Crossed aphasias can be mirror image or anomalous. Case reports, review and hypothesis

Individual cases of crossed aphasia (aphasia after a right hemisphere lesion in a right-hander) have often been reported. A number of theories have been proposed as to the neuropsychological and/or nerobiological mechanisms that might underlie this phenomenon, but there is still disagreement about its language phenomenology and possible significance. We report 2 cases of crossed aphasia after stroke and review 34 cases from the literature with anatomical documentation of lesion site. Analysis of this material suggests that they represent at least two populations. There may be general conclusions concerning mechanisms of cerebral lateralization to be learned from the investigation of anomalous groups such as crossed aphasics.