Histopathologic correlation of spiral ganglion cell count and new bone formation in the cochlea following meningogenic labyrinthitis and deafness.

Bacterial meningitis is a common cause of profound deafness and, hence, a common cause of deafness in published series of patients treated with a cochlear prosthesis. Labyrinthitis ossificans is a common finding in meningogenic labyrinthitis and has been considered a relative contraindication to cochlear implantation. In the present study, the numbers of remaining spiral ganglion cells in cases of meningogenic labyrinthitis were correlated with the severity of new bone formation within the inner ear. Six temporal bones in which profound sensorineural hearing loss occurred in life secondary to meningogenic labyrinthitis were studied by serial section light microscopy. Some degree of labyrinthitis ossificans was found in four of six. There was a moderately strong negative correlation between the number of years of total deafness and the percentage of normal of the remaining spiral ganglion cell count. There was a strong negative correlation between the degree of bony occlusion by labyrinthitis ossificans and the normality of the spiral ganglion cell count. The percentage of bony occlusion of the membranous labyrinth increased with the years of total deafness. The significance of these findings for cochlear implantation of individuals with meningogenic labyrinthitis is discussed.