Histological considerations in implant patients.

The selection of patients for cochlear implantation requires consideration of a variety of anatomical and histological facts. Mechanical impediments to cochlear implantation, including the consequences of chronic otitis media, bony obliteration of the membranous labyrinth, or labyrinthitis ossificans, following bacterial labyrinthitis or vascular compromise of the inner ear, obliterative otosclerosis, and middle-ear dysplasias may present difficulties in access to the inner ear and placement of electrodes. Consideration of the histopathological features of known causes of profound deafness will help predict the presence or absence of inner ear structures essential for successful implantation. The identity of these critical structures and the histopathologic characteristics of bacterial labyrinthitis, fungal meningitis, syphilis of the inner ear, otosclerosis, presbycusis, genetically determined degenerations, trauma, intoxications, inflammatory, autoimmune and idiopathic disorders are presented in terms of their relevance for cochlear implantation.