Functional MRI for language lateralization in individuals with intellectual and cognitive dysfunction: Two clinical case examples

Objective: Task-based functional MRI (fMRI) is a common non-invasive method of confirming hemispheric language dominance prior to neurosurgery in epilepsy. However, the use of this method is not recommended for individuals with cognitive dysfunction and in those with IQ below 70 due to concerns about accuracy of task performance in the scanner. This manuscript describes successful use of task-based functional MRI to lateralize language dominance in two individuals with cognitive dysfunction and intellectual disability. Methods: Two patients completed a pre-surgical epilepsy work-up at the QEII Health Sciences Centre in Halifax, Nova Scotia, which included comprehensive neuropsychological assessment. They also completed an fMRI paradigm that involved semantic category fluency, sentence completion, naming to description and passage listening tasks with stimuli delivered both visually and auditorily. Results: In both cases, fMRI maps were successful in lateralizing language dominance in relation to other clinical data, including intraoperative cortical mapping in one of the cases. Conclusions: This manuscript is the first to demonstrate that task-based fMRI can be used successfully to lateralize language in adult patients with cognitive and intellectual disabilities, and is the first to propose a specific paradigm for this purpose.