Health Service in England.

Operationalised   To define something in terms of the operations used to determine it.

PAN   Computer network used for data transmission amongst devices such as computers, telephones, tablets, and personal digital assistants.

Passive infrared (PIR)   Electronic sensor that measures infrared (IR) light radiating from objects in its field of view.

Personal digital assistant (PDA)   Also known as a handheld PC; mobile device that functions as a personal information manager.

PIC   Programmable or peripheral interface controller (microcontroller IC).

Plantarflexion   Extension movement of the ankle and a movement of the toes away from the shin.

Premorbid   Before the onset of the injury or illness.

Prospective memory   Cognitive processes involved in performing or recalling a future intention.

Psychotechnologists   Those who apply technology for the purposes of psychology.

Radio frequency (RF)   Any of the electromagnetic wave frequencies that lie in the range extending from around 20 to 300  GHz, roughly the frequencies used in radio communication.

Redundancy   Inclusion of extra components that are not strictly necessary to functioning, in case of failure in other components.

Registered social landlord (RSL)   General name for not-for-profit housing providers approved and regulated by the government.

Remote sensing   Acquiring information from a distance, often with the view of making inferences using that information (e.g., inferring behaviour from GPS position over time).

RF   Radiofrequency.

Scoliosis   Side curvature of the spine.

Self-autonomy   Independence in functioning without the need for external support, influence, or compensation.

Sensor   Device, module, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics.

Shoulder protraction   When the shoulders are drawn forward (anterior to the trunk).

Shoulder retraction   When the shoulders are drawn backward (posterior to the trunk).

Slave   Device or process that is controlled, along with other devices or processes, by a single device or process (known as a master).

SPIU   Specialist peripheral interface unit of an ECS

Technology acceptance model (TAM)   Model outlining the factors that influence the use and acceptance of technology. Key factors include perceived ease of use (how easy it will be to use) and perceived usefulness (how useful it will be for its purpose).

Telecare   Term for offering remote care of older and physically less able people, providing the care and reassurance needed to allow them to remain living independently in their own home.

Telehealth   Collection of means or methods for enhancing health care, public health, and health education delivery and support by using telecommunications technologies.

Temporal lobe   One of the four lobes of the human brain (frontal, parietal, temporal, and occipital); temporal lobe is located at both sides of the cerebrum below the lateral fissure.

Topology   Arrangement of a network, including its nodes and connecting lines.

Transceiver   Device that can both transmit and receive communications, in particular a combined radio transmitter and receiver.

Twisted pair   Type of wiring in which two conductors of a single circuit are twisted together for the purposes of cancelling out electromagnetic interference (EMI) from external sources.

Vascular dementia   Degenerative disease caused by problems in the blood supply to the brain. Commonly, this is a series of minor strokes that lead to incremental cognitive decline.

Web Accessibility   Field and practice of making information and services accessed over the Internet more accessible to those with disabilities.

WiFi   Radio transmission to allow localised remote access to Internet or IT network.

WiFi   Set of media access control and physical layer specifications for implementing wireless local area network computer communication; this allows remote operations.

WiFi hub   Control hub for control of appliances in the home connected by WiFi.

Wordpredict   Suggested predictions of the word being typed, as each letter is added.

1

Basic Neurosciences With Relevance to Electronic Assistive Technology

Charlie Fairhurst     Paediatric Neurosciences, Evelina London Children’s Hospital, Guys and Saint Thomas’ NHS Foundation Trust, London, United Kingdom

Abstract

This chapter takes the reader through the development of the nervous system and the human body as relevant to those involved in the delivery of assistive technology. It describes the areas of the brain and the functions each controls alongside the impact of damage to these structures. This forms the basis for the description of some of the conditions commonly seen in rehabilitation and assistive technology services.

Keywords

Assistive technology; Human development; Neurophysiology; Neurosciences; Pathologies; Rehabilitation

Chapter Outline

Introduction

Concepts of Impairment Function and Participation

Basic Neurosciences

How the Central Nervous System Is Made – Neuroembryology

Blood Supply

Basic Structural Anatomy and Physiology

Basic Neurophysiology

Central Nervous System

Motor System

When Things Don’t Work

Specific Conditions

References

Further Reading

Introduction

The brain is as complicated and yet as simple as you want to make it, honestly! Talk to a neurologist and they can confuse you within seconds and ramble on for months. Back in the old days, when medical school focused entirely on the minutiae, the complexity of the anatomy and physiology taught was mind numbing. We parrot learnt and forgot it all instantaneously as no relevance was given – I’ve always thought it didn’t need to be like that.

We are fundamentally a limited chemical soup, structured in a series of interlinked computerised pathways with a variety of interrelated inputs, mediators and outputs; working on areas of feeling, moving and reasoning. As we develop we start simply and become more and more differentiated. What we can functionally do is initially challenged by child growth; muddled then by our emotional and structural fragilities through adulthood and finally limited by our capacity to maintain senses and biomechanical abilities into old age.

