This article includes Supplementary Video, available online at

jws-mds.20496.mpg13688K Segment 1. Case 1 at age 3, demonstrating a paroxysmal dyskinesia after getting out of the car. This episode is followed by an event of paroxysmal activity captured in sleep. The subsequent images are from events at age 5 and show another event occurring part in sleep and part while awake. Following next is an event of chorea upon awakening. The last event demonstrates running as a precipitant to a paroxysmal attack strong enough to induce a fall. Segment 2. Three events of Case 2 are documented. The first two clips are at age 3 and demonstrate an event while standing, strong enough to induce a fall, followed by one nocturnal choreic event. The last clip is at age 11 and is taken after a long car ride with difficulty getting out of the car because of dyskinesia. Segment 3. Case 3 at age 9 demonstrating a typical, choreic attack occurring during the day both while standing and seated. Segment 4. Case 4 at 14 months capturing an event in sleep followed by a waking event occurring on his mother's lap. He is unable to stand with support during the episode. This video presentation has been abbreviated. The full version will appear on theMovementDisorders DVD Supplement, which is issued bi-annually.

Please note: Wiley Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.