[Instrumental study of vertigo: when and how?]

Any case of vertigo and equilibrium disorder for which an origin is not rapidly determined requires exploration for diagnosis. This exploration comprises two parts: first, that of peripheral components, including a standard audiometric examination, completed by study of the evoked auditory potentials. This is followed by vestibular examination comprising at least caloric tests of both ears, usually associated with rotation tests; second, exploration of the central pathways, by electro-oculography, study of pursuit and saccadic movements. The techniques of posturography, especially dynamic posturography by the equi-test, allow determination of the role of the vestibular apparatus in equilibrium and to define the respective roles of the labyrinth, vision and sensitivity in equilibrium. The technique is rapidly developing and will no doubt include the study of coordination of head and eye movements, study of stabilisation of vision and the head, and in particular study of otolithic function.