ICTAL TC-99M ETHYL CYSTEINATE DIMER SINGLE-PHOTON EMISSION TOMOGRAPHIC FINDINGS AND PROPAGATION OF EPILEPTIC SEIZURE ACTIVITY IN PATIENTS WITH EXTRATEMPORAL EPILEPSIES

Although ictal single-photon emission tomography (SPET) with technetiu m-99m ethyl cysteinate dimer (ECD) has a well-established role in the diagnostic evaluation of patients with temporal lobe epilepsy who are being considered for epilepsy surgery, its use in cases of extratempor al epilepsy is still limited, We investigated the influence of the pro pagation of extratemporal epileptic seizure activity on the regional i ncrease in cerebral blood flow, which is usually associated with epile ptic seizure activity. Forty-two consecutive patients with extratempor al epilepsies were prospectively evaluated. All patients underwent ict al SPET studies with simultaneous electroencephalography (EEG) and vid eo recordings of habitual seizures and imaging studies including crani al magnetic resonance imaging and positron emission tomography with 2- [F-18]-fluoro-2-deoxy-D-glucose. Propagation of epilptic seizure activ ity (PESA) was defined as the absence of hyperperfusion on ictal ECD S PET in the lobe of seizure onset, but its presence in another ipsilate ral or contralateral lobe, Observers analysing the SPET images were no t informed of the other results. PESA was observed in 8 of the 42 pati ents (19%) and was ipsilateral to the seizure onset in five (63%) of t hese eight patients. The time between clinical seizure onset and injec tion of the ECD tracer ranged from 14 to 61 s (mean 34 s). Seven patie nts (88%) with PESA had parieto-occipital epilepsy and one patient had a frontal epilepsy. PESA was statistically more frequent in patients with parieto-occipital lobe epilepsies (58%) than in the remaining ext ratemporal epilepsy syndromes (3%) (P<0.0002). These findings indicate that ictal SPET studies require simultaneous EEG-video recordings in patients with extratemporal epilepsies. PESA should be considered when interpreting ictal SPET studies in these patients. Patients with PESA are more likely to have parieto-occipital lobe epilepsy than seizure onset in other extratemporal regions.