Surgical successes and failures of invasive video-EEG monitoring in the presurgical evaluation of epilepsy

Invasive monitoring with intracranial electrodes continues to play a critical role in the presurgical evaluation of patients with medically intractable epilepsy. Intracranial monitoring helps in localizing the epileptogenic zone and can be used to delineate eloquent cortical areas adjacent to this zone. In this review we analyzed surgical successes and failures of invasive video-electroencephalography (EEG) monitoring. Thorough understanding of all potential complications is of paramount importance not only for detection and successful management of intractable epilepsy but also for medicolegal purposes, as patients and their relatives need to be fully informed about the possible risks associated with invasive monitoring. A mortality rate between 0.5% and 2.8% has been reported. Cerebrospinal fluid (CSF) leaks and infections are the most frequent complications, with an incidence ranging from 0-31.3% and from 0-17.4%, respectively. The incidence of intracranial hemorrhage is reported to be up to 14% with subdural hematomas being the most prevalent. Epidural hematomas are less frequent and encountered in up to 2.6% of cases. Intraparenchymal hematomas are even less frequent and are typically associated with the placement of depth electrodes. In 47-98% of cases, invasive video-EEG monitoring results into resective surgery. Invasive video-EEG monitoring is a reasonably safe and effective method to help delineate the epileptogenic zone and its relation to eloquent cortex.