The trapezoid rotation test (±2, 4, 6, 8, and 10°/ sec2) with Contraves' computerized rotary chair sys-tem was performed in 37 patients with sudden deafness and vertigo and in 2 patients with vestibular neuronitis.
The test results were classified into four types:
1) contralateral labyrinthine preponderance (LPc),
2) ipsilateral labyrinthine preponderance (LPi),
3) recruitment (Rec), and
4) normal.
A correlation of subjective symptoms and shifts in the 4 types of test results during the clinical course showed 4 stages in the development of unilateral vestibular disorder with vertigo :
(i)initial onset of LPc type
(ii)shift to LPc type from LPi type
(iii)shift to LPi type from LPc type
(iv)shift to LPi type from atypical LPc type
In the stage of appearance of the Rec or normal type, vertigo was not a complaint.
