Revisiting Simultaneous Irrigation for Videonystagmography

Abstract

Purpose: Videonystagmography is a standard clinical evaluation of the peripheral vestibular system, part of which includes irrigation of individual ears with water 7°C above and below average body temperature. Irrigation elicits nystagmus, compensatory eye movements due to activation of the vestibulo-ocular reflex. The irrigations give valuable insight into the function of the vestibular system, but induces dizziness in the patient, often to the point of discomfort and sometimes to the point of nausea. It has been suggested by Brookler (2002) suggested that no diagnosis of “normal” in a patient with vestibular complaints is complete without simultaneous bilateral irrigation, because of the sensitivity of this test. The goal of my investigation is to determine if simultaneous irrigation of both ears can be performed before or even instead of alternating irrigation as a more comfortable, yet accurate, screen for normal function. The simultaneous method was tested for effectiveness, order effect, and subjective comfort ratings Methods: Standard irrigation protocols as well as simultaneous binaural irrigations were performed on 10 subjects ranging in age from 19 to 64. All subjects reported self-perception of normal vestibular function. Half of the subjects received the simultaneous irrigations first, and half received conventional alternating irrigations first. Each rated their comfort using a Likert-like scale at baseline and after each irrigation. Results: Order effect was not found to be present. Comfort ratings strongly favor the simultaneous test method. Promising correlation of warm water simultaneous and alternating irrigations were found, but without enough statistical strength to be conclusive. Unexpectedly, multiple result types were found in subjects all perceiving themselves to have normal vestibular function. Conclusions: Simultaneous irrigation is perceived as generally more comfortable than alternating irrigations. Performing simultaneous irrigations first rather than as a last resort does not affect the information-gathering process toward diagnosis. However, without statistical strength to show that the two tests provide similar information, no conclusion can yet be drawn as to using simultaneous irrigation as a screen for vestibular function. Further investigation is warranted. More subjects will be required to make correlations of needed strength, and separate normative data for types within normal subjects may be needed.