motor manifestation myoclonic jerk finding A myoclonic jerk is the brief, involuntary twitching of a muscle or group of muscles. It may be caused either by a sudden muscle contraction, or a sudden lapse of contraction. This happens when a person is on the verge of falling asleep, and suddenly have a sensation or feeling that they are free falling through the air. Contractions are called positive myoclonus; relaxations are called negative myoclonus. When falling asleep, it is common for people to experience a type of myoclonic jerk known as a hypnic jerk. Hiccups are also a kind of myoclonic jerk specifically affecting the diaphragm. http://house.wikia.com/wiki/Myoclonic_jerk