Air cushion as a cause of inadequate coupling in a patient with a cochlear implant

We report the case of a woman, who was bilaterally supplied with hearing aids at the age of 12 years. 7 years later, she was provided with a cochlear implant (CI) on the right side due to progressive hearing impairment. After another 13 months, a CI was implanted also on the left side. Speech comprehension developed very well. 10 months later, the patient complained about fluctuating hearing perception with her left CI, especially after sneezing, yawning and blowing her nose. This hearing impairment could be provoked by Valsalva maneuver and was associated with an increase of electrode impedances. Pressure onto the skin above the implant led immediately decrease impedances. An integrity test of all internal and external parts of the CI did not reveal any kind of failure. Suspicion fell upon some possible air inclusion underneath the skin and above the implant case. Imaging showed that the implant was located in the rear part of the pneumatized mastoid and confirmed the hypothesis. First, non-invasive interventions were carried out, including re-programming the reference electrode from case to ring, application of a stronger magnet and compression bandages, and nasal spray for better ventilation. Since the problem remained, a revision surgery was indicated. The implant was moved in a cranial and posterior direction. One day after surgery, the CI was switched-on again. No parameters of the speech processors’ map needed to be change. The patient has not had the fluctuating hearing perception since.