[¹⁸F]fluorodeoxyglucose-positron emission tomography study of genetically confirmed patients with Dravet syndrome

To understand cerebral brain dysfunction in patients with Dravet syndrome (DS), we conducted a [¹⁸F]fluorodeoxyglucose-positron emission tomography (FDG-PET) study in patients with DS whose SCN1A gene variant was confirmed.

FDG-PET was performed on eight patients with DS. A SCN1A mutation analysis revealed missense variants in four patients and truncation variants in four patients. The patients' ages at the time of the PET study were 2, 2, 2, 3, 6, 13, 20, and 29 years old, respectively. The patients' developmental/intelligence quotient at the time of the PET study were 62, 52, 64, 35, 30, 15, and <25, respectively. The mean standardized uptake value (SUV) was calculated in four segments (frontal, temporal, parietal, and occipital) for the semi-quantitative analysis of ¹⁸F-FDG uptake. This value represents the average of the regions of interest in each lobe and was divided by the average SUV of the cerebellar hemisphere of each patient and compared between the patients with DS and the diseased controls.

Glucose uptake in patients with DS decreased significantly, particularly in those ≥6 years old. Importantly, a comparison between the younger and older patients with DS revealed that glucose uptake was normal in patients who were ≤3 years (2, 2, 2, and 3 years), whereas a profound reduction in glucose uptake in the fronto-temporo-parietal-occipital cortices was observed in patients ≥ 6 years (6, 13, 20, and 29 years). Magnetic resonance imaging revealed no detectable atrophic legions or other changes in the cerebral cortices of patients ≥ 6 years of age.

The present study showed a remarkable reduction in cerebral glucose metabolism in multiple lobes for the first time, which became obvious after the late infantile period. These findings may indicate a functional neuroimaging aspect of epileptic encephalopathy of DS or a feature of the SCN1A variant itself.