Concepts of Impairment Function and Participation

Old concepts of how health impairments lead to physical disability and then handicap were revised by the World Health Organisation (2002), when they developed a ‘common language for functioning, disability and health’, the International Classification of Functioning, Disability and Health (ICF) (Fig. 1-1).

This structures the states of:

1. Health in terms of function, activity and participation; and

2. Disability in terms of impairment, limitation of activity and restriction in participation; from both an individual and societal perspective.

This utilises aspects of both a medical and social model of disability to balance the problems of internal health and developmental challenges and the external responses to them, to help us all in developing pathways of appropriate, holistic management.

These factors are key when thinking about how we support children and adults with health disorders. Minimise the impact on the individual by maximising health, potential individual function and participation: health and habilitation. Medical therapy teams, engineers, innovators and social support all working together to potentiate ability and minimise disability.

Figure 1-1  International classification of functioning disability and health ( WHO, 2012 ).

Basic Neurosciences

Before we concentrate on different health disorders often seen in individuals accessing electronic assistive technology, it is important to focus on the basics of how we work. Functionally, the two critical areas for a level of independent life are communication and mobility.

How the Central Nervous System Is Made – Neuroembryology

We are all made the same way; how that happens is obviously up to personal practice, but fundamentally a sperm and egg get it together, share their nuclear information and start to double up and double up until a ball of cells is formed – an early embryological blastocyst (Fig. 1-2).

At this early point we differentiate into three fundamental layers of cell type:

• Endoderm (inner) develops into most of our internal organs.

• Mesoderm (middle) develops into muscle and bone.

• Ectoderm (outer) develops into skin and the nervous system.

By the fourth week of foetal development, this ball squashes down to a plate, with the ectoderm on one side differentiating into a plate of primitive nervous tissue – the neuroectoderm. This plate develops a groove and the pizza oval folds up into a calzone, thereby creating a tube with internal neuroectoderm (central nervous system (CNS)) and external ectoderm (skin). This closes from the middle so that complete internalisation occurs at both ends by around day 24, with an obvious top rostral neuropore and bottom caudal neuropore.

Figure 1-2  Basic embryology of the nervous system. 

Courtesy of Fig. 2-1 The development of the nervous system. Barnes, L., Fairhurst, C., 2011. Hemiplegia Handbook for Parent and Professionals. Mackeith Press.

The head end then bends, flexes and wraps up on itself into what is by 11  weeks a fairly recognisable fore-, mid- and hindbrain with a clear caudal spinal projection.

From there, there is lot of neuronal (nerve cell) and pathway specialisation that occurs within the brain while the rest of our body development catches up. The brain cortex folds in on itself to form a large surface area of grey matter within a relatively small volume; core pockets of cells differentiate into a series of integrated central circuits – the basal ganglia; central white matter pathways are constantly created and regress together with a vast differentiation of supporting cell types forming and supporting the nascent system.

We used to think that the development of embryological pathways from the CNS out to their specific peripheral effector organs was a carefully structured process. It seems there is a lot more of a blunderbuss approach. The whole cortex sends early projections down circuits to the terminal fields of projection, both on the same side (ipsilateral) and opposite side (contralateral), not just to the areas that they end up innervating but pretty well everywhere. The specific remodelling and restriction of circuits and tract development from certain key areas of the brain is extremely dynamic. Pathways specialise much later in humans than in other mammals, in comparison to the overall timing of foetal development that allows us to increase the complexity of our circuits.

By 24/40  weeks of gestation the wiring (axons) from the cells has developed to the lower end of the cord. Rhythmical patterns of movement at an early stage of foetal growth modify innervation, tracts nip and regress, facilitating specialisation of the pathways. By full term, 40/40, there is relatively complete innervation to the peripheries with much more in the way of crossing of messages from one side of the brain to the opposite side of the body.

With all the cellular organisation and specification, by the time we are born the brain is more than 10% of our entire body weight, whereas by the time we’re adult it’s only 2%. Though the period of most rapid growth and differentiation occurs in foetal stages, it continues markedly during infancy and early childhood. Ever-changing new cell types are being made, and new pathways are created and subsequently altered. The wiring between different areas of central and cortical grey matter becomes more differentiated, with development of normal insulation of the nerve fibres in the central and peripheral nervous systems increasing the potential speed of nerve signal transition by the laying down of concentric fatty myelin sheathes. In this phase of rapid differentiation and specification there is a considerably greater capacity for neuroplasticity or potential for pathway and neuronal relearning in the stage before myelination is complete. By the time we are 4–5  years of age, the process is pretty stuck; plasticity or pathway modification is much more difficult.

