Vestibular changes after guinea pig cytomegalovirus infection.

A guinea pig model of viral labyrinthitis was established by inoculating guinea pig cytomegalovirus into the inner ear and then determine its effect on vestibular function. Neither spontaneous nor positional nystagmus could be detected postoperatively. Nine out of 18 (50%) animals had caloric hyperfunction in the virus-inoculated ear at 1 to 3 weeks postoperatively. Five of these 9 animals also had caloric hyperfunction in the control ear. A morphological study in animals with caloric hyperfunction showed no change in the peripheral vestibular apparatus by light microscopy. It is thus assumed that caloric hyperfunction in experimental viral labyrinthitis is transient and functional.