Electrical stimulation of the auditory system in children deafened by meningitis

Twenty-five children deafened by meningitis were compared with 10 congenitally deaf children on cochlear implant performance. All subjects had met the audiologic criterion of profound deafness as required for implant surgery. Twenty subjects in the meningitis group had some degree of ossification at the round window, and drilling was required for electrode insertion into the scala tympani. In six of these subjects, bone completely filled the scala. There was a significant relationship between extensive ossification and the etiologic pathogen Diplococcus pneumoniae, as determined by radiologic and surgical reports. Postoperative results revealed that all subjects could be electrically stimulated, except for one with extensive bone formation. On implant performance, the meningitis group demonstrated sound-field thresholds comparable to those of the group with congenital deafness but required significantly higher voltage settings. These findings suggest that even with extensive labyrinthine ossification caused by meningitic deafness, neural elements are present and can be stimulated if enough power can be safely provided.