Temporal lobe epilepsy with bilateral seizure origin studied by [18F]FDG-positron emission tomography

Nine patients who underwent presurgical evaluation because of medically refractory temporal lobe epilepsy (TLE) showed either unilateral, although alternating in side, or bilateral simultaneous seizure onsets in both temporal lobes (TL). EEG recordings with semi-invasive foramen ovale electrodes revealed in seven patients a predominance of seizure onset in one TL of between 50% and 88%. In two patients the majority of seizures originated simultaneously in both TL. In four patients a unilateral selective amygdalohippocampectomy resulted in a good to excellent seizure outcome without noteworthy memory deficits and confirmed the preoperative lateralization of the primary epileptogenic focus by interictal ¹⁸F-fluorodeoxyglucose positron emission tomography (PET). Five patients were rejected from surgery due to strong bilaterality of their epilepsy and/or divergent presurgical findings. PET contributed to the decision of whether surgery should be performed: all patients who underwent surgery had a unilateral TL hypometabolism which was concordant with the findings of other tests. Patients in whom surgery was denied had either bilateral temporal hypometabolism or the PET findings were discordant with other results obtained during the presurgical evaluation.