Electronystagmography: positional and caloric findings in a 71-year-old woman with dizziness.

A 71-year-old woman came to the office complaining that she had awakened with rotary vertigo 9 days earlier. Since then, she continued to experience episodes while lying down or bending over. She experienced no such problem when her head was erect. Approximately 18 months earlier, she had experienced similar dizziness along with transient hearing loss in the right ear. During her latest series of episodes, she had experienced hearing loss in the left ear, although hearing in that ear had partially returned. She also said that she had had intermittent tinnitus in both ears for several years. The tinnitus was worst in the spring and fall and since the onset of her dizziness. Aural fullness had been present in both ears for the previous 12 months.

The physical examination was remarkable only for a positive Romberg's test. Electronystagmography detected a spontaneous right-beating nystagmus. Both the alternate and the simultaneous binaural bithermal stimuli elicited a reduced vestibular response (RVR) right. The important findings in this case were the spontaneous nystagmus, which suggested a left-sided lesion, and the caloric responses, which showed a right-sided lesion.

Spontaneous nystagmus is believed to be an irritative phenomenon in which the direction of the fast phase is opposite that of the other ear. In this case, the hearing symptoms suggested a left-sided problem, while the RVR showed a right-sided lesion. Because her spontaneous pre-existing nystagmus remained unchanged regardless of position, any induced nystagmus had to be taken into consideration so that it could be corrected for.

If one is able to predict the side of an RVR on the basis of any accompanying unilateral hearing loss, then this vestibular test shows that hearing loss can occur in one ear while dizziness can originate in the other. While the side that produces symptoms is usually the hypoactive side, these findings may also be a demonstration of the vestibular equivalent of auditory recruitment, and therefore the spontaneous nystagmus would be consistent with the side of an irritative lesion. The caloric test results did reveal the mismatched vestibular information that was emanating from the inner ears, and it explained this patient's symptoms.

There is a generally held concept that vestibular function decreases with age. The velocity of the responses in this patient shows that with the simultaneous binaural warm stimulus, there was a hyperactive response.

From Neurotologic Associates, P.C., New York City.