Electrical Stimulation in Stereoelectroencephalography. Experience in a Public Hospital in Argentina

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

Washington DC

Congreso; American Epilepsy Congress; 2017

American Epilepsy Society

Rationale: Stereoelectroencephalography (SEEG)- based presurgical evaluation of epilepsies has a double objective: to define the epileptogenic zone (EZ) and to map cortex functionally in relation with the surgical plan. The aim of this study is to analize electrical stimulation (ES) findings in our population of patients.Methods We analized 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 From the 17 patients, we trigger theirs usual seizures in 15 (89%). From them, we trigger the seizures in 82 opportunities. 13 (15.85%) were trigger when we stimulated hippocampus, 5 (6.09%) amygdala, 28 (34.15%) other temporal areas, 42 (51.21%) frontal areas, 13 (15.85%) parieto-occipital areas. In 10 (58.82%) patients we map eloquent brain regions finding 18 clinical answers, 6 (35,3%) language, 4 (23.53%) patients were evaluated the motor area, 2 (11.76%)sensitive areas, 3 (17.65%) visual and 3 (17.65%) auditory sensations. We define EZ in 15 (88.23%) of patients, 3 (17.65%) mesial temporal lobe epilepsy, 7 (41.18%) frontal lobe epilepsy, 4 (23.53%) parieto-occipital epilepsy, 1 (5.88%) insular epilepsy. In 4 patients the ZE was shared with the eloquent zone, 3 visual and 1 language. In all the patients we defined the ZE: 5 p (29,41%) mesial temporal, 7 p (41.18%) frontal, 4 p (23.53%) parieto-occipital y 1 p (5.88%) ínsula. Evolution From the 17 patients, 7 were under surgery, 2 with a frontal ZE, 3 temporal ZE and 2 occipital.The outcome up to this moment is good, with an Engel I-II.One of the seven patients that went under surgery has involvemente of eloquent areas, with a worst outcome than the other six, meaning that these patients are more complex and need a deeply presurgical evaluationConclusionsES is a procedure that allowed us, along with the electroclinical analysis of the spontaneous seizures and the interictal recording, the accurate location of the EZ, the temporal space dynamics of the epiletogenic network and the functional mapping, to plan cortical resection without overlap and to improve post-surgical prognosis.