Study of the Effect of Vagus Nerve Stimulation on Human Brown Adipose Tissue Activity

Inclusion Criteria: * Subjects treated with VNS for epilepsy, aged 18-65 years, with a Body Mass Index (BMI) ≤ 28 kg/m2. Exclusion Criteria: * Body Mass Index \> 28 kg/m2 * Daily epileptic insults. * Subjects that need 'Rapid Cycling' VNS to control their frequency of epileptic insults. * Psychological unstable subjects (as judged by the treating neurologist). * subjects with mental retardation (as judged by the treating neurologist). * subjects with severe behaviour disorders (as judged by the treating neurologist). * Pregnant subjects. * Subjects that previously underwent high dose radiation for diagnostic or therapeutic purposes (radiotherapy, high frequency CT-scans). * The use of the following medication is an exclusion criterium; * ß-blockers, * Ketogenic diet