Unilateral vestibular disorders were induced in 3 cats by means of the
injection of a small amount of sodium hydroxide into the middle ear,
and vestibulo-ocular responses (VOR) to various kinds of pendular stim
ulation were investigated at 1 week and at 1, 2. 3, 4, and 5 months af
ter the operation. The pendular rotation test was performed at frequen
cies of 0.025, 0.1, 0.25 and 0.5 Hz, and peak velocities of 50, 100, 1
50, and 200 degrees/s, and the directional preponderance of the VOR ga
in (DP%) was measured using a computer. DP% 1 week after the operation
was still very high at each frequency and velocity of the stimulation
. On the other hand, DP% more than 1 month after the operation had dec
reased markedly, although it increased with an increase in the velocit
y of stimulation at all frequencies except at 0.5 Hz, and DP% at a vel
ocity of 200 degrees/s was still high even 5 months later. This sugges
ts that high velocity pendular stimulation should be used to detect un
ilateral vestibular disorders.