This article analyses a conversational episode among aphasic and non-aphasic individuals in an inter-active situation. My purpose is to briefly contemplate two reflexive movements derived from the definition of aphasia as a metalinguistic problem or as a loss/alternation of linguistic competence: i) the first problem stands out processes of establishment and maintenance of discourse topic; ii) the second distinguishes that the co-occurrence of semiotic processes is essential both to the conversational relevance and to the discourse topic maintenance.