A novel approach for stereoelectroencephalography
Stereotactic EEG, or the placement of multiple intracranial depth electrodes, has gained popularity as a means of intracranial monitoring for seizure localization in the US, due to lower risk of morbidity compared to historical controls who were monitored with intracranial grid and strip electrodes. These depth electrodes record from a smaller volume of tissue, leading to reluctance in some groups to adopt this newer approach. In addition, many centers feel that grids and strips are necessary for extraoperative mapping of functional cortex. The Case Western group has published a new approach for sEEG which entails implanting multiple depth electrodes in a 3 dimensional grid that overcomes limitations of previous techniques. The novel approach can be done at the initial implantation, or as a 2nd operation, implanting additional electrodes to refine the localization of the epileptogenic zone. They report performing both cortical and subcortical mapping of motor, sensory, visual, speech and auditory function with this system. The morbidity in 254 electrodes in 20 patients consisted of 2 patients with transient weakness that lasted < 24 hours. This represents a novel approach to intracranial monitoring which affords safety for the patient while allowing traditional electrophysiologic localization of eloquent function.