Abstracts

Rationale: To quantify extrastriatal and striatal D2/D3 receptor binding in patients with juvenile myoclonic epilepsy (JME) using the high affinity dopamine D2/D3 receptor PET-ligand 18F-Fallypride. Methods: Twelve patients with JME (defined by seizure semiology and interictal EEG) and 21 age matched control subjects were studied. Dynamic images (180 minutes) were acquired after injection of 18F-Fallypride. Patients were seizure free for all seizure types for at least 10 days before scanning. Parametric images of binding potential (BP) were created using the simplified reference tissue model. The images were stereotactically normalized using a ligand-specific template. We performed a voxel-based analysis with statistical parametric mapping (SPM2). ROI analysis was done comparing the BP of thalamus, caudate nucleus, anterior (ventral) and posterior (dorsal) putamen, ventral striatum and temporal lobe. Results: Compared to controls patients with JME showed a significant decrease in 18F-Fallypride binding potential (BP)(SPM analysis corr. p < 0.001 at cluster level) restricted to the bilateral posterior putamen. There was no significant alteration of 18F-Fallypride binding in other brains regions. Region of interest (ROI) analysis revealed a significant (p<0.05) decrease of 18F-Fallypride BP in the left (mean: -14.8%) and right (mean: -16.9%) posterior putamen, but not in anterior putamen, caudate, ventral striatum, thalamus and temporal lobe. Conclusions: Patients with JME show a reduction in D2/3 receptor binding restricted to the bilateral posterior putamen, suggesting a specific alteration of the dopaminergic system. Whether these changes can be regarded as merely functional or relate to the pathophysiology of juvenile myoclonic epilepsy remains so far unclear.