Depth Electrodes (DE) are usually inserted under general anesthesia in children less than 13 years old, but can be inserted under local anesthesia supplemented by conscious sedation in older children. Since the recording of seizures during electrode implantation is not a goal of the procedure, anticonvulsants generally are not tapered nor withdrawn to induce intraoperative seizures.

Temporal DE can be inserted either via a posterior parietal-occipital site, with a trajectory along the axis of the temporal lobe into the amygdala and hippocampus, or transversely via the middle temporal gyrus into the medial structures. The posterior approach has the advantage of positioning several contacts along the longitudinal axis in the frequently epileptogenic medial temporal region while the lateral approach places the electrodes in site and structure specific locations. This method requires a number of incisions for all of the electrodes versus one for the parieto-occipital method. As a result, we prefer the parieto-occipital method in both adults and children.

Inferofrontal or parietooccipital electrodes can also be placed stereotactically as necessary to define spread of the seizures or to rule out a frontal focus. Frontal DE are routinely inserted via the second or third frontal gyrus, 12 to 15 degrees lateral to the midline, far enough anterior to the coronal suture to avoid traversing the frontal horn of the lateral ventricle, and terminate in the inferior, medial frontal lobes. DE wires are tunneled subcutaneously, secured with large sutures or staples to the scalp at multiple sites, and carefully marked as to their location.

Although the risk of infection is low with DE, postoperative antibiotics are routinely administered at our center because of a previously documented increased incidence of infection in children. EEG monitoring can be initiated on the day of surgery and localizing information is usually obtained within 2 weeks.

With a complication rate of 3 to 10%, mostly hemorrhagic, morbidity from DE is slightly higher than that of subdural strips and comparable to subdural grids.