A Pilot Study to Investigate the Relationship Between Interaural Differences in Temporal Bone Anatomy and Normal Variations in Caloric Asymmetry

Carpenter, David; Kaylie, David M.; Frank‐Ito, Dennis O.

doi:10.1044/2017_aja-16-0048

Cited by 2 publications

(3 citation statements)

References 23 publications

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“…Scientifically, then, it is evident that there is much more going on with the caloric test than just temperature-induced buoyancy. Nevertheless, the idea that thermal gradients are responsible for the observed nystagmus has almost universally prevailed [4,10]. To account for persistence under zero-g, some have proposed that temperature causes a direct expansion of the endolymph in the canal, and hence deflection of the cupula [3,22,26], or thermal effects on the neural structures themselves [14,20].…”

Section: The Caloric Response Work In Zero Gravitymentioning

confidence: 99%

“…Patki et al [45] surveyed various thermal conduction studies over the decades and raised the question of whether canal temperature can in fact be regarded as a true marker of the observed vestibular responses. The same group [10] investigated correlations between anatomical dimensions extracted from CT scans and caloric response parameters, but the correlations were weak -a multivariate model required almost as many parameters (nine) as subjects (eleven) to provide a fit, suggesting something crucial may have been missed.…”

Section: The Thermal Stimulus Is Minusculementioning

confidence: 99%

“…Other vestibular tests (which stimulate bilaterally) are unable to make this distinction. Although in modern times the caloric test has become less common -it is unpleasant and takes much clinical time -it is still the gold standard for assessing balance problems [10]. Nowadays the vHIT test (the video Head Impulse Test) is more often employed because it is quicker, easier, and better tolerated, even though it cannot determine the side of weakness [11,12].…”

Section: Introductionmentioning

confidence: 99%

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What Bárány’s Caloric Test Might Have Overlooked: The Primary Factor May Be the Middle Ear Muscles

Bell¹

2019

J Hear Sci

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The caloric test of vestibular function, originating from Bárány in the early 1900s, has conventionally been understood as a test of the effect of temperature on the horizontal semicircular canals of the inner ear. Warm water introduced into the external auditory meatus will, if the vestibular system is intact, cause back-and-forth beating of the eyes (nystagmus) in one direction; cold water will cause beating in the reverse direction. The text-book explanation is that the eye movements are caused by a thermal gradient across the horizontal canal, which in turn causes convection in the fluid within. The convective motion stimulates the vestibular hair cells, causing nystagmus, dizziness, nausea, and often vomiting. But here an alternative mechanism is proposed: warm or cold water causes the tensor tympani muscle in the middle ear to increase in tension (warm water) or decrease in tension (cold water), and in this way changes the force exerted by the ossicles on the inner ear fluids behind the oval window. Altered force on the stapes therefore means a change of hydraulic pressure inside the sealed labyrinth, and this pressure could directly stimulate hair cells within the inner ear -including the semicircular canals -and so generate nystagmus. If correct, this means the caloric test is really a test of the temperature sensitivity of the middle ear muscles, although the vestibular system still needs to be intact in order to register a positive response. The new hypothesis explains a range of anomalies surrounding the caloric test, and these are systematically reviewed.

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