Short Description or Definition

“Aphasia is an acquired communication disorder caused by brain damage, characterized by impairments of language modalities; speaking, listening, reading and writing; it is not the result of a sensory or motor deficit, a general intellectual deficit, confusion or a psychiatric disorder” (Hallowell and Chapey 2008, p. 3). Aphasia is typically acquired suddenly as a result of a stroke or traumatic brain injury but can appear more slowly accompanying other neurological events such as tumor or disease. When aphasia develops slowly over time and is the only behavioral symptom present, the diagnosis is primary progressive aphasia (PPA). Aphasia is often classified according to the appearance of a constellation of behavioral symptoms including impairment in auditory comprehension, reading comprehension, naming, production of grammatically correct sentences, repetition, writing, and presence of paraphasic (substitution) sound or word errors (e.g., saying table for chair or pork for fork). Aphasia disrupts communication ability, sometimes so severely that a person with aphasia withdraws from social interaction and other times only minimally so that the person with aphasia continues his or her life activities.

Aphasia Classification

Many systems have been proposed to classify aphasia types (Kertesz 1979). Each system represents a theoretical perspective of aphasia and identifies aphasia types according to a constellation of behavioral characteristics. Classification systems can be dichotomous (e.g., fluent vs. nonfluent or comprehension deficit vs. production deficit), anatomically based (e.g., Boston classification system of aphasia types, such as Broca’s aphasia), and behaviorally based (e.g., Schuell’s system of multimodality, unidimensional impairment, such as aphasia with visual involvement), can be based on severity (e.g., mild, moderate, or severe), or can follow a processing model (e.g., cognitive neuropsychological model of naming; Kay et al. 1996). Classification systems are useful for a general understanding of an individual’s communication ability; however, controversy exists regarding their clinical utility. Some individuals with aphasia show symptoms that match more than one type of aphasia, and others show symptoms that do not fit into any of the classification categories. Studies examining classification report 35–70% success in classifying participants as one aphasia type (Caramazza 1984; Crary et al. 1992). Table 1 shows three classification systems, with general characteristics of each aphasia type.

Aphasia, Table 1 Three examples of aphasia classification systems showing aphasia types and general characteristics of each type
Full size table

Epidemiology

Aphasia resulting from stroke occurs in approximately 30% of the 15 million people worldwide who experience a stroke each year. In the United States alone, 80,000 new occurrences of aphasia appear each year, and at any point in time, approximately one million people are living with aphasia following stroke. Aphasia resulting from traumatic brain injury and other causes is difficult to estimate.

Natural History, Prognostic Factors, and Outcomes

Reports of language disorder following brain injury have existed for hundreds of years, initially as case reports. Paul Broca and Carl Wernicke in the late 1800s presented clinical data relating behavioral and anatomical information, localizing language ability to the left hemisphere, and ultimately having their names adopted to identify anatomical areas in the brain related to patterns of language deficit. Current studies of persons with aphasia use neuroimaging techniques to further elucidate the behavioral and anatomical relationship.

Aphasia in the first few months after a stroke is the acute stage and is often characterized by spontaneous recovery of language and communication deficits. In the chronic stage, an individual learns to live with aphasia and returns to life activities. Prognosis for recovery is variable and dependent upon both internal patient factors (e.g., severity of aphasia, type and extent of lesion, or concomitant medical problems), external factors (e.g., family support or communication interaction opportunities), and other ambient experiences (McClung et al. 2010). Personal variables such as age, education, and gender do not systematically influence prognosis (Basso 1992; Pedersen et al. 2004; Plowman et al. 2012).

Aphasia recovery occurs most rapidly immediately following the brain injury as the brain begins to heal itself. Studies have shown that recovery also continues for years post-stroke and following treatment (Moss and Nicholas 2006). Outcome measures documenting change are impairment based (e.g., change in naming ability) or activity/participation based (e.g., increased participation in social activities), following the World Health Organization’s International Classification of Functioning, Disability and Health (ICF; WHO 2001). In addition to measuring functional communication outcomes, patient-reported outcomes (PRO) are gaining importance as a component of patient-oriented treatment (Hula et al. 2015). Some persons with aphasia recover to near-normal premorbid language and communication performance, while others remain severely aphasic. Almost every person has the potential for some level of functional communication, from being an independent communicator in a variety of communication interactions to being dependent upon an alternative or augmentative communication system or a conversational partner (Hachioui et al. 2013).

