Abstracts

Excisional surgery is challenging in children with medically refractory partial epilepsy and normal neuroimaging studies. We assessed the utility of ictal SPECT to define the epileptogenic zone and assist surgical planning in this population. We retrospectively reviewed records of 31 children (ages 9 mo-17 yrs; mean, 8.8 yrs) who underwent surgery for medically refractory partial epilepsy and who had normal or non-specific neuroimaging. All patients underwent ictal SPECT (three headed Multispect Siemens[rsquo] Medical System) performed following injection of HMPAO (300 microcuries/kilogram) within 16-30 sec of ictal onset. The SPECT images were classified as focal or non-localizing. Focal areas of hyperperfusion were compared for convergence with localization of the epileptogenic zone defined on scalp EEG/ECoG (n=4) or chronic intracranial EEG (n=27). Resections were temporal (n=6), extratemporal (n=20) and multilobar (n=5). Ictal SPECT revealed focal hyperperfusion in 26/31 patients (84%) and was non-localizing in 5. In the focal group, 23 out of 26 (88%) were convergent with EEG localization. At follow up, 12/23 convergent patients (52%) are seizure-free, 1 has [gt]90% reduction, 3 had [gt]50% reduction, and 7 were unchanged. 3/8 patients with non- convergent/non-localizing SPECT are seizure free, 1 [gt]90% reduction, 1[gt]50% reduction, and 3 unchanged. When performed early after seizure onset ictal SPECT reliably defines focal hyperperfusion in a large majority of pediatric epilepsy surgical candidates with normal or non-specific neuroimaging studies. Used in conjunction with EEG data, ictal SPECT permits accurate characterization of the epileptogenic zone and facilitates surgical planning.