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Updated: Jun 24, 2026
Performing Intracochlear Electrocochleography During Cochlear Implantation
Published on: March 8, 2022
Detection of bacteria in healthy middle ears during cochlear implantation
Edith L Tonnaer1, Emmanuel A Mylanus, Jef J Mulder
1Department of Otorhinolaryngology, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands. e.tonnaer@kno.umcn.nl
Insights
Bacteria, including biofilms, were found in the middle ear cavities of children undergoing cochlear implantation. This presence may explain post-operative infections, though direct contamination during surgery is unlikely.
Area of Science:
- Otolaryngology
- Microbiology
- Surgical Innovation
Background:
- The middle ear cavity is typically considered sterile in healthy individuals.
- Infectious complications can occur after cochlear implantation surgery.
- Understanding the microbial environment of the middle ear is crucial for patient safety.
Purpose of the Study:
- To investigate the presence of free-living and biofilm bacteria in the middle ear cavity prior to cochlear implant electrode insertion.
- To determine if the middle ear cavity harbors bacteria in children undergoing cochlear implantation.
Main Methods:
- Prospective study conducted at a tertiary academic hospital.
- Inclusion of 45 healthy children undergoing cochlear implantation.
- Utilized transmission electron microscopy and scanning electron microscopy to detect bacteria in middle ear mucosal biopsies.
Main Results:
- A majority of middle ear mucosal specimens showed inflammatory areas and dispersed, non-matrix-enclosed bacteria.
- Rare fragments of bacterial biofilms were identified on the epithelial surfaces.
- Clinically healthy tympanic cavities were not sterile.
Conclusions:
- The presence of bacteria in the middle ear cavity may contribute to infectious complications following cochlear implantation.
- The dispersed and limited nature of bacterial presence suggests a low likelihood of direct electrode contamination during insertion.
- This finding offers a potential explanation for post-cochlear implantation infections while also accounting for their relatively low incidence.
Objective:
To assess whether free-living and/or biofilm bacteria are present in the putative sterile middle ear cavity before insertion of the electrode array during cochlear implantation.
Design:
Prospective study.
Setting:
Tertiary academic hospital.
Patients:
The study included 45 healthy children (with or without a history of otitis media) undergoing cochlear implantation.
Interventions:
Transmission electron microscopy or scanning electron microscopy was used to detect the presence of bacteria.
Main Outcome Measure:
Presence of both free-living bacteria and biofilm bacteria on the epithelial surface of biopsy specimens of middle ear mucosa.
Results:
A majority of all mucosal specimens from clinically healthy tympanic cavities displayed inflammatory areas as well as dispersed, nonmatrix-enclosed bacteria. Also, rarely, fragments of biofilms were found.
Conclusions:
The presence of bacteria in the tympanic cavity, which is generally assumed to be sterile in healthy individuals, may provide an explanation for infectious complications after cochlear implantation. However, the possibility that the electrode array of a cochlear implant will actually become contaminated during insertion is unlikely because of the small amounts and dispersed presence of bacteria, which may account for the relatively low incidence of infectious complications after cochlear implantation.