Visual-Vestibular-Interaction Test with Rotatory Chamber in the Diagnosis of Vertigo pp. 173-186
Authors: (Angelo Salami, Renzo Mora, Barbara Crippa, Massimo Dellepiane, ENT Department, University of Genoa, Italy)
Abstract: The aim of this chapter is to determine the diagnostic value of the visual-vestibular interaction test with rotatory chamber in the diagnosis of vertigo. The patient, head blocked, sit on a ―Tönnies rotatory chair‖ which is placed in the middle of a rotatory cylindrical chamber (2 metres in diameter and 1.9 metres in height). The rotatory cylinder is driven by a direct current engine which turned it clockwise and counterclockwise, up to 200 degrees/sec., and its internal area is covered with thirty-two black vertical contrast. Patients are submitted to rotatory vestibular stimulation by Stop test, to optokinetic stimulation and to contemporary rotatory vestibular and optokinetic stimulation (VVOR): a pause of 300 seconds was taken between each stimulation. In the dark, vestibular-ocular-reflex (VOR) is evoked by stop test from a constant angular velocity of 90 degrees/sec (for 60 seconds), reached by a subliminal chair acceleration of 0.5°/sec˛, in both clockwise (cw) and counterclockwise (ccw) directions. We study the optokinetic nystagmus (OKN) stare type: subjects are asked to watch the stripes on the internal area of the drum, without fixing. In the light, optokinetic reflex is tested by a rotation of the drum at an angular velocity of 30 degrees/sec for 60 sec (in both cw and ccw directions).