Relationship of depth electrode complications to implant trajectory

From December 1980 to December 1991, 171 depth electrode implantations, involving 711 trajectories, were performed on 164 ablative seizure surgery candidates. Twenty-seven complications (15.8%) occurred in 21 patients. There were 14 trajectory-related complications. Eight were related to vertex entry amygdaloid implants. This included two permanent complications (1.2%), one hemiparesis, and one hemiparesis with aphasia. In addition, one transient hemiparesis, one transient aphasia, one transient severe headache, two asymptomatic hematomas, and one symptomatic hematoma occurred. Five cases of transient global amnesia were related to occipital entry mesial temporal implants, all computed tomography (CT) guided. One case of transient lower extremity monoparesis was related to a parietal entry anterior cingulate implant. There were 13 nontrajectoryrelated, temporary complications. This included two brain abscesses, two skin infections, one symptomatic hematoma associated with one slowly resolving hemiparesis, ventriculitis (one septic and three chemical), one asymptomatic hematoma, and two broken anchor bolts. No permanent complications occurred in the last 99 patients. The risk of neurologic complications has been reduced by no longer using vertex-amygdalar trajectories and creating depth-electrode tracts prior to implantation. The risk of hemorrhage has been reduced by careful study of preimplant angiograms for avascular entry sites and not advancing any electrode through the meninges until hemostasis has been assured.