Language retaining resection of a focal cortical dysplasia adjacent to Broca's language area. Direct cortical stimulation facilitates epilepsy surgery in a case previously considered to be inoperable

We report the case of a 14-year-old male with a history of focal seizures since the age of six due to a focal cortical dysplasia located within the left frontal lobe. The patient's seizures proved to be refractory to treatments with Oxcarbazepine, Lamotrigine, Valproate, and Clobazame. Because fMRI for language mapping suggested a close spatial relationship of the lesion and Broca's area, invasive language mapping was performed using a subdural grid for direct cortical stimulation. This suggested a clear topographic distinction between the lesion and Broca's area, finally enabling language retaining lesionectomy. This case illustrates some pitfalls of fMRI language mapping in preoperative workup for epilepsy surgery.