Assessing the cervico-ocular reflex system via modifying the ocular vestibular-evoked myogenic potential test

Abstract

Purpose The aim of this study was to devise a novel test for assessing the cervico-ocular reflex (COR) system via head vibration (termed h-COR) or neck vibration (termed n-COR) method. Materials and methods Thirteen patients with complete loss of bilateral vestibulo-ocular reflex (VOR) showing oscillopsia were assigned to Group A, while 13 patients with bilateral VOR loss but no oscillopsia were Group B. Another 13 healthy elderly served as a control. The COR test was performed via modifying the ocular vestibular-evoked myogenic potential (oVEMP) test by tapping at the forehead with head rotation (h-COR) or at mid-dorsal neck with head straight (n-COR). Results Both h-COR and n-COR tests displayed similar cI–cII waveforms. None of the Group A or healthy elderly showed present h-COR, while 8% of Group A and 31% of the healthy elderly revealed present n-COR. In contrast, present h-COR and n-COR were elicited in 85 and 77% of Group B, respectively. Restated, significantly higher response rate of COR in Group B (without oscillopsia) than Group A (with oscillopsia) indicates that present COR is related to the alleviation of oscillopsia. Conclusions Head vibration method (h-COR test) is superior to neck vibration method (n-COR test) for assessing the COR system.