Voltar What does the dissociation between the results of video head impulse versus caloric testingreveal about the vestibular dysfunction in Ménière’s disease?

McGarvie LA1, Curthoys IS, MacDougall HG, Halmagyi GM.
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1Institute of Clinical Neurosciences, Royal Prince Alfred Hospital , Camperdown NSW , Australia.
Abstract

CONCLUSION:

It is suggested that the different results of rotational (video head impulse – vHIT) and caloric tests in patients with Ménière’s disease (MD) may be a consequence of the physical enlargement of the membranous duct in the hydropic labyrinths in MD, causing a reduced response to caloric stimulation.

OBJECTIVES:

There have been reports that the results of two tests of semicircular canal function, the caloric response and the responses to vHIT do not agree. This retrospective study at a tertiary referral hospital examined this disagreement.

METHODS:

This study reviewed the data of 22 patients who met the AAO-HNS criteria for MD and who had both caloric and vHIT testing.

RESULTS:

There was a clear dissociation: patients with MD had a small or absent response to caloric stimulation of their affected ear, whilst their response to vHIT was in the normal range.

DISCUSSION:

The accepted Gentine model of the mechanism of caloric stimulation could account for this dissociation: the increased diameter of the semicircular duct in hydropic labyrinths resulting in endolymph circulation within the duct itself and so a smaller thermally induced pressure across the cupula. The increased duct diameter will have little effect on responses to rotation.

KEYWORDS:

VOR; head impulse test; nystagmus; semicircular canal; vHIT

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