Etomidate accurately localizes the epileptic area in patients with temporal lobe epilepsy.
OBJECTIVE
A variety of drugs have been used to activate and identify the epileptogenic area in patients during presurgical evaluation. We have evaluated the safety and usefulness of etomidate in identifying the epileptic zone by measuring bioelectrical brain activity and cerebral blood flow (CBF).


METHODS
We studied 13 men and 9 women under presurgical evaluation for temporal lobe epilepsy. We applied etomidate (0.1 mg/kg) while patients were monitored by video-electroencephalography (VEEG) with foramen ovale electrodes. In a subset of 15 patients, we also measured CBF with single photon emission computed tomography (SPECT).


RESULTS
(1) Etomidate induced seizures in 2 of 22 patients. (2) The main side-effects observed were myoclonus (14 of 20) and moderate pain (3 of 20). (3) No changes in capillary oxygen saturation, respiration, or heart rate were observed. (4) Irritative activity specifically increased in the temporal mesial and lateral areas. No spikes were observed in other areas, aside from those observed under baseline conditions. (5) Irritative activity induced by etomidate correctly lateralized the ictal onset zone in 19 of 20 patients. In addition, the two etomidate-induced seizures appeared in the same regions as spontaneous ones. (6) The kinetics of pharmacologically induced activity was higher in the region of the ictal-onset zone. (7) Etomidate increased the CBF in the basal ganglia and especially in the posterior hippocampus of the temporal mesial region contralateral to the ictal-onset zone.


CONCLUSIONS
Etomidate activation is a safe, specific, and quick test that can be used to identify the epileptic region in patients evaluated as candidates for temporal lobe epilepsy surgery.
Pastor
Jesús
J
Clinical Neurophysiology, Hospital Universitario de La Princesa, C/Diego de León 62, Madrid, Spain. jpastor.hlpr@salud.madrid.org
Wix
Rybel
R
Meilán
María Luisa
ML
Martínez-Chacón
José Luís
JL
de Dios
Eva
E
Domínguez-Gadea
Luis
L
Herrera-Peco
Iván
I
Sola
Rafael G
RG
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods; D004569:Electroencephalography / Q000187:drug effects*; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D017029:Epilepsy, Complex Partial / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D004829:Epilepsy, Generalized / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D005045:Etomidate / Q000009:adverse effects; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000009:adverse effects; D007262:Infusions, Intravenous; D008297:Male; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013702:Temporal Lobe / Q000098:blood supply* / Q000000981:diagnostic imaging; D015899:Tomography, Emission-Computed, Single-Photon; D055815:Young Adult
D006993:Hypnotics and Sedatives; D005045:Etomidate