Introduction

The primary purpose of this chapter is to review the evidence concerning cognitive-communication disorders and their treatments post moderate to severe ABI. Due to the vast number of changes in treatment approaches and concepts over the past 30 years, (e.g., the advancement of computerized software and hardware), a decision was made to focus on treatments and therapies developed over the past 20 years. We have therefore, included all RCTS and non-RCTS (prospective control and cohort studies) published between 1992 and 2012. All other inclusion criteria have remained the same (see Module 1- Introduction and Methodology for more details).

For this edition, we, once again, engaged in an expanded search of the literature using subject headings from the module and the following: social communication (discourse, pragmatics, social communication/

social cognition, social perception, self regulation and ABI, TBI or BI); verbal expression (word finding, word retrieval, naming, language formulation, verbal expression, sentence formulation and ABI, TBI or BI); auditory or listening comprehension (auditory and listening comprehension, receptive language, inference and figurative language); reading comprehension (visual processing, and oral reading and ABI, TBI and BI); written expression (discourse and formulation) and community and family communication; academic and academic supports and vocational communication and ABI, TBI and BI. This was an effort to capture all of the published materials available.

The term cognitive-communication disorder was adopted by the American Speech and Hearing Association (ASHA, 1987) to distinguish the unique characteristics of communication post-ABI from those of aphasia following stroke. While there were inconsistencies in terminology throughout the 1980s and 1990s, the term cognitive-communication disorder is now widely used in the literature.Traditionally, descriptions of communication disorders in the ABI population fall into 4 main groups: apraxia, aphasia, dysarthria and cognitive-communication.

In an earlier study, Sarno and colleagues (1986) reviewed the charts of 125 individuals who had sustained a mild to severe ABI. They found 29.6% of individuals were diagnosed with aphasia (fluent aphasia, nonfluent aphasia, global aphasia), 34.4% were diagnosed with dysarthria and another 36% were diagnosed with subclinical aphasia. Further, individuals diagnosed with subclinical aphasia consistently outperformed those with classic aphasia on a variety of tasks, such as visual naming, sentence repetition, word fluency and the token test. Individuals diagnosed with dysarthria performed significantly better (p=0.03) than those with aphasia on all tasks. More recently, Duffy (2001) reviewed data obtained from the Mayo Clinic (1987-1990 and 1993-2001). Dysarthria was the most commonly diagnosed communication disorder, followed by other cognitive language disorders (including nonaphasic cognitive communication deficits that are associated with ABI).

The College of Audiologists and Speech-Language Pathologists of Ontario (CASLPO) 2002 provides the following definition of cognitive-communication disorders: 

Cognitive-communication disorders are communication impairments resulting from underlying cognitive deficits due to neurological impairment.  These are difficulties in communicative competence (listening, speaking, reading, writing, conversation, and social interaction) that result from underlying cognitive impairments (attention, memory, organization, information processing, problem solving and executive functions) (CASLPO, 2002).

Previous editions of this module separated cognition from communication impairments for ease of authorship across multiple sites; however, in this edition a decision was made to acknowledge the cognitive underpinnings on communication post ABI.

Communication deficits in brain-injured patients may include aphasic-like symptoms such as naming errors and word-finding problems, impaired self-monitoring, and auditory recognition impairments. These constraints may also be coupled with other cognitive-communication impairments, such as attention and perception difficulties, impaired memory, impulsivity, and severe impairment of the individual’s overall communicative proficiency within functional situations. These constraints can prevent the brain-injured individual from exhibiting even simple communication skills (Lennox & Brune, 1993).

The study of language disorders following ABI has been challenging; conceivably more than any other area of communication disorders. Clinicians are required to deal with issues of language use or pragmatics to a greater extent than for other acquired neurological communication disorders.  In some instances, the language disorders found among individuals with ABI are more than just a reflection of underlying cognitive deficits. At other times, precise language processing deficits occur in conjunction with cognitively associated communication disorders (Kennedy & Deruyter, 1991).

Bloom and Lahey (1978) define language as, “knowledge of a code for representing ideas about the world through an conventional system of arbitrary signals for communication.”  Language is comprised of some aspect of content or meaning, that is coded or represented in a linguistic manner for the purpose of use in a particular context (Bloom & Lahey, 1978).

