Niemann Pick type C: eye movements

This 20-year-old man had developmental delay but did well until recently, with some memory decline, dysarthria, and imbalance since his late teens. The video begins with intact horizontal saccades, then vertical saccades that are slow and limited in range, followed by intact horizontal pursuit and then limited vertical pursuit. (Courtesy of www.neuroophthalmology.ca. Contributed by Dr. Jason Barton.)