jerky — characterized by jerks or sudden starts; spasmodic.
lurching — Archaic. the act of lurking or state of watchfulness.
jolting — to jar, shake, or cause to move by or as if by a sudden rough thrust; shake up roughly: The bus jolted its passengers as it went down the rocky road.
adj paroxysmal
convulsive — A convulsive movement or action is sudden and cannot be controlled.
