Abstracts

Scalp ictal EEG and 2-deoxy-2[¹⁸F]fluoro-D-glucose (FDG) PET are commonly used to localize epileptic foci during presurgical evaluation of children with extratemporal epilepsy. PET scanning with [¹¹C]flumazenil (FMZ) may be useful in further localizing neocortical epileptic foci, but its added clinical value has not been systematically evaluated in children who have undergone intracranial EEG monitoring. The purpose of this study was to evaluate the added localizing information of FMZ PET as compared to scalp ictal EEG and FDG PET in children with non-lesional neocortical epilepsy. Twenty-six children (mean age: 7.3 years) with intractable partial epilepsy (N=19) or infantile spasms (N=7) were studied prospectively. All of them had normal MRI scans. Focal cortical areas of decreased FMZ binding were delineated objectively as regions with abnormal asymmetry and correlated with localizing information provided by ictal scalp EEG and FDG PET and, subsequently, by intracranial EEG monitoring. Decreased cortical FMZ binding was found on objective analysis in the lobe(s) of seizure onset in 20 children (77%). Sensitivity of FMZ PET was higher in children with partial epilepsy (89%) than in those with infantile spasms (43%; p=0.028). FMZ PET provided additional information as compared to scalp ictal EEG findings in 14 patients (54%), including: (1) further localization of the seizure onset zone when scalp EEG onset was poorly localizing (N=7); (2) identification of an additional region of seizure onset (N=4); (3) and identification of an area remote from the onset with rapid involvement in seizure spread or frequent interictal spiking on intracranial EEG monitoring (N=3). FMZ PET also provided localization information in addition to FDG PET in 12 patients, including: (1) showing a smaller PET abnormality that was more specific for seizure onset than corresponding areas of glucose hypometabolism (N=7); (2) detecting a seizure onset area that was missed by FDG PET (N=2); (3) and showing an additional area of either rapid spread (N=2) or frequent interictal spiking (N=1) on intracranial EEG. Altogether, FMZ PET provided localization information for intracranial EEG abnormalities in addition to [italic]both[/italic] scalp ictal EEG [italic]and[/italic] FDG PET in 7 patients, including 2 children with infantile spasms. FMZ PET detects extratemporal seizure foci in about four-fifth of children with intractable partial epilepsy and provides independent localizing information in addition to scalp ictal EEG and FDG PET in a considerable proportion of these children. Focal FMZ abnormalities are less likely to occur in children with infantile spasms, but can still be useful in presurgical evaluation of such children. (Supported by NIH grant NS 34488)