Augmentative and Alternative Communication Interventions for Individuals with Developmental Disabilities
Key Considerations in Augmentative and Alternative Communication Intervention for People with Developmental Disabilities
This section of the book (Part III) focuses specifically on AAC interventions to enhance the communication of individuals who have developmental disabilities, such as
cerebral palsy, Down syndrome, intellectual and developmental disability, autism spectrum disorder (ASD), and childhood apraxia of speech. These individuals have disabilities that were either present since birth or acquired early in life and that significantly affect one or more aspects of development (e.g., communication/language, motor, sensory, social, cognitive). AAC interventions are used routinely with people who experience developmental disabilities to enhance communication, promote language development, increase participation, and reduce challenging behaviors. In this chapter, some of the most common developmental disabilities are described, as well as key issues related to AAC intervention. The remaining chapters in this part of the book consider AAC interventions for individuals with developmental disabilities in more detail, including those for beginning communicators who are just learning language and communication skills (Chapter 10
), AAC interventions to build more advanced skills to support communicative competence (Chapter 11
), interventions to teach literacy skills (Chapter 12
), and interventions to maximize participation in society (Chapter 13
Cerebral palsy refers to a group of neurological disorders that affect muscle movement, coordination, and posture (National Institute of Neurological Disorders and Stroke, NINDS, 2013). These motor impairments appear in infancy or early childhood and are caused by damage or abnormalities in the developing brain. Cerebral palsy specifically affects the motor cortex of the brain and disrupts the ability to control movement, causing activity limitations (Rosenbaum, Paneth, Leviton, Goldstein, & Bax, 2007). The damage is permanent and the disabilities that result from cerebral palsy are lifelong.
A healthy mind holds no boundaries or limitations. We, as non-speaking people, are likely to be more expressive or vocal than people who can speak. If we write out who we are as individuals and keep writing about our own identities, then others will see who we really are. (Tony Diamanti, a man with cerebral
palsy, in Diamanti, 2000, p. 98)
Cerebral palsy is the most common motor disability experienced by children (Centers for Disease Control and Prevention [CDC], 2019b). In the United States, the
prevalence is estimated to be approximately 1 in every 300 children (Autism and Developmental Disabilities Monitoring [ADDM] CP Network, 2013; March of Dimes, 2014). Cerebral palsy is more common among boys than girls and among Black children than White or Hispanic children (ADDM CP Network, 2013). There is a wide range of potential causes, including genetic abnormalities, congenital brain malformations, lack of oxygen, maternal infection, or fetal injury. A small number of children acquire cerebral palsy after birth from brain damage that occurs within the first months of their lives (e.g., from traumatic brain injury, meningitis, encephalitis, or cerebral hemorrhage). In many cases, the specific cause of cerebral palsy remains unknown (CDC, 2019b).
Characteristics of Individuals with Cerebral Palsy
The defining characteristic of cerebral palsy is difficulty with motor control; however, the specific difficulties may vary substantially among individuals in terms of severity, number of limbs involved, and type of motor difficulty. Some individuals experience only mild difficulties with motor control and balance and are typically able to walk and rely on their natural speech to communicate. Other individuals experience more severe challenges with motor control that may limit many aspects of daily functioning, including mobility, natural speech, and writing. These individuals require AAC intervention to enhance their communication and increase their participation. Some individuals with cerebral palsy experience motor control difficulties that extend to all four limbs (i.e., quadri-); others may experience difficulties with only two limbs (i.e., hemi-). Some individuals with cerebral palsy experience weakness (i.e., paresis); others may have paralysis (i.e., plegia-; NINDS, 2013). Thus, the term hemiplegia
indicates that the individual has weakness in half the body; the term quadriplegia
indicates that the individual has paralysis in all four limbs. More than half (58%) of children with cerebral palsy are able to walk; 11% use handheld mobility aids (e.g., cane, walker); and 30% require the use of a wheelchair (ADDM CP Network, 2013).
Depending on the location and extent of the brain lesion, individuals with cerebral palsy experience different types of motor control difficulties (NINDS, 2013). The most common condition, spastic
cerebral palsy, involves hypertonia (increased muscle tone) that results in muscle stiffness and tightness; approximately 77% of individuals with cerebral palsy have
spastic cerebral palsy (CDC, 2019b). A second condition, dyskinetic
cerebral palsy (including athetoid, choreoathetoid, and dystonic cerebral palsy) is characterized by slow involuntary writhing movements as well as changing patterns of muscle tone throughout the day (CDC, 2019b). Finally, ataxic
cerebral palsy, which can be associated with either increased or decreased muscle tone, causes problems with balance, coordination, and positioning the trunk and limbs in space (CDC, 2019b). Some individuals have mixed
cerebral palsy, which includes more than one type of motor pattern (e.g., spastic-athetoid cerebral palsy).
