Corticospinal physiology in patients with prader-willi syndrome: A transcranial magnetic stimulation study

Background: Prader-Willi syndrome (PWS) is a genetic developmental disorder, mostly caused by a deletion on the paternal chromosome 15 or by a maternal uniparental disomy 15. Some PWS clinical and neurochemical features suggest an involvement of the corticospinal motor structures. Objective: To explore the corticospinal physiology of PWS by transcranial magnetic stimulation. Setting: A community-based hospital. Methods: We studied motor evoked potentials in the first dorsal interosseous muscle of 21 young-adult patients with PWS. Thirteen patients had a deletion at chromosome 15; 8 had a uniparental disomy. We measured the following variables: relaxed motor threshold, central motor conduction time, duration of the central silent period, and short-interval intracortical inhibition and facilitation. We also recorded F waves in the first dorsal interosseous muscle. We had 11 normal controls. Results: In the whole PWS group, motor threshold was higher as compared with controls (P