A quantitative rotational test of vestibular function.

This paper describes a quantitative vestibular test in which the stimulus is a constant angular acceleration of 3 degrees/sec2 for 80 sec. The nystagmus output is plotted as cumulative slow phase eye displacement against time and is displayed on an oscilloscope screen along with the output from a mathematical model describing vestibulo-oculomotor function. External dials allow one to change the equation constants thereby altering the shape of the model output. Values for equation constants which match the model output to the patient can be read directly from the dials, thus providing a description of the vestibular system under test. Results indicate that vestibular asymmetry (manifest by spontaneous nystagmus is not uncommon in normals, and only when spontaneous nystagmus is coupled with vestibular gain does one get a measure of abnormality. The significance of altered vestibular parameters in certain pathological states is discussed.