The brain normally weighs about 350–400  g at birth and 1  kg by 1  year, and by 2  years of age its relative size, proportions and subdivisions are similar to that of an adult. It’s this massive growth of the brain after we are born that differentiates us from other mammals. Unlike wildebeest that need for obvious reasons to speed off across the plains straight after birth, the complex reorganisation that occurs in the human brain postnatally increases the potential complexity of sensory, motor and in particular cognitive interaction and reasoning that we have. As such we are unusual because we have the largest brain of all animals, in comparison to body weight, and most of this growth occurs postnatally.

But this time of rapid brain growth is also a period of great risk for the development of a number of neurological problems. Each structure in the nervous system has a period when it is particularly sensitive to the normal influences of the chemical, physical and physiological environment surrounding the foetus in the developing womb, such as intrinsic blood supply and external oxygenation, nutrients, growth factors and hormones. If these are compromised at critical points, then focal or global development of the brain can be compromised. It’s a process fraught with the possibilities of grey matter structures developing wrongly or white matter pathways going haywire.

So far so easy? If you look in clinic at the anatomical picture provided by a magnetic resonance image (MRI) of the brain, it is relatively identical in a 2-year-old, a 12-year-old and a 32-year-old. However, with the advent of functional neuroimaging (in particular fMRI) we have been able to look at how the fine wiring of the system develops rather than just purely the block macroscopic picture, and we can see how that alters over time. Advanced imaging methods such as diffusion MRI can be used to study the structural connections of the brain. In this example (Fig. 1-3), tractography has been used to show the major pathways, including the corticospinal tracts (blue fibres) and corpus callosum (red fibres).

Figure 1-3  Advanced imaging methods such as Diffusion MRI can be used to study the structural connections of the brain 

Courtesy of center for the developing brain, Kings College London.

In adolescence there is a massive reorganisation of pathways within the CNS; it’s like someone has run into an old-fashioned telephone exchange, yanked all the wires out and stuck them back completely higgledy-piggledy. fMRI allows us to see how our CNS circuits mature, lighting up new organisations like Christmas lights in the teenage brain. Frankly, it’s a miracle they can put one foot in front of the other, just when we expect them to start doing complex exams.

Blood Supply

To maintain the integrity of such a complex organ, a mirrored development of an integral blood supply is vital. This blood supply up to the brain from the heart is divided in two. The major branches start from the front of the brain and flow back (internal carotid arteries), and the lesser from the back developing frontward (vertebral arteries).

The embryonic blood supply is initiated toward the end of the first third of pregnancy (first trimester). The fragile early blood flow is limited, with arterial supply starting at the surface and migrating inward toward the centre of the forming brain (Fig. 1-4). The ability to maintain brain oxygenation and energy supply independently of the maternal placenta doesn’t happen until around the middle of the second trimester (about 23–24  weeks). Even then the immature and fragile blood supply can easily be disrupted. When looking for antenatal cause, impairments often arise by imperceivable chance rather than by any specific sequelae of obstetric problems, such as maternal infection or variation in blood pressure.

As the blood supply forms at the front and back of the surface of the brain (Fig. 1-4) and creeps toward the centre, burrowing deeper, we can see that the areas most susceptible to damage associated with a lack of oxygen or energy are likely to be deep and toward the middle of the brain – the periventricular zones (for more anatomy, see later). These periventricular areas are predominantly associated with the long motor pathways – the corticospinal tracts, which relay messages from the brain motor cortex down to specific levels of the spinal cord and from there to the musculoskeletal system. The closer any bleed (or haemorrhage) followed by subsequent necrosis of the white matter (periventricular leukomalacia (PVL)) is to the lateral ventricle, the further down the body is the involvement.

Figure 1-4  Embryological development of the blood supply to the brain. 

Courtesy of Fig. 2-2 The blood supply to the brain. Barnes, L., Fairhurst, C., 2011. Hemiplegia Handbook for Parent and Professionals. Mackeith Press.

By 40  weeks of foetal development – full term – most of the brain, especially the cortex, copes relatively well with the transient challenges to blood flow, oxygenation and energy supply that can occur at the time of delivery. At this stage it is the deep grey matter structures of the brain (the basal ganglia) which are most active metabolically and have the greatest energy need. They therefore become prone to damage if starved of oxygen and/or energy for a relatively short period of say 10–15  minutes, resulting in hypoxic/ischaemic encephalopathy (low oxygen, poor blood supply-associated brain damage).

Basic Structural Anatomy and Physiology

Basic Neurophysiology

The main cells of the nervous system are called neurons; they are key to the input, integration and transmission of electrical signals. The cell body receives electrical input from branches called dendrites and outputs signal via a single elongated axon that transmits to another neuron or a specific end ‘effector’ organ such as a muscle or gland.

Different types of neurons have different neural functions throughout all nervous systems and have a variety of microscopic structures, sizes, speeds and types of transmission. The transmitting cells of the CNS are supported and nourished by a variety of other cell types called neuroglia, such