Cochlear Implantation through the Middle Fossa Approach: A Review of Related Temporal Bone Studies and Reported Cases

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Introduction Middle fossa approach has been suggested as an alternative for patients in whom other routes of electrode insertion are contraindicated. Even though there are temporal bone studies about the feasibility of introducing the cochlear implant through the middle fossa, until now, very few studies have described results when cochlear implant surgery is done through this approach. Objective The objective of this study is to review a series of temporal bone studies related to cochlear implantation through the middle fossa and the results obtained by
different surgical groups after cochlear implantation through this approach. Data Sources PubMed, MD consult and Ovid-SP databases.

Data Synthesis A total of 8 human cadaveric temporal bone studies and 6 studies reporting cochlear implant surgery through the middle fossa approach met the inclusion criteria. Temporal bone studies show that it is feasible to perform cochlear implantation through this route. So far, only two surgical groups have performed cochlear implantation through the middle fossa with a total of 15 implanted patients.

One group entered the cochlea in the most upper part of the basal turn, inserting the implant in the direction of the middle and apical turns; meanwhile, the other group inserted the implant in the apical turn directed in a retrograde fashion to the middle and basal turns. Results obtained in both groups were similar. Conclusions Themiddle fossa approach is a good alternative for cochlear implantation when other routes of electrode insertion are contraindicated.

Cochlear implantation is an effective method for the rehabilitation of patients with severe and profound sensorineural hearing loss. The great technological advances in cochlear implants and the good auditory results obtained have widened the selection criteria for candidacy. Hence, there is great involvement from surgeons to develop different and less traumatic electrode insertion techniques. Simple mastoidectomy with a posterior tympanotomy is considered the classic route for cochlear implant surgery and it is still the most practiced technique. Other less common techniques for cochlear implantation include the suprameatal and transcanal
approaches, both offering good results. In cases of patients with chronic suppurative otitis media, unstable
mastoid cavities with recurrent otorrhea, partially ossified.