Navigated transcranial magnetic stimulation for preoperative cortical mapping of expressive language in children: Development of a method.

We adjusted an object-naming task with repetitive navigated transcranial magnetic stimulation (rnTMS) originally developed for preoperative cortical language mapping in adults in order for it to be used in children. Two series of pictures were chosen for children above and below 10 years of age, respectively. Firstly, the series of pictures and the preferred speed of presentation were assessed for their applicability in children of different ages and abilities. Secondly, these series were used with rnTMS preoperatively in five children with epilepsy. Naming errors induced by the stimulation comprised no response, delayed response, semantic error, phonological error, and self-correction. Language laterality was compared with the results of a dichotic listening test and with neuropsychological tests with respect to general laterality, and general language abilities were considered with respect to the results of stimulation. One participant had below normal general language abilities, two had below-normal rapid naming, and three had slow and indistinct articulation. Laterality was only clear in two of the participants. All children required breaks of various durations during the process, and individual adjustments of the interpicture interval and other stimulation parameters were also made. We conclude that, after adjustment, rnTMS combined with an object-naming task can be useful for preoperative language mapping in children.