Every aspect of language (content, form and use) includes cognitive processing. Impairment of any cognitive process may affect any and all components of language. It is the mutually dependent relationship between cognition and language that gives individuals the ability to generate, assimilate, retain, retrieve, organize, monitor, respond to and learn from the environment (Kennedy & Deruyter, 1991).

Several aspects of cognition that may affect language identified by the American Speech-Language-Hearing Association (ASLHA) subcommittee of Cognition and Language are:

1)

impaired attention, perception or memory

2)

inflexibility, impulsivity, or disorganized thinking or acting

3)

inefficient processing of information (rate, amount and complexity)

4)

difficulty processing abstract information

5)

difficulty learning new information, rules and procedures

6)

inefficient retrieval of old or stored information

7)

ineffective problem solving and judgment

8)

inappropriate or unconventional social behaviour

9)

impaired executive functions; self-awareness of strengths and weaknesses, goal setting, planning, self-initiating, self-inhibiting, self-monitoring, self-evaluating”ASLHA (1987) as cited in (Kennedy & Deruyter, 1991 p 128-129).

Due to the integral relationship between cognition and language, a “disruption in these processes may affect the language processes of phonology, syntax, semantics and pragmatics, and compromise the symptomatology after ABI, that is, the cognitive, language, and behavioral deficits” (Kennedy & Deruyter, 1991 p 129).

A significant amount of data on the number of ABIs that occur per year and survival rates may readily be found in the ABI literature. However, specific to the topic of communication, there is a real absence of data documenting how many of these individuals have communication impairments following their injury.  Additionally, much of the literature focuses on the assessment of communication deficits rather than reporting treatment efficacy. 

Many brain injury survivors, unlike individuals with developmental communication disorders, have a history of normal learning, language and speech. Typically, they are younger than stroke survivors, and have greater concerns regarding transitions back to school and work. The mechanism of injury is unique, and is related to a collection of cognitive-communication disorders. Therefore, it is important to regard acquired brain-injured individuals as a distinct group (Turkstra, 1998).

Ylvisaker & Szekeres (1994) noted that communication impairments in ABI patients are generally described as nonaphasic in nature. This is a different type of communication impairment than that seen following stroke and this distinction is an important one. In ABI, communication challenges are often observed along with otherwise intact speech, fluency, comprehension and grammar (Ylvisaker & Szekeres, 1994). The communication style of those with an ABI has been described as “the language of confusion” (Halpern et al.,  1973) as cited in (Ylvisaker & Szekeres, 1994).

Ylvisaker & Szekeres (1994) noted that prior to 1980, Speech-Language Pathologists (SLPs) working in the area of ABI were uncommon. While there has been a significant expansion in the outcome research and clinical services over the past 15 years it is apparent from this review that evidence-based research into therapeutic interventions is lagging.

There is a limited number of high quality RCTs within the literature dedicated to cognitive-communication impairments and the therapies performed to assist with the improvement of these deficits, especially impairments related to linguistic organization, reading comprehension, written expression and information processing. In a review conducted by Perdices et al. (2006) on brain injury, it was found that 39% of the studies conducted were single subject designs (SSD) and 22% were case series. In fact, only 21% were RCTs; this may be due to the challenges in conducting these research studies to answer questions of treatment efficacy (Vanderploeg et al., 2006).Difficulties conducting RCTs with those who have sustained an ABI include the complexity of the disorder, the lack of homogeneity in this population, costs, specificity of treatment and the informed consent procedure (i.e. discomfort in potentially being randomized to an alternative treatment) (Struchen, 2005; Wiseman-Hakes et al., 2010). Further, blinding participants to their treatment group, and team members who are responsible for providing the treatment is “nearly impossible”(Kennedy and Turkstra, 2006).

An additional challenge to writing this module was the relatively large number of descriptive studies that delineate characteristic deficits in the ABI population relative to “normal” or uninjured participants. While this evidence is of interest, it was not within the scope of this current project and thus these papers have not been included in this module.  Rather, this review focuses on published empirical treatment research studies involving the trial of one or more treatments. Inclusion criteria for studies in this module are: the study is a controlled treatment trial that includes a meaningful sample of individuals with ABI, and a robust methodological research design.