Cochlear Histopathology as Observed in Two Patients With a Cochlear Implant Electrode With Positioner

Abstract

Hypothesis This study reports the cochlear histopathology of two cases who during life underwent cochlear implantation with a positioner. Background A silastic positioner introduced by the Advanced Bionics Corporation in 1999 was designed to position the electrode of the cochlear implant close to the modiolus. The positioner was recalled in the United States in July 2002 because of an apparent higher incidence of bacterial meningitis in patients in whom the positioner had been placed. Methods Four celloidin-embedded temporal bones from two patients with cochlear implants with a positioner from the temporal bone collection of the Massachusetts Eye and Ear Infirmary were included in the study. In a previous study, we reported histopathologic findings in Case 1, and in this report, we present the findings in a second case in a 94-year-old woman (Case 2), and the similarities and differences between the two cases. All four specimens were prepared for histologic study by conventional techniques and 2-D reconstruction. Results Evidence of insertion trauma was seen in all three implanted specimens. More significant trauma was found in Case 2 than Case 1 including disruption of the osseous spiral lamina and the basilar membrane. In addition, there was more new fibrous tissue and bone in Case 2 than Case 1. There was a large fluid space in all three implanted temporal bones around the electrode and positioner. Conclusion The findings seen in the two cases may help to explain the increased risk of meningitis in patients implanted with a positioner.

Macrophages in the Human Cochlea: Saviors or Predators—A Study Using Super-Resolution Immunohistochemistry

“…A representation of the possible interactions between macrophages in the human cochlea is shown in Figure 10 . The insertion of prostheses into the cochlea inflicts potential trauma to cochlear tissue ( 54 , 55 ) that could result in secondary immune responses and activate macrophage signaling. O’Malley et al ( 56 ) presented evidence of foreign body responses in the cochlea to both platinum and silicone after CI, which may be responsible for device failure ( 57 ) and electrode extrusion ( 58 ).…”

Correlation between word recognition score and intracochlear new bone and fibrous tissue after cochlear implantation in the human

“…These data support implantation of the electrode in the scala tympani in order to promote atraumatic insertion as well as to achieve a perimodiolar position. In addition, fracture of the osseous spiral lamina by traumatic insertion may promote otogenic meningitis after cochlear implantation (Wei et al, 2007; Kamakura and Nadol, 2016). The % volume of fibrous tissue was not correlated with the damage scores within the cochlea.…”