Relationship between Functional Lateralization by Interictal Cerebral 18-FDG PET and by Intracarotid Amobarbital Procedure in Temporal Lobe Epilepsy

ABSTRACT

BACKGROUND: Many studies have reported that intracarotid amobarbital procedure (IAP) and 18-FDG PET of the brain are tests for focal functional integrity used in preoperative evaluation of temporal lobe epilepsy (TLE). And these tests have been used for assisting in lateralization of the epileptogenic focus. OBJECTS We wanted to determine the relationship between functional lateralization by PET and by IAP and the role of those tests for lateralization in patients with TLE. METHODS & PATIENTS All patients underwent long-term video/EEG monitoring, MRI of the brain, 18-FDG PET, IAP and some patients also had invasive EEG monitoring. The side of the epileptogenic focus was determined by interictal and ictal EEG, ictal semiology, SPECT, and MRI of the brain. Patients with mass lesion were excluded. Twenty seven had epileptogenic focus in the right temporal lobe and twenty six in the left temporal lobe. RESULTS: PET showed temporal lobe hypometabolism ipsilateral to the epileptogenic focus in 90% (48 of 53). Two patients showed bilateral temporal hypometabolism and two did normal findings. But these four patients showed Ipsilateral memory impairment to the epileptogenic focus in IAP. IAP revealed ipsilateral memory impairment to the epileptogenic focus in 70% (37 of 53) patients. Fifteen patients (28%, 15 of 53) showed ipsilateral temporal hypometabolism to the epileptogenic focus. Only one patient showed contralateral memory impairment to the epileptogenic focus but bilateral hypometabolism in PET. CONCLUSION: We find the convergence of data from MRI, EEG, IAP and PET to be very helpful in selection process of patients for temporal lobectomy.