Direction-fixed fluctuating positional nystagmus in a dizzy patient who had a drop attack.

A 59-year-old woman came to the office with a 5-year history of dizziness that came in distinct spells. Sometimes she experienced a wobbly, unsteady feeling while walking and at other times she experienced a significant loss of balance. Her spells usually lasted between 1 and 4 hours. On one occasion, she experienced a drop attack--that is, an inability to maintain an upright posture without losing consciousness. During another spell, she experienced nausea, vomiting, and diarrhea. During the previous 11 months, she had experienced an estimated 10 spells. In the 5 weeks prior to her office visit, she had experienced an attack every weekend, one of which lasted 2 days. Between these spells, she felt fine.

The patient also reported that she had been aware of a hearing loss in her left ear for the previous 5 years. The hearing loss was of gradual onset and fluctuated in intensity. She did not know if it was becoming worse or if it only became worse with the dizziness. During the previous year, she had also experienced tinnitus in the left ear during each dizzy spell. The tinnitus manifested as an intermittent whistle that disappeared when the dizziness did. She reported no aural fullness.

On physical examination, the patient had difficulty performing the sharpened tandem Romberg's test. She also had tenderness over the left nuchal area. Electronystagmography identified a strong right-beating nystagmus in all positions that was inconsistent and ranged from 8 [degrees] to 10 [degrees] per second; in the 30 [degrees] caloric position, the nystagmus ranged from 7 [degrees] per second before caloric testing to 14 [degrees] per second after caloric testing. This is a strong sign of a vestibular disorder. It is also a clue that the nystagmus velocity values seen on alternate binaural bithermal testing are only estimates, because the pre-existing nystagmus varies in velocity. Therefore, calculations of reduced vestibular response and directional preponderance are inaccurate. Consequently, the caloric stimuli during the alternate binaural bithermal test would be expected to result in a left-beating nystagmus, but it failed to do so. Similarly, the simultaneous binaural bithermal stimulus failed to induce a left-beating nystagmus. Only the ice-water caloric test in the right ear produced a left-beating nystagmus. Suppression of ocular fixation of the positional and caloric nystagmus was present. All of the foregoing findings are consistent with the presence of a peripheral vestibular disorder.

Audiometry revealed that the patient had a mild to moderate, generally flat sensorineural hearing loss in the left ear with an 80% speech discrimination. The acoustic stapedial reflexes were present, indicating that the hearing loss was cochlear in the left ear. Magnetic resonance imaging with enhancement was negative for any abnormality.

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