Abstracts

The neurological substrates associated with continuous spike-wave activity during slow wave sleep (CSWS) are poorly understood, but can be studied with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET). Data were analyzed from six children with CSWS (ages: 4-8 years; 3 girls), all of whom had presented with intractable epilepsy and global neuropsychological and language decline upon the onset of seizures. Spike-wave discharges were present in more than 85% of slow-wave sleep EEG segments during PET scanning in all patients, which satisfied the original definition for the diagnosis of CSWS. FDG PET imaging was visually analyzed and focal brain areas showing increase of glucose metabolism compared to the homotopic area were documented. EEG during FDG PET scanning was quantitatively analyzed, and the frequency of interictal epileptic activity was measured. Subsequently, apparently generalized spike-wave discharges on EEG were averaged at least 50 times, and sequential voltage mapping of spike potential fields was applied to the averaged generalized spike-wave discharge. The relationship between brain glucose metabolism patterns on PET and EEG parameters such as origin of spike activity was analyzed. FDG PET imaging revealed focal brain regions showing increased glucose metabolism in five patients. Focal brain regions showing increased glucose metabolism had a correlation with the presumed origin of averaged generalized spike-wave activity in all five patients (patients #1-5). A single patient (patient #2) had a cortical resection involving the areas of focal hypermetabolism on PET and has been seizure-free for two years. Another patient (patient #1) is scheduled for surgery. Conversely, no increase of focal glucose metabolism was seen on FDG PET in the remaining patient (patient #6). The origin of averaged spike-wave activity was not lateralized in this patient. [table1] The areas of glucose hypermetabolism may be well correlated to the presumed origin of the generalized spike-wave activity in children with CSWS. This finding adds further support to the hypothesis that the generalized spike-wave in most cases of CSWS is the result of secondary bilateral synchrony. Resective surgery may be effective in selected patients with uncontrolled seizures and CSWS, if there is concordance of focal abnormalities on both PET and EEG.