Teaching NeuroImage: Fasting EEG in Glucose Transporter-1 Deficiency Syndrome

A 12-year-old boy presented for the evaluation of chorea induced by fasting and exercise. EEG, brain MRI, spectroscopy, and metabolic and microarray evaluations were unremarkable. Fasting EEG showed diffuse spike-wave discharges with postprandial normalization (Figure); chorea was not captured. Genetic testing confirmed a pathogenic SLC2A1 variation consistent with glucose transporter-1 (GLUT-1) deficiency syndrome, which is uniquely responsive to ketogenic diet. EEG findings in this syndrome may include multifocal or generalized spikes, with postprandial improvement.(1,2) This case suggests a supportive role for fasting EEG in the diagnosis of glucose transporter-1 deficiency syndrome, but the sensitivity and specificity remain unclear.