Cochlear Implant Impedance Fluctuation in Ménière's Disease: A Case Study.

OBJECTIVE

To contribute to the understanding of hearing fluctuation in Ménière's disease (MD) by disseminating a case study of a cochlear implanted ear with ongoing fluctuation of electrode impedances with episodic tinnitus and no associated vestibular symptoms.

STUDY

DESIGN

Retrospective case review.

SETTING

Tertiary referral audiology clinic.

PATIENT: Man, born in 1936, with a total hearing loss in the right ear because of Mumps at age 8 years and a fluctuating progressive hearing loss in the left ear because of Ménière's disease since age 63 years.

INTERVENTION: Sequential bilateral cochlear implantation right ear in August 2002 and left ear in March 2006.

MAIN OUTCOME MEASURE: Impedance measurements of implanted intracochlear electrodes via common ground stimulation using proprietor programming software.

RESULTS

Electrode impedances in the MD showed significant ongoing variation since implantation, whereas the contralateral non-MD ear remained stable over a period of 9 years.

CONCLUSION

Electrode impedances in the ear with MD showed a variation pattern similar to that found in the hearing fluctuation characteristic of the disease. These findings raise the possibility that the same physiological mechanisms of hearing fluctuation may be responsible for intracochlear electrode impedance changes. We hypothesize that impedance fluctuation is because of changes in the permeability of the blood-labyrinth barrier because of cyclic immune activity in the inner ear which alters the electrical resistance between scala tympani and blood.