Use of an intraventricular strip electrode for mesial temporal monitoring in children with medically intractable epilepsy

Abstract

OBJECTIVE The objective of this study was to evaluate mesial temporal electroencephalographic (EEG) monitoring, using an intraventricular strip electrode (IVSE) along the ventricular surface of the hippocampus, in children with medically intractable epilepsy. METHODS The authors reviewed 10 consecutive cases in which subdural electrode placements and mesial temporal monitoring were recommended. The median age of the patients was 12.7 years (range 4.5–19.3 years). Both grids and IVSE were placed in all patients. The 4-contact IVSE was used in 5 cases, and the 6-contact IVSE in the other 5 cases. The median number of contacts, including IVSE contacts, was 122 (range 66–181). A total of 182 seizures were analyzed. RESULTS The IVSE localized seizure-onset zones in 8 patients. The seizure-onset zone was identified exclusively by IVSE in 3 patients and was simultaneous in IVSE and subdural electrodes in 5 patients. Among the 5 patients with simultaneous onset on both IVSE and subdural electrodes, 4 had basal temporal onset and one had orbitofrontal and lateral midtemporal onset. In the remaining 2 patients, the absence of IVSE seizure onset permitted sparing of mesial temporal structures. An Engel Class Ia outcome was achieved in 9 of 10 cases. No complication was associated with IVSE placement. CONCLUSIONS Intracranial monitoring using IVSE offers an alternative in terms of quality of EEG recording. IVSE was useful in children who already required open craniotomy for intracranial monitoring over an extensive network of hyper-excitability.