Abstracts

Sturge-Weber syndrome (SWS) is a sporadic neuro-cutaneous disorder with epilepsy as a common manifestation. Leptomeningeal angiomatosis, the hallmark of cerebral pathology in SWS, is often unilateral and is accompanied by progressive cortical atrophy and calcifications. However, the extent of structural involvement often does not predict clinical outcome including seizures. PET scans using 2-deoxy-2[¹⁸F]fluoro-D-glucose (FDG) can be used to evaluate involvement of brain regions beyond structural abnormalities. We are performing a prospective, longitudinal neuroimaging study (including PET and MRI) in children with unilateral SWS to characterize its natural history and to understand the dynamics of its pathophysiology. Thus far 12 children (7 girls, age 3 months - 8 years) underwent at least two FDG PET scans at 7 months - 3 years intervals. In this analysis, longitudinal FDG PET changes (focal hypo- or hypermetabolism) were characterized and correlated with seizure frequency and interictal EEG findings recorded during the PET studies. Four characteristic types of focal metabolic changes were observed: (1) Three young children (age: 0.2-1.9 years) showed an initial [italic]interictal hypermetabolism[/italic] on the side of the angioma, followed by onset of intractable seizures and switch to focal hypometabolism on the later scans. (2) Four patients (age 0.4-3.9 years) showed [italic]severe[/italic] multilobar, unilateral [italic]hypometabolism[/italic] even on the first scan, without a considerable change at follow-up. These 4 patients were either seizure-free or had very rare seizures, and had no epileptiform activity on their EEG at the time of the second PET scan. (3) Moderate progression of the hypometabolic area[/italic] ipsilateral to the angioma in 5 children (age 1.3-8.4 years; including 2 with hypermetabolism on their first scan); all but one of these children had occasional seizures; (4) [italic]Improvement of focal hypometabolism[/italic], (N=3, including one with a previous progression on PET; age 2.7-8.4 years). This was accompanied by sustained seizure-freedom and disappearance of interictal epileptiform activity over the previously hypometabolic area. Focal glucose metabolic changes in SWS are complex and reflect the dynamic aspects of the underlying pathology, although seizure-related transient metabolic disturbances should also be considered. Interictal hypermetabolism in the early stages of SWS predicts imminent seizures. Early, severe hemispheric hypometabolism can be associated with good seizure control, while slower progression of hemispheric hypometabolism is associated with continuing seizures. Focal hypometabolism outside the angioma can be partially reversible if seizures become controlled. FDG PET provides insights into dynamic changes of brain metabolism in SWS and provides unique information that is clinically useful, assisting in management of this disorder. (Supported by NIH grant NS041922 (to Dr. Juhasz).)