Constraint-Induced Aphasia Therapy

By: Kimberly L. Frey, MS, CCC-SLP (1), Jody K. Newman, MA, CCC-SLP (1), David B. Arciniegas, MD (1)

Over the past several years, the neurorehabilitation community has begun to recognize the impairment-based and functional outcomes of a treatment approach designed for motor recovery. This treatment, constraint-induced motor therapy (CIMT) [1], improves motor impairments and functional ability associated with stroke and other focal cerebral lesions, and appears to confer such benefits even when it is provided in the late post-injury period [1, 2, 10]. In light of these results, the underlying premise and principles of CIMT are now being applied to rehabilitation of post-stroke aphasia [7-9]. This approach, constraint-induced aphasia (or language) therapy (CIAT or CILT, respectively) [7, 9], is described and reviewed briefly in this article in order to familiarize readers of the Neurotrauma Letter with this promising method of aphasia rehabilitation.

CIMT has as its theoretical premise, the maladaptive effects of “learned non-use.”  Essentially this means that when use of arm or leg is made more difficult by the neurologic injury, a person begins to habitually avoid use of that injured extremity.  Non-use of the extremity is accompanied by cortical changes that contribute further to motor impairment and functional limitations. The cycle of learned non-use is maladaptive: the less one uses an impaired arm/leg, the less functionally useful that extremity becomes, and the neural networks supporting the function of the arm/leg reorganize in a manner that maintains impairment and disability. The converse may also be true, however; it is possible that increased use of the impaired extremity may reduce motor impairments, improve functional use of the affected extremity, and facilitate reorganization of the neural networks supporting the function of the arm/leg in a manner that maintains improved motor ability and functional status.

CIMT incorporates three core processes that are not elements of conventional motor therapies: 1) constraint, which involves restraining use of the patient’s unaffected limb in order to force use of the affected limb; 2) active engagement, which refers to employing real-world therapy tasks that require the patient to work with intention; and 3) intense massed practice, which consists of task repetitions sufficient to produce within-session learning plateaus (saturation) as well as frequency of training sessions sufficient to foster additional incremental motor performance improvements – typically through provision of therapy for at least three consecutive hours per day, five days a week, over two or more weeks.

Constraint-Induced Aphasia Therapy (CIAT)

CIAT is analogous to CIMT in that its theoretical foundation is that aphasia is complicated by “learned non-use” which may be overcome by treatment directed at this problem. While the focus of CIMT is on non-use of an arm or leg, the target of CIAT is overcoming the adverse effects of non-use of verbal expression.  This non-use is habituated by the exasperation associated with difficult or failed verbal expression and the relative success associated with compensatory strategies [7].  In other words, when persons with aphasia have difficulty producing a word, they experience frustration if not failure and resultantly tend to produce the easiest expression, typically in the form of paraphasias (expressive errors involving incorrect sound or word substitutions), circumlocution (an indirect or “roundabout” manner of expression as a result of word finding difficulty), or stereotypy (a nonproductive but frequently and automatically produced word or phrase).  These types of verbal expressions impair functional communication, leading patients to adopt non-verbal compensatory strategies (e.g., drawing, gesturing, allowing others to speak for them). These strategies decrease frustration and may allow communication, but further diminish patients’ verbal expressions.

CIAT employs a structured language exchange between patient and therapist centered on a game that requires patients both to request and also to respond to requests for pictures. In order to optimize within-session task performance, the therapist shapes the complexity of the task to match each patient’s skill level – that is, the therapist gives verbal or visual cues or modifies the therapy materials and tasks to help the participant produce the correct request at the current level of complexity. Similar to CIMT, CIAT employs constraint, active engagement, and intense practice as processes through which learned non-use of verbal expression is overcome.

Constraint

Constraint in CIAT is accomplished by requiring patients to use only speech, and only very specific speech elements, when expressing themselves. In other words, the use of non-verbal expression and/or other compensatory strategies is constrained. This approach is understood most accurately as a behavioral intervention that is coupled with techniques that direct the patient toward effective language use [8]. The behavioral intervention directs communicative efforts toward successful verbal expression and away from non-verbal expression, use of other compensatory strategies, or avoiding verbal communication altogether. By matching treatment complexity to linguistic abilities, verbal successes provide positive reinforcement for verbal expression; concurrently, reliance on and use of non-verbal communication strategies decreases. Effective language use refers to a technique that facilitates exact word use and thereby reduces paraphasias, circumlocutions, stereotypies, and other non-productive utterances. For example, patients participating in group-based CIAT are required to state other patients names rather than pointing or using pronouns (i.e., “you,” “him,” “she”), to use exact and individualized target words and phrases, and to employ descriptive qualifiers when naming pictures of objects (e.g., “three”, “red”, “small”). These types of communication constraints, implemented through the specific therapist-patient interactions and language games used in CIAT, foster verbal communication and effective use of language.

Active Engagement

Active engagement is accomplished by requiring patients to participate actively and expend effort to communicate verbally. As compared to traditional naming therapy, which tends to be clinician-directed and unidirectional (i.e., the therapist-driven task targets semantic lexical or phonologic features of an object name), CIAT uses language barrier games that force practice of language skills in natural communication tasks. The characteristics of these language barrier games model natural communication in a manner rather unlike that of traditional naming therapy. More specifically, CIAT parallels natural communication in several ways. First, at each step of the exchange, the content of information that will be communicated is not entirely predictable to or known by one of the participants in that exchange (i.e., meaning one person does not know what the other will say and vice versa). Second, the communication is bi- or multi-directional, dynamic, interactive, and involves a variety of exchanges [11]. Third, language and action are intertwined, with cortical and subcortical motor systems both engaged in language use [8]. On this last point, and unlike a traditional naming therapy task, verbal and stimulus exchanges in CIAT activate motor systems concurrently with language networks; this combination may engage a more distributed set of neural networks whose activity is correlated (rather than simply co-incidental) and might thereby increase the likelihood of CIAT-related development of stable neural networks that more effectively support effective language use.

