Vestibular findings in a 69-year-old man with dizziness.

A 69-year-old man presented with a chief complaint of dizziness. Five years earlier, he had awakened in the middle of the night to go to the bathroom and had fallen over on his bed. The experience was momentary. Several weeks later, while lying supine and turning his head from the right to the left, he experienced a feeling that the room was spinning for a minute. During this time he developed "violent" headaches that had since subsided. He said his dizziness would come and go, but after 3 months these episodes had disappeared.

Three months before his office visit, his symptoms had returned. They alternated between a lightheaded feeling and a feeling of unsteadiness. He noted that his symptoms were most frequent when he arose from bed. He also experienced some intermittent feelings of "room spinning," and he complained of "bouncing objects" in his visual field. He reported no subjective hearing loss, tinnitus, or aural fullness. His family history was positive with respect to his 66-year-old sister, who had an "inner ear problem."

Clinical examination revealed only that the patient had difficulty performing the sharpened tandem Romberg's test. Electronystagmography detected no spontaneous, positional, or neck-torsion nystagmus. The alternate binaural bithermal caloric test showed no significant reduced vestibular response and a directional preponderance (DP) of 23% left. Both of these findings are within the range of normal (<30%). The simultaneous binaural bithermal caloric test elicited a type 3 response--that is, a left-beating nystagmus with both cool and warm simultaneous stimuli. This finding is the equivalent of DP, and it has no localizing value. However, one point of interest was that although the DP on altemate testing did not reach 30%, it did point to a left-beating preponderance.

These findings provide objective evidence of a vestibular system abnormality. The asynchrony of input from the vestibular periphery is seen on the simultaneous binaural bithermal caloric test. Eithermotion-induced asynchrony or processes within the vestibular system are likely to produce the pathophysiologic elements in the brainstem that would be necessary to cause this patient's symptoms.