Hyperventilation and vertigo.

An electronystagmographic study was conducted on 19 normal subjects, in order to observe whether the subjective sensation of dizziness provoked by hyperventilation could be confirmed objectively by nystagmus. Each of them had two electronystagmograms, the first being a routine ENG and the second a repetition of the first, but with additional periods of 90 sec. of hyperventilation at certain precise pre-determined moments of the test. Hyperventilation was not shown to have significant effect on the slow phase of post caloric nystagmus; however, it increased significantly (p = 0.061) the number of positions in which nystagmus was elicited. Hyperventilation would have such an effect in producing a certain degree of cerebral hypoxia through cerebral vasoconstriction and the Bohr effect.