The influence of post-meningitic obliteration and ossification of the cochlea on cochlear microphonics.

Cochlear microphonics are electrical stimulus responses of the inner ear. They are generated by mechanical displacement of the hair cells caused by acoustic stimulation and can be recorded from the cochlear promontory via a needle electrode. In individuals with post-meningitic deafness, fibrous obliteration or ossification of the cochlea may occur. The aim of the present investigation was to establish whether obliteration or ossification leads to any alteration in the extent to which cochlear microphonics can be recorded (as compared with that in patients with a fluid-filled cochlea whose deafness was not post-meningitic), as an indication of changes in the mechanical displacement of the remaining hair cells. Cochlear microphonics in 15 individuals with proven obliteration or ossification of the cochlea were compared with those in 15 control subjects (deaf individuals whose hearing loss was not post-meningitic, and who had a fluid-filled cochlea). Our findings reveal no statistically significant differences between the two groups in the degree to which cochlear microphonics can be recorded. This study does not demonstrate evidence of a change in this property due to ossification or obliteration of the cochlea.