Assessing and Treating a Severe Word-Finding Deficit in a Person with Transcortical Sensory Aphasia: A Single Case Study

Simply defined, aphasia is a language-specific disorder that results from an acquired neurological injury. There are many different types of aphasia, but one of the rarer and therefore less understood forms is transcortical sensory aphasia (TSA). Individuals with TSA often exhibit fluent output with many paraphasias, a strong ability to repeat, and poor auditory comprehension skills. Furthermore, given that almost all individuals with aphasia present with some degree of anomia or word-finding difficulty, naming impairments are also commonly observed in individuals with TSA. Several treatment approaches have been developed to target word-finding in individuals with aphasia, including Verb Network Strengthening Treatment (VNeST). VNeST is based on the assumption that verbs have argument structure (i.e., thematic roles such as agent and theme). As such, when a verb is activated (e.g., bake), activation spreads to the associated nouns that could potentially fill the verb’s thematic roles (e.g., agent: baker, cook; theme: bread, lasagna). There is considerable evidence demonstrating that VNeST is an effective and efficacious approach to improving word-finding in spontaneous speech. Interestingly, none of the studies supporting its use have included individuals with TSA. Thus, it is unknown how individuals with this aphasia type would respond to VNeST; in fact, because TSA occurs so infrequently, there is very little guidance offered in the literature for clinicians to follow regarding how to approach treatment with this population. This thesis describes a person (“John”) with TSA who received intense VNeST therapy for his severe anomia. A single case study design was implemented in three phases: 1) pre-treatment/baseline, 2) treatment, and 3) post-treatment. In the pre-treatment phase, a comprehensive profile of John’s relative strengths and deficits was obtained using various assessments of speech, language, communication, and cognition. Once baseline performance and functioning were established, John was trained on ten verbs via VNeST for a total of thirty hours (i.e., three hours a day for ten consecutive days). Following completion of the treatment phase, select assessments were re-administered immediately post-treatment and one month later to evaluate generalization and maintenance. Results revealed generalization to verbs trained in VNeST but not to untrained verbs that were semantically related to the trained verbs (e.g., trained verb: read; untrained verb: write). John produced more agents and themes for trained items following treatment than at baseline, whereas no change in performance was noted across time points for untrained items (a finding that is contradictory to what has been reported in the literature). While no observable gains were detected for untrained verbs, John’s communicative informativeness and efficiency as measured by the number of relevant content words that he produced in discourse increased from baseline. John also achieved a higher overall score on the Porch Index of Communicative Ability (PICA) after treatment, suggesting that he had made some improvement in his general ability to communicate through different modalities. Furthermore, John independently generated more verbs on a confrontational naming task post-treatment than prior to treatment (although this was not found for noun naming). All of the gains identified in this study were maintained for at least one month after treatment had concluded. In terms of gains made in the areas of sentence production and comprehension, results were mixed and were most likely impacted by various internal and external factors. Though quality of life was not formally assessed following treatment, John and his wife reported high satisfaction with VNeST, stating that he had made some slight but personally significant progress in his ability to functionally communicate at home. This study continues to show that VNeST is an effective and efficacious approach to targeting naming/word-finding deficits in individuals with aphasia. More specifically, it is one of the first studies to support the use of VNeST with individuals who have TSA and a severe anomia. The findings from this study also raise several new and interesting questions regarding neurolinguistic processing that should be explored in future research investigations.