Acoustic middle ear muscle reflexes in patients with otosclerosis.

Thirty-four ears with otosclerosis were examined with respect to presence of middle ear muscle reflexes. Nearly all ears with disease duration of less than five years exhibited typical otosclerosis reflexes of the negative-going on-off type. If symptoms had been present for more than 10 years, reflexes were totally missing. The hypothesis is proposed that the peculiar reflex pattern, which is highly specific for otosclerosis, may be due to partial fixation of the stapes foot plate at the anterior end, so that movements during a reflex become rotational around a vertical axis at the anterior edge.