Do the Symptoms of Kleine-Levin Syndrome Correlate With the Hypometabolism of the Thalamus on FDG PET?

A 15-year-old adolescent boy had experienced intermittent, recurrent hypersomnia lasting for 1 week to 3 weeks for more than 3 years. He was diagnosed with Kleine-Levin Syndrome clinically. The brain MRI, video EEG, and serum and cerebrospinal fluid analysis did not show any abnormality. An FDG PET/CT scanning was acquired when the patient was symptomatic, showing marked symmetric hypometabolism in the thalamus and hypothalamus in the symptomatic phase, as well as mild homogeneous decreased glucose metabolism in the cortex. Interestingly, another FDG PET/CT scan acquired when the patient was asymptomatic found much less severe hypometabolism in the thalamus and hypothalamus.