Answer
The following tests commonly are performed to evaluate patients with vertigo.
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Electronystagmography with caloric testing
This test has 2 parts, namely, oculomotor testing (pursuit and saccades) and caloric testing. Eye position is monitored by using electro-oculography, which relies on the dipole of the eye. In caloric testing, the ear canals are irrigated with water or air that is 7°C above or below body temperature. The goal of the test is to determine if significant asymmetry is present in the response of the labyrinths, which can indicate peripheral vestibular disease. Evidence of CNS disorders also can be identified on electronystagmography.
The caloric test may be helpful in determining the side of the lesion; however, it has several significant limitations. First, the test has a relatively poor reliability; test-retest values change markedly in the same patient. Second, the test can be used to examine only a small portion of the balance system (ie, the lateral canals) through a small range of frequencies. Hence, results of the test may not be generalized to the entire labyrinthine function of the tested subject.
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MRI of a 26-year-old woman with progressive disequilibrium and bidirectional horizontal nystagmus shows the periventricular areas of demyelination that are characteristic of multiple sclerosis.
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MRI of a 56-year-old woman with right cerebellar ischemia. Her history included brief episodes of vertigo and a sensation of turning to the right. Her initial MRI was negative. The brief episodes were followed by prolonged episodes of vertigo, nausea and vomiting, and truncal ataxia, which prompted a second MRI study.
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MRI of a 48-year-old woman with progressive unsteadiness, projectile vomiting, and headache. She was referred for an evaluation of vertigo. Pathology proved the posterior fossa mass to be a medulloblastoma.
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MRI of a 26-year-old woman with unsteadiness and vertical nystagmus. Arrow points to an Arnold-Chiari malformation.
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Anatomy of the labyrinth.
