Functional brain mapping using depth electrodes

Abstract

ObjectiveThis study investigated the neurological symptoms and stimulus intensities in the stimulation of deep structures and subcortical fibers with the depth electrodes. MethodsSeventeen patients with drug-refractory epilepsy who underwent functional brain mapping with the depth electrodes were enrolled. The 50 Hz electrical stimulation was applied, and the diffusion tensor image was used to identify subcortical fibers. The responsible structures and stimulus intensities for the induced neurological symptoms were evaluated. ResultsNeurological symptoms were induced in 11 of 17 patients. The opercular stimulation elicited the neurological symptoms in six patients at the median threshold of 4.0 mA (visceral/face/hand sensory, hand/throat motor, negative motor and auditory symptoms). The insular stimulation induced the neurological symptoms in four patients at the median threshold of 4.0 mA (auditory, negative motor, and sensory symptoms). The stimulation of subcortical fibers induced in five of nine patients at the median threshold of 4.5 mA. The thresholds of depth electrodes were significantly lower than those of subdural electrodes in eight patients who used both subdural and depth electrodes and induced symptoms with both electrodes. ConclusionThe stimulation of depth electrodes can identify the function of deep structures and subcortical fibers with lower intensities than subdural electrodes.