Technical case report: intractable focal seizures related to bifrontal transmantle heterotopia subserving peculiar homotopic motor distribution treated by responsive neurostimulation therapy.

NeuroPace responsive neurostimulation (RNS® ) therapy was used in a case of intractable focal epilepsy with bifrontal transmantle heterotopia subserving peculiar homotopic motor distribution in a 16-year-old, right-handed male with intractable seizures. Brain MRI demonstrated bifrontal transmantle heterotopia extending from the central sulcus to subjacent lateral ventricles along with polymicrogyria along the overlying cortex suspected to be the motor cortex. Functional MRI demonstrated homotopic distribution of finger and foot motor function (deeper) within the polymicrogyria. Invasive intracranial monitoring with depth electrodes and extraoperative brain mapping revealed eloquent cortical tissue which corresponded to the right leg and right shoulder motor function.