Immunological mechanisms are considered to be among the causes of Meniere's disease. Immunological techniques have been used by many investigators to produce endolymphatic hydrops models, but these techniques have heretofore brought little success in producing models which simulate the idiopathic endolymphatic hydrops of Meniere's disease, where no inflammatory changes exist in the perilymphatic spaces. In this experiment, the immunological induction of this type of condition was attempted by injecting the antigen HRP into the endolymphatic sacs of 120 anesthetized guinea pigs which had been systematically sensitized to this antigen.
After a certain survival time, three tests were performed on these guinea pigs.
(1) Vestibular functions were checked by performing a swimming test on a group of 49 guinea pigs. A total of 20 displayed abnormal swimming pattenns ; of this number. 8 swam clockwise and 4 counterclockwise. In a group of 90 guinea pigs, only one case of spontaneous nystagmus was observed.
(2) Auditory functions were measured by electrocochleography. It was found that the action potential thresholds were elevated in guinea pigs with severe endolymphatic hydrops.
(3) After the completion of these tests histopathological studies were performed ; 78 of the 120 guinea pigs in the test group showed endolymphatic hydrops ; 75 of these displayed no inflammatory changes in the perilymphatic spaces. The endolymphatic sacs of the guinea pigs were packed with soft granulation tissue induced by the immunological mechanism; disturbances in the absorption of endolymph due to this tissue are felt to be the cause of the hydrops.
These results were compared with the histopathological findings obtained in another group of guinea pigs in which the antigen had been injected into the stylomastoid forman. A small number displayed mild endolymphatic hydrops, but considerable precipitation in the scala vestibuli was present.
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