knee-jerk reaction. Fig. an automatic or reflex reaction; an immediate reaction made without examining causes or facts. With one of his typical knee-jerk reactions, he said no immediately, citing some moral argument that no one understood. See also: reaction.
What did you see when the patients head was rolled to the opposite side? In horizontal canal BPPV, you should have seen a direction change. When the horizontal nystagmus is geotropic, the BPPV is suspected to be canalithiasis, occurring on the side with the more intense nystagmus.
Horizontal Undulatory Progression or Lateral Progression for short. This method of movement is accomplished by the snake lashing it's body back and forth causing lateral waves that force longitudinal motion. To put it another way: They go forward by moving sideways. So imagine a person jumping in diagonal leaps.