Abstracts

Rationale: SUDEP is a significant cause of epilepsy mortality with identifiable clinical risk factors. Potential biomarkers including structural imaging have been studied. Here we explore the role of functional imaging using fluoro-deoxy-glucose positron emission tomography (FDG-PET) to help identify additional predictors for SUDEP.  Methods: Patients with refractory epilepsy with confirmed seizures via admission to the Epilepsy Monitoring Unit were assessed for their risk of SUDEP using the revised SUDEP-7 inventory. Patients were included if they had an interictal FDG-PET. Patients with postsurgical PET and those with large, multilobar structural lesions were excluded. FDG-PET visual assessment was carried out and classified based on lobar involvement.  Results: Twenty-four refractory epilepsy patients aged 17 to 60 years (mean = 39.2 years) were included. SUDEP-7 inventory score was calculated at closest encounter to FDG-PET scan and ranged 1 to 10 (mean=4.12).  Visual PET assessment revealed an average 2.4 hypometabolic lobes per patient with the following distribution: left (n=4), right (n=4), bilateral (n=13), none (n=3).  Most patients (n=19) had temporal lobe hypometabolism, nine had frontal lobe hypometabolism including seven with specifically left frontal lobe hypometabolism.  In an unpaired t-test, mean SUDEP score was higher in those who had left frontal lobe hypometabolism (n=7) as compared to those with no left frontal involvement (n=17): 5.4±2.4 vs. 3.6±1.5, respectively (p=0.03).  In the high-risk group (SUDEP-7 score ≥4, n=13), there was a mild trend for higher number of hypometabolic lobe(s) (3.2 vs. 2.1,p=0.17) and higher number of hypometabolic frontal lobe(s) (0.8 vs. 0.3, p=0.16).  Conclusions: Left frontal lobe hypometabolism was associated with a higher SUDEP-7 score.  A previous pilot study of FDG-PET in four confirmed cases of SUDEP using Statistical Parametric Mapping also showed the presence of frontal lobe hypometabolism with left predominance (Shah, Juhasz, Pilli, et al.: Structural and functional neuroimaging as biomarkers of sudden unexpected death in epilepsy (SUDEP). J Neurol Sci 2017 (381): 155.).  Larger studies with multi-variable analysis should be done to confirm left frontal hypometabolism as an independent predictive risk factor for SUDEP. Funding: No funding