Regional difference in susceptibility to damage of vestibulo-semicircular canals in experimental labyrinthine lesion.

In the study on regional difference in susceptibility to damage of vestibulo-semicircular canals upon causing labyrinthine lesion by four different procedures, namely, by intracranial approach, through the middle ear, through the facial nerve and by means of experimental endolymphatic hydrops, the following results were obtained. 1. The crista of posterior semicircular canal among the semicircular canals and the macula of the saccule within the vestibule were most susceptible to impairment. In other words, the most susceptible region was the so-called pars inferior. In regard to the impairment of the cupulas, the posterior semicircular canal was the most susceptible region. 2. Recovery from markedly reduced caloric nystagmus within a short period so as to see provocation of caloric nystagmus may result from the reconstruction of the cupulas and the normalization of vacuole-like findings of the sensory epithelium.