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.
If the user is using postprocessed H-Star (2005 GeoXH) then they can still expect the same accuracy ratio only that it is sub-foot at this 2005 GeoXH model. If the user is using a GeoXT and the New DeltaPhase processing engine, then they can expect 50cm in horizontal and about 100cm in the vertical.