Models of Language, Communication, and Aphasia

Numerous models serve to guide assessment and treatment of persons with aphasia and foster understanding of how aphasia affects persons with aphasia and their family members. Theoretical influences underpinning these models range from impairment-based models, such as cognitive neuropsychological models of language processing, to models based on psychosocial theory, such as the A-FROM (Kagan et al. 2008). Cognitive neuropsychology brought to aphasia evaluation and treatment a set of models of human cognitive mechanisms and processes thought to underlie language performance. An individual’s performance on several linguistic tasks is examined for patterns of impaired and spared cognitive processes in order to infer the cognitive architecture that underlies the performance. For example, in a model of lexical processing, the linguistic tasks might be lexical recognition (word/nonword identification), auditory comprehension (pointing to a named word), and naming a picture (confrontation naming). An individual who scores high on auditory comprehension and reading words tasks but low on confrontation naming may be inferred to show a deficit in phonological output lexicon but have an intact semantic system and ability to use phonic skills to read a word. That is, the individual may have intact semantic knowledge and be aware of the phonological form of a word and be able to read it but lack the phonological skills to generate the verbal label. The pattern of performance is important to note and serves to direct treatment to the impaired processes, using the spared processes as strengths. Cognitive neuropsychological models of language processing frequently used in aphasia assessment and treatment, however, are not without criticism as being descriptive and not prescriptive and requiring time-consuming assessment.

In contrast to the deficit-specific models of cognitive neuropsychology, other models recognize the importance of an individual’s psychosocial state, quality of life, functional communication abilities, and communication network. Tanner (2003) proposed an eclectic approach to examine the psychology of aphasia from three perspectives: effects of brain injury, psychological defenses and coping styles, and responses to loss. This view speaks to the importance of an individual’s premorbid personal characteristics, their ability to adjust to change, and their external support network as they and their family learn to live with aphasia. Several models and tools exist to guide assessment and treatment in these areas. For example, quality-of-life scales ask questions about topics such as family support and general outlook on life (e.g., communication-related quality-of-life scale; Cruice et al. 2003). An important model, the A-FROM (Living with Aphasia: Framework for Outcome Measurement; Kagan et al. 2008) espouses an integrated approach to aphasia assessment. The A-FROM clarifies outcomes in five domains: participation, aphasia severity, language and communication environment, personal factors/identity, and life with aphasia. Social network diagrams illustrate the breadth and depth of an individual’s support and communication networks (e.g., Blackstone and Berg 2003).

While aphasia tests are founded on specific models of language, communication, or cognition, assessment and treatment activities often reflect a combination of impairment-based and activity/participation-based models.

Evaluation

Approaches to evaluation of aphasia vary with the conceptualization of aphasia.

Some approaches take an impairment-based approach, viewing aphasia as a disorder of selected abilities, while others, such as the Life Participation Approach to Aphasia (LPAA 2000) take an activity/participation approach, viewing aphasia as a disruption to communication and placing the person with aphasia and his or her family at the center of clinical decision-making activities. Schuell et al. (1964) proposed assessment based on the definition of aphasia as language deficit that crosses all modalities, all of which are examined in the Minnesota Test for the Differential Diagnosis of Aphasia (Schuell 1965). Chapey (2008) suggested that evaluation stem from a cognitive stimulation model, which views communication as a problem-solving and decision-making task. Following the World Health Organization ICF (2001), models of assessment and treatment typically incorporate information at levels of impairment and activity/participation.

In contrast to language-based evaluation tools, some approaches to evaluation consider the circumstances in which treatment will be conducted. Group treatment has gained popularity in recent years, recognizing the value of social connectedness, and some assessment tools examine the social desires and needs of a person with aphasia (Avent 1997; Kearns and Elman 2008). Lubinski (2008) discussed an environmental model, suggesting that clinicians consider physical and social environments of a person with aphasia to enhance treatment effects. Finally, psychosocial models of intervention focus on integrating an individual into a communicating society and promoting their participation in personally relevant activities (Simmons-Mackie 2008). Regardless of the approach, in order to understand the linguistic and communicative abilities and needs of an individual, it is important to conduct evaluation within a culturally sensitive framework.

Three types of aphasia tests are commonly used to assess language and communication abilities in persons who have aphasia: screening tests (short assessments that may be administered at bedside), comprehensive aphasia tests (batteries containing several subtests to examine language behavior such as naming, reading, and writing), and tests of specific linguistic or communicative function (e.g., syntactic function or naming) (Patterson 2008). In addition, assessment of aphasia and its impact on a person’s life include testing cognitive abilities (e.g., memory), testing executive functioning (e.g., divided attention), observing a person in activities of daily communication, and interviewing the person with aphasia and family members about the impact of aphasia on life participation and functional communication.

