Vestibular velocity step test and normal limits for the Chinese]

Vestibular velocity steps test (VVST) to impulsive stimulus of horizontal rotation (90 degrees/S and 180 degrees/S) were performed in 22 normal subjects. Gain (G) was defined as the ratio of the initial slow phase eye velocity (ISPV) to head velocity. The time constant (T) was the time to find the point where it was 0.37 of ISPV. Duration (D) of induced nystagmus was the time between first and final nystagmus. The directional preponderance (DP) for G, T and D was calculated from the formula, (R-L)/(R+L) x 100%. These normal limits were 0.37-1.09 and 0.27-0.83 for G, 8.0--20.4s and 6.5-17.3s for T, 30.4-65.0s and 30.0-54.4s for D, +/- 21.4% and +/- 21.5% for DP(G), +/- 24.2% and +/- 20.3% for DP(T), +/- 16.5% and +/- 17.9% for DP(D) of 90 degrees/S and 180 degrees/S, respectively. The advantages and shortcomings of VVST and its value were discussed.