We devised a method to calculate the rotatory angle in the Foulage test. The middle of both thenar eminences, the pivot of the body rotation, is fixed at 5 cm forward from the center of the stabilometer. A mean deviation of the last 10 seconds period (X, Y) in the 60 seconds examination is almost the whole body's center of gravity of the end. The rotatory angle (θ) can be calculated as follows.
θ=tan-1(-X)/(5-Y)
The calculated angles (θ) of 43 vertigo patients rotated over 10 degrees were correlated very strongly with the angles measured manually with a protractor (y=0.84x+0.39 R2=0.87).
