Electrical Stimulation in Stereoelectroencephalography. Analysis of clinical response.

ODDO SILVIA; CLAUDIA COMINOTTI; B, GIAGANTE; NAHUEL PEREIRA DA SILVA; SANTIAGO COLLAVINI; P.SOLIS; MUNERA CLAUDIA; JUAN PABLO PRINCICH; PABLO SEOANE; KOCHEN S

Wshington DC

Congreso; American Epilepsy Congress; 2017

American Epilepsy Society

Rationale Stereoelectroencephalography (SEEG) based presurgical evaluation of epilepsies has two objectives: to define the epileptogenic zone (EZ) and to map cortex functionally in relation with the surgical plan. The aim of this study is to analyze electrical stimulation (ES) findings in our population of patients and to observe if there is a difference of response between different anatomical regions depending of the setting of stimulation. Methods We analyzed 17 patients from the Video-EEG Unit of the Neuroscience Service from El Cruce Hospital, with drug resistant epilepsy who underwent a SEEG as part of a surgical plan. Electrode size diameter of 1,57 to 1,12 mm, contacts 1.57 to 2.41 mm long, separated by 5 mm from one another.ES is applied between two adjacent leads of one electrode. Stimulation parameters: Bipolar 40Hz - 1mseg , T 2 a 5 seg, Pulse width and train frequency generally are kept constant throughout the whole stimulation procedure, intensity range from 1 to 10 mA, charge density (uC/cm2) from 12,34 to 123,38, until trigger after-discharges (AD), or clinical response.Cognitive tasks: hand tapping, naming, automatic speech (counting), reading and verbal fluency. Results Data were divided into 6 anatomical areas for analysis: hippocampus, Amygdala, Frontal, Temporal, Insula and Parieto-occipital and we evaluated any evoked clinical response with changes in the electric activity depending on the charge density.We found that in Amygdala the arithmetic average of charge density that is needed to evoke a clinical and electrical response was 49.35 uC/cm2 (SD: 37.01uC/cm2), in hippocampus was 49 uC/cm2(SD: 24uC/cm2), Frontal areas was 83uC/cm2 (SD: 49uC/cm2), in Temporal areas was 82.23 uC/cm2 (SD: 32.89uC/cm2), in Insula areas was 82.23uC/cm2 (SD: 49,39 uC/cm2) and in Parieto-occipital areas was 65.78uC/cm2 (SD: 32.89uC/cm2).Discussion In this analysis we observed that hippocampus and amygdala regions were more susceptible to evoke a clinical response with minimal charge density, while Frontal, lateral Temporal, Insula and parieto-occipital regions needs more charge density to trigger a clinical response.