Cortical Localization of Scalp Electrodes on Three-Dimensional Brain Surface Using Frameless Stereotactic Image Guidance System

Kim, Daeyoung; Joo, Eun Yeon; Tae, Woo Suk; Han, Sun Jung; Cho, Jae Wook; Seo, Dae Won; Hong, Seung Bong

Abstract

BACKGROUND: The purpose of this study was to localize the cortical regions reflected by overlying scalp electrodes.
METHODS
We enrolled 10 patients with epilepsy (5 males, mean age 29.7 years old). Thin slice coronal T1 weighted MR images were obtained and then scalp EEG electrodes were placed based on an international 10-20 system. Cortical locations of scalp electrodes were determined using a real-time frameless stereotactic image guidance system, Brainsight(R).
RESULTS
The locations of 19 scalp electrodes were marked on the 3D rendered cortical surface of one representative patient's MRI; Fp1 (Fp2) on the anterior pole of the middle frontal gyrus, Fz on the mid-point of the interhemispheric fissure in the frontal lobe, F3 (F4) on the mid-portion of the middle frontal gyrus, F7 (F8) on the pars triangularis of the inferior frontal gyrus, Cz on the interhemispheric fissure where a lateral precentral gyrus starts, C3 (C4) scattered around postcentral gyrus, T3 (T4) on the middle temporal gyrus, P3 (P4) on the angular gyrus, Pz on the mid-point of the interhemispheric fissure in the parietal lobe, T5 (T6) on the posterior part of the inferior temporal gyrus, and O1 (O2) on the occipital pole.
CONCLUSIONS
The locations of scalp electrodes were well correlated with conventional concepts of their cortical locations. The individual differences of the scalp electrode locations may be due to the different sizes and morphologies of the brains in each of the patients. Real time cortical localization of scalp electrodes using the Frameless Stereotactic Image Guidance System may provide useful information for more accurate localization of focal cerebral activity in partial epilepsy patients.