Electronystagmography in a patient with a peripheral vestibular disorder. (Vestibulology Clinic).

A 56-year-old man came to the office with a 5-year history of dizziness. His initial spells were marked by rotary vertigo accompanied by nausea, and they lasted 2 to 3 hours. Initially, the episodes had recurred at 3- to 4-month intervals, but they had now become much more frequent--in one case, three times in one day. The more recent spells were shorter and they varied in severity; rotary vertigo and nausea were still present. During the dizzy spells, the patient had difficulty keeping his balance. One year after the onset of the dizziness, the patient noted a fluctuating hearing loss in both ears; his hearing was better on the left. At about the same time, he also began to experience tinnitus in the left ear. The tinnitus was characterized by an intermittent ringing that did not correlate with the dizziness. During the 4 months prior to his visit, the tinnitus had not been present in the left ear. Aural fullness had been present in both ears for 2 years; the fullness seemed to correlate with the hearing loss. At the time of his first visit, the fullness was absent in the left ear.

The patient's family history was positive for hearing loss and tinnitus. He had difficulty performing the sharpened tandem Romberg test and he demonstrated nuchal tenderness and spasms bilaterally, more so on the right.

Audiology revealed a flat, moderate sensorineural hearing loss and impaired discrimination in the right ear. The left ear exhibited a mild low-tone and a moderate high-tone sensorineural hearing loss, a mild to moderate threshold, and excellent discrimination.

Electronystagmography revealed a direction-fixed right-beating nystagmus in all positions, but greatest in the right neck-torsion position. The alternate binaural bithermal test elicited a hypoactive warm response in the right ear; the results showed a reduced vestibular response of 53% on the right and a normal directional preponderance. The simultaneous binaural bithermal caloric test elicited a type 4 response with a left-beating nystagmus on warm caloric stimulus.

These findings were consistent with a right peripheral vestibular disorder. In this instance, the direction of the positional nystagmus would suggest a left peripheral vestibular disorder, and the simultaneous binaural bithermal test did not elicit a type 2 response. However, the left-beating nystagmus on warm-water stimulus in both ears was consistent with a right peripheral vestibular disorder.

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