Advanced disconnectomic analyses reveal repetition pathways in a case of mixed transcortical aphasia

Mixed Transcortical Aphasia (MTA) is an infrequent aphasic syndrome, characterized by poor comprehension and production in oral language abilities and poor performance in written language abilities. However, individuals with MTA typically retain the ability to repeat. Our patient, a woman who suffered from a left hemisphere ischemic stroke involving perisylvian areas, presented with repetition preserved for words, non-words, sentences and numbers, together with marginally preserved reading abilities. Given the peculiarity of her linguistic profile, we employed recently developed lesion-based approaches for probabilistic estimation of white matter disconnections to reveal which white matter tracts are likely to be related to her preserved linguistic abilities. Our analysis revealed that while the left arcuate fasciculus (AF)-a tract commonly associated with repetition-was partially affected, its posterior and long branches were estimated to be disconnected, whereas the anterior branch remained intact. This disconnection pattern may explain the pattern of preserved repetition abilities observed in this MTA patient.