In aphasia assessment, it is as important to determine the presence or absence of aphasia and the presence of concomitant disorders, as it is to classify aphasia type, describe aphasia symptoms, and understand how the aphasia affects the individual and family. Sometimes only some of these goals can be achieved. Examples of disorders that may accompany aphasia but that are not aphasia are apraxia of speech, dysarthria, dementia, memory impairment, or psychiatric problems. These concomitant disorders will affect treatment planning and task selection. Medical conditions, such as diabetes, cardiovascular disease, and any medications the patient takes, may affect performance and should also be noted in the assessment report.

Sometimes people with aphasia experience depression, and several scales have been developed to screen for depression. Some have a linguistic bias or rely on caregiver report, while others have been adapted to be “aphasia friendly” and not depend exclusively on complex written sentences. Three examples of instruments to examine depression are the Stroke Aphasia Depression Questionnaire (SADQ) (Lincoln et al. 2000), the Aphasia Depression Questionnaire (Benaim et al. 2004), and the Visual Analog Mood Scale (Stern et al. 1997). The SADQ while designed for persons with aphasia has a linguistic bias and is intended to rely on caregiver report. The ADQ is a nine-item tool used to assess post-stroke depression in persons who are hospitalized after a stroke. The VAMS is an example of a nonlinguistic mood scale used for self-report of depressive symptoms.

The goals of evaluation will vary depending upon factors such as severity of aphasia, age, and time post-onset. For example, an individual with mild aphasia who anticipates returning to work should have an assessment that includes detailed information on linguistic processing and a job task analysis to determine the linguistic requirements of the position. This information may be used to determine the individual’s ability to return to a job, to identify communication requirements of the job, and to guide employment-related treatment. In contrast, evaluation for an individual with severe aphasia and concomitant severe apraxia of speech may require an evaluation focused on functional communication strategies to use with familiar communication partners within a contained environment.

Treatment

The acute stage of aphasia is the first few months after a stroke as the brain recovers from injury and is often characterized by spontaneous recovery of language and communication deficits, while in the chronic stage of aphasia, an individual learns to live with aphasia and returns to life activities. There are many well-validated, effective techniques for aphasia rehabilitation, particularly for chronic aphasia. These range from general stimulation approaches to treatments aimed at specific signs of aphasia and are chosen according to the patient’s individual needs, goals, aphasia characteristics, and etiology. For aphasia due to acute-onset causes (e.g., vascular etiologies or trauma), therapy has been demonstrated to be effective both early after onset (Carpenter and Cherney 2016) and in the chronic stage. For aphasia due to progressive etiologies, therapy has been shown to be effective in maintaining functional communication and maximizing quality of communication life to the extent possible given the medical diagnosis (Beeson et al. 2011).

Pharmacological intervention for aphasia may be undertaken for direct treatment of the language deficit or administered to address a concomitant disorder, such as depression. Although research in this area is encouraging, to date, no pharmacologic treatment has emerged as consistently improving linguistic function without adverse side effects (Greener et al. 2001; Murray and Clark 2006; Troisi et al. 2002).

Treatment for aphasia historically focused primarily on restitution of function using impairment-based treatment techniques, with treatment targets such as word or sentence production or writing. Examples of these treatment techniques are Melodic Intonation Therapy, a semantic or phonologic cueing hierarchy, and confrontation naming. More recently, treatment goals have expanded to include activity/participation-based treatments such as functional communication and group therapy. Examples of activity/participation treatment methods are book groups for persons with aphasia (with the linguistic level of the book modified to be aphasia friendly), reciprocal scaffolding (e.g., Avent et al. 2009), and supported conversation (e.g., Kagan et al. 2001).

Recently intensive treatment has become a focus for aphasia rehabilitation. Intensive treatment can be measured by the amount and frequency of delivery of a treatment protocol. Warren et al. (2007) suggest using cumulative intervention intensity (a produce of dose of treatment, frequency, and total duration) to equate intensity across various treatments. Evidence supports intensive treatment for aphasia under careful considerations of treatment protocol and patient characteristics. Intensive treatment can be effective at all stages of recovery from aphasia. Another form of intensive treatment is the Intensive Comprehensive Aphasia Program (ICAP; Babbitt et al. 2015) where individuals with aphasia spend several hours each day for a few weeks completing multiple treatment activities.

The four principles of evidence-based practice, current best practices, clinical expertise, client/patient values, and context of treatment, guide treatment planning. Clinical practice research and clinical trials support the efficacy and effectiveness of aphasia therapy. Systematic reviews, such as the one for constraint-induced language therapy (Cherney et al. 2008), and meta-analyses (e.g., Robey 1998) report the evidence from group studies and single-subject research studies for a specific treatment or aphasia therapy in general. Cherney and Robey (2008) and the Academy of Neurological Communication Disorders and Sciences (ANCDS 2016) present analyses of treatment effect sizes of aphasia treatment for specific treatment areas such as syntax and language comprehension.

Cross-References