Stereotactic Electroencephalography Is a Safe Procedure, Including for Insular Implantations.

Background: In some cases of drug-resistant focal epilepsy, noninvasive presurgical investigation may be insufficient to identify the ictal onset zone and the eloquent cortical areas. In such situations, invasive investigations are proposed using either stereotactic electroencephalography (SEEG) or subdural grid electrodes. Meta-analysis suggests that SEEG is safer than subdural grid electrodes, but insular implantation of SEEG electrodes has been thought to carry an additional risk of intraparenchymal hemorrhagic complications. Our objectives were to determine whether an insular SEEG trajectory is a risk factor for intracranial hematoma and to report the global safety of the procedure and provide some guidelines to prevent and detect complications.

Methods: In a retrospective analysis of a surgical series of 525 consecutive procedures between 1995 and 2015, all electrodes were classified according to their insular or extrainsular trajectory. All complications were classified as major or minor according to their potential consequences regarding patient neurologic status.

Results: Four intraparenchymal hematomas, all related to extrainsular electrodes (4/4974; 0.08%) were reported; no hematoma was found along insular electrodes (0/1042; 0%). There were 8 major complications (1.52%): 7 intracranial hematomas (1.33%) and 1 case of meningitis. Two patients had long-term neurologic impairment (0.38%), and 1 death (not directly related to the procedure) occurred (0.19%). Eleven minor complications (2.09%) were encountered, including broken electrode (1.52%), acute pneumocephalus (0.38%), and local cutaneous infection (0.19%).

Conclusions: SEEG is a safe procedure. Insular trajectories cannot be considered an additional risk of intracranial bleeding.