Abstracts

To study the evolution of cerebral glucose metabolism after partial seizure onset in children, and its relation to clinical variables. Thirty-eight children had 3.4 [plusmn].8 ¹⁸FDG-PET scans over 3.0 [plusmn] 1.3 years; the first was within one year of their third unprovoked partial seizure. Mean age at seizure onset was 5.8 (range 0.9-11.9) and mean epilepsy duration 1.1 years (0.3-2.3) before the first PET scan; mean seizure number was 27 (3-200). ¹⁸FDG-PET was analyzed with a region of interest template. Scans with absolute asymmetry index, |AI|, greater than 0.13 in at least two regions in one scan, or one region in two scans, were considered abnormal. Standard clinical t1 and t2-weighted MRI was obtained. Patients were grouped into three clinical categories: seizure-free (on or off AEDs), moderate control (fewer than six seizures per year) or poor control. There were four PET categories: always normal, initially normal becoming abnormal, always abnormal, and initially abnormal becoming normal. Twenty-one patients had persistently normal PET scans; 7 initially normal, then abnormal; 7 always abnormal; 2 initially abnormal, then normal; and one fluctuating findings. Patients with initial normal PET were significantly more likely to remain in good seizure control than those with abnormal initial PET (x² 9.9; p[lt]0.01). There was a non-significant trend for patients with normal initial PET to have fewer prescan seizures than patients with abnormal initial PET. Patients with initially normal PET scans that became abnormal had longer epilepsy duration before the first PET scan (1.9 [plusmn] 1.5 vs 0.8[plusmn] 0.7 years, p [lt]0.05), but not greater seizure frequency, than those with PET always normal. Six of the seven patients whose PET scans were always abnormal had poor seizure control. The two whose scans were initially abnormal, and then became normal, were seizure-free, while the one child with fluctuating PET results (normal-abnormal-normal) had moderate control. Febrile seizure history did not affect PET findings. MRI was strongly predictive of initial PET results (x² = 13.1; p[lt]0.02) but not did not predict progression. A model combining MRI and initial PET was strongly predictive of clinical course (F-ratio 6.96; p [lt]0.001). Initial FDG-PET and MRI predicted seizure control over three years in children with new onset complex partial seizures. Twenty-five percent with initial normal PET developed focal temporal hypometabolism over three years. In this subgroup, there was no difference in seizure control between patients who did and did not develop hypometabolism. Children who have had at least 3 partial seizures and FDG PET showing temporal hypometabolism are at risk for persistent uncontrolled seizures (Supported by NINDS Division of Intramural Research.)