Communication impairments are common sequelae to
cerebral palsy. Articulation disorders and impaired speech intelligibility may occur due to poor respiratory control, laryngeal and velopharyngeal dysfunction, and oral articulation difficulties that result from restricted movement in the oral-facial muscles. Language delays or disorders are also common and may be compounded by limited access to language-learning opportunities. In a longitudinal study, Hustad, Groton, and Lee (2010) found that, at age 4, approximately 32% of children with cerebral palsy were unable to speak, 18% demonstrated both motor-speech and language impairments, 26% demonstrated motor-speech disorders but no language impairment, and 24% demonstrated typical motor speech and language skills.
Individuals with cerebral palsy, especially those with severe motor impairments, often experience associated problems, including intellectual disability, hearing and/or vision impairments, and seizures (ADDM CP Network, 2013; CDC, 2019b). Approximately 30% to 50% of children with cerebral palsy experience intellectual disabilities; these are more likely to occur in individuals with spastic quadriplegia than other types of cerebral palsy (NINDS, 2013). In addition, it is not uncommon for individuals with cerebral palsy to have visual problems that may include eye muscle imbalances (e.g., strabismus), visual field cuts, visual-perceptual problems, loss of visual acuity (especially farsightedness), and/or cortical visual impairment, any of which can significantly affect learning and communication. Almost half of children with cerebral palsy have seizure activity, with the incidence highest among those children with the most severe motor impairments (ADDM CP Network, 2013). Feeding problems, growth difficulties, emotional/behavioral disorders, and learning disabilities may be present as well.
In addition to coping with challenges like these, people with cerebral palsy may struggle with a lack of social acceptance, as described by Magdalena Rackowska, a woman from Poland with cerebral palsy:
I do not like when people pity me. Like those ladies in the shops or people on the streets. They stare at me as if I were a weirdo. I really hate that look. I want people to accept me as I am. Sometimes, I just want to stick my tongue out at them. But I never do. I think to myself, it’s not worth it. Often, I ask myself the question, “Why don’t people want to understand me, isn’t it so simple?” (Rackowska, 2000, p. 88)
Key Considerations for AAC Intervention
Many individuals with cerebral palsy benefit from AAC intervention. Depending on their needs and skills, some individuals may rely completely on AAC to express themselves; others may use speech to interact with familiar communication partners around known topics but may require AAC to communicate with unfamiliar partners or to communicate about novel and complex topics; still others may rely primarily on their speech to communicate and may draw on AAC to provide clarification as required. Three issues require special attention from AAC teams that plan and implement AAC interventions for people with cerebral palsy: using a
team approach, ensuring access, and planning intervention across the life span.
Using a Team Approach Individuals with cerebral palsy who have complex communication needs experience significant motor impairments and may face a wide range of associated challenges. As a result, AAC interventions require the expertise of a team of professionals from a number of disciplines, perhaps more so than with any other developmental disability. During assessment and intervention, the wide variety of motor impairments in this population necessitates the involvement of professionals such as occupational and physical therapists, orthotics specialists, and rehabilitation engineers. Given potential speech and language difficulties, intellectual disabilities, vision and hearing impairments, seizure disorder, and/or social challenges, the team also requires expert input from medical professionals (e.g., neurology, orthopedics), speech-language pathologists, vision experts, audiologists, educators, psychologists, and so on. Vision, hearing, and motor skills are of fundamental importance when interacting with the world; the team should therefore address these issues early in the assessment process to establish viable channels of input (accommodating vision and hearing difficulties as required) as well as to determine reliable motor responses.
Individuals with cerebral palsy present with needs in a wide range of domains, necessitating multiple different interventions. AAC intervention must be balanced with the range of interventions targeting other needs (Beukelman, 1987). For example, it is not unusual for a school-aged child with cerebral palsy to be involved in mobility training to learn to drive a powered wheelchair, physiotherapy to maintain motor function, instruction in a new access technique (e.g., eye gaze) to improve control of AAC and other assistive technologies, speech therapy, feeding intervention, instruction in literacy and other academic subjects, as well as AAC intervention. All of these interventions must be balanced within the individual’s life while also preserving time for enjoyable leisure activities and downtime to relax. Ultimately the time and effort devoted to each of these interventions must be determined by the needs and skills of the individual and the priorities identified by the individual and family.
Because of impairment to muscle movement, coordination, and posture, individuals with cerebral palsy ...