Intense practice

Analogous to CIMT, intense practice is an essential element of CIAT.  Treatment intensity is defined by the ratio of treatment hours per therapy week, and it is modified by the amount of time between practice sessions (no time or hours or days). Intense treatment facilitates not only learning or acquisition of a task but also generalization and/or transfer of skills. Treatment intensity also influences rehabilitation outcomes [12, 13]. A minimum number of treatment hours appear to be required before a treatment is adequately intensive and treatment effects are observed. Bhogal et al., [12] identified and compared the outcomes of all stroke rehabilitation clinical trials from 1975 through 2002, and estimated that at a minimum, 8.8 treatment hours a week were necessary to produce a significant treatment effect. The intensity of CIAT can be quantified at approximately 12:1 ratio of treatment hours to treatment weeks respectively; by contrast, the ratio of conventional aphasia therapy provided in the post-acute injury period generally is approximately 2-3:1. 

Within each 3-hour CIAT session, treatment stimuli are presented in variable orders, interspersed with delays and breaks. This manner of presenting stimuli is a mediating factor in acquisition, retention, and transfer of learning. Variable practice involves high interference (e.g., changing the order of stimuli practice), and facilitates retention and between-task transfer of motor and verbal skills [14, 15].  CIAT sessions also create practice opportunities through varying task constructs, demands, and complexities. Breaks are inserted into each treatment set and session through alternating request/response exchanges, phrase reconstruction, and changes in linguistic complexity. These processes facilitate retention and transfer of learning by ensuring that the therapy tasks are optimally challenging as well as variably distributed. In other words, these tasks involve effortful activation, not mere use, of motor and cognitive faculties (i.e., “desirable difficulties” [16]) and allow for memory consolidation through repeated yet distributed deconstruction and reconstruction of the learned behavior (i.e., “contextual interference” [17, 18]).

Intense practice also involves daily therapy sessions over the two-week (or longer) period of CIAT. The intervals between treatment sets and sessions are designed to facilitate consolidation of the language and functional communication skills acquired through treatment. This within- and between-treatment schedule comports well with motor and declarative learning studies demonstrating improved retention and transfer of skills when acquisition is undertaken in this manner [19].

Conclusions and Future Application

CIAT appears to be an effective treatment approach for both the expressive and receptive communication difficulties associated with post-stroke aphasia, and may effect improvements in language and functional communication even among persons with chronic aphasias and who have not responded to traditional aphasia therapies. Objectively-measured improvements include performance on standardized aphasia assessments, including overall aphasia score, naming, repetition, fluency, and auditory comprehension, as well as blinded ratings of communication effectiveness (amount of communication in everyday life) and clinician judgment of story re-tell (e.g., word accuracy, concepts conveyed, and word fluency) [7, 9, 20-23]. In addition to patient self-reports, subjective CIAT-associated improvements include family ratings of communication abilities (e.g., quantity and quality of communication) [7, 9, 20-23].

These findings are encouraging of the potential benefits of CIAT and provide a source of therapeutic optimism for persons with chronic and/or otherwise difficult-to-treat post-stroke aphasias. However, it is premature to suggest that CIAT could be applied to the entire population of persons with aphasia. Subjects enrolled in such studies are generally those with chronic, rather than acute or subacute, aphasias. At the time of this writing, only one CIAT study [24] describes benefits associated with its provision in the subacute post-stroke period (i.e., 1-2 months after stroke). While communicative improvements have been reported in both persons with non-fluent and fluent aphasias, persons with non-fluent aphasias are over-represented in CIAT studies [7, 20, 22, 25] making it difficult to assess the relative benefits of this treatment for persons with fluent aphasia. Additionally, CIAT may improve the mean language performance in groups of subjects but its effects in any individual patient are variable. These and related issues are discussed in Cherney et al. (2008) [26], to which readers are referred for an evidence-based review of CIAT.

Additional research is needed to better define both the types of aphasia and also the characteristics of persons with aphasias that predict benefit from CIAT, and to clarify the range of times after aphasia-onset at which its provision is appropriate. For example, animal and human studies of CIMT therapy suggest that it is best implemented after 15 days post-injury [27, 28]. It also appears that CIMT is most effective and safest when treatment intensity is limited to two hours per day of therapy and a total of six hours per day of constraint use [29]. Constraint-based rehabilitation, timed appropriately, may facilitate beneficial and stable neural changes that improve language and functional communication. Ill-timed interventions, however, risk exacerbating neural injury and aggravating aphasia and related disability.

Finally, the influence of concurrent cognitive, emotional, behavioral, and sensorimotor impairments on CIAT responsiveness remain unknown. It is possible that certain types or severities of such problems may limit a patient’s responsiveness to CIAT.  Conversely, it is possible that CIAT may concurrently benefit some such impairments and/or mitigate their contributions to impaired functional communication. Continued exploration of CIAT’s constructs, application, and neurobiological underpinnings is therefore warranted.

Affiliations

1. Neurobehavioral Disorders Program, Anschutz Medical Campus, University of Colorado Denver, Aurora, CO.

Corresponding Author

Kimberly L. Frey, MS, CCC-SLP, CBIS
Neurobehavioral Disorders Program
University of Colorado Denver
13001 East 17th Avenue, Campus Box F546
Aurora, CO 80045
Phone: 303-724-4990
Fax: 303-724-3594
Email: Kim.Frey@UCDenver.edu

Key Words

Stroke, aphasia, language, constraint-induced therapy

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