Topic use following right hemisphere brain damage during three semi-structured conversational discourse samples

Background: Right hemisphere brain damage (RHBD) has been linked to a diverse range of discourse-level communicative deficits generally based on subjective impressions. Investigative evidence to support or refute the reports is limited and what evidence is available is frequently restricted in the conclusions it can make as a result of small sample sizes, inadequate reporting of onset time, and site of lesion. Comparisons with matched NBD individuals' performance are rare. Many of the descriptions could reflect a difficulty with the use of topic. Disorganised, verbose, tangential discourse with poor topic maintenance may reflect difficulties with the structural aspects of topic use, i.e., topic coherence. Other descriptions of discourse with an excessive focus on details, personalisations, and anecdotal elements are also prevalent but are not reflected within a topic coherence model. They may be linked to a deficit in the management of topic on an utterance by utterance level. Aims: To explore topic coherence and topic management during semi-structured conversational discourse by individuals with RHBD as a result of stroke. Methods and Procedures: Three cue-elicited conversational discourse samples were taken from a group of 17 individuals with post-stroke RHBD and a matched group of 51 non-brain-damaged individuals. The participants with RHBD were sampled at 1 and 6 months post-stroke. Discourse samples were transcribed and analysed in terms of topic coherence and management. The intra-test, inter-test, and test-retest reliability of the analysis was also evaluated. Outcomes and Results: The method of discourse sampling and the topic coherence and management analyses used proved to be reliable. There was no indication of a widespread consistent difference in the use of topic by the RHBD and NBD groups during the discourse samples. The exploratory results suggest the individuals with RHBD had some difficulties with topic coherence at subdivisional levels in comparison to NBD individuals. The groups' use of main topics differed little. Some differences between the RHBD and NBD individuals' use of fillers and repetition were observed. The proportion of on-topic utterances rather than off-topic or topic-shading utterances also indicated some between-group differences. Conclusions: These exploratory results provide little support for the perception that the RHBD population experiences widespread topic difficulties. The results highlight specific elements of discourse topic use that may differ between the RHBD and NBD individuals, but which requires